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Mosquito Larvae (mosquito + larva)
Selected AbstractsOviposition habitat selection for a predator refuge and food source in a mosquitoECOLOGICAL ENTOMOLOGY, Issue 3 2005J. Guillermo Bond Abstract., 1.,The influence of filamentous algae on oviposition habitat selection by the mosquito Anopheles pseudopunctipennis and the consequences of oviposition decisions on the diet, development, body size, and survival of offspring were examined. 2.,A natural population of An. pseudopunctipennis in Chiapas, Mexico, oviposited almost exclusively in containers with filamentous algae. Algae represented 47% of the gut contents of mosquito larvae sampled from the natural population. Mosquito larvae fed on an exclusive diet of algae developed as quickly and achieved the same adult body size (wing length) as their conspecifics fed on a standard laboratory diet. 3.,Multiple regression of survival of mosquito larvae on percentage surface area cover of algae (0,99%) and the density of predatory fish (zero to four fish per container) was best described by a second-order polynomial model. Increasing fish densities resulted in a reduction in mosquito survival in all algal treatments. The highest incidence of survival was observed at intermediate (66%) algal cover in all treatments. 4.,The presence of fish significantly extended larval development times whereas algal cover had no significant effect. The presence of fish resulted in emergence of smaller adults due to reduced feeding opportunities and predator avoidance behaviour. Algal cover also affected mosquito wing length but differently at each fish density. 5.,Oviposition habitat selection improves survival in the presence of predators and feeding opportunities for An. pseudopunctipennis larvae. [source] Spanning the gap: experimental determination of paratenic host specificity of horsehair worms (Nematomorpha: Gordiida)INVERTEBRATE BIOLOGY, Issue 1 2003Ben Hanelt Abstract. Details of the life cycle of freshwater nematomorphs (gordiids) remain unclear. Free-living aquatic larval gordiids must make a critical transition from an epibenthic aquatic environment to terrestrial hosts. In order to identify potential hosts capable of bridging this ecological gap, the specificity of paratenic hosts of three common species of North American gordiids was investigated. All three species were characterized by an identical infection pattern: low host specificity. Gordiids were able to encyst within annelids, mollusks, crustaceans, insects and a vertebrate. Three species of putative host (a turbellarian, a water mite, and a mosquito larva) were not infected with any of the gordiid species. Internal defense reactions (IDR) and feeding behaviors are implicated as preventing infection in these species. Several of the other host species produced either an IDR or an immune reaction to the cysts, although reactions to the cysts were highly variable between species. In most species, IDR did not cause noticeable harm to the encysted larvae. It is proposed that although many species are easily infected with gordiid cysts, most do not act as natural paratenic hosts. For some of these host groups, especially snails, a role as reservoir host is suggested. Of all hosts included in this study, aquatic insects were identified as the hosts likely responsible for spanning the ecological gap and acting as true hosts for gordiids. [source] Oviposition decreased in response to enriched water: a field study of the pitcher-plant mosquito, Wyeomyia smithiiECOLOGICAL ENTOMOLOGY, Issue 1 2007DAVID HOEKMAN Abstract 1.,Environmental cues are known to influence oviposition behaviour in mosquitoes, with important consequences for larval survival and insect population dynamics. Enriched microhabitats have been shown to be preferred oviposition sites. 2.,In a field experiment designed to determine whether ovipositing mosquitoes are sensitive to different levels of nutrient enrichment, new pitcher-plant (Sarracenia purpurea) leaves were opened and enriched with 0, 2, or 20 dead ants, and the number of pitcher-plant mosquito (Wyeomyia smithii) larvae resulting from subsequent oviposition were measured. 3.,Oviposition rates were higher in leaves with low levels of enrichment (0 and 2 ants per leaf), although larval development was enhanced at the highest enrichment level. 4.,Results suggest that, although these mosquito larvae are nutrient limited, ovipositing females preferentially avoid highly enriched leaves. This counterintuitive result may be due to low oxygen concentrations or a masked cue in enriched leaves, and contrasts with other oviposition studies. [source] Oviposition habitat selection for a predator refuge and food source in a mosquitoECOLOGICAL ENTOMOLOGY, Issue 3 2005J. Guillermo Bond Abstract., 1.,The influence of filamentous algae on oviposition habitat selection by the mosquito Anopheles pseudopunctipennis and the consequences of oviposition decisions on the diet, development, body size, and survival of offspring were examined. 2.,A natural population of An. pseudopunctipennis in Chiapas, Mexico, oviposited almost exclusively in containers with filamentous algae. Algae represented 47% of the gut contents of mosquito larvae sampled from the natural population. Mosquito larvae fed on an exclusive diet of algae developed as quickly and achieved the same adult body size (wing length) as their conspecifics fed on a standard laboratory diet. 3.,Multiple regression of survival of mosquito larvae on percentage surface area cover of algae (0,99%) and the density of predatory fish (zero to four fish per container) was best described by a second-order polynomial model. Increasing fish densities resulted in a reduction in mosquito survival in all algal treatments. The highest incidence of survival was observed at intermediate (66%) algal cover in all treatments. 4.,The presence of fish significantly extended larval development times whereas algal cover had no significant effect. The presence of fish resulted in emergence of smaller adults due to reduced feeding opportunities and predator avoidance behaviour. Algal cover also affected mosquito wing length but differently at each fish density. 5.,Oviposition habitat selection improves survival in the presence of predators and feeding opportunities for An. pseudopunctipennis larvae. [source] Biological warfare in the garden pond: tadpoles suppress the growth of mosquito larvaeECOLOGICAL ENTOMOLOGY, Issue 1 2003Allie Mokany Abstract. 1. Although tadpoles and mosquito larvae may compete for scarce resources in natural freshwater systems, the mechanisms involved in such competition remain largely unstudied. 2. Replicated artificial ponds were set up to examine the role of pathogenic interference (water-borne growth inhibitors) in two tadpole,mosquito systems from south-eastern Australia. One system comprised taxa that are commonly sympatric in freshwater ponds (tadpoles of Limnodynastes peronii and larvae of Culex quinquefasciatus) while the other comprised species that co-occur in brackish water ponds (tadpoles of Crinia signifera and larvae of Ochlerotatus australis). 3. Water that had previously contained tadpoles suppressed the rates of survival and pupation of mosquito larvae in both systems. Fungicide reduced or eliminated this effect, suggesting that the growth inhibitors may be fungal organisms (possibly the yeast Rhodotorula glutinis) from tadpole faeces. Fungicide also enhanced growth rates of tadpoles. 4. These results suggest that interference competition between tadpoles and mosquito larvae is mediated by other organisms in some ecological systems. [source] Selective and frequency dependent predation of aquatic mosquito predator Diplonychus indicus Venkatesan & Rao (Hemiptera: Belostomatidae) on immature stages of three mosquito speciesENTOMOLOGICAL RESEARCH, Issue 6 2009Narayanasamy SIVAGNANAME Abstract Frequency dependent mosquito larval size (II and IV instars) and species selection by the water bug Diplonychus indicus against three mosquito species Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi was studied in the laboratory. The different frequencies used for each species selection were 20:30:50, 30:50:20, 50:20:30, 25:35:40, 35:40:25 and 40:25:35 of fourth instars of the respective three prey species. All nymphal water bugs (I,V instars) selected IV instar mosquito larvae and the mean proportion of late (larger) larvae eaten by the predator instars was significantly higher than the mean proportion of early (smaller) larvae eaten (F= 2.28; P < 0.001). In all six ratios used to determine the frequency dependent mosquito species selection, all the stages of the water bug selected Ae. aegypti over the other two species (F= 452.43; P < 0.001). The mean number of mosquito larvae eaten increased as its density increased based on various ratios of larvae offered. The study indicated that the predatory efficiency of D. indicus was high when Ae. aegypti was offered as prey, suggesting the utility of this mosquito predator in the control of dengue vectors. [source] Correlation between population dynamics of mosquito larvae and their habitat qualitiesENTOMOLOGICAL RESEARCH, Issue 4 2008Lalit Mohan RANJEETA Abstract Surveillance of anopheline and culicine larvae was conducted fortnightly to determine population composition and density at seven sites in the area of the Mathura Refinery, Mathura, India during 2005,2006. The correlation between population of the vectors and their habitat quality was established. Temperature (0.978 and 0.85°C), pH (0.99 and 0.95), conductivity (0.98 and 0.98 mho) and calcium ion hardness (0.978 and 0.85 p.p.m.) were positively correlated with the populations of both larval species. In contrast, the correlation coefficients between the parameters total hardness, magnesium ion hardness, biochemical oxygen demand and chemical oxygen demand varied with the larval species. The anopheline larval population was dominant over the culicine population in the surveillance area. The distribution of anopheline mosquito larvae during the study period was found to be constant, and the average density of anopheline and culicine larvae was 84.70 and 15.30%, respectively, across all seven sites. Thus, the study demonstrated spatial and temporal population differences of mosquito larvae with respect to environmental factors, including water quality. [source] Modelling the relationship between a pitcher plant (Sarracenia purpurea) and its phytotelma community: mutualism or parasitism?FUNCTIONAL ECOLOGY, Issue 4 2008N. Mouquet Summary 1To improve our understanding of the relationship between the pitcher plant (Sarracenia purpurea) and the phytotelma community inhabiting its leaves we built an exploratory, mechanistic model based on stochiometric constraints on carbon and nitrogen associated with prey decomposition. 2Our theoretical results suggest that the phytotelma community is acting as a mineralizing system producing nitrogen for the plant. This is confirmed by data collected in the field and in the literature, that show the amount of nitrogen produced by the decomposition of prey is sufficiently high to be considered as a major source of nitrogen for the plant. 3In our model, nitrogen yield is higher if the phytotelma community is restricted to bacteria alone than when the full food web is present. Nitrogen availability is negatively affected by bacterivores (rotifers and protozoa mostly) and positively affected by a cascading effect of mosquito larvae. 4When sedimentation rate is high, mosquitoes have a global positive effect on nitrogen production because they indirectly reduce the amount of nitrogen lost through sedimentation more than they export nitrogen through pupation. On the other hand, when sedimentation rate is low there is a hump-shaped relationship between the uptake rate of bacterivores by mosquito larvae and the nitrogen yield in the plant. 5We conclude that plant,bacteria and plant,mosquito interactions are predominantly mutualistic, whereas plant,bacterivore interactions are predominantly parasitic. Our work also illustrates how ecosystem properties (here nitrogen production by the phytotelma community) can be understood as a function of trophic complexity and can be seen as a product of selection at the scale of a community. [source] Aedes aegypti transducing densovirus pathogenesis and expression in Aedes aegypti and Anopheles gambiae larvaeINSECT MOLECULAR BIOLOGY, Issue 5 2001T. W. Ward Abstract Aedes aegypti densovirus (AeDNV) is a small DNA virus that has been developed into an expression and transducing vector for mosquitoes [Afanasiev et al. (1994) Exp Parasitol 79: 322,339; Afanasiev et al. (1999) Virology 257: 62,72; Carlson et al. (2000) Insect Transgenesis: Methods and Applications (Handler, A.M. & James, A.A., eds), pp. 139,159. CRC Press, Boca Raton]. Virions carrying a recombinant genome expressing the GFP gene were used to characterize the pathogenesis of the virus in 255 individual Aedes aegypti larvae. The anal papillae of the larvae were the primary site of infection confirming previous observations (Afanasiev et al., 1999; Allen-Muira et al. (1999) Virology 257: 54,61). GFP expression was observed in most cases to spread from the anal papillae to cells of the fat body, and subsequently to many other tissues including muscle fibers and nerves. Infected anal papillae were also observed to shrink, or melanize and subsequently fall off in a virus dependent manner. Three to four day-old larvae were less susceptible to viral infection and, if infected, were more likely to survive into adulthood, with 14% of them still expressing GFP as adults. Higher salt concentrations of 0.10,0.15 m inhibited viral infection. Anopheles gambiae larvae also showed infection of the anal papillae (17%) but subsequent viral dissemination did not occur. The persistence of the reporter gene expression into adulthood of Aedes aegypti indicates that transduction of mosquito larvae with recombinant AeDNV may be a means of introducing a gene of interest into a mosquito population for transient expression. [source] Acute toxicity of water extract of Tephrosia vogelii Hook to species relevant in aquaculture ponds: rotifers, Cyclops, mosquito larvae and fishJOURNAL OF APPLIED ICHTHYOLOGY, Issue 6 2004A. Agbon Summary Rotenone is used to clear ponds of unwanted organisms and trash fish which may predate on fish when the ponds are stocked. Toxicity tests using water extract of the leaves of Tephrosia vogelii Hook, which contains rotenone, were conducted on rotifers (Brachionus species), Cyclops, mosquito larvae (Culex species) and fish (Aphyosemion gardneri nigerianum) in static bioassays. The 48-h LC50s were derived from probit curves using the probit-analysis method, while chi-square was used to test for significant differences between observed mean mortalities and predicted mean mortality values. These showed no significant differences (P > 0.05). The variance ratio of the replicates in each treatment also showed no significant difference (P > 0.05). The 48-h LC50s were found to be 2.89, 1.04, 4.48 and 0.24 mg L,1 for rotifers, Cyclops, mosquito larvae and fish, respectively. The probit mortalities were positively correlated with the log-concentration, except for the rotifers bioassay, which was negative. The fish, A. gardneri nigerianum, was the most sensitive; the mosquito larvae were the least sensitive. [source] Factors influencing the abundance of Japanese encephalitis vectors in ricefields in India , II.MEDICAL AND VETERINARY ENTOMOLOGY, Issue 1 2002Biotic Abstract. The relationship of insect predators and phytoplankton with the abundance of Culex tritaeniorhynchus Giles, Cx. vishnui Theobald and Cx. pseudovishnui Colless mosquito larvae and pupae (Diptera: Culicidae) in ricefields was investigated during three rice growing seasons. Notonectids were the most abundant insect predators, whereas diatoms dominated among phytoplankton. Multiple regression analysis showed that the occurrence of notonectids (both nymphs and adults) was negatively associated with larval abundance. Phytoplankton, especially diatoms and blue green algae (BGA), were found to favour abundance of culicine immatures during Navarai and Kuruvai crops, respectively. Larval gut analysis showed that the intake of algae by late instars was high, with 93%, 58% and 24% of diatoms, BGA and green algae, respectively. Filamentous algae may not necessarily be of nutritive value, but they are observed to form mats, which provide protection to the mosquito immatures from the predators. [source] Breeding of Anopheles mosquitoes in irrigated areas of South Punjab, PakistanMEDICAL AND VETERINARY ENTOMOLOGY, Issue 3 2001N. Herrel Abstract. As part of investigations on potential linkages between irrigation and malaria transmission, all surface water bodies in and around three villages along an irrigation distributary in South Punjab, Pakistan, were surveyed for anopheline mosquito larvae (Diptera: Culicidae) from April 1999 to March 2000. Samples were characterized according to exposure to sunlight, substratum, presence of vegetation, fauna, inorganic matter and physical water condition (clear/turbid/foul). Also water temperature, dissolved oxygen (DO), electroconductivity (EC) and pH of sites were recorded. A total of 37 982 Anopheles larvae of six morphological types were collected from 2992 samples taken from irrigation/agricultural and village/domestic aquatic habitats. Anopheles subpictus Grassi sensu lato was by far the most abundant (74.3%), followed by An. culicifacies Giles s.l. (4.1%), An. stephensi Liston s.l. (2.6%), An. pulcherrimus Theobald (1.8%), An. peditaeniatus Leicester (0.3%) and An. nigerrimus Giles (0.1%). The four most abundant species were significantly associated with waterlogged fields and communal village drinking-water tanks. Habitat characteristics most correlated with occurrence of anophelines were the physical water condition and the absence/presence of fauna, particularly predators. Occurrence and abundance of Anopheles immatures were not significantly correlated with water temperature, DO, EC or pH. Malaria vectors of the Anopheles culicifacies complex occurred at relatively low densities, mainly in irrigated and waterlogged fields. In South Punjab, where rainfall is very low, it should be possible to reduce anopheline breeding through water management, as larvae develop mainly in water bodies that are directly or indirectly related to the extensive canal-irrigation system. [source] Paradoxical effects of sublethal exposure to the naturally derived insecticide spinosad in the dengue vector mosquito, Aedes aegyptiPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 3 2009Gloria E Antonio Abstract BACKGROUND: Recent studies have indicated that spinosad, a mixture of two tetracyclic macrolide compounds produced during the fermentation of a soil actinomycete, may be suitable for controlling a number of medically important mosquito species, including the dengue vector, Aedes aegypti L. The authors determined the effects of a 1 h exposure to a 50% lethal concentration (LC50) of spinosad in the larval stage on the wing length, longevity and reproductive capacity of the adult survivors. RESULTS: The LC50 of spinosad for a wild-caught population of Ae. aegypti from Chiapas, southern Mexico, was estimated to be 0.06 mg AI L,1 in late third instars. Paradoxically, the female survivors of exposure to this concentration were significantly larger (as determined by wing length) laid more eggs, but were slightly less fertile than control females. This was probably due to elimination of the smaller and more susceptible fraction of mosquito larvae from the experimental population following spinosad treatment. Male survivors, in contrast, were significantly smaller than controls. No significant differences were detected in the adult longevity of treated and control insects of either sex. CONCLUSIONS: The increase in reproductive capacity of spinosad-treated females did not compensate for mortality in the larval stage and would be unlikely to result in population increase in this mosquito under the conditions that were employed. Sustained-release formulations would likely assist in minimizing the occurrence of sublethal concentrations of this naturally derived product in mosquito breeding sites. Copyright © 2008 Society of Chemical Industry [source] Synthesis and characterization of some dibutylbis{5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoato}tin(IV) compounds.APPLIED ORGANOMETALLIC CHEMISTRY, Issue 5 2003Toxicity studies of di-, tri-organotin complexes on the second instar of Aedes aegypti mosquito larvae Abstract The preparation and spectroscopic characterization of some complexes of the type Bu2Sn(LH)2 (LH = 5-[(E)-2-(aryl)-1-diazenyl]-2-hydroxybenzoate) are reported. On the basis of spectroscopic evidence (1H, 13C, 119Sn NMR, IR and 119mSn Mössbauer) the compounds were judged to adopt the usual dicarboxylato structural type with a skew trapezoidal arrangement. This was further confirmed by X-ray crystallography in the case of Bu2Sn(L5H)2 (L5H = 5-[(E)-2-(4-chlorophenyl)-1-diazenyl]-2-hydroxybenzoate). Toxicity studies of the di- and tri-organotin compounds on the second larval instar of Aedes aegypti mosquito larvae are reported. Copyright © 2003 John Wiley & Sons, Ltd. [source] Pond attributes influence competitive interactions between tadpoles and mosquito larvaeAUSTRAL ECOLOGY, Issue 4 2002Allie Mokany Abstract Tadpoles and mosquito larvae often coexist in natural freshwater bodies. We studied competitive interactions between: (i) tadpoles of the striped marsh frog (Limnodynastes peronii) and larvae of the mosquito Culex quinquefasciatus; and (ii) tadpoles of the common eastern froglet (Crinia signifera) and larvae of the mosquito Aedes australis. These two sets of taxa occur in natural water bodies in the Sydney region. Laboratory trials revealed competition between mosquito larvae and tadpoles in both systems. For example, mosquitoes displayed reduced rates of survival, growth and development, and smaller size at metamorphosis, when they were raised with tadpoles. The intensity of competitive suppression was influenced by attributes such as pond size (and hence, larval density), the location of food (on the water surface vs the substrate), and the extent of opportunities for direct physical interactions between the two competing organisms. These effects differed between the two study systems, suggesting that the mechanisms of suppression also differed. Limnodynastes peronii tadpoles suppressed C. quinquefasciatus even when the two types of organisms were separated by a physical partition, suggesting that chemical or microbiological cues may be responsible. Pond attributes also affected the impact of C. signifera tadpoles on Aedes larvae, but (unlike the Limnodynastes,Culex system) these effects disappeared when densities were lowered or when the tadpoles and mosquito larvae were physically separated. Thus, direct physical interactions may suppress mosquitoes in the Crinia,Aedes system. Our results suggest that tadpoles suppress the viability of larval mosquitoes by multiple pathways. [source] Crystallization and preliminary X-ray diffraction studies of a mosquito-larvicidal toxin from Bacillus thuringiensis subsp. israelensisACTA CRYSTALLOGRAPHICA SECTION D, Issue 3 2003Panadda Boonserm The Cry4B ,-endotoxin from Bacillus thuringiensis subsp. israelensis is specifically toxic to mosquito larvae. For a better understanding of the mechanism of toxicity, chymotrypsin-activated Cry4B toxin (68,kDa) has been purified and crystallized in sodium bromide at neutral pH. The well formed crystals belong to the rhombohedral space group R32, with unit-cell parameters a = b = 185.82, c = 187.93,Å, and diffracted X-rays to 1.75,Å resolution. The asymmetric unit contains one toxin molecule and 74% solvent content, as shown by molecular replacement from a composite model of the homologous Cry3A and Cry1Aa. The purified protein and crystals both possessed mosquitocidal activity. 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