RESUMEN

Helicoverpa armigera, the cotton bollworm moth, is one of the world's most important crop pests, and is spreading throughout the New World from its original range in the Old World. In Brazil, invasive H. armigera has been reported to hybridize with local populations of Helicoverpa zea. The correct identification of H. armigera-H. zea hybrids is important in understanding the origin, spread and future outlook for New World regions that are affected by outbreaks, given that hybridization can potentially facilitate H. zea pesticide resistance and host plant range via introgression of H. armigera genes. Here, we present a genome admixture analysis of high quality genome sequences generated from two H. armigera-H. zea F1 hybrids generated in two different labs. Our admixture pipeline predicts 48.8% and 48.9% H. armigera for the two F1 hybrids, confirming its accuracy. Genome sequences from five H. zea and one H. armigera that were generated as part of the study show no evidence of hybridization. Interestingly, we show that four H. zea genomes generated from a previous study are predicted to possess a proportion of H. armigera genetic material. Using unsupervised clustering to identify non-hybridized H. armigera and H. zea genomes, 8511 ancestry informative markers (AIMs) were identified. Their relative frequencies are consistent with a minor H. armigera component in the four genomes, however its origin remains to be established. We show that the size and quality of genomic reference datasets are critical for accurate hybridization prediction. Consequently, we discuss potential pitfalls in genome admixture analysis of H. armigera-H. zea hybrids, and suggest measures that will improve such analyses.

RESUMEN

BACKGROUND: Biogenic metallic and oxide metal nanoparticles have potential as alternatives for several current problems in agriculture, such as the control of caterpillars which cause huge losses in the production of important crops. In the present study, capped and uncapped silver, iron oxide and titanium dioxide nanoparticles were synthesized from the filtrate of Beauveria bassiana and evaluated in regard to physico-chemical characteristics, capping composition, cytotoxicity, genotoxicity and biological activity on Helicoverpa armigera and Spodoptera frugiperda caterpillars. RESULTS: A difference in the physico-chemical parameters of the capped and uncapped nanoparticles was observed, with larger aggregation and lower stability of the uncapped. In regard to the study of the capping, the presence of functional groups of biomolecules as well as the activity of B. bassiana hydrolytic enzymes were observed. Cytotoxic effects on the tested cell lines were not observed and DNA damage levels increased with more intense effects of the uncapped nanoparticles. In regard to the biological activity against Noctuidae pests, the uncapped and capped iron oxide, and uncapped titanium dioxide nanoparticles occasioned higher mortality (76%, 60% and 51%, respectively) but no differences in LC50 were recorded. Moreover, sublethal effects were reported on Helicoverpa armigera whereas Spodoptera frugiperda showed low susceptibility to the nanoparticles. CONCLUSION: The results demonstrate that biogenic metallic and oxide metal nanoparticles might show promising effects for the control of caterpillars which cause damage on important agricultural crops. Further investigations are necessary to understand the mechanisms of action and optimize the biological activity of these new nanomaterials. © 2023 Society of Chemical Industry.

Asunto(s)

RESUMEN

Enhancement of plant defense by exogenous elicitors is a promising tool for integrated pest management strategy. In the present study, cotton plants were treated with different concentrations (0, 0.01, 0.1, and 1.0 mM) of the natural plant defense elicitor, jasmonic acid (JA), and defense-related indicators in the plants were then determined. The cotton bollworm larvae were fed with JA-treated cotton leaves and larvae performances were discussed in terms of larvae relative growth rate (RGR), larval duration, pupal mass, humoral immunity, and activities of a target enzyme, three detoxification enzymes and two metabolic enzymes. Research results showed that JA treatment increased the contents of gossypol and H2O2, and decreased that of the total soluble carbohydrates, and 0.1 mM JA was more powerful in the induction of defense-related parameters. As a consequence, cotton bollworm larvae reared on JA-treated cotton leaves showed slower RGR, prolonged larvae duration, and decreased pupal mass. In addition, when larvae were fed with JA-treated cotton leaves, activities of phenoloxidae (an indicator of humoral immunity) and acetylcholinesterase (AchE, a target enzyme), alkaline phosphatases (ALP), acidic phosphatase (ACP), and three detoxification enzymes, carboxylesterase (CarE), glutathione S-transferase (GST), and cytochrome P450 (P450), were all reduced compared to the control. Taken together, the results suggest that JA can be an alternative agent for pest management by delaying insect growth and inhibiting immune defense and detoxification capacity of the cotton bollworm, which may reduce the use of synthetic pesticides.

Asunto(s)

RESUMEN

Leaf cuticular wax plays important role in host selection, oviposition, and feeding of phytophagous insects. Thus, the role of cuticular wax of sesame (Sesamum indicum) cultivars (Savitri and Nirmala) in host selection of 3 generalist pests (Spilosoma obliqua Walker, Helicoverpa armigera Hübner, and Spodoptera litura Fabricius) was investigated under laboratory conditions. The GC-MS and GC-FID analyses of leaf surface waxes of both cultivars indicated the presence of 14 n-alkanes from n-C9 to n-C44 and 12 free fatty acids (FFAs) from C9:0 to C20:0. The most predominant n-alkane and FFA of the cultivars were n-C26 (94.3 ± 7.27 µg leaf-1) and C18:1 (110.8 ± 10.07 µg leaf-1), respectively present in Savitri cultivar. The generalists used visual (color and shape), olfactory (odorous n-alkanes and FFAs), tactile (surface ultra-structure), and gustatory (cuticular wax) cues in a synergistic manner for their host selection through attraction (adults and larvae) followed by oviposition (adults) and feeding (larvae) on studied cultivars (Savitri > Nirmala). Their olfactory responses were maximum towards 2 leaf equivalent amount, whereas oviposition and feeding preference were maximum towards 4 leaf equivalent amount of the combined synthetic (4 n-alkanes (n-C16, n-C22, n-C24, n-C26) + 3 FFAs (C12:0, C14:0, C18:1)) mixture-treated intact leaf of cultivar Savitri. This finding can suggest that the synthetic blend (4 n-alkanes + 3 FFAs) in leaf equivalent amount (396.6 ± 4.13 µg leaf-1) or more from cultivar Savitri can be used as lures to develop baited trap. In addition, the cultivar Nirmala can be used as a resistant cultivar in the ecological pest management (EPM) framework of these target pest species.

Asunto(s)

RESUMEN

Helicoverpa armigera is a major insect pest of several crops worldwide. This insect is susceptible to some Bacillus thuringiensis (Bt) Cry insecticidal proteins expressed in transgenic crops or used in biopesticides. Previously, we identified H. armigera prohibitin (HaPHB) as a Cry1Ac-binding protein. Here, we further analyzed the potential role of PHB as a Cry toxin receptor in comparison to cadherin (CAD), well recognized as a Cry1Ac receptor. HaPHB-2 midgut protein and HaCAD toxin-binding region (TBR) fragment from H. armigera were expressed in Escherichia coli cells, and binding assays with different Cry1 toxins were performed. We demonstrated that Cry1Ab, Cry1Ac, and Cry1Fa toxins bound to HaPHB-2 in a manner similar to that seen with HaCAD-TBR. Different Cry1Ab mutant toxins located in domain II (Cry1AbF371A and Cry1AbG439D) or domain III (Cry1AbL511A and Cry1AbN514A), which were previously characterized and found to be affected in receptor binding, were analyzed regarding their binding interaction with HaPHB-2 and toxicity against H. armigera One ß-16 mutant (Cry1AbN514A) showed increased binding to HaPHB-2 that correlated with 6-fold-higher toxicity against H. armigera, whereas the other ß-16 mutant (Cry1AbL511A) was affected in binding to HaPHB-2 and lost toxicity against H. armigera Our data indicate that ß-16 from domain III of Cry1Ab is involved in interactions with HaPHB-2 and in toxicity. This report identifies a region of Cry1Ab involved in binding to HaPHB-2 from a Lepidoptera insect, suggesting that this protein may participate as a novel receptor in the mechanism of action of the Cry1 toxins in H. armigeraIMPORTANCEHelicoverpa armigera is a polyphagous pest that feeds on important crops worldwide. This insect pest is sensitive to different Cry1 toxins from Bacillus thuringiensis In this study, we analyzed the potential role of PHB-2 as a Cry1 toxin receptor in comparison to CAD. We show that different Cry1 toxins bound to HaPHB-2 and HaCAD-TBR similarly and identify ß-16 from domain III of Cry1Ab as a binding region involved in the interaction with HaPHB-2 and in toxicity. This report characterized HaPHB-Cry1 binding interaction, providing novel insights into potential target sites for improving Cry1 toxicity against H. armigera.

Asunto(s)

RESUMEN

A lagarta Helicoverpa armigera ocorre desde a emergência das plantas até a fase reprodutiva da cultura da soja, podendo causar perdas expressivas. Como praga inicial, podem ser encontradas tanto lagartas neonatas como lagartas mais desenvolvidas, estas últimas provenientes da cultura anterior. O uso de cultivares Bt e de inseticidas em tratamento de sementes são alternativas para manejo da praga no início do desenvolvimento da soja, porém existem dúvidas sobre a eficácia destes métodos de controle. Dessa forma, objetivou-se avaliar o efeito protetivo de inseticidas aplicados às sementes e da proteína Cry 1Ac, em relação ao ataque da lagarta H. armigera, como praga inicial em plantas de soja. Os resultados comprovam que, em condições de laboratório, os inseticidas ciantraniliprole (60 g i.a./100 kg de sementes) e clorantraniliprole (62,5 g i.a./100 kg de sementes) protegem a soja em relação às injúrias das lagartas de H. armigera de 3º-4º instares, em cotilédones e folhas unifolioladas e trifolioladas, aos 5 dias após a emergência das plantas. A proteína Cry 1Ac protege as plantas de soja desse tipo de injúria causado tanto por lagartas de 3º-4º e como 5º-6º instares, aos 5 e 10 dias após a emergência.

The Helicoverpa armigera caterpillar occurs from the emergence of the plants to the reproductive stage of the soybean crop, which can cause significant losses. As an initial pest, both neonate and more developed caterpillars can be found, the latter from the previous crop.The use of Bt cultivars and insecticides in seed treatment are options to pest management at the beginning of soybean development, but there are doubts about the efficacy of these control methods. Thus, the objective was to evaluate the protective effect of insecticides applied to seeds and Cry 1Ac protein, in relation to the attack of the H. armigera caterpillar, as an initial pest in soybean plants. Our results confirm that under laboratory conditions the insecticides cyantraniliprole (60 g ai / 100 kg of seeds) and chlorantraniliprole (62.5 g ai / 100 kg of seeds) protect the soybean against the injuries of H. armigera 3º-4º instars, in cotyledons and unifoliolate and trifoliolate leaves, at 5 days after the emergence of the plants. The protein Cry 1Ac protects the soybean plants from this type of injury caused by both 3rd-4th and 5th-6th instars caterpillars, at 5 and 10 days after emergence.

Asunto(s)

RESUMEN

A lagarta Helicoverpa armigera ocorre desde a emergência das plantas até a fase reprodutiva da cultura da soja, podendo causar perdas expressivas. Como praga inicial, podem ser encontradas tanto lagartas neonatas como lagartas mais desenvolvidas, estas últimas provenientes da cultura anterior. O uso de cultivares Bt e de inseticidas em tratamento de sementes são alternativas para manejo da praga no início do desenvolvimento da soja, porém existem dúvidas sobre a eficácia destes métodos de controle. Dessa forma, objetivou-se avaliar o efeito protetivo de inseticidas aplicados às sementes e da proteína Cry 1Ac, em relação ao ataque da lagarta H. armigera, como praga inicial em plantas de soja. Os resultados comprovam que, em condições de laboratório, os inseticidas ciantraniliprole (60 g i.a./100 kg de sementes) e clorantraniliprole (62,5 g i.a./100 kg de sementes) protegem a soja em relação às injúrias das lagartas de H. armigera de 3º-4º instares, em cotilédones e folhas unifolioladas e trifolioladas, aos 5 dias após a emergência das plantas. A proteína Cry 1Ac protege as plantas de soja desse tipo de injúria causado tanto por lagartas de 3º-4º e como 5º-6º instares, aos 5 e 10 dias após a emergência.(AU)

The Helicoverpa armigera caterpillar occurs from the emergence of the plants to the reproductive stage of the soybean crop, which can cause significant losses. As an initial pest, both neonate and more developed caterpillars can be found, the latter from the previous crop.The use of Bt cultivars and insecticides in seed treatment are options to pest management at the beginning of soybean development, but there are doubts about the efficacy of these control methods. Thus, the objective was to evaluate the protective effect of insecticides applied to seeds and Cry 1Ac protein, in relation to the attack of the H. armigera caterpillar, as an initial pest in soybean plants. Our results confirm that under laboratory conditions the insecticides cyantraniliprole (60 g ai / 100 kg of seeds) and chlorantraniliprole (62.5 g ai / 100 kg of seeds) protect the soybean against the injuries of H. armigera 3º-4º instars, in cotyledons and unifoliolate and trifoliolate leaves, at 5 days after the emergence of the plants. The protein Cry 1Ac protects the soybean plants from this type of injury caused by both 3rd-4th and 5th-6th instars caterpillars, at 5 and 10 days after emergence.(AU)

Asunto(s)

RESUMEN

The bacterium Bacillus thuringiensis produces insecticidal Vip3 proteins during the vegetative growth phase with activity against several lepidopteran pests. To date, three different Vip3 protein families have been identified based on sequence identity: Vip3A, Vip3B, and Vip3C. In this study, we report the construction of chimeras by exchanging domains between Vip3Aa and Vip3Ca, two proteins with marked specificity differences against lepidopteran pests. We found that some domain combinations made proteins insoluble or prone to degradation by trypsin as most abundant insect gut protease. The soluble and trypsin-stable chimeras, along with the parental proteins Vip3Aa and Vip3Ca, were tested against lepidopteran pests from different continents: Spodopteraexigua, Spodopteralittoralis, Spodopterafrugiperda,Helicoverpaarmigera, Mamestrabrassicae, Anticarsiagemmatalis, and Ostriniafurnacalis. The exchange of the Nt domain (188 N-terminal amino acids) had little effect on the stability and toxicity (equal or slightly lower) of the resulting chimeric protein against all insects except for S.frugiperda, for which the chimera with the Nt domain from Vip3Aa and the rest of the protein from Vip3Ca showed a significant increase in toxicity compared to the parental Vip3Ca. Chimeras with the C-terminal domain from Vip3Aa (from amino acid 510 of Vip3Aa to the Ct) with the central domain of Vip3Ca (amino acids 189-509 based on the Vip3Aa sequence) made proteins that could not be solubilized. Finally, the chimera including the Ct domain of Vip3Ca and the Nt and central domain from Vip3Aa was unstable. Importantly, an insect species tolerant to Vip3Aa but susceptible to Vip3Ca, such as Ostriniafurnacalis, was also susceptible to chimeras maintaining the Ct domain from Vip3Ca, in agreement with the hypothesis that the Ct region of the protein is the one conferring specificity to Vip3 proteins.

Asunto(s)

RESUMEN

Abstract Development of transgenic Bt crops with stable and high level of Bt protein expression over generations under different environmental conditions is critical for successful deployment at field level. In the present study, progenies of transgenic cotton Coker310 event, CH12 expressing novel cry2AX1 gene were evaluated in T3 generation for stable integration, expression and resistance against cotton bollworm, Helicoverpa armigera. The cry2AX1 gene showed stable inheritance and integration in the T3 progeny plants as revealed by PCR and Southern blot hybridization. The expression of Cry2AX1 protein on 90 days after sowing (DAS) was in the range of 1.055 to 1.5 µg/g of fresh leaf tissue except one plant which showed 0.806 µg/g of fresh leaf tissue and after 30 days (i.e., on 120 DAS) three plants recorded in between 0.69 to 0.82 µg/g and other plants are in range of 0.918 to 1.058 µg/g of fresh leaf tissue. Detached leaf bit bioassay in T3 progeny on 110 DAS recorded mortality of 73.33 to 93.33 per cent against H. armigera and severe growth retardation in surviving larvae. These results indicate that the expression of chimeric cry2AX1 is stable and exhibits insecticidal activity against H. armigera in T3 progeny of CH12 event of transgenic cotton.

Asunto(s)

RESUMEN

Horizontal transmission of Helicoverpa armigera nucleopolyhedrovirus (HearNPV) has been found to occur through several pathways involving abiotic factors such as soil, wind, and rain, and biotic factors such as predators, parasitoids, and infected hosts. Previous studies examining horizontal transmission through certain biological carriers speculated they were likely not significant in increasing infection rates, however; these studies only focused on a relatively small number of arthropods present within a field setting. This study was conducted to evaluate the horizontal transmission potential of HearNPV by all potential biological carriers when applied as a foliar bioinsecticide or as virus-infected, nonmotile Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) larvae in a soybean field. Soybean plots were either sprayed with HearNPV or infested with late-stage HearNPV-infected larvae, and sample zones were sampled 3, 7, 10, 14, 17, and 21 days after the infestation, and analyzed for viral presence using PCR. We then identified HearNPV carriers through contamination from the application (involuntary) or through contact with a HearNPV-infected larva (voluntary). Both were confirmed through PCR analysis. Regardless of application technique, on average, HearNPV was capable of disseminating up to 61.0 m in 3 d after inoculation and was found within the sampled canopy 13-21 d after inoculation. Several arthropods were identified as novel carriers of HearNPV. Results from this study indicate that many novel HearNPV carriers are likely important in disseminating HearNPV.

Asunto(s)

RESUMEN

The cotton bollworm Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is a widespread pest of many cultivated and wild plants in Europe, Africa, Asia, and Australia. In 2013, this species was reported in Brazil, attacking various host crops in the midwestern and northeastern regions of the country and is now found countrywide. Aiming to understand the effects of different host plants on the life cycle of H. armigera, we selected seven species of host plants that mature in different seasons and are commonly grown in these regions: cotton (Gossypium hirsutum, "FM993"), corn (Zea mays, "2B587"), soybean (Glycine max, "99R01"), rattlepods (Crotalaria spectabilis), millet (Pennisetum glaucum, "ADR300"), sorghum (Sorghum bicolor, "AGROMEN70G35"), and cowpea (Vigna unguiculata, "SEMPRE VERDE"). The development time of immatures, body weight, survivorship, and fecundity of H. armigera were evaluated on each host plant under laboratory conditions. The bollworms did not survive on corn, millet, or sorghum and showed very low survival rates on rattlepods. Survival rates were highest on soybean, followed by cotton and cowpea. The values for relative fitness found on soybean, cotton, cowpea, and rattlepods were 1, 0.5, 0.43, and 0.03, respectively. Survivorship, faster development time, and fecundity on soybean, cotton, and cowpea were positively correlated. Larger pupae and greater fecundity were found on soybean and cotton. The results indicated that soybean, cotton, and cowpea are the most suitable plants to support the reproduction of H. armigera in the field.

Asunto(s)

RESUMEN

Newly developed Phytopesticidal formulations from pongam and neem oils were evaluated for their feeding deterrent activity using leaf disc choice and no-choice methods, and genotoxic study using comet assay against Helicoverpa armigera at different concentrations of 5, 10, 15, and 20 ppm. Among various phytopesticidal formulations, neem and pongam oils at 1:1 ratio, called PONNEEM showed significant feeding deterrent activity against H. armigera at 20 ppm concentration and wasgenotoxic to H. armigera (P>0.001). The comet parameters, namely tail moment (arbitrary units), tail length (µm) and tail DNA (%) were observed at all the concentrations of PONNEEM. Statistically significant changes in all the comet parameters of H. armigera were observed at 20 ppm (P<0.001). Feeding deterrent and genotoxicity effect of PONNEEM could be applied as phytopesticide for controlling the lepidopteran insect pests.

RESUMEN

This research was carried out to examine cytopathological effects of Helicoverpa armigera Cytoplasmic polyhedrosis virus (HaCPV) on infected midgut cotton bollworm (Helicoverpa armigera) using transmission and scanning electron microscope. The symptoms on infected host larvae of the host, compared with healthy ones, were getting swollen with milky-white and fragile Histopathological examinations showed infection with HaCPV small polyhedral inclusion bodies (PIB) after 1 or 2 days which were observed in columnar cells of midgut. Virions were partially or completely occupied in a polyhedral matrix to form polyhedral inclusion bodies (PIB) at periphery of virogenic stroma. PIBs were measured 0.5 to 3.5 mm and virions about 46 nm in diameter. Microvilli of infected columnar cells were affected and degenerated immediately prior to rupture of the cell. Some infected columnar cells ruptured to release PIB into the gut lumen 3 days after infection. In addition,PIB were found in goblet cells, 5 or 6 days after infection. Infected goblet cells degenerate to such an extent that only a few of the original microvillus-like cytoplasmic projections and cell organells were left. These cytopathic effects caused in the midgut by HaCPV on cotton bollworm larvae are essentially similar to those have been reported for lepidoperan and dipteran infection by CPV.

Asunto(s)

RESUMEN

This research was carried out to examine cytopathological effects of Helicoverpa armigera Cytoplasmic polyhedrosis virus (HaCPV) on infected midgut cotton bollworm (Helicoverpa armigera) using transmission and scanning electron microscope. The symptoms on infected host larvae of the host, compared with healthy ones, were getting swollen with milky-white and fragile Histopathological examinations showed infection with HaCPV small polyhedral inclusion bodies (PIB) after 1 or 2 days which were observed in columnar cells of midgut. Virions were partially or completely occupied in a polyhedral matrix to form polyhedral inclusion bodies (PIB) at periphery of virogenic stroma. PIBs were measured 0.5 to 3.5 µm and virions about 46 nm in diameter. Microvilli of infected columnar cells were affected and degenerated immediately prior to rupture of the cell. Some infected columnar cells ruptured to release PIB into the gut lumen 3 days after infection. In addition, PIB were found in goblet cells, 5 or 6 days after infection. Infected goblet cells degenerate to such an extent that only a few of the original microvillus-like cytoplasmic projections and cell organells were left. These cytopathic effects caused in the midgut by HaCPV on cotton bollworm larvae are essentially similar to those have been reported for lepidoperan and dipteran infection by CPV.

Asunto(s)

RESUMEN

This research was carried out to examine cytopathological effects of Helicoverpa armigera Cytoplasmic polyhedrosis virus (HaCPV) on infected midgut cotton bollworm (Helicoverpa armigera) using transmission and scanning electron microscope. The symptoms on infected host larvae of the host, compared with healthy ones, were getting swollen with milky-white and fragile Histopathological examinations showed infection with HaCPV small polyhedral inclusion bodies (PIB) after 1 or 2 days which were observed in columnar cells of midgut. Virions were partially or completely occupied in a polyhedral matrix to form polyhedral inclusion bodies (PIB) at periphery of virogenic stroma. PIBs were measured 0.5 to 3.5 mm and virions about 46 nm in diameter. Microvilli of infected columnar cells were affected and degenerated immediately prior to rupture of the cell. Some infected columnar cells ruptured to release PIB into the gut lumen 3 days after infection. In addition,PIB were found in goblet cells, 5 or 6 days after infection. Infected goblet cells degenerate to such an extent that only a few of the original microvillus-like cytoplasmic projections and cell organells were left. These cytopathic effects caused in the midgut by HaCPV on cotton bollworm larvae are essentially similar to those have been reported for lepidoperan and dipteran infection by CPV.

RESUMEN

Australian funnel-web spiders are relatively large primitive hunting spiders. Male Atrax robustus spiders have been responsible for a number of human deaths. Venom was collected from the species Hadronyche infensa (Hickman) [female], H. formidabilis [male and female], H. versuta [female], and A. robustus (Cambridge) [male] and was fractionated by high performance liquid chromatography. This resulted in the isolation and purification of a homologous series of 7 insecticidal peptides of relatively low molecular mass (approximately 4kDa). The amino acid sequences of these toxins consisted of 36 or 37 amino acids and were named atracotoxins. For the major bioassay of these toxins, we used the cotton bollworm, Helicoverpa armigera (Hubner), due to the great damage it causes to crops worldwide. These toxins, when injected subcutaneously into fifth or sixth instar larvae of Helicoverpa armigera,were lethal or caused an apparently irreversible writhing. The toxin from H. versuta venom showed no significant toxicity when subcutaneously injected into newborn mice. One of the toxins was found to have a free acid carboxyl terminus. These toxins have great potential as lead compounds for insecticide design or for incorporation in recombinant baculovirus insecticides.

RESUMEN

Australian funnel-web spiders are relatively large primitive hunting spiders. Male Atrax robustus spiders have been responsible for a number of human deaths. Venom was collected from the species Hadronyche infensa (Hickman) [female], H. formidabilis [male and female], H. versuta [female], and A. robustus (Cambridge) [male] and was fractionated by high performance liquid chromatography. This resulted in the isolation and purification of a homologous series of 7 insecticidal peptides of relatively low molecular mass (approximately 4kDa). The amino acid sequences of these toxins consisted of 36 or 37 amino acids and were named atracotoxins. For the major bioassay of these toxins, we used the cotton bollworm, Helicoverpa armigera (Hubner), due to the great damage it causes to crops worldwide. These toxins, when injected subcutaneously into fifth or sixth instar larvae of Helicoverpa armigera,were lethal or caused an apparently irreversible writhing. The toxin from H. versuta venom showed no significant toxicity when subcutaneously injected into newborn mice. One of the toxins was found to have a free acid carboxyl terminus. These toxins have great potential as lead compounds for insecticide design or for incorporation in recombinant baculovirus insecticides.