Pupation Of Larvae Research Articles

Host location behavior of Cotesia plutellae Kurdjumov (Hymenoptera: Braconidae) in ambient and moderately elevated ozone in field conditions

In field O(3)-enrichment experiments increased herbivore densities have been reported, which could be due to negatively affected host location behavior of natural enemies. We addressed the impact of doubling background O(3) on the host location of the parasitoid Cotesia plutellae by conducting 24-h trials in an open-air O(3)-fumigation system during two consecutive years. Two circles (radii 1.40 and 4.00 m) of Plutella xylostella-infested potted cabbage plants were placed in the O(3) and ambient plots. Female wasps were released into each plot from the center, and observed 5 times over a 24-h period to assess their host location capability. Thereafter, plants were kept in laboratory conditions until larvae pupation to determine parasitism rates. No significant differences were detected between ambient and O(3)-enriched environments either in the number of wasps found in the field, or in the percentages of parasitized larvae. This suggests that moderately elevated O(3) will not affect the behavior of this parasitoid.

First Record of Fossorial Behavior in Hawaiian Leafroller Moth Larvae, Omiodes continuatalis (Lepidoptera: Crambidae)1

Larvae of the endemic Hawaiian leafroller moth, Omiodes continuatalis (Wallengren), were used in controlled exposure trials on the island of Maui, Hawai‘i, in May–August 2006, to examine effects of introduced parasitoids on native Hawaiian Lepidoptera. During the trials we observed O. continuatalis larvae burrowing up to 14 cm into the soil beneath plants on which they were deployed. This discovery reflects the first record of fossorial behavior not associated with pupation in larvae of Hawaiian Omiodes and suggests how O. continuatalis, a species once listed as extinct by the U.S. Fish and Wildlife Service, may persist despite intense pressure from introduced biological control agents.

Effects of Neem Leaf Dust and a Commercial Formulation of a Neem Compound on the Longevity, Fecundity and Ovarian Development of the Melon Fly, Bactrocera cucurbitae (Coquillett) and the Oriental Fruit Fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

Neem leaf dust and a commercial formulation of neem were tested on adult Bactrocera cucurbitae (Coquillett) and Bactrocera dorsalis (Hendel) to determine their effects on the longevity, fecundity and ovarian development. Different combinations of neem leaf dust and a commercial formulation of a neem compound incorporated with sugar solution and adult rearing diets were tested. The Laboratory tests showed that ingestion of neem can significantly reduced the longevity and fertility of both the fly species. Significantly fewer pupae were collected from adults fed on laboratory rearing diet and nimbicidine as water source. Effect of neem treatment on the pupation and subsequent adult emergence of late-instar larvae was negligible. Microscopic observation indicated that the decreased fecundity was due to the block of ovarian development. Experimental results confirmed that neem can be effectively used as a safe alternative insecticide for the control of Bactrocera species.

Thermoregulation in Larval Aggregations of Carrion-Feeding Blow Flies (Diptera: Calliphoridae)

The growth and development of carrion-feeding calliphorid (Diptera: Calliphoridae) larvae, or maggots, is of great interest to forensic sciences, especially for estimation of a postmortem interval (PMI). The development rate of calliphorid larvae is influenced by the temperature of their immediate environment. Heat generation in larval feeding aggregations (=maggot masses) is a well-known phenomenon, but it has not been quantitatively described. Calculated development rates that do not include internally generated temperatures will result in overestimation of PMI. Over a period of 2.5 yr, 80 pig, Sus scrofa L., carcasses were placed out at study sites in north central Florida and northwestern Indiana. Once larval aggregations started to form, multiple internal and external temperatures, and weather observations were taken daily or every few days between 1400 and 1800 hours until pupation of the larvae. Volume of each aggregation was determined by measuring surface area and average depth. Live and preserved samples of larvae were taken for species identification. The four most common species collected were Lucilia coeruleiviridis (=Phaenicia) (Macquart) (77%), Cochliomyia macellaria (F.) (8.3%), Chrysomya rufifaces (Macquart) (7.7%), and Phormnia regina (Meigen) (5.5%). Statistical analyses showed that 1) volume of a larval mass had a strong influence on its temperature, 2) internal temperatures of masses on the ground were influenced by soil temperature and mass volume, 3) internal temperatures of masses smaller than 20 cm3 were influenced by ambient air temperature and mass volume, and 4) masses larger than 20 cm3 on the carcass had strongly regulated internal temperatures determined only by the volume of the mass, with larger volumes associated with higher temperatures. Nonsignificant factors included presence of rain or clouds, shape of the aggregation, weight of the carcass, species composition of the aggregation, time since death, or season.

Effect of Kaolin on Fitness and Behavior of Choristoneura rosaceana (Lepidoptera: Tortricidae) Larvae

The mechanisms by which kaolin, a clay particle film formulation, affects the fitness and behavior of larvae of obliquebanded leafroller, Choristoneura rosaceana (Harris), were investigated. Feeding experiments tested kaolin as a physical barrier versus a physiological toxin for larvae that consumed kaolin applied either to apple (Malus spp.) leaves or mixed in artificial diet. Behavioral experiments tested the effects of kaolin applied to apple leaves on neonate dispersal and leaf rolling by third and fourth instars. When larvae fed on apple leaves sprayed with kaolin, mortality and time to pupation of larvae increased significantly, whereas pupal mass significantly decreased. When larvae consumed kaolin mixed into an artificial diet, however, the effects on mortality, pupation time, and pupal mass were negligible. There may be minor physiological effects from consumption because male time to pupation was delayed for larvae fed diets containing the highest concentration of kaolin. In behavioral experiments, neonate larvae dispersed more quickly off plants covered with kaolin than control plants, and kaolin delayed the construction of leaf shelters by third and fourth instars. We showed that the effects of kaolin on C. rosaceana larvae are primarily physical, causing changes in dispersal and rolling behaviors and as a physical barrier to feeding.

Synthesis and Anti-Juvenile Hormone Activity of Ethyl 4-[2-(6-Methyl-3-pyridyloxy)alkyloxy]benzoates

A series of ethyl 4-[2-(6-methyl-3-pyridyloxy)alkyloxy]benzoates was prepared and tested for activity to induce precocious metamorphosis in larvae of the silkworm, Bombyx mori. Of the compounds tested, ethyl 4-[4-methyl-2-(6-methyl-3-pyridyloxy)pentyloxy]benzoate (5) was the most effective when applied to 24 hr-old 3rd instar larvae. There was no significant difference in precocious metamorphosis-inducing activity between 5R(+)- and 5S(−)-enatiomers. The activity of compound 5 could be fully counteracted by methoprene, a juvenile hormone (JH) agonist, but not by the dietary administration of 20-hydroxyecdysone. When 3rd instar larvae were treated with compound 5, hemolymph JH esterase activity, which is indispensable for the initiation of pupation in normal last instar larvae, was induced during the 4th instar. © Pesticide Science Society of Japan

Biology and Seasonality of Fulcidax monstrosa (F.) (Chrysomelidae: Chlamisinae)

Abstract The phenology of Fulcidax monstrosa (F.) on its host plant Byrsonima sericea DC. was studied from November 2000 to June 2003 at the Restinga de Jurubatiba National Park, Rio de Janeiro, Brazil. During this period, observations on the biology and behavior of the species were also conducted in the field and in laboratory. The female lays single eggs on young stems of its host plant and covers them with feces, building an excremental shell. The hatched larva remains within it and adds more of its own feces to the case as it grows. After a maximum of four months, the larva pupates within the case, which remains closed for another four months before adult emergence. Diapause seems to occur in the adult stage inside the pupal case before emergence. Fulcidax monstrosa is a univoltine species and showed a highly seasonal distribution along the years for all stages of development. Climatic factors as well as resource availability are suggested to influence the species seasonality.

Relative Fitness of Cry1A-Resistant and -Susceptible <I>Helicoverpa armigera</I> (Lepidoptera: Noctuidae) on Conventional and Transgenic Cotton

Glasshouse and laboratory experiments were conducted to evaluate the relative fitness of Cry1A-susceptible and laboratory-selected resistant strains of Helicoverpa armigera (Hübner). Life history parameters of H. armigera larvae feeding on young cotton plants showed a significant developmental delay of up to 7 d for the resistant strain compared with the susceptible strain on non-Bacillus thuringiensis (Bt) cotton. This fitness cost was not evident on artificial diet. There was no developmental delay in the F1 hybrid progeny from the reciprocal backcross of the resistant and susceptible strains, indicating that the fitness cost is recessive. In two cohorts tested, survival to pupation of resistant larvae on Bt cotton expressing Cry1Ac was 54 and 51% lower than on non-Bt cotton, whereas all susceptible and F1 larvae tested on Cry1Ac cotton were killed. Mortality of susceptible larvae occurred in the first or second instar, whereas the F1 larvae were able to develop to later instars before dying, demonstrating that resistance is incompletely recessive. The intrinsic rate of increase was reduced by >50% in the resistant strain on Cry1Ac cotton compared with the susceptible strain on non-Bt cotton. There was a significant reduction in the survival of postdiapausal adults from the resistant strain and the F1 strains, indicating that there is a nonrecessive overwintering cost associated with Cry1A resistance in H. armigera.

Diapause Termination in Overwintering Larvae of a Greek Strain ofAdoxophyes orana(Lepidoptera: Tortricidae)

The course of diapause development under field conditions for diapausing larvae of Adoxophyes orana (F.v.R.) (Lepidoptera: Tortricidae) was investigated. Larvae of A. orana were collected during the winter and early spring from 1996 to1999 from peach and cherry trees in the area of Naousa in northern Greece. Each larva was placed individually in a plastic cylindrical cell with a piece of artificial diet at 20°C under long-day (16:8 L:D) or short-day photoperiods (8:16 L:D). Photoperiod had a significant influence on diapause development. Duration in days, from transfer from the orchard to the laboratory until first molt and pupation of larvae, was also significantly affected by sampling date. Photoperiodic sensitivity was no longer detected after late January. Short-day photoperiod maintained diapause for larvae sampled until late January. Thus, A. orana may complete diapause development in late January, but it will not break diapause until spring, when temperatures are sufficiently high to induce diapause break.

Biological warfare in the garden pond: tadpoles suppress the growth of mosquito larvae

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.

Oviposition by introduced Ophelimus eucalypti (Hymenoptera: Eulophidae) and morphogenesis of female-induced galls on Eucalyptus saligna(Myrtaceae) in New Zealand.

An Australian gall-inducing eulophid, Ophelimus eucalypti (Gahan) was first recorded on the foliage of Eucalyptus botryoides after it invaded New Zealand in 1987. It has spread throughout the eucalypt plantations in the North Island and in the northern parts of the South Island affecting several species of Eucalyptus in the section Transversaria (subgenus Symphyomyrtus). Because gall-inducing insects usually have extremely narrow host ranges, O. eucalypti that induces galls on E. saligna and E. botryoides is currently recognized as a biotype, O. eucalypti(Transversaria). Heavily galled leaves abscise from the plant. Repeated defoliation led to widespread die-back of susceptible eucalypt species in the 1990s. Female larvae of O. eucalypti induce circular, protruding galls on the leaves of E. botryoides and E. saligna, whereas the males induce pit galls on the same species. The biology of O. eucalypti females and the development of their galls are described. Adult female O. eucalypti antennate the leaf surface before inserting the ovipositor (otherwise concealed within the metasomal apex) into the young host leaf. The egg is inserted at approximately 45 degrees and discharged between differentiating palisade cells. Callus-type cells surround the egg chamber, but cytologically specialized nutritive cells appear once the egg hatches and the larva begins to feed. The gall also differentiates a multi-layered sclerenchymatous tissue around the nutritive tissue. After feeding for many months, the larva pupates and the active nutritive tissue degenerates. The adult wasp emerges after cutting an exit hole through to the outside of the gall. Abscission of heavily galled leaves results in widespread defoliation and loss of growth and vigour in susceptible trees in New Zealand.

Compatibility of Spinosad, Tebufenozide and Azadirachtin with Eggs and Pupae of the Predator Chrysoperla carnea (Stephens) Under Laboratory Conditions

Under laboratory conditions, the toxicity of three novel insecticides, spinosad (Tracer ® ), tebufenozide (Mimic ® ) and azadirachtin (Align ® ), was tested against eggs and pupae of the predator Chrysoperla carnea (Stephens). In a first series of assays, eggs were dipped in an aqueous concentration and no ovicidal activity was scored for the three insecticides. In the second, when females were ovipositing on treated substrate for 24 h, fecundity and hatching percentages were similar as compared to controls and the offspring developed normally until the adult stage. However, spinosad, at the highest concentrations tested, caused a slight, significant reduction in the adult life span and fecundity. In a third series of experiments, pupae developed into normal adults after topical treatment for the three insecticides. Herewith, a pharmacokinetic study indicated low accumulation in the body after pupal cuticle penetration when administrating 14 C-labelled insecticide. Fourthly, pupation of last-instar larvae in treated substrate was normal for spinosad and tebufenozide. Only azadirachtin caused a slight reduction in the number of pupae and adults; however, fecundity and fertility of surviving adults was normal. In conclusion, the current results indicate that the three insecticides are not toxic to eggs and pupae of C. carnea .

Effect of starvation and feeding of larvae during 4th stadia on pupation and adult size in Dacne picta (Coleoptera: Erotylidae).

The effects of feeding and starvation during the 4th larval stadium on the later development of Dacne picta (Coleoptera: Erotylidae) were observed by rearing under various diet regimens on dried fruiting bodies of shiitake mushroom, Lentinula edodes. When the food was removed after different durations of feeding, pupation occurred at ca. 7 d after removal of the food resource irrespective of the duration of the feeding period. The body size of eclosed adults increased with longer feeding periods. We investigated the feeding response of larvae provided mushrooms as food after different durations of initial feeding and starvation periods. Two responses were observed. Larvae either resumed feeding on the mushrooms (re-feeding individuals) or did not resume feeding (non re-feeding individuals), and these patterns resulted in large and small adult size, respectively. Re-feeding during the larval stage only influenced the body size of individuals which had had short initial feeding and starvation periods, and the percentage of re-feeding individuals also decreased with the protraction of the initial feeding and starvation periods. Adult body size of non re-feeding individuals decreased with protraction of the starvation period between feedings. This indicates that the pupation of larvae depends on larval mass and duration of the starvation period. The threshold larval size of males at metamorphosis was significantly smaller than that of females. This pattern of larval growth and pupation of the beetles would be advantageous when completing immature development on a short-lasting food resource. Further, such size dependent pupation of larvae would result in larger size of females than males, and synchronization of pupation and eclosion.

Regulation of development of the grain beetle Tenebrio molitor by neuropeptides

Summary Two neuropeptides (NPs), hydra head activator (HHA), and the luteinizing hormone releasing hormone (LHRH), were used to study their effects on the development of the larvae of the grain beetle Tenebrio molitor (mealworms). The larvae received the NPs in the course of development at the beginning or at the end of instar. The LHRH given at the beginning of the instar stimulated molting and pupation in larvae; it did not affect molting in the late period of the instar. The C-end fragment of LHRH(9–10) produced fewer molts and increased the duration of the instar period. The effect of this fragment was weak when it was injected at the initial period of the instar; it was considerably stronger in the end of the instar. It inhibited development when administered during the last instar. On the contrary, the N-end fragment of the LHRH(1–2) stimulated growth and development of larvae. The action of these NPs can be connected to the function of the hormones of metamorphosis. The HHA administrated to the larvae at different days of the instar stimulated molting but in the last instar it delayed pupation. The C-end of the HHA(7–11) stimulated molting when injected during the whole period of the instar. The other C-end fragments, the HHA(8–11) and HHA(9–11) had inhibitory effects on the molting. The injection of the N-end fragment of the HHA(1–5) had no effect. The action of HHA and its fragments did not correlate with the function of the hormones of metamorphosis.

Residual susceptibility of fifth instar Plodia interpunctella to cyfluthrin wettable powder

Wandering-phase fifth instar Plodia interpuntella (Hübner) were exposed at 3-week intervals for 0.5, 1, 2, and 4 h on concrete treated with sprays of 100, 150, and 200 mg 20% cyfluthrin wettable powder (WP) per m 2 over a 15-week period. Pupation rate and adult emergence were not significantly different ( P≥0.05) with respect to exposure interval at any application rate. Of the larvae exposed at week 0 (1 day after treatment) on concrete treated with 100 mg per m 2 cyfluthrin WP, 8.7±3.8% reached the pupal stage and 3.8±1.5% emerged as adults, but adult emergence at all subsequent weeks was at least 63.8%. No adults emerged from larvae exposed at week 0 or week 3 on concrete treated with 150 mg cyfluthrin WP per m 2. Pupation and adult emergence for larvae exposed at week 0 on concrete treated with 200 mg cyflutrhin WP per m 2 was 12.7±6.8 and 11.4±6.6%, respectively, but adult emergence at week 3 was only 1.9±1.0%. Residual control, defined as the time when pupation and adult emergence were less than 10%, exceeded 3-week only at the intermediate label rate of 150 mg cyfluthrin WP per m 2.

Evidence for two juvenile hormone esterase-related genes in the Colorado potato beetle.

Juvenile hormone esterase (JHE) activity in the haemolymph of the Colorado potato beetle is necessary to initiate pupation in larvae as well as diapause in adults. The enzyme appears in the haemolymph as a dimer consisting of two 57 kDa subunits. The sequence of an encoding cDNA, JHE.A, is distinct from lepidopteran JHEs. In this study, RT-PCR using primers designed on the basis of the 5'- and 3'-ends of the coding region revealed the existence of a related gene, JHE.B. The presence of two JHE-related genes was also shown by PCR amplification on genomic DNA from different individual beetles followed by restriction enzyme analysis. Both forms, probably paralogues, were transcribed since they could be amplified on messenger RNA from fat bodies. The size of the PCR products generated with mRNA and genomic DNA were both 1.6 kb, suggesting the absence of introns in the genomic JHE coding sequence. The sequence of a genomic clone, which encoded JHE.B, was 77% identical and 82% similar in amino acids compared to JHE.A. No introns were found in the coding sequence of these coleopteran JHE-related genes, in contrast to lepidopteran JHE genes. Southern blot analysis of digested genomic DNA confirmed the presence of two JHE-related genes.

Growth-blocking peptide expressed in the insect nervous system--cloning and functional characterization.

Growth-blocking peptide (GBP) is an insect biogenic peptide that retards larval growth and, consequently, delays the onset of pupation of lepidopteran larvae. Transcription of the GBP gene has been proven to be regulated in a tissue-dependent manner by an approximately 0.8-kb mRNA transcript in fat body and 2.5-kb transcript in the brain central nervous system (CNS) [Hayakawa, Y., Ohnishi, A., Yamanaka, A., Izumi, S. & Tomino, S. (1995) FEBS Lett. 367, 185-189]. The GBP cDNA in the brain CNS was isolated, sequenced and found to be almost identical with that in the fat body, except that it encodes a long 5'-untranslated region (approximately 1.1 kb), thus indicating that the brain CNS is synthesized as a polyprotein precursor and released through posttranslational processing in the same manner as that predicted in the fat body. Sequence analyses of the genomic GBP gene fragments demonstrated that the 5'-untranslated region contains an intron encoding a sequence element, TGATAA, which has been reported to be important for expression in the insect larval fat body, suggesting that this element contributes to a tissue-specific expression of the shorter GBP mRNA in fat body. Ribonuclease protection assays showed that parasitization by a parasitic wasp elevated the expression of GBP mRNA in brain CNS. The parasitization-induced increase of GBP precursor and GBP concentrations was also demonstrated in brain CNS. Brain CNS dopamine was increased eightfold by incubating the tissue with GBP for 8 h through the elevation of dopa decarboxylase activity by a transcriptional enhancement perhaps due to GBP-induced increase of cytoplasmic Ca2+ concentration. Dopamine elevation reduced in vitro incorporation of methionine into proteins synthesized in brain CNS.

Larval Survival and Development of the Fall Armyworm (Lepidoptera: Noctuidae) on Normal and Transgenic Cotton Expressing the Bacillus Thuringiensis CryIA (c) δ-endotoxin

Survival and development of fall armyworms, Spodoptera frugiperda (J. E. Smith), on leaves and bolls of normal (variety DP 5415) and transgenic cotton plants, Gossypium hirsutum L., expressing the Bacillus thuringiensis Berliner (Bt) CryIA(c) -endotoxin (variety NuCOTN 33B) were examined. No significant differences were observed in larval survival between the 2 varieties at 2, 4, 6, 8, 10, and 12 d after exposure. In addition, no significant differences were observed between varieties in the number of larvae that pupated and eclosed as adults. However, larval weights of fall armyworms were significantly higher at 6 and 12 d after exposure on DP 5415 leaves than NuCOTN 33B leaves, and time to pupation and adult eclosion were significantly shorter on DP 5415 leaves than on NuCOTN 33B leaves. No significant differences between varieties were observed for sex ratio, but neonate survival of the subsequent generation was significantly lower from insects reared on NuCOTN 33B.Larval survival to pupation and adult eclosion for larvae fed a combination of DP 5415 foliage (early instars) and bolls (late instars) were significantly higher than for larvae fed NuCOTN 33B foliage and bolls. The effects of a single generation selection of fall armyworms on NuCOTN 33B leaves were also measured. Fall armyworms originally reared on DP 5415 and NuCOTN 33B were fed either normal (DP 5690) or transgenic Bt cotton (NuCOTN 35B ) leaves. Larval survival at 2, 4, 6 d after exposure and adult survivorship were not significantly affected by 1 generation of rearing on transgenic Bt cotton. Single generation exposure to NuCOTN 33B did not affect larval weights of the subsequent generation when reared on transgenic Bt cotton.

Peanut Fungicides: Effect on Survival and Development of the Corn Earworm, Fall Armyworm, and Velvetbean Caterpillar1

Abstract The fungicides chlorothalonil, tebuconazole, and propiconazole commonly used for control of peanut diseases were evaluated for activity against the corn earworm [Helicoverpa zea (Boddie)], fall armyworm [Spodoptera frugiperda (J. E. Smith)], and velvetbean caterpillar (Anticarsia gemmatalis Hübner). Chlorothalonil most adversely affected early establishment and survival of neonates of all three insect species on peanut terminal buds. Chlorothalonil also decreased the weight of larvae of all three species at 10 d and extended the time to pupation for fall armyworm and velvetbean caterpillar larvae. Similarly, tebuconazole adversely affected early survival and establishment, decreased 10-d weight and extended time to pupation of corn earworm and velvetbean caterpillar larvae, but had little effect on fall armyworm larvae. Propiconazole had no effect on establishment and survival of corn earworm and fall armyworm larvae on peanut terminals, and actually increased the weight of 10-d-old larvae for all three insects over that recorded for the untreated control. Orthogonal comparisons of the activity of five chlorothalonil-based fungicides against the fall army-worm showed that the activity was due to chlorothalonil rather than to formulation. At equivalent concentrations used in the field, Bravo Ultrex® was significantly more active against larvae of the fall armyworm than was a comparable concentration of Bravo 72®. However, regression lines did not differ for the two fungicides for any of the developmental parameters measured when larvae of all three species were fed different concentrations of Bravo 720® and Bravo Ultrex® in their meridic diet.

Wandering speed and time, and location for the pupation of fully-grown larvae of the Indian-meal moth, Plodia interpunctella H.

Wandering speed and time, and location for the pupation of fully-grown larvae of the Indian-meal moth, <i>Plodia interpunctella</i> H.