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Mature Larvae (mature + larva)
Selected AbstractsCocoon-spinning larvae of Oriental fruit moth and Indianmeal moth do not produce aggregation pheromoneAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2009Zaid Jumean Abstract 1,Mature larvae of the Oriental fruit moth (OFM) Grapholita molesta (Lepidoptera: Tortricidae) and the Indianmeal moth (IMM) Plodia interpunctella (Lepidoptera: Pyralidae) leave their food source in search of suitable pupation sites in which to spin cocoons. These sites are typically well-concealed cracks and crevices within the environment. Such cocooning behaviour is also observed in larvae of the codling moth (CM) Cydia pomonella (Lepidoptera: Tortricidae), which aggregate prior to pupation in response to a pheromone blend produced by cocoon-spinning conspecific larvae. 2,In laboratory experiments, we tested whether cocoon-spinning OFM and IMM larvae produce aggregation pheromones and whether CM larvae are cross-attracted to closely-related OFM larvae. 3,Fifth-instar OFM and IMM larvae were not attracted to, or arrested by, cocoon-spinning conspecifics. Moreover, fifth-instar CM larvae were not cross-attracted to either cocoon-spinning OFM or IMM larvae. 4,Analyses of volatiles released from cocoon-spinning OFM and IMM larvae revealed that both OFM and IMM lack components that are present in the aggregation pheromone of CM larvae. This information may help explain why CM larvae are not cross-attracted to cocooning OFM or IMM larvae. [source] Dispersal capacity in the Mediterranean corn borer, Sesamia nonagrioidesENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2004M. Eizaguirre Abstract Corn (Zea mays L.) borers are the primary target of Bacillus thuringiensis Berliner (Bt) transgenic maize. Management of corn borer resistance to Bt requires information on larval and adult dispersal capacities, a feature that is particularly unknown in Sesamia nonagrioides Lefèbvre (Lepidoptera: Noctuidae), the most damaging corn borer in Spain. Larval dispersal was studied over a 3 year period by infesting plants with egg masses and dissecting the neighbouring plants 7, 14, and 32 days later to measure larval dispersal at several ages. The number and age of larvae were recorded in the dissected plants. Only mature larvae dispersed in significant numbers; they moved at least to rows adjacent to those containing the infested plant, and down the row five plants. The percentage of larvae that dispersed from the infested plant was density-dependent. Adult dispersal was studied with directional light and pheromone uni-traps over 5 and 3 year periods, respectively. Directional light traps were placed in the margins between Bt and non-Bt maize fields, half oriented towards each of the two kinds of maize field. Pheromone traps were placed in the Bt and non-Bt fields at increasing distances (0,100 m) from the border. The numbers of males and females caught in directional light traps were not different in traps oriented towards Bt or non-Bt fields, but the number of males caught in the third flight in Bt fields was lower than in non-Bt fields. These results suggest that males from adjacent Bt and non-Bt fields mate indiscriminately with females emerging in any of the two kinds of maize fields. However, male movement in the third flight may not be sufficient to randomly distribute males between the two fields. [source] Life history and host specificity of the Japanese flea beetles Trachyaphthona sordida and T. nigrita (Coleoptera: Chrysomelidae), potential biological control agents against skunk vine, Paederia foetida (Rubiaceae), in the southeastern parts of the United States and HawaiiENTOMOLOGICAL SCIENCE, Issue 2 2008Chie OKAMOTO Abstract Skunk vine, Paederia foetida (Rubiaceae), is native to Asia and has been recognized as an invasive weedy vine of natural areas in Florida and Hawaii. Two insects, Trachyaphthona sordida and Trachyaphthona nigrita (Coleoptera: Chrysomelidae) from Japan are being considered as potential biological control agents against skunk vine. To gather fundamental information on their biology, we carried out field surveys and laboratory experiments in Kyushu, southern Japan, between 2003 and 2006. We found that T. sordida is commonly distributed in Kyushu and T. nigrita is restricted to the southern parts of Kagoshima Prefecture on the southern part of Kyushu. These species are fundamentally univoltine and adults appear in late April to early July. Trachyaphthona sordida overwinters as mature larvae and T. nigrita as mature larvae or rarely as adults. Larvae of both species feed on fine roots of P. foetida in the field and Serissa foetida (Rubiaceae) under rearing conditions, and they appear to have tribe-level host specificity in their host range. On the basis of these results, we suggest that both species are suitable as biological control agents. [source] Prey switching in four species of carnivorous stonefliesFRESHWATER BIOLOGY, Issue 6 2004J. M. Elliott Summary 1. Previous studies compared the functional responses to their prey, and both intraspecific and interspecific interference, in mature larvae of Dinocras cephalotes, Perla bipunctata, Isoperla grammatica and Perlodes microcephalus. The present study examines switching by larvae of the same species presented with different proportions of two contrasting prey types; larvae of Baetis rhodani and Chironomus sp. In each experiment, 200 prey were arranged in nine different combinations of the two prey types (20 : 180, 40 : 160, 60 : 140, 80 : 120, 100 : 100, 120 : 80, 140 : 60, 160 : 40, 180 : 20). Prey were replaced as they were eaten. A model predicted the functional response in the absence of switching and provided a null hypothesis against which any tendency for switching could be tested. 2. No evidence for prey switching by Dinocras and Perla was obtained, both species showing a slight preference for Baetis over Chironomus. Prey switching occurred in Isoperla and Perlodes. As the relative abundance of one prey type increased in relation to the alternative, the proportion eaten of the former prey changed from less to more than expected from its availability, the relationship being described by an S-shaped curve. Isoperla and Perlodes switched to a preference for Baetis when its percentage of the total available prey exceeded 57 and 42%, respectively. Equivalent values for Chironomus were 43 and 58% for Isoperla and Perlodes, respectively. Switching was strongest in Perlodes. 3. Non-switching in Dinocras and Perla was related to their feeding strategy, both species being more successful when using a non-selective ambush strategy at dusk and dawn rather than a search strategy during the night. Both Isoperla and Perlodes used a search strategy. The smaller Isoperla fed chiefly at dusk and dawn, and preferred Chironomus larvae, whereas most of the larger Perlodes fed continuously from dusk to dawn and preferred Baetis larvae. [source] Interspecific interference and the functional response of four species of carnivorous stonefliesFRESHWATER BIOLOGY, Issue 9 2003J.M. Elliott Summary 1.,A previous study compared the functional responses to their prey and intraspecific interference in mature larvae of Perlodes microcephalus, Isoperla grammatica, Dinocras cephalotes and Perla bipunctata. The present study extends this work by assessing interspecific interference between pairs of these species in equal numbers (one, two or three larvae per species) to provide total predator densities of two, four or six larvae. Baetis larvae as prey were replaced as they were eaten, and their density per predator was varied between 20 and 200 larvae. 2.,The number of prey eaten by each competing species increased curvilinearly with prey density, the relationship being well described by a Type II model. Of the two constants in the model, handling time varied considerably between species, mean values being shortest for Perlodes, slightly higher for Isoperla, and much higher for Dinocras and Perla. It was not affected significantly either by predator density or the identity of the competing species. 3.,Attack rate also varied between species and decreased with predator density. This decrease was slight for Perlodes, and also for Dinocras and Perla in competition with Isoperla. The decrease in Dinocras and Perla was similar to that for intraspecific interference. 4.,The decrease in attack rate was described by a convex curve for Perlodes with the other three species and for Dinocras/Perla with Isoperla, but by a concave curve (negative power function) for Isoperla competing with the other three species, and for both Dinocras and Perla in competition with Perlodes. Prey consumption also decreased with predator density, the severity of competition with different species reflecting that for attack rate. 5.,A comparison with previous results for intraspecific interference showed that the latter was dominant for Perlodes in all contests and for Dinocras or Perla competing with Isoperla, whilst interspecific interference dominated for Isoperla in all contests and for Dinocras and Perla competing with Perlodes. Both types of interference were applicable to competition between Dinocras and Perla. Isoperla was the least, and Perlodes the most, aggressive of the four species with Dinocras and Perla intermediate. [source] Gamma radiation sensitivity of the eggs, larvae and pupae of Indian meal moth Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae)PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 5 2008Abdurrahman Ayvaz Abstract BACKGROUND: This study focused on determining the minimal effective gamma radiation dose that prevents commodity damage caused by the Indian meal moth Plodia interpunctella (Hübner). The study was also designed to assess the effect of releasing either partially sterilized males alone or both partially sterilized males and females on the reproductive potential of P. interpunctella populations. RESULTS: The dose of radiation required to prevent larval emergence from irradiated eggs was 350 Gy, and the same dose was also required to prevent adult emergence from mature larvae. A dose of 300 Gy was not able to prevent adult emergence from irradiated pupae. The dose at which 100% sterility was achieved in treated females mated to treated males was 300 Gy for the parental generation of irradiated pupae. Fertility of the parental males from irradiated pupae was 48.17% at 300 Gy in treated males crossed with untreated females, but male progeny of irradiated male parents had a residual fertility of 11.06% at the same dose. CONCLUSION: F1 males from irradiated pupae were more sterile than parental males. To prevent larval emergence from irradiated eggs, a dose of 350 Gy is required. The same dose is required to prevent the larvae from reaching the adult stage. Copyright © 2008 Society of Chemical Industry [source] | ||||||||||