Interaction of HaNPVs with two novel insecticides against Helicoverpa armigera Hubner (Noctuidae: Lepidoptera)

Nucleopolyhedrosis viruses can be utilized for effective management of agriculture pests. Their efficacy can be increased if they are mixed with certain insecticides. In the current study, HaNPV was mixed with two insecticides: spinetoram and emamectin benzoate in various combinations and applied to larvae of H. armigera in laboratory conditions. There were a total of 15 combinations of HaNPV with each of the two insecticides in addition to five doses of HaNPV and three doses of insecticides alone. The synergistic and antagonistic effects of combinations were explored. The results revealed that there was synergistic effect of HaNPV @ 0.5 × 10⁹ PIB/ml × Spinetoram @ 40, 20, 10 ml/100 L of water. In case of emamectin benzoate, synergistic effects were recorded at 1 × 10⁹ PIB/ml HaNPV × emamectin benzoate @ 100 ml/100 L of water. However, 0.5 × 10⁹ PIB/ml HaNPV has synergistic effects with all three doses of emamectin benzoate. The results suggested that HaNPV can be used in combination with spinetoram and emamectin benzoate for the management of resistant population of H. armigera.     

Heterochrony in cotton bollworm, Earias vitella (Fb) following ethoxyprecocene administration

Administration of a synthetic precocene analogue, 7-ethoxy-6-methoxy-2,2-dimethyl chromene to fourth and last instar larvae of E. vitella results into heterochrony, viz. prothetely and metathetely. These disturbances are due to interference with the endocrine system and application of juvenile hormone to treated larvae abolishes the effect of ethoxyprecocene.     

Effects of neem-based insecticides on beet armyworm （Lepidoptera： Noctuidae）

Abstract Three commercial neem [ Azadirachta indica A. Juss (Meliaceae)]-based insecticides, Agroneem, Ecozin, and Neemix, and a non-commercial neem leaf powder, were evaluated for oviposition deterrence, antifeedant effect on larvae, and toxicity to eggs and larvae of the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), on cotton leaves in the laboratory. Oviposition deterrence in no-choice, and two- and fivechoice assays, was observed for the neem-based insecticide treatments when compared with a non-treated control. Neem-based insecticides also deterred feeding by beet armyworm larvae. Direct contact with neem-based insecticides decreased the survival of beet armyworm eggs. Survival of beet armyworm larvae fed for 7 days on leaves treated with neembased insecticides was reduced to 27, 33, 60, and 61% for neem leaf powder, Ecozin, Agroneem, and Neemix, respectively. Possibilities for adoption of neem-based insecticides in commercial cotton for beet armyworm control are discussed.     

Field evaluation of nucleopolyhedrosis virus and some biorational insecticides against Helicoverpa armigera Hubner (Noctuidae: Lepidoptera)

American bolloworm, Helicoverpa armigera Hubner (Noctuidae: Lepidoptera) is considered as a major pest of various crops all over the world. It is mainly controlled by indiscriminate use of synthetic insecticides in the world due to which this pest developed resistance to most of the available insecticides. Therefore, in the current study, the efficacy of virulent strain of HaNPV (0.5 × 10⁹ PIB/ml) alone and in combination with recommended doses of spintoram (20 g/100 L of water) and emamectin benzoate (200 ml/100 L of water) was tested in field. The combination of HaNPV with spintoram and emamectin benzoate 100% reduced the larval population as compared to emamectin benzoate and HaNPV alone. This suggested that the combination of spintoram and emamectin benzoate with HaNPV could be used in field to manage the infestation of H. armigera.     

Efficacy of insecticides of different chemistries against Helicoverpa zea (Lepidoptera: Noctuidae) in transgenic Bacillus thuringiensis and conventional cotton

Six insecticides of different chemistries were evaluated against the cotton bollworm, Helicoverpa zea (Boddie), in non-B.t. (Deltapine 'DP 5415', Deltapine 'DP 5415RR') and transgenic Bacillus thuringiensis (Berliner) (B.t.) (Deltapine 'NuCOTN 33B', Deltapine 'DP 458 B/RR') cotton. In 1998, treatments consisted of three rates each of a pyrethroid (lambda-cyhalothrin), spinosyn (spinosad), carbamate (thiodicarb), pyrrole (chlorfenapyr), oxadiazine (indoxacarb), and avermectin (emamectin benzoate) in a nonirrigated field. In 1999, treatments consisted of three rates each of lambda-cyhalothrin, spinosad, thiodicarb, and indoxacarb in an irrigated and a nonirrigated (dryland) field. The highest rate of each insecticide corresponded to normal grower-use rates. Spinosad and thiodicarb controlled H. zea in non-B.t. cotton, whereas other materials were less effective. Even though H. zea is becoming increasingly resistant to pyrethroid insecticides, lambda-cyhalothrin was highly effective in dryland B. thuringiensis cotton. Spinosad and thiodicarb were equally effective. Data indicated that reduced rates of lambda-cyhalothrin, spinosad, and thiodicarb could be used for control of H. zea in dryland B.t. cotton systems. However, reduced rates of these insecticides in a heavily irrigated B.t. cotton system did not provide adequate control.     

Microsatellite variation in Helicoverpa gelotopoeon (Lepidoptera: Noctuidae) populations from Argentina

1. Helicoverpa gelotopoeon (Dyar) (Lepidoptera: Noctuidae) is a polyphagous pest that has been reported causing damage in many agricultural crops such as soybean, chickpea and cotton. This species, together with Helicoverpa zea (Boddie), Helicoverpa armigera (Hübner) and Chloridea virescens (Fabricius), belongs to the Heliothinae complex of economic importance in Northwestern Argentina.
2. Many species in the Heliothinae subfamily have developed resistance to insecticides and insecticidal proteins from Bacillus thuringiensis (Bt). Managing resistance to these control tactics in H. gelotopoeon is of high importance and dependant on knowledge of population genetics of this species.
3. The objective of this study was to evaluate the genetic variability and structure of H. gelotopoeon populations from different host plants and geographic regions of Argentina. Towards this goal, six microsatellite loci were screened across 196 individuals.
4. The results obtained revealed high genetic diversity and lack of clear structure among the populations of H. gelotopoeon studied. This genetic homogeneity between populations from different geographical regions and hosts could be attributed to the long-range migratory capacity of Heliothinae and the generalist behaviour of H. gelotopoeon.

     

In-season changes in resistance to insecticides in Helicoverpa armigera (Lepidoptera: Noctuidae) in India

Discriminating doses of fenvalerate, cypermethrin, quinalphos, and endosulfan were determined with an insecticide-susceptible Helicoverpa armigera (Hübner) strain. In-season changes in insecticide resistance were monitored with discriminating dose assays at weekly intervals throughout the cropping season for 6 yr from 1993 to 1999 in central India. Resistance to pyrethroids was high throughout all seasons. Resistance to 0.75 microg of quinalphos was consistent, with seasonal averages ranging from 23 to 27% survival over the 6 yr. Resistance to 10.0 microg of endosulfan was moderately high at an average of 40-47% survival during 1993-1994 and in 1997-1998. It was lower in 1996-1997 at 27%, and in 1998-1999 at 33%. The weekly monitoring data for all seasons were pooled and the consolidated 6-yr seasonal average profile indicated that resistance to quinalphos and endosulfan was low during September at 21 and 27% survival, respectively, but increased to 28 and 37% by the end of November. Resistance levels to organophosphates and endosulfan increased during the season, depending on the use of these compounds. At almost all monitoring sites, the within-season changes in quinalphos resistance for all seasons through the study period followed a trend similar to that of endosulfan. The results suggest the possibility of cross-resistance between these compounds. Based on this study and the existing information on cotton pest management, we have developed a "window strategy" for cotton pest management with specific emphasis on the management of insecticides for effective control of H. armigera. This strategy has contributed to improved control at reduced costs in extensive trials.     

Use of Bacillus thuringiensis toxins for control of the cotton pest Earias insulana (Boisd.) (Lepidoptera: Noctuidae)

Thirteen of the most common lepidopteran-specific Cry proteins of Bacillus thuringiensis have been tested for their efficacy against newly hatched larvae of two populations of the spiny bollworm, Earias insulana. At a concentration of 100 microg of toxin per milliliter of artificial diet, six Cry toxins (Cry1Ca, Cry1Ea, Cry1Fa, Cry1Ja, Cry2Aa, and Cry2Ab) were not toxic at all. Cry1Aa, Cry1Ja, and Cry2Aa did not cause mortality but caused significant inhibition of growth. The other Cry toxins (Cry1Ab, Cry1Ac, Cry1Ba, Cry1Da, Cry1Ia, and Cry9Ca) were toxic to E. insulana larvae. The 50% lethal concentration values of these toxins ranged from 0.39 to 21.13 microg/ml (for Cry9Ca and Cry1Ia, respectively) for an E. insulana laboratory colony originating from Egypt and from 0.20 to 4.25 microg/ml (for Cry9Ca and Cry1Da, respectively) for a laboratory colony originating from Spain. The relative potencies of the toxins in the population from Egypt were highest for Cry9Ca and Cry1Ab, and they were both significantly more toxic than Cry1Ac and Cry1Ba, followed by Cry1Da and finally Cry1Ia. In the population from Spain, Cry9Ca was the most toxic, followed in decreasing order by Cry1Ac and Cry1Ba, and the least toxic was Cry1Da. Binding experiments were performed to test whether the toxic Cry proteins shared binding sites in this insect. 125I-labeled Cry1Ac and Cry1Ab and biotinylated Cry1Ba, Cry1Ia, and Cry9Ca showed specific binding to the brush border membrane vesicles from E. insulana. Competition binding experiments among these toxins showed that only Cry1Ab and Cry1Ac competed for the same binding sites, indicating a high possibility that this insect may develop cross-resistance to Cry1Ab upon exposure to Cry1Ac transgenic cotton but not to the other toxins tested.     

Use of Bacillus thuringiensis Toxins for Control of the Cotton Pest Earias insulana (Boisd.) (Lepidoptera: Noctuidae)

Thirteen of the most common lepidopteran-specific Cry proteins of Bacillus thuringiensis have been tested for their efficacy against newly hatched larvae of two populations of the spiny bollworm, Earias insulana. At a concentration of 100 μg of toxin per milliliter of artificial diet, six Cry toxins (Cry1Ca, Cry1Ea, Cry1Fa, Cry1Ja, Cry2Aa, and Cry2Ab) were not toxic at all. Cry1Aa, Cry1Ja, and Cry2Aa did not cause mortality but caused significant inhibition of growth. The other Cry toxins (Cry1Ab, Cry1Ac, Cry1Ba, Cry1Da, Cry1Ia, and Cry9Ca) were toxic to E. insulana larvae. The 50% lethal concentration values of these toxins ranged from 0.39 to 21.13 μg/ml (for Cry9Ca and Cry1Ia, respectively) for an E. insulana laboratory colony originating from Egypt and from 0.20 to 4.25 μg/ml (for Cry9Ca and Cry1Da, respectively) for a laboratory colony originating from Spain. The relative potencies of the toxins in the population from Egypt were highest for Cry9Ca and Cry1Ab, and they were both significantly more toxic than Cry1Ac and Cry1Ba, followed by Cry1Da and finally Cry1Ia. In the population from Spain, Cry9Ca was the most toxic, followed in decreasing order by Cry1Ac and Cry1Ba, and the least toxic was Cry1Da. Binding experiments were performed to test whether the toxic Cry proteins shared binding sites in this insect. ¹²⁵I-labeled Cry1Ac and Cry1Ab and biotinylated Cry1Ba, Cry1Ia, and Cry9Ca showed specific binding to the brush border membrane vesicles from E. insulana. Competition binding experiments among these toxins showed that only Cry1Ab and Cry1Ac competed for the same binding sites, indicating a high possibility that this insect may develop cross-resistance to Cry1Ab upon exposure to Cry1Ac transgenic cotton but not to the other toxins tested.     

杀菌剂丙环唑对斜纹夜蛾的毒性

在研究比较了11种农药对斜纹夜蛾Spodoptera litura细胞（简称SL细胞）的毒杀活性基础上,选择毒杀活性最高的杀菌剂丙环唑,对其毒理学机理进行进一步研究。结果表明,丙环唑的细胞毒力最高,在100 μg/mL浓度下处理后48 h,SL细胞的死亡率为98.08％。处理后36 h,丙环唑对SL细胞的LC₅₀值为20.31 μg/mL。丙环唑能明显降低SL细胞的蛋白质含量。以0.5 μg/头的丙环唑注射斜纹夜蛾4龄幼虫,处理后72 h,试虫血淋巴总含量及血细胞数分别下降了26.80％和25.26％;在1.0 μg/头的剂量下,则分别下降了37.67%和36.32%。以0.5 μg/头和1.0 μg/头的丙环唑注射处理后,斜纹夜蛾幼虫体重显著降低。此外,丙环唑能降低斜纹夜蛾幼虫血淋巴含糖量及血淋巴蛋白质含量。在注射处理后96 h和120 h,丙环唑对斜纹夜蛾4龄幼虫的LD₅₀值分别为0.59 μg/头和0.45 μg/头。丙环唑对SL细胞和斜纹夜蛾幼虫均具有较好的毒杀活性,显示出丙环唑类似物控制害虫的可能性。     

Candidate insecticides for the control of larvae of Mamestra brassicae (Lepidoptera) (Noctuidae)

Fifteen insecticides were tested in the laboratory against larvae of Mamestra brassicae, a chrysanthemum pest. Seven of these, methomyl, chlorpyrifos, leptophos, iodofenphos, methamidophos, mephosfolan and fenitrothion were significantly more potent than carbaryl, the standard adopted. The performance of the insecticides is discussed in relation to selective action against insects and to mammalian toxicity, to identify those which might be suitable for integrated control or chemical control of noctuid larvae under glass. A technique for monitoring the amount of pesticide deposited on to a target by a Potter Tower sprayer is described.     

Exposure to herbicides reduces larval sensitivity to insecticides in Spodoptera litura (Lepidoptera: Noctuidae)

Herbicides and insecticides are widely used in modern agriculture. It has been reported in various studies that application of insecticides can increase tolerance of herbivorous insects to insecticides. However, limited information exists on susceptibility to insecticides when insects are exposed to herbicides. This study was conducted to investigate the potential impact of the herbicides trifluralin and 2-methyl-4-chlorophenoxyacetic acid sodium salt (MCPA-Na) on the susceptibility of the nocturnal moth Spodoptera litura to the insecticides X-cyhalothrin, phoxim and bifenthrin. We found that larvae exposed to trifluralin or MCPA-Na became significantly less susceptible to both insecticides than nonexposed control larvae. Herbicide-treated larvae did not show altered growth under the used test conditions. However, heads of herbicide-treated larvae showed increased expression of the acetylcholinesterase genes SI Ace I and SI Ace 2. Moreover, the fat body and midgut of herbicide-treated larvae displayed elevated expression of detoxification genes (the carboxylesterase gene SI CarE;the glutathione S-transferase genes SlGSTe2 and SlGSTe3\ the cytochrome P450 monooxygenase genes CYP6B48, CYP9A40 and CYP321B1). The CYP6B48 gene exhibited highest inducibility. In conclusion, the data of this study suggest that exposure of S. litura larvae to herbicides may stimulate detoxification mechanisms that compromise the efficacy of insecticides.     

斜纹夜蛾抗性种群中酶抑制剂对杀虫剂的增效作用（英文）

采用浸液生测法研究了斜纹夜蛾Spodoptera litura巴基斯坦抗性种群中酶抑制剂［胡椒基丁醚（PBO）和脱叶膦（DEF)］对丙溴磷、灭多威、硫双灭多威、氯氰菊酯、氯氟氰菊酯、联苯菊酯、茚虫威和多杀菌素等杀虫剂的增效作用。结果表明：PPO和DEF对氨基甲酸酯杀虫剂灭多威和硫双灭多威均具有增效作用,但对有机磷杀虫剂丙溴磷不具有增效作用。两种抑制剂对氯氰菊酯均产生增效作用,但对联苯菊酯没有增效作用。PPO 和DEF增加了氯氟氰菊酯对Multan种群的毒性,但没有增加其对Mailsi种群的毒性。DEF对多杀菌素具有增效作用,但PBO对其没有增效作用。PBO和DEF对氨基甲酸酯杀虫剂、拟除虫菊酯杀虫剂、茚虫威和多杀菌素具有明显的增效作用,这说明细胞色素P450单加氧酶和酯酶的解毒作用至少部分参与了斜纹夜蛾对这些杀虫剂的抗性过程。不过,两种增效剂对杀虫剂增效作用范围有限,暗示对于斜纹夜蛾巴基斯坦种群而言,其他的机制（如靶位点不敏感、表皮穿透作用降低）可能是更重要的抗性机制。     

Larval hemocytes in Noctuidae (Insecta: Lepidoptera)

An attempt was made to relate certain physical characteristics of hemocytes and the taxonomy or ecophysiology of species in one family of insects. Composition of the hemocyte complex and features of the cell types varied widely among larvae of 85 species sampled from the family Noctuidae (Lepidoptera). The complex ranged from a basic one of 4 functioning types, the plasmatocytes, granulocytes, spherulocytes and oenocytoids, to ones that also included extreme variants of the plasmatocyte line. Except for the granolocytes, each type had features of size, form and structure that could vary also with species. Some species can be identified by these characters, but there is no apparent relationship of the characters to species biology and little to present taxonomic arrangements.     

Efficacy of new insecticides for management of Helicoverpa spp. (Lepidoptera: Noctuidae) in Australian grain crops

Abstract  Insecticide resistance in Helicoverpa armigera (Hübner) has led to the reduced efficacy of some older insecticide groups (pyrethroids and carbamates) and serious crop losses. Eight small-plot experiments were conducted to evaluate new insecticides for the management of H. armigera in grain crops. Several products showed efficacy equivalent to or better than the commercial standard, thiodicarb. Indoxacarb and spinosad at rates 50% or less of the registered rates for cotton were consistently superior to other tested products across the range of crops treated and provided residual protection for up to 14 d. The insect growth regulator compound, methoxyfenozide, was slower acting than other products tested, but demonstrated potential for H. armigera management. Pyridalyl performed well and warrants further evaluation in grain crops. We discuss the positioning of new compounds in an Insecticide Resistance Management Strategy (IRMS) in relation to a farming system that incorporates both grain and cotton crops. Use guidelines are recommended for indoxacarb, the first new compound to be registered in selected grain crops and cotton in Australia. These guidelines include restricted-use periods and limits on the number of applications per crop. It is anticipated that additional new compounds will be registered in grain crops, leading to the reduced selection pressure on the limited number of efficacious products. Coordinated insecticide use across farming systems and compatibility with developing integrated pest management programs should be fundamental considerations for the future IRMS.     

草地贪夜蛾幼虫对常用杀虫剂相对敏感基线的建立

[目的]本研究旨在建立草地贪夜蛾Spodoptera frugiperda对常用杀虫剂的相对敏感基线,为我国草地贪夜蛾的抗药性系统性监测提供依据.[方法]从玉米田采集草地贪夜蛾在室内不接触任何杀虫剂连续饲养5～7代,采用浸叶法和点滴法测定了草地贪夜蛾3龄幼虫以及采用饲料药膜法测定了草地贪夜蛾2龄幼虫对6大类共7种常用杀...     

A kairomone based attract-and-kill system effective against alfalfa looper (Lepidoptera: Noctuidae)

A chemical lure derived from flowers that are visited by moths attracts male and female alfalfa loopers, Autographa californica (Speyer) (Lepidoptera: Noctuidae). This feeding attractant is dispensed from polypropylene bottles that provide controlled release for several weeks. A killing station was tested in the laboratory, in a screenhouse, and in the field in combination with this lure as an "attract-and-kill" system. Starved alfalfa looper adults (moths) were strongly attracted to the attract-and-kill station in a flight tunnel, and 90.9% of female moths and 87.6% of male moths that contacted the station died. In commercial fields of alfalfa hay, female moths captured in monitoring traps were reduced by 80-93% in plots receiving 125 attract-and-kill stations per hectare. In screenhouse trials using two attract-and-kill stations per screenhouse, oviposition on potted lettuce plants by starved female alfalfa looper moths was reduced by 98.5%. Moths were less likely to be attracted to lures when provided sugar before flight tunnel assays, and oviposition by fed moths was much less affected by attract-and-kill stations in screenhouse trials, compared with starved moths. This method has potential as a means to manage alfalfa looper populations in vegetable and other agricultural crops. However, consideration must be given to competing food and odor sources in the field.     

Susceptibility to insecticides of Glyptapanteles militaris (Hymenoptera: Braconidae), a Parasitoid of Pseudaletia unipuncta (Lepidoptera: Noctuidae)

The susceptibility of cocoons and adults of Glyptapanteles militaris (Walsh) were studied. One organophosphate insecticide (trichlorfon), one organochlorine insecticide (endosulfan), one pyrethroid (deltamethrin) and a commercial formulation of Bacillus thuringiensis subsp. Kurstaki were selected for testing. All the tests were carried out with fresh solutions of commercial insecticides applied on host larvae at the recommended concentration. One- and 6-day-old cocoons were sprayed with the insecticide solutions by means of a Potter Tower and held for adult emergence. Adults were exposed to residues of insecticides inside plastic vials. The B. thuringiensis formulation had no harmful effect on the cocoons nor on the adults. Trichlorfon and endosulfan were highly toxic to all the tested stages. Deltamethrin was highly toxic to adults but relatively safe when applied on parasitoid cocoons. Based on these results, field applications of deltamethrin would be least disruptive of tested insecticides to populations of G. militaris.     

Foliar persistence and residual activity of methoxyfenozide against beet armyworm (Lepidoptera: Noctuidae)

A greenhouse study was conducted to investigate the persistence of methoxyfenozide in pepper (Capsicum annuum L.) foliage. An aqueous suspension of methoxyfenozide was sprayed on pepper plants at concentrations of 72 and 144 mg of active ingredient (a.i.)/L. Foliage was collected at different intervals of time (0, 3, 5, 10, 20, 30, 40, and 50 days) after the treatment, and the methoxyfenozide residue was measured by high‐performance liquid chromatography. The foliage was also used in bioassays to determine the residual toxicity on and the consumption rate of the third‐instar larvae of the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae). The methoxyfenozide concentrations observed after 50 days had decreased to 19 and 69 μg/g per sample, corresponding to a loss of 61% and 28% from the application concentrations of 72 and 144 mg a.i./L, respectively. When fitting a first‐order kinetics degradation model, the half‐life (DT₅₀) of this compound was 76 days. Both application concentrations of methoxyfenozide caused a high mortality rate (≥97%) when the larvae were fed the pepper foliage collected at all of the time intervals. Lastly, at all of the time points, the consumption rate by the larvae was reduced to between 57% and 92% for both concentrations that were bioassayed. Our results indicate that, under the present greenhouse conditions, the degradation of methoxyfenozide was slower than that reported by other authors and that its residues were highly toxic to S. exigua larvae. The implications of these results for the management programs of this pest are discussed.     

Widespread decoupling of mtDNA variation and species integrity in Grammia tiger moths (Lepidoptera: Noctuidae)

Abstract. We investigate the diversity of the North American tiger moth genus Grammia Rambur (Lepidoptera: Noctuidae) by comparing mitochondrial DNA (mtDNA) ‘barcode’ fragments of cytochrome oxidase I with non‐molecular characters such as morphology, ecology, behaviour and distribution. Mitochondrial DNA genealogy is strikingly at odds with morpho‐species taxonomy for most of the 28 sampled species, as haplotypic polyphyly not only is taxonomically widespread, but involves multiple shared haplotypes among two to four species. Morpho‐ecological traits show that those species sharing haplotypes are often not closely related. Furthermore, high mtDNA divergences occur within species. Haplotypic variation is highly discordant with species taxonomy, but variation at a continental scale reveals significant geographic structuring of haplogroups, transcending morpho‐species boundaries. A nested clade analysis and comparison of non‐molecular with mtDNA data indicate that most discordance between mtDNA and taxonomy in Grammia is explained best by taxonomically and geographically widespread ongoing hybridization events resulting in mtDNA introgression. We hypothesize that broad areas of sympatry, interspecifically compatible genitalic structure, and species overlap in pheromone components facilitate hybridization, with disparate interspecies abundances promoting mitochondrial introgression. The molecular evolution of Grammia challenges the view that interspecific gene exchange occurs rarely and is restricted to recently diverged species. These results show the value of mtDNA in detecting cryptic hybridization, while highlighting the inherent dangers of drawing taxonomic conclusions based solely on mtDNA.