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Insect Pests (insect + pest)
Kinds of Insect Pests Terms modified by Insect Pests Selected AbstractsInsect Pests in Tropical ForestryAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 1 2002Article first published online: 26 FEB 200 No abstract is available for this article. [source] Insect pests and natural enemies in two varieties of quinua (Chenopodium quinoa) at Cusco, PeruJOURNAL OF APPLIED ENTOMOLOGY, Issue 6 2002E. Yįbar The quinua varieties differ, among other traits, in their content of saponins (secondary metabolites associated to plant resistance) late in the season. Whereas Agromyzidae and Cicadellidae were abundant only in the early season, both Chrysomelidae and Aphididae populations showed fluctuations. Likewise, Araneae and Braconidae showed fluctuating numbers during the season. The abundance of Coccinellidae peaked at mid-season whereas that of Syrphidae was high only in the late season. Although the overall abundance of insects was very similar in both varieties of quinua, there were different patterns depending on the season. In the early season there was a tendency towards greater insect numbers on Blanca, but in contrast, in the late season Amarilla (the high-saponin variety) had a higher load of insect pests. This suggests that saponins do not play a major role in quinua resistance against insects. In the early season, no significant relationship between pests and natural enemies held across quinua varieties. In the late season, Aphididae and Coccinellidae were negatively and significantly correlated in both varieties. The temporal population dynamics of Aphididae and both Coccinellidae and Braconidae resembled the traditional predator,prey dynamics. [source] Choosing natural enemies for conservation biological control: use of the prey detectability half-life to rank key predators of Colorado potato beetleENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2010Matthew H. Greenstone Abstract Determining relative strengths of trophic links is critical for ranking predators for conservation biological control. Molecular gut-content analysis enables ranking by incidence of prey remains in the gut, but differential digestive rates bias such rankings toward predators with slower rates. This bias can be reduced by indexing each predator's half-life to that of the middle-most half-life in a predator complex. We demonstrate this with data from key species in the predator complex of Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), comprising adults and immatures of four taxonomically diverse species. These animals display order-of-magnitude variation in detectability half-life for the cytochrome oxidase I DNA sequence of a single CPB egg: from 7.0 h in larval Coleomegilla maculata (DeGeer) (Coleoptera: Coccinellidae) to 84.4 h in nymphal Perillus bioculatus (Fabricius) (Hemiptera: Pentatomidae). The raw species-specific incidence of L. decemlineata DNA in the guts of 351 field-collected predators ranged from 11 to 95%, ranking them as follows: C. maculata adults < Lebia grandis Hentz (Coleoptera: Carabidae) adults < Podisus maculiventris (Say) (Hemiptera: Pentatomidae) adults < P. maculiventris nymphs < P. bioculatus adults < P. bioculatus nymphs. Half-life adjustment reorders the rankings: C. maculata adults < P. bioculatus adults < P. bioculatus nymphs < P. maculiventris nymphs < L. grandis adults < P. maculiventris adults. These changes in status demonstrate the value of half-life-adjusted molecular gut-content data for ranking predators. This is the first study to measure prey detectability half-lives for the key arthropod predators of a major insect pest, and to use them to evaluate the relative impact of all adults and immatures in this predator complex. [source] Naturally occurring egg parasitoids of the genus Trichogramma (Hymenoptera: Trichogrammatidae) in a pomegranate orchard in TunisiaENTOMOLOGICAL SCIENCE, Issue 1 2010Ines KSENTINI Abstract Four Trichogramma species were found in a pomegranate orchard in Gabčs, an arid region of Tunisia, from parasitized eggs of Ectomyelois ceratoniae Zeller (Lepidoptera: Pyralidae), an economically important insect pest. Identification based on assessment of male genitalia and internal transcribed spacer 2 (ITS2) sequences showed that they were T. bourarachae Pintureau and Babault, 1988, T. oleae Voegelé and Pointel, 1979, T. cacoeciae Marchal, 1927 and T. evanescens Westwood, 1833. Trichogramma evanescens is reported for the first time in Tunisia. Trichogramma cacoeciae was the largely dominant species in the analyzed samples, whereas T. bourarachae was present in a minor portion of 1.38%. The implications of these results for attempts at controlling E. ceratoniae are discussed. [source] Pharmacological characterization of cis -nitromethylene neonicotinoids in relation to imidacloprid binding sites in the brown planthopper, Nilaparvata lugensINSECT MOLECULAR BIOLOGY, Issue 1 2010X. Xu Abstract Neonicotinoid insecticides, such as imidacloprid, are selective agonists of the insect nicotinic acetylcholine receptors (nAChRs) and extensively used in areas of crop protection and animal health to control a variety of insect pest species. Here we describe that two cis -nitromethylene neonicotinoids (IPPA152002 and IPPA152004), recently synthesized in our laboratory, discriminated between the high and low affinity imidacloprid binding sites in the brown planthopper, Nilaparvata lugens, a major insect pest of rice crops in many parts of Asia. [3H]imidacloprid has two binding sites with different affinities (Kd value of 0.0035 ± 0.0006 nM for the high-affinity site and 1.47 ± 0.22 nM for the low-affinity site). Although the cis -nitromethylene neonicotinoids showed low displacement ability (Ki values of 0.15 ± 0.03 µM and 0.42 ± 0.07 µM for IPPA152002 and IPPA152004, respectively) against [3H]imidacloprid binding, low concentrations (0.01 µM) of IPPA152002 completely inhibited [3H]imidacloprid binding at its high-affinity site. In Xenopus oocytes co-injected with cRNA encoding Nl,1 and rat ,2 subunits, obvious inward currents were detected in response to applications of IPPA152002 and IPPA152004, although the agonist potency is reduced to that of imidacloprid. The previously identified Y151S mutation in Nl,1 showed significant effects on the agonist potency of IPPA152002 and IPPA152004, such as a 75.8% and 70.6% reduction in Imax, and a 2.4- and 2.1-fold increase in EC50. This data clearly shows that the two newly described cis -nitromethylene neonicotinoids act on insect nAChRs and like imidacloprid, discriminated between high and low affinity binding sites in N. lugens native nAChRs. These compounds may be useful tools to further elucidate the pharmacology and nature of neonicotinoid binding sites. [source] Efficacy of an esfenvalerate plus methoprene aerosol for the control of eggs and fifth instars of Plodia interpunctella (Lepidoptera: Pyralidae)INSECT SCIENCE, Issue 1 2010Emily A. Jenson Abstract, Aerosol insecticides may provide an alternative to fumigants for control of the Indianmeal moth, Plodia interpunctella (Hübner), the Indianmeal moth, a major insect pest of stored processed food. In this study, eggs and larvae (5th instars) of P. interpunctella were exposed to aerosol applications of the pyrethroid esfenvalerate and insect growth regulator methoprene, alone and in combination, in open and obstructed positions inside small sheds. When larvae were exposed to methoprene alone, adult emergence from those exposed larvae was 7.1%± 1.5%. In contrast, adult emergence was 92.5%± 3.5% when larvae were exposed to esfenvalerate alone. When eggs were exposed to methoprene, adult emergence of those exposed eggs was approximately 75%; however, when eggs were exposed to esfenvalerate, adult emergence was approximately 35%. In the combination treatment of methoprene plus esfenvalerate at their respective label rates, adult emergence following larval exposure was 0.91%± 0.61% compared to 16.3%± 9.6% when eggs were exposed. Based on our results, methoprene alone is highly effective in reducing adult emergence after larval exposure. However, it is not as effective on eggs as esfenvalerate. A combination treatment of esfenvalerate plus methoprene could be used to control eggs and the wandering-phase larval stages of P. interpunctella. An economic risk analysis also supports a strategy of combining methoprene and esfenvalerate. [source] The seasonal abundance of blowflies infesting drying fish in south-west IndiaJOURNAL OF APPLIED ECOLOGY, Issue 2 2001R. Wall Summary 1Blowfly infestation of sun-drying fish is a major economic problem in many developing countries of Asia, Africa and the Pacific. To consider the ecology of infestation, adult and larval blowfly populations were monitored between 27 October 1997 and 27 April 1999 at a fish landing and drying site, approximately 5 km north of Calicut, in Kerala state on the coast of south-west India. 2During the 548-day sampling period, a total of 96 953 adult Diptera was collected from 16 sticky targets, placed inside and outside eight fish-storage sheds. Of these, 91 912 (95%) were Chrysomya megacephala, 3719 (4%) were other Calliphoridae and 1322 (1%) were other species, largely Sarcophagidae. 3The population of C. megacephala showed pronounced seasonal fluctuations in response to climate, particularly relative humidity. Significantly shorter-frequency fluctuations within fish-processing sheds were also evident, the periodicity of which corresponded approximately to C. megacephala generation cycles. Spatial variation in C. megacephala abundance was evident within the site, higher populations occurring closest to the beach and numbers declining with distance inland. 4The pattern of drying fish infestation by C. megacephala broadly followed changes in the density of adult flies and the seasonal change in weather, with peaks during the monsoon and troughs in the dry hot periods. High relative humidity played a significant but secondary role in increasing infestation. 5Quantification of the relationship between larval infestation and percentage fish loss suggests that, given the infestation levels observed, between 10% and 60% post-harvest wet weight losses would be expected in the monsoon period, depending on the species of fish landed. 6The study emphasizes the importance of developing a clear understanding of the basic ecology and spatial and temporal dynamics of an insect pest, prior to the design or implementation of any pest management programme. [source] The fruit fly PUB: a phagostimulation unit bioassay system to quantitatively measure ingestion of baits by individual fliesJOURNAL OF APPLIED ENTOMOLOGY, Issue 9-10 2004D. Nestel Abstract:, A bioassay to investigate quantitative phagostimulation and ingestion physiology of baits on individual fruit flies is presented. The study was undertaken using two fruit fly species: the Mediterranean fruit fly (Ceratitis capitata), a cosmopolitan insect pest, and the Ethiopian fruit fly (Dacus ciliatus), a quarantine insect in Israel. Our model bait suspension included spinosad as the toxic agent, and 1% yeast hydrolysate with 10% sucrose as phagostimulant. A preliminary toxicology study showed that the two fruit flies are highly sensitive to low concentrations of spinosad baited with this phagostimulant. The maximum concentration needed to kill 90% of the female flies was 4.2 and 8.5 p.p.m. for C. capitata and D. ciliatus, respectively. The bioassay was able to detect the ingestion of low volumes (e.g. 1 ,l) of tested solutions. The bioassay was also able to detect differences in intake of different concentrations of spinosad solutions and relate ingestion to fruit fly mortality. Additionally, the bioassay was sensitive enough to highlight differences in intake related to the physiological status of the fruit fly and fly species. The bioassay can also be used to follow ingestion kinetics of baits. We expect that this bioassay will contribute in the exploration of more efficient bait systems for fruit flies. [source] Host,parasitoid population density prediction using artificial neural networks: diamondback moth and its natural enemiesAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 3 2010Henri E. Z. Tonnang 1An integrated pest management (IPM) system incorporating the introduction and field release of Diadegma semiclausum (Hellén), a parasitoid of diamondback moth (DBM) Plutella xylostella (L.), comprising the worst insect pest of the cabbage family, has been developed in Kenya to replace the pesticides-only approach. 2Mathematical modelling using differential equations has been used in theoretical studies of host,parasitoid systems. Although, this method helps in gaining an understanding of the system's dynamics, it is generally less accurate when used for prediction. The artificial neural network (ANN) approach was therefore chosen to aid prediction. 3The ANN methodology was applied to predict the population density of the DBM and D. semiclausum, its larval parasitoid. Two data sets, each from different release areas in the Kenya highlands, and both collected during a 3-year period after the release of the parasitoid, were used in the present study. Two ANN models were developed using these data. 4The ANN approach gave satisfactory results for DBM and for D. semiclausum. Sensitivity analysis suggested that pest populations may be naturally controlled by rainfall. 5The ANN provides a powerful tool for predicting host,parasitoid population densities and made few assumptions on the field data. The approach allowed the use of data collected at any appropriate scale of the system, bypassing the assumptions and uncertainties that could have occurred when parameters are imported from other systems. The methodology can be explored with respect to the development of tools for monitoring and forecasting the population densities of a pest and its natural enemies. In addition, the model can be used to evaluate the relative effectiveness of the natural enemies and to investigate augmentative biological control strategies. [source] Dispersal of the emerald ash borer, Agrilus planipennis, in newly-colonized sitesAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 4 2009Rodrigo J. Mercader Abstract 1Emerald ash borer Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is an invasive forest insect pest threatening more than 8 billion ash (Fraxinus spp.) trees in North America. Development of effective survey methods and strategies to slow the spread of A. planipennis requires an understanding of dispersal, particularly in recently established satellite populations. 2We assessed the dispersal of A. planipennis beetles over a single generation at two sites by intensively sampling ash trees at known distances from infested ash logs, the point source of the infestations. Larval density was recorded from more than 100 trees at each site. 3Density of A. planipennis larvae by distance for one site was fit to the Ricker function, inverse power function, and the negative exponential function using a maximum likelihood approach. The prediction of the best model, a negative exponential function, was compared with the results from both sites. 4The present study demonstrates that larval densities rapidly declined with distance, and that most larvae (88.9 and 90.3%) were on trees within 100 m of the emergence point of the adults at each site. The larval distribution pattern observed at both sites was adequately described by the negative exponential function. [source] Western corn rootworm (Diabrotica virgifera virgifera LeConte) population dynamicsAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2009Lance J. Meinke Abstract 1,The western corn rootworm Diabrotica virgifera virgifera LeConte is a major insect pest of field maize, Zea mays L. Larvae can cause substantial injury by feeding on maize roots. Larval feeding may destroy individual roots or root nodes, and reduce plant growth, stability, and yield. Costs associated with managing corn rootworms in continuous maize are annually one of the largest expenditures for insect management in the United States Corn Belt. 2,Even though D. virgifera virgifera has been studied intensively for over 50 years, there is renewed interest in the biology, ecology, and genetics of this species because of its ability to rapidly adapt to management tactics, and its aggressive invasive nature. 3,This article provides a comprehensive review of D. virgifera virgifera population dynamics, specifically: diapause, larval and adult development, seasonality, spatial and temporal dynamics at local and landscape scales, invasiveness in North America and Europe, and non-trophic interactions with other arthropods. 4,Gaps in current knowledge are identified and discussed especially within the context of challenges that scientists in North America and Europe are currently facing regarding pest dynamics and the need to develop appropriate management strategies for each geographic area. [source] Green peach aphid, Myzus persicae (Hemiptera: Aphididae), reproduction during exposure to sublethal concentrations of imidacloprid and azadirachtinPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 2 2009G Christopher Cutler Abstract BACKGROUND: Resurgence of insect pests following insecticide applications is often attributed to natural enemy disturbance, but hormesis could be an alternative or additional mechanism. Green peach aphid, Myzus persicae (Sulzer), is an important insect pest of many crops worldwide that may be exposed to sublethal insecticide concentrations over time. Here, the hypothesis that exposure to low concentrations of imidacloprid and azadirachtin can induce hormetic responses in M. persicae is tested in the laboratory. RESULTS: When insects were exposed to potato leaf discs dipped in sublethal concentrations of insecticide, almost all measured endpoints,adult longevity, F1 production, F1 survival and F2 production,were affected, and a statistically significant (P < 0.05) stimulatory response was recorded for F2 production following exposure to imidacloprid. No other measures for hormesis were statistically significant, but other trends of hormetic response were consistently observed. CONCLUSIONS: Given that variable distribution and degradation of insecticides in the field would result in a wide range of concentrations over time and space, these laboratory experiments suggest that exposure to sublethal concentrations of imidacloprid and azadirachtin could stimulate reproduction in M. persicae. Copyright © 2008 Society of Chemical Industry [source] Risk assessment of thiacloprid and its chemical decontamination on eggplant, Solanum melongena L.PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 2 2009Jayakrishnan Saimandir Abstract BACKGROUND: Thiacloprid [(Z)-3-(6-chloro-3-pyridylmethyl)-1,3-thiazolidin-2-ylidenecyanamide; CalypsoŌ] is a systemic insecticide having persistence in the plant system. It was chosen for the management of the eggplant shoot and fruit borer, Leucinodes orbonalis Guen. Management of this insect pest is difficult because it harbours inside the shoot and fruit portions of eggplant. The persistence of thiacloprid on eggplant has not been studied in India. The Food and Agriculture Organisation (FAO) has proposed its maximum residue limit (MRL) on eggplant as 0.7 mg kg,1, and there is a need to validate this value. Since residues were found to be above this level, five different decontamination agents were tested for the decontamination of thiacloprid from eggplant. RESULTS: The half-life of thiacloprid was 11.1 and 11.6 days from trials in 2 years. Safety factors such as theoretical maximum daily intake (TMDI) and maximum permissible intake (MPI) were used to arrive at a risk assessment to human health from the analytical data obtained from the field trials. Thiacloprid at the doses tested (30 and 60 g AI ha,1) was not effective in managing eggplant fruit borer. A waiting period of 3 days before harvest of the fruits after insecticide application and a processing factor (PF) could not ensure a sufficient margin of safety (MOS). Subjecting the data to a processing factor of 60% could not bring the residues below the proposed MRL. CONCLUSION: Thiacloprid is not found to be an appropriate and effective agent for application to eggplant. Either the proposed MRL needs to be revised or good agricultural practice involving thiacloprid for plant protection in eggplant cultivation is required. Copyright © 2008 Society of Chemical Industry [source] Floral attractants for the female soybean looper, Thysanoplusia orichalcea (Lepidoptera: Noctuidae)PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 12 2008Lloyd D Stringer Abstract BACKGROUND: The soybean looper, Thysanoplusia orichalcea (F.), is a polyphagous insect pest of vegetable crops. Indonesian in origin, it has spread to Europe, India, Africa, Australia and New Zealand. The identification of an attractant for female T. orichalcea could enable the development of alternative pest management strategies to those provided by insecticides or sex pheromones, which are often only attractive to males. RESULTS: Traps baited with synthetic lures derived from Canada thistle, Cirsium arvense (L.) Scop., floral volatiles attracted female T. orichalcea. Phenylacetaldehyde, a floral compound attractive to many Lepidoptera and present in C. arvense, was tested alone as an attractant for the soybean looper and caught significantly more female than male T. orichalcea. Trap catch was greatest when phenylacetaldehyde was combined with five prevalent volatiles present in C. arvense headspace collections: 2-phenylethyl alcohol, methyl salicylate, dimethyl salicylate, benzaldehyde and benzyl alcohol. Twice as many female moths as males were collected. CONCLUSION: Successful trapping of female T. orichalcea in either a lure-and-kill or a mass trapping system may offer an effective way to manage its population size. Copyright © 2008 Society of Chemical Industry [source] Toxicity of insecticides to the sweetpotato whitefly (Hemiptera: Aleyrodidae) and its natural enemiesPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 7 2007Leandro Bacci Abstract Efficient chemical control is achieved when insecticides are active against insect pests and safe to natural enemies. In this study, the toxicity of 17 insecticides to the sweetpotato whitefly, Bemisia tabaci (Gennadius), and the selectivity of seven insecticides to natural enemies of this insect pest were evaluated. To determine the insecticide toxicity, B. tabaci adults were exposed to abamectin, acephate, acetamiprid, cartap, imidacloprid, malathion, methamidophos, bifenthrin, cypermethrin, deltamethrin, esfenvalerate, fenitrothion, fenpropathrin, fenthion, phenthoate, permethrin and trichlorphon at 50 and 100% of the field rate (FR), and to water (untreated control). To determine the insecticide selectivity, adults of Encarsia sp., Acanthinus sp., Discodon sp. and Lasiochilus sp. were exposed to abamectin, acephate, acetamiprid, cartap, imidacloprid, malathion and methamidophos at 50 and 100% FR, and to water. Groups of each insect species were exposed to kale leaves preimmersed in each treatment under laboratory conditions. Mortality of exposed individuals was recorded 24 h after treatment. Cartap and imidacloprid at 50 and 100% FR and abamectin and acetamiprid at 100% FR showed insecticidal activity to B. tabaci adults. Abamectin at 50 and 100% FR was the least insecticidal compound to the natural enemies Acanthinus sp., Discodon sp. and Lasiochilus sp. The present results suggest that abamectin at 100% FR may decrease B. tabaci field populations but can still be harmless to predators. Implications of these results within an integrated pest management context are discussed. Copyright © 2007 Society of Chemical Industry [source] Activity of Bacillus thuringiensis toxins against cocoa pod borer larvaePEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 8 2004Djoko Santoso Abstract Twelve Cry proteins from Bacillus thuringiensis Berliner were tested in bioassays on cacao plantations in Indonesia for activity against the larvae of cocoa pod borer (Conopomorpha cramerella (Snellen)), an insect pest of the cacao tree. Through the damage caused by their feeding, the larvae of cocoa pod borer cause the pods of the cocoa tree to ripen prematurely. They are difficult to control with conventional measures. Preliminary assays identified five toxins that were more active than others. In two subsequent bioassays the activity of selected toxins was determined more accurately. Three Cry1 proteins with relatively little homology were all found to be toxic, opening perspectives for controlling cocoa pod borer by expression of Cry proteins in transgenic plants. Copyright © 2004 Society of Chemical Industry [source] Effects of Crude and Partially Purified Extracts from UV-B,irradiated Rice Leaves on Helicoverpa armigera (Hübner),PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2005Merdelyn T. Caasi-Lit ABSTRACT The effect of crude and partially purified extracts from ultraviolet-B (UV-B),irradiated rice (Oryza sativa L.) leaves on the growth and development of corn earworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), was investigated. Fifty ,L droplets of a liquid diet containing different concentrations of the crude and partially purified extracts were fed to H. armigera neonates to determine possible short-term toxicity effects. A choice test using a solid artificial diet was also performed to determine larval feeding preferences and antifeedant effects. To study effects on the life history of the insect, different concentrations of the crude and partially purified extracts were also incorporated in the artificial diet and fed to individually confined neonates of H. armigera. The neonates were reared up to the adult stage. Results showed that crude and partially purified extracts of UV-B,irradiated rice leaves demonstrated antifeedant, growth-inhibitory and antibiotic properties against H. armigera. At high concentrations, the extract initially stimulated larval feeding; however, there were subsequent negative effects on pupal and adult traits, thereby reducing the reproductive potential of adults. These partially purified extracts appeared to have an antifertility effect because adults laid fewer eggs and, of those eggs laid, viability was lower. These results suggest that the accumulated flavonoids or other phenolics in UV-B,irradiated leaves, extracted from UV-B,resistant rice cultivar ,M202,' affected the growth, development and reproduction of H. armigera, a polyphagous insect pest. [source] Pest reduction services by birds in shade and sun coffee in JamaicaANIMAL CONSERVATION, Issue 2 2010M. D. Johnson Abstract The reduction of insect pests by birds in agriculture may provide an incentive for farming practices that enhance the conservation value of farms for birds and other wildlife. We investigated pest reduction services by insectivorous birds on a coffee farm in Jamaica, West Indies. Our results suggest that birds reduced insect pests on our study site. Infestation by the coffee berry borer Hypothenemus hampei, the world's most damaging insect pest in coffee, was significantly elevated on coffee shrubs from which birds were experimentally excluded from foraging. Overall, we estimated the economic value of the reduction of coffee berry borer by birds on the 18 ha farm to be US$310 ha,1 for the 2006 harvest season. These results provide additional evidence that birds can reduce numbers of economically damaging pests and enhance crop yields in coffee farms. Differences in the magnitude of pest reduction within the farm may have resulted from variation in shade management and surrounding habitats, and these factors merit further investigation. [source] The impact of irrigation frequency on population density of thrips, Thrips tabaci Rom (Thripidae, Thysanoptera) and yield of onion in E1 Rahad, SudanANNALS OF APPLIED BIOLOGY, Issue 2 2001H O KANNAN Summary Vegetable farmers of the El Rahad Scheme (a newly developed scheme situated between latitude 13°31,,14°25, north and longitude 33°31,34°32, east) used to extend irrigation frequency for onion production as they believed it would hamper and suppress thrips incidence. Thrips, T. tabaci, is the only major insect pest of onion in the El Rahad Scheme and the influence of irrigation intervals on the population density of the pest and on onion yield was not quantified. Irrigation is a factor in the development of crop pests and the levels of the pest population are related to the commencement of irrigation. The effect of irrigation frequency on the development of onion thrips and yield was investigated and the response was found to be a significant increase in the population density of the pests from February to March with shorter irrigation frequency. A steady increase of thrips population was noted from February and March and a sharp decline was recorded in April during both the 1992/93 and 1993/94 seasons. At wider irrigation intervals, levels of the pest population were significantly less from February to March during both seasons. Total bulb yield and average bulb weight were significantly higher at shorter irrigation frequencies when compared with extended frequencies. The same pattern of results existed throughout the course of the experiment. [source] Molecular characterization of mariner -like elements in emerald ash borer, Agrilus planipennis (Coleoptera, Polyphaga)ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 4 2010L. Rivera-Vega Abstract Emerald ash borer (EAB, Agrilus planipennis), an exotic invasive pest, has killed millions of ash trees (Fraxinus spp.) in North America and continues to threaten the very survival of the entire Fraxinus genus. Despite its high-impact status, to date very little knowledge exists for this devastating insect pest at the molecular level. Mariner-like elements (MLEs) are transposable elements, which are ubiquitous in occurrence in insects and other invertebrates. Because of their low specificity and broad host range, they can be used for epitope-tagging, gene mapping, and in vitro mutagenesis. The majority of the known MLEs are inactive due to in-frame shifts and stop codons within the open reading frame (ORF). We report on the cloning and characterization of two MLEs in A. planipennis genome (Apmar1 and Apmar2). Southern analysis indicated a very high copy number for Apmar1 and a moderate copy number for Apmar2. Phylogenetic analysis revealed that both elements belong to the irritans subfamily. Based on the high copy number for Apmar1, the full-length sequence was obtained using degenerate primers designed to the inverted terminal repeat (ITR) sequences of irritans MLEs. The recovered nucleotide sequence for Apmar1 consisted of 1,292 bases with perfect ITRs, and an ORF of 1,050 bases encoding a putative transposase of 349 amino acids. The deduced amino acid sequence of Apmar1 contained the conserved regions of mariner transposases including WVPHEL and YSPDLAP, and the D,D(34)D motif. Both Apmar1 and Apmar2 could represent useful genetic tools and provide insights on EAB adaptation. © 2010 Wiley Periodicals, Inc. [source] Multiple cryptic genetic units in Hypothenemus hampei (Coleoptera: Scolytinae): evidence from microsatellite and mitochondrial DNA sequence dataBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2010NATHALIE GAUTHIER Hypothenemus hampei is the most important insect pest of coffee and has spread to most coffee-growing countries worldwide. There have been very few studies and none have addressed the population genetics of the beetle using microsatellite markers. In the present study, 683 individuals collected from 37 locations in 18 countries worldwide were screened at nine polymorphic microsatellite loci. Sixty-five out the 683 and six additional individuals were analyzed on a 400-bp fragment of the mitochondrial cytochrome oxidase I gene. Bayesian clustering analysis and phylogenetic approaches were used to infer the genetic structure of H. hampei over the sampling that encompassed almost all its range. Microsatellite markers made it possible to achieve sufficiently significant power for the delineation of five morphocryptic evolutionary units. Supported by 27 new COI haplotypes, an unexpected considerably high level of genetic differentiation and genetic divergence was revealed between five geographically delineated clusters. Both markers and approaches showed that the clusters included specimens from (1) Ethiopia, (2) Kenya and Uganda, (3) Brazil, (4) Central America excluding Jamaica, and (5) all samples from Asia, West Africa, and Jamaica. These findings clearly suggest the existence of a ,species complex in H. hampei'. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 113,129. [source] Seasonal variation in the migration strategies of the green lacewing Chrysoperla carnea species complexECOLOGICAL ENTOMOLOGY, Issue 4 2006JASON W. CHAPMAN Abstract 1. Insect migration strategies are generally poorly understood due to the propensity for high-altitude flight of many insect species, and the technical difficulties associated with observing these movements. While some progress has been made in the study of the migration of important insect pests, the migration strategies of insect natural enemies are often unknown. 2. Suction trapping, radar monitoring, and high-altitude aerial netting were used to characterise the seasonal migrations in the U.K. of an assemblage of aphid predators: three green lacewings in the Chrysoperla carnea species complex. 3. Chrysoperla carnea sens. str. was found to be very abundant at high altitudes during their summer migration, and some individuals were capable of migrating distances of , 300 km during their pre-ovipositional period. In contrast, high-altitude flights were absent in the autumn migration period, probably due to a behavioural adaptation that increases the probability that migrants will encounter their over-wintering sites. The other two species in the complex, C. lucasina and C. pallida, were much rarer, making up , 3% of the total airborne populations throughout the study period. 4. The summer migration of C. carnea sens. str. was not directly temporally associated with the summer migration of its cereal aphid prey, but lagged behind by about 4 weeks. There was also no evidence of spatial association between aphid and lacewing populations. 5. The results show that to understand the population ecology of highly mobile insect species, it is necessary to characterise fully all aspects of their migration behaviour, including the role of high-altitude flights. [source] Parasitism by the mite Trombidium breei on four U.K. butterfly speciesECOLOGICAL ENTOMOLOGY, Issue 6 2002L. Conradt Abstract 1. The incidence of parasitism by larvae of the mite species Trombidium breei was reported in one population of the lycaenid butterfly Polyommatus icarus, four populations of the satyrine butterfly Maniola jurtina, one population of the satyrine butterfly Aphantopus hyperanthus, and two populations of the satyrine butterfly Pyronia tithonus, as well as on one specimen of the dipteran Alophorus hemiptera. A considerable proportion of butterflies (11-50%) was infested in all study populations. 2. The pattern of infestation was examined in detail in M. jurtina. Males had a significantly higher incidence of infestation than females, and middle-aged butterflies had a higher incidence of infestation than old or young butterflies. The incidence of infestation peaked in the middle of the flight season, and this seasonal effect was independent of the effect of butterfly age. 3. Using a model based on capture-recapture data, it was estimated that a hypothetical ideal male M. jurtina that lives exactly the mean expected lifespan of 9-10 days has an approximately 75% chance of becoming infested with mites at least once during its lifetime, a mean time to first infestation of 3-4 days, and an average infestation persistence time of 2-3 days. 4. Capture-recapture data failed to show any effect of mite infestation on the lifespan or within-habitat movement rate of M. jurtina. 5. In experiments in which individual butterflies were taken out of their normal habitat and released, M. jurtina and P. tithonus that were infested with mite larvae did not differ from uninfested individuals in the efficiency with which they returned to suitable habitat. Thus, parasitism by T. breei larvae had no detectable effects on flight performance or orientation ability. 6. The results suggest that trombidiid mite larvae have limited potential in the biological control of insect pests. [source] Mortality dynamics and population regulation in Bemisia tabaciENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2005Steven E. Naranjo Abstract Natural mortality is an important determinant of the population dynamics of a species, and an understanding of mortality forces should aid in the development of better management strategies for insect pests. An in situ, observational method was used to construct cohort-based life tables for Bemisia tabaci (Gennadius) Biotype B (Homoptera: Aleyrodidae) over 14 generations on cotton in central Arizona, USA, from 1997 to 1999. In descending order, median marginal rates of mortality were highest for predation, dislodgment, unknown causes, egg inviability, and parasitism. The highest mortality occurred during the 4th nymphal stadium, and the median rate of immature survival over 14 generations was 6.6%. Predation during the 4th nymphal stadium was the primary key factor. Irreplaceable mortality was highest for predation and dislodgment, with the absence of these mortality factors leading to the greatest increases in estimated net reproduction. There was little evidence of direct or delayed density-dependence for any mortality factor. Wind, rainfall, and predator densities were associated with dislodgment, and rates of predation were related to densities of Geocoris spp., Orius tristicolor (White), Chrysoperla carnea s.l. Stephens, and Lygus hesperus Knight. Simulations suggest that immigration and emigration play important roles in site-specific dynamics by explaining departures from observed population trajectories based solely on endogenous reproduction and mortality. By a direct measurement of these mortality factors and indirect evidence of adult movement, we conclude that efficient pest management may be best accomplished by fostering greater mortality during the 4th stadium, largely through a conservation of predators and by managing immigrating adult populations at their sources. [source] Regulatory impact on insect biotechnology and pest managementENTOMOLOGICAL RESEARCH, Issue 4 2007Chris A. WOZNIAK Abstract The application of insect biotechnology is promising for the development of environmentally compatible pest management solutions. As we have refined and enhanced genetic engineering techniques in several insect species that cause significant economic loss and public health injury, it has become clear that insect biotechnology will move forward as one of the key tools of pest management in agriculture and in the human environment. Well characterized genetic elements can be manipulated toward specific aims and maintain a viable insect, albeit one with diminished capacity to exchange genetic material, vector a virus or bacterium, or complete its life cycle. Despite this degree of knowledge and precision, there remain unanswered questions regarding environmental fate, release and public acceptance of this technology. The uncertainty surrounding any novel technology inevitably increases the level of regulatory scrutiny associated with its use. Although the term "insect biotechnology" has many connotations, it certainly includes the genetic modification of symbiotic or commensally associated microbes as a means of delivering a trait (e.g. a toxin) to manage plant and human diseases and insect pests. The distinction between this paratransgenic approach and direct genetic modification of insect pests is an important one biologically as well as from a regulatory standpoint. The regulatory framework for microbial applications to agriculture is in many instances in place; however, we must strive to forge the development of guidelines and regulations that will foster deployment of insect biotechnologies. [source] Insecticides with novel modes of action: Mechanism, selectivity and cross-resistanceENTOMOLOGICAL RESEARCH, Issue 3 2007Isaac ISHAAYA Abstract Efforts have been made during the past two decades to develop insecticides with selective properties that act specifically on biochemical sites present in particular insect groups, but whose properties differ from other insecticides. This approach has led to the discovery of compounds that affect the hormonal regulation of molting and developmental processes in insects; for example, ecdysone agonists, juvenile hormone mimics and chitin synthesis inhibitors. In addition, compounds that selectively interact with the insect nicotinic acetylcholine receptor, such as imidacloprid, acetamiprid and thiamethoxam, have been introduced for the control of aphids, whiteflies and other insect species. Natural products acting selectively on insect pests, such as avermectins, spinosad and azadirachtin, have been introduced for controlling selected groups of insect pests. Compounds acting on the nervous site that controls the sucking pump of aphids and whiteflies, such as pymetrozine, or respiration, such as diafenthiuron, have been introduced for controlling sucking pests. All the above compounds are important components in pest and resistance management programs. [source] Susceptibility of black fly larvae (Diptera: Simuliidae) to lawn-care insecticides individually and as mixturesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2003Jay P. Overmyer Abstract Urban and suburban watersheds have the potential to be highly impacted by chemicals, especially insecticides to control insect pests on lawns, ornamental plants, and home gardens. Three of the most common lawn-care insecticides detected in urban watersheds, carbaryl, chlorpyrifos, and malathion, have been evaluated using an acute orbital shaker toxicity test to determine their respective concentrations that produce 50% mortality (LC50) in Simulium vittatum Zetterstedt cytospecies IS-7 larvae. Results of the 48-h LC50 tests show chlorpyrifos to be the most toxic to black fly larvae (LC50 = 0.28 ,g/L) followed by carbaryl (LC50 = 23.72 ,g/L) and malathion (LC50 = 54.20 ,g/L). These insecticides were also tested as binary and ternary mixtures using the toxic unit (TU) approach. Toxicity was shown to be greater than additive for the ternary mixture of chlorpyrifos,carbaryl,malathion (LC50 = 0.56 TU) and the binary mixtures of chlorpyrifos,malathion (LC50 = 0.72 TU) and carbaryl-malathion (LC50 = 0.78 TU). The binary combination of chlorpyrifos and carbaryl was shown to be additive (LC50 = 0.98 TU). These results indicate that aquatic invertebrate populations in urban and suburban streams may experience a higher-than-expected increase in toxicity-related effects when all three chemicals are present in the waterway. [source] Vegetative growth and development of irrigated forage turnip (Brassica rapa var. rapa)GRASS & FORAGE SCIENCE, Issue 4 2008J. E. Neilsen Abstract Field and greenhouse experiments were conducted to identify visual markers and predictors of changes in the vegetative growth rate of forage turnip (Brassica rapa var. rapa) as a potential tool to improve the timing of inputs of N and irrigation to periods of maximum demand. The onset of root expansion, which was associated with a colour change and the death of cotyledons, was identified as a critical marker for the beginning of the rapid growth of the crop and the accumulation of starch in the storage root but indicators of subsequent changes in vegetative growth rate were not identifiable. The results suggested that management inputs can be more readily targeted to the beginning of the exponential growth phase but targeting of later vegetative growth stages will remain arbitrary. The vegetative growth and development of the crop was also studied to elucidate the process of leaf emergence and senescence (turnover) as they affected both leaf and root yield. The sequential senescence of leaves, which began immediately after cotyledon death, and translocation of carbohydrate to the storage root, coupled with high leaf area index (LAI), probably account for the high growth rates of 220 kg ha,1 day,1 maintained for periods of 10 weeks after the onset of root expansion. High yields can be expected if high LAI is maintained by ensuring that leaf emergence rates are not limited by nutrient or water deficiencies and leaves are protected from insect pests. Forage turnip is particularly robust because new leaf continues to emerge as older and damaged leaves senesce and carbohydrate is stored as starch in the storage root. [source] Characterization of the proteases in the midgut of the xylophagous larvae of Oemona hirta (Coleoptera: Cerambycidae)INSECT SCIENCE, Issue 5 2009Brian David Shaw Abstract, The protein digestive capability of the larvae of the longhorn beetle (Oemona hirta, Coleoptera: Cerambycidae, Fabricius, 1775) was investigated. This species feeds only on wood where there is a high proportion of vascular tissue. The pH of the midgut, the major digestive organ, was alkaline and protein hydrolysis was maximal at alkaline pH. Use of specific synthetic peptide substrates showed that the major protease activities were the endopeptidases, trypsin and chymotrypsin-like activity, and the exopeptidase, leucine aminopeptidase and the pH curves corresponded to that with protein substrate. Studies using a range of serine protease inhibitors as well as specific inhibitors of metalloproteases, cysteine proteases and aspartate proteases confirmed a serine protease-based digestive system similar to earlier reports of sapwood-feeding Cerambycids. Control of these insect pests using protease inhibitors is discussed. [source] Diatomaceous earths as alternatives to chemical insecticides in stored grainINSECT SCIENCE, Issue 6 2006AMIN NIKPAY Abstract Diatomaceous earth (DE) is a natural inert dust used to control insect pests in stored grain as an alternative to synthetic residual insecticides. Various DE formulations are now registered as a grain protectant or for structural treatment in many different countries throughout the world. The mode of action of DE is through the absorption of cuticular waxes in the insect cuticle, and insect death occurs from desiccation. The main advantages of using DE are its low mammalian toxicity and its stability. The main limitations to widespread commercial use of DE are reduction of the bulk density and flowability of grain, irritant hazards during application and reduction in efficacy at high moisture contents. This paper is an updated review of published results of researches related to the use of DEs and discusses their potential use in large-scale, commercial storage and in small scale applications. [source] | |||||||||||||||||||||||||||||||||||||