Is Mythimna turca (Lepidoptera: Noctuidae) a migrant?

The double line moth, Mythimna turca (Linnaeus, 1761) (Lepidoptera: Noctuidae), is an important widely distributed insect species. Studies on the moth in European countries have focused on population monitoring and in China on taxonomy of Mythimna and distribution surveys of M. turca. However, whether M. turca is a migratory insect is unknown. Here, migration of the moth population was monitored using a searchlight trap from 2004 to 2020 on Beihuang island, Northern China, providing direct evidence that M. turca migrates across the Bohai Strait seasonally, in late May to early September. Population dynamics, ovarian development, wind direction and possible migration trajectories were also analyzed. Most moths migrated in June and at the end of August and the beginning of September, and a few migrated in May, July and October. The average duration of this windborne migratory period of M. turca was 93 d. Migratory trajectories demonstrated that M. turca mainly moved northward in spells of southerly winds from June to August and moved southward in spells of northerly winds during September. This new key information about the ecology of M. turca population will aid the formulation of M. turca management strategies.     

Modeling Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) damages on cotton

We studied and modeled damage caused by Helicoverpa armigera larvae on cotton with the aim of developing a coupled crop pest model. Two damage components were studied: the voracity (quantity of fresh matter and number of organs consumed) and feeding preferences (type of organ infested). The laboratory no-choice study of voracity on excised squares and bolls revealed that an H. armigera larva consumes 2,856 mg of fresh matter throughout its larval life, with the sixth instar consuming 86% of this quantity. This consumption rate corresponded to 23.6 squares, or 7.8 bolls. We developed equations to predict the quantity of fresh matter uptake from an individual plant organ, according to the organ mass and the larval instar. The field study of feeding preference confirmed previous findings that larvae prefer squares to bolls, with this preference decreasing as the larval age increases. However, no significant relationship was noted between the age of larvae and the size of infested organs within each organ class (square or boll). We developed a logistic model to predict the probability of a larva infesting a boll rather than a square. According to this model, the relative organ availability in the field and the larval instar were found to be significant factors.     

Biological aspects of Autoplusia egena (Guenée) (Lepidoptera: Noctuidae, Plusiinae)

Autoplusia egena (Guenée) is a moth distributed throughout the Western hemisphere. The larvae have already been found feeding on several different plant families, including important crops such soybeans and beans. To contribute to the knowledge of its biology in laboratory conditions, and considering the duration and the morphometry of each development stage, a laboratorial rearing was accomplished at 25 +/- 1 degrees C, 70 +/- 10% RH and 14h photophase. The larvae were fed with black bean leaves and the adults were fed with a honey solution at 10%. The results, expressed by the mean (+/- SE), for the periods of each stage were: egg 3.0 +/- 0.00 d; larva 15.7 +/- 1.25 d; pre-pupa 1.9 +/- 0.05 d; pupa 8.8 +/- 0.09 d and adult: longevity 12.1 +/- 0.95 d, pre-oviposition 5.4 +/- 0.50 d, oviposition 6.3 +/- 1.10 d and post-oviposition 1.4 +/- 0.87 d. The larvae went through five instars, for which the mean width of the cephalic capsules were 0.302 +/- 0.001 mm; 0.500 +/- 0.003 mm; 0.854 +/- 0.008 mm; 1.424 +/- 0.011 mm and 2.744 +/- 0.053 mm. The average length, width, and weight of the pupae were 16.965 +/- 0.003 mm, 4.674 +/- 0.040 mm and 0.217 +/- 0.003 g, respectively.     

Last instar larva and pupa of Melipotis cellaris (Guenée) (Lepidoptera: Noctuidae)

The last instar larva and pupa of Melipotis cellaris (Guenée) are described and illustrated, based on specimens collected in northern Chile, associated with Acacia macracantha (Fabaceae).     

First record of Peridroma saucia Hübner (Lepidoptera: Noctuidae) in transgenic soybeans

The widespread cultivation of transgenic soybeans has caused significant changes in the spectrum of Lepidoptera larvae, both in the number of species as well as on their densities in the field. Transgenic crops producing Bacillus thuringiensis (Bt) insecticidal proteins have successfully reduced the incidence of the most common caterpillars infesting soybeans, namely Anticarsia gemmatalis (Lepidoptera: Erebidae) and Chrysodeixis includens (Lepidoptera: Noctuidae). However, lepidopteran species not previously recorded on the crop have been recently found, and are of concern due to the possibility of adaptation to the genetically modified cultivars. The occurrence of Peridroma saucia Hübner (Lepidoptera: Noctuidae) is described for the first time in Brazil feeding on genetically modified soybean cultivars.     

Development and fecundity of Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) on different soybean cultivars

The life history of Spodoptera exigua was studied under laboratory conditions at temperature of 25°C ± 1°C, relative humidity (RH) of 60% ± 5% and a photoperiod of 16:8 h (Light:Dark) on nine soybean (Glycine max L.) cultivars: 032, 033, Hill, M4, M7, M9, M11, TMS and Zan. Larval and pupal development times were longest on M7 cultivar (14.09 ± 0.078 and 7.78 ± 0.090 days) and shortest on 033 cultivar (11.98 ± 0.054 and 7.033 ± 0.090 days). The longest and shortest female and male longevities were observed on Hill and Zan cultivars, respectively. The results showed that the whole life span varied from 32.80 ± 0.89 to 37 ± 0.98 days for females and from 33.3 ± 0.66 to 38.74 ± 0.95 days for males. The highest daily fecundity was obtained on M9 (102. 38 eggs), and the lowest on Hill (75.87 eggs). Mean total fecundity per female during adult life was highest on 033 (1156.20 eggs) and lowest on M7 cultivars (841.68 eggs). Clustering analysis of the biological parameters of S. exigua confirmed that 033 and Hill cultivars were the susceptible and the resistant cultivars, respectively.     

Karyomorphological effects of two new oil formulations on Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

The cotton bollworm Helicoverpa armigera is a serious pest of many economically important crops. Since this pest has become resistant to the conventional synthetic insecticides, newer compounds and formulations are being developed against this insect pest. Many natural compounds isolated from the plants were tested against this pest. Among them Hyptis suaveolens and Melochia corchorifolia showed insecticidal properties against H. arnigera. Based on bioefficacy studies, caryophyllene and β-sitosterol were isolated from H. suaveolens and M. corchorifolia respectively. The isolated natural compounds were further developed as formulations in various combinations with neem (Azadirachta indica) and karanj (Pongamia pinnata) oils. The present study indicated that the formulations influenced the karyomorphology of H. armigera.     

Structure and ultrastructure of the silk glands and spinneret of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

This study provides comprehensive documentation of silk production in the pest moth Helicoverpa armigera from gland secretion to extrusion of silk thread. The structure of the silk glands, accessory structures and extrusion apparatus are reported. The general schema of the paired silk glands follows that found for Lepidoptera. Morphology of the duct, silk press, muscle attachments and spigot are presented as a three-dimensional reconstruction and the cuticular crescent-shaped profile of the silk press is demonstrated in both open and closed forms with attendant muscle blocks, allowing advances in our knowledge of how the silk press functions to regulate the extrusion of silk. Growth of the spigot across instars is documented showing a distinctive developmental pattern for this extrusion device. Its shape and structure are related to use and load-bearing activity.     

Ovicidal activity of Couroupita guianensis (Aubl.) against cotton bollworm Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

There is a great demand for food with increasing population of the world. Many chemical fertilisers and pesticides are used to increase crop productivity. Over use of pesticides and fertilisers has affected the environment and non-target organisms severely; minor pests have become major destructive pests. Hence, eco-friendly approaches are needed. The present study reports the effect of hexane, chloroform and ethyl acetate extract of Couroupita guianensis on the eggs of Helicoverpa armigera. All the extracts showed ovicidal activity, and among them hexane extract showed 64.28% ovicidal activity with LC₅₀ value of 2.62% and regression of (R ²) 83.5%. All the original data showed normality and homogeneity. The active hexane extract was fractionated; finally, eight fractions were obtained and studied at different concentrations. Among the fractions, fraction 8 showed 75% ovicidal activity with R ² of 90%. It showed LC₅₀ value of 322.94?ppm with χ ² value at 0.5%. C. guianensis could be used in pest management programme.     

Mechanisms of premating isolation between Helicoverpa armigera (Hübner) and Helicoverpa assulta (Guenée) (Lepidoptera: Noctuidae)

Helicoverpa armigera and Helicoverpa assulta are sympatric sibling species, and in the laboratory they can interbreed and produce viable offspring. To assess the contributions of temporal barriers and sexual barriers to premating isolation, we investigated both the temporal rhythms of calling behavior and pheromone titers of H. armigera and H. assulta females and the behavioral responses of males to conspecific and heterospecific calling females in a wind tunnel. Both H. armigera and H. assulta females called throughout the scotophase, and there was more calling during the second half of the scotophase than during the first half. Maximal pheromone titer and maximal calling activity in H. armigera synchronously occurred at the sixth hour into the scotophase, whereas, in H. assulta, the maximal pheromone titer occurred 2 h before the peak of calling. Pheromone blend ratios of the two species were opposite and, within each species, changes in the ratio within the scotophase and at different ages were relatively small. Males of both H. armigera and H. assulta responded strongly to their conspecific calling females in the wind tunnel and completed the whole courtship sequence. In contrast, they did not land and had no copulation attempts in response to heterospecific calling females. These results show that the two species do not have obvious temporal differences in calling behavior and pheromone production, and the specificity of sex pheromone blend emitted by females plays a key role in their premating isolation. In addition, we summarized the potential isolation mechanisms of H. armigera and H. assulta.     

Transcytosis of Junonia coenia densovirus VP4 across the gut epithelium of Spodoptera frugiperda(Lepidoptera:Noctuidae)

The Junonia coenia densovirus rapidly traverses the gut epithelium of the host lepidopteran without replicating in the gut cells.The ability of this virus to transcytose across the gut epithelium is of interest for the potential use of virus structural proteins as delivery vehicles for insecticidal peptides that act within the insect hemocoel,rather than in the gut.In this study,we used fall armyworm,Spodoptera frugiperda to examine the binding of the virus to brush border membrane vesicle proteins by two-dimensional ligand blot analysis.We also assessed the rate of flux of the primary viral structural protein,VP4 fused to eGFP with a proline-rich linker(VP4-P-eGFP)through the gut epithelium ex vivo in an Ussing chamber.The mechanisms involved with transcytosis of VP4-P-eGFP were assessed by use of inhibitors.Bovine serum albumin(BSA)and eGFP were used as positive and negative control proteins,respectively.In contrast to BSA,which binds to multiple proteins on the brush border membrane,VP4-P-eGFP binding was specific to a protein of high molecular mass.Protein flux was significantly higher for VP4-P-eGFP after 2 h than for albumin or eGFP,with rapid transcytosis of VP4-P-eGFP within the first 30 min.In contrast to BSA which transcytosed following clathrin-mediated endocytosis,the movement of VP4-P-eGFP was vesicle-mediated but clathrin-independent.The specificity of binding combined with the efficiency of transport across the gut epithelium suggest that VP4 will provide a useful carrier for insecticidal peptides active within the hemocoel of key lepidopteran pests including S.frugiperda.     

Do Larvae of Bertha armyworm,Mamestra configurata (Walker) (Lepidoptera: Noctuidae), express induced feeding responses?

The Bertha armyworm, Mamestra configurata (Walker) (Lepidoptera: Noctuidae), is a polyphagous Nearctic insect known to feed on over 40 different host plant species, and can be a pest of canola (Brassica napus L. and Brassica rapa L.), flax (Linum usitatissimum L.), and alfalfa (Medicago sativa L.) in the Northern Great Plains. Bertha armyworm is known to sometimes switch hosts through between‐field movements, prompting this study to investigate its adherence to a particular host plant species after completing a period of initial development on it. In a laboratory study, larvae were reared to either their fourth or sixth instars on either intact or excised leaf tissue of one of seven host species, and were then allowed to select feeding hosts from various choices that included canola, B. napus and B. rapa (Brassicaceae), Canada thistle, Cirsium arvense (L.) Scop. (Compositae), flax, L. usitatissimum (Linaceae), field pea and alfalfa, Pisum sativum L. and M. sativa (Leguminosae), and lamb’s quarters, Chenopodium album L. (Chenopodiaceae). In general, Bertha armyworm larvae showed little propensity to feed on the host plant species on which they had been reared in their early life stages. Exceptions occurred for larvae reared on intact tissue of B. rapa and P. sativum, where larvae were subsequently observed feeding on these hosts significantly more frequently than on other host plants. When larvae of Bertha armyworm were reared through early developmental stages on intact plant tissue of a single host, B. rapa was frequently the choice for subsequent feeding. Movements of Bertha armyworm larvae between fields therefore appear to result from larvae that have exploited food resources in one area and are dispersing to regions of improved host plant availability.     

Joint toxicity of methoxyfenozide and lufenuron on larvae of Spodoptera exigua Hübner (Lepidoptera: Noctuidae)

The joint action and sublethal effects of methoxyfenozide and lufenuron were measured against Spodoptera exigua. Methoxyfenozide and lufenuron exhibited optimum synergistic toxicity on S. exigua at a mass ratio of 4:6, and the co-toxicity coefficient (CTC) was 165.705. Third instars larvae of S. exigua were treated with methoxyfenozide (LC₁₅ = 21.004 ng/cm²), lufenuron (LC₁₅ = 27.134 ng/cm²), or a mixture of methoxyfenozide and lufenuron (MML, LC₁₅ = 16.503 ng/cm²) through feeding for 72 h. Ingestion of MML by larvae significantly inhibited larval and pupal weights and pupation rate, and prolonged the larval and pupal development of S. exigua compared to individual treatment ofmethoxyfenozide or lufenuron. Both methoxyfenozide and MML treatments significantly decreased the fertility of female S. exigua. No significant changes were observed in case of adult emergence and egg hatching for different treatments. The MML-treated S. exigua exhibited significantly lower activities of polyphenol oxidase (PPO) and cytochrome P450 (CYP450) than those in S. exigua treated separately with methoxyfenozide or lufenuron. Finally, methoxyfenozide, lufenuron, and MML treatments decreased chitinase, acetylcholinesterase (AChE), carboxylesterase (CarE), and glutathione-s-transferase (GST) activities in S. exigua.     

Repellent,antifeedant and toxic effects of Ageratum conyzoides (Linnaeus) (Asteraceae) extract against Helicovepra armigera (Hübner) (Lepidoptera: Noctuidae)

Repellent, antifeedant and toxic effect of crude hexane extract of Ageratum conyzoides were investigated against Helicoverpa armigera. In orientation bioassay, the extract exhibited dose-dependent repellency against neonates. Extract significantly increased the mortality and decreased growth of different larval stages when administrated orally in artificial diet. EC₅₀ value was at 0.11% for larval growth inhibition. Toxicity of the extract was manifested by high mortality of first instar larvae after 7 days of feeding on diet containing 0.05–0.4% of extract with LC₅₀ of 0.17%. Under choice bioassay, extract showed strong antifeedant activity against fifth instar larvae with DI₅₀ of 0.21%. In nutritional bioassay, extract significantly reduced RCR, RGR, ECI and ECD of fifth instar larvae with increased AD. When RGR were plotted against RCR, the growth efficiency of larvae fed on treated diet was significantly lower than the control fed larvae suggesting the antifeedant and toxic effect of extract.     

Electrophysiological responses of female Helicoverpa armigera (Hübner) (Lepidoptera; Noctuidae) to synthetic host odours

Studies were conducted to investigate the electroantennographic (EAG) responses of adult female Helicoverpa armigera to a range of known and putative kairomone components. The studies show that at a given dose the EAG responses elicited by a series of straight-chain aliphatic primary alcohols were not dependent on volatility since butan-1-ol and pentan-1-ol elicited EAG responses that were significantly smaller than those elicited by hexan-1-ol. The amplitudes of responses to hexan-1-ol were found to be dose dependent with a dose of 10(-1) μmol at source in a non-volatile solvent eliciting the largest response. Similarly, changes in functionality in a range of C(6) straight-chain aliphatic compounds significantly changed the amplitude of response elicited, with aldehydes eliciting smaller responses than the related primary alcohols and saturated compounds eliciting higher responses than related unsaturated compounds. Of the range of nine host plant-produced terpenoids tested, ocimene and beta-phellandrene elicited the highest responses and of the six aromatic compounds tested phenylacetaldehyde and benzaldehyde elicited the largest responses, at the doses tested. The significance of these findings for analysis of floral odours by gas chromatography linked to electroantennography as a means of identifying kairomone components attractive to H. armigera are discussed.     

Antifeedant activity of numb and salty taste compounds against the larvae of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

Helicoverpa armigera, an important polyphagous insect pest in agriculture, attacks more than 200 plant species of more than 30 families. Our previous study showed that the choice feeding percentages of H. armigera larvae to tobacco leaf discs treated with sweet, bitter, and hot taste substances were higher than the control leaf discs, while numb and salty substances could significantly inhibit their feeding. To quantitatively determine the synergistic effect of numb and salty substances, in this paper, the antifeeding activities of numb and salty substances and their mixtures blended in different doses or volume ratios were assayed on H. armigera larvae. The first bioassay was designed to elucidate the relative feeding preference of the larvae to the leaves from several common host species, each paired with tobacco leaf discs, and the result indicated that the most preferred host leaf by the larvae was tobacco leaf, followed by cotton and peanut leaves, suggesting that tobacco leaf was the most suitable matrix for the antifeeding bioassay, and the larval consumption of maize, pepper, or tomato leaves were significantly lower than that of tobacco leaf. The second bioassay was to test the choice feeding response of H. armigera larvae to tobacco leaf discs treated with Zanthoxylum bungeanum extracts obtained with different solvents, and the result showed that the antifeeding activity of the alcohol extracts was the strongest (93.38%), and the leaf consumption in the treatment and the control showed extremely significant difference (t = 4.23, t_0.01 = 3.25, P = 0.0022), followed by the dichloromethane extracts (47.64%), while the other three solvents (water, acetone, and n-hexane) could not extract the active antifeeding components from Z. bungeanum. The larval consumption of tobacco leaf discs treated with the alcohol extracts of Z. bungeanum and NaCl solution were significantly less than their corresponding controls. The mean larval consumption of the treated leaf discs decreased with ever-increasing dosage, and the consumption of tobacco leaf discs coated with different doses of alcohol extracts of Z. bungeanum or NaCl solution showed extremely significant difference (F_{alcohol extract of Z. bungeanum} = 3.88, F_0.01 = 3.58, P = 0.0064; F_{NaCl solution} = 54.29, F_0.01 = 3.58, P = 0.0000), with maximum antifeeding effects at a dosage of 30 μL per 1.5 cm ID leaf disc. We further tested the larval consumption of tobacco leaf discs treated with alcohol extracts of Z. bungeanum in saturated NaCl solution mixed in different volume ratios, and the result showed that the choice antifeeding percentages of the treatments with 15 μL or more Z. bungeanum alcohol extracts were higher than 90%, among which the mixture with 25:15 volume ratio of Z. bungeanum alcohol extracts and saturated NaCl solution exhibited the strongest antifeeding activity, and the mean consumed leaf area of tobacco leaf discs coated with this blend was only 0.10 mm². In the further test on feeding dose-response of the 25:15 mixture, the mean leaf consumption decreased linearly with ever-increasing dosage, with a regression equation y = ?3.9356x + 120.78(R² = 0.9998), and the 30 μL dose could completely inhibit H. armigera feeding.     

Effect of the populations of Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) on cotton crop at two sowing distances

The objective of this research was to evaluate the incidence of damage by the leafworm Alabama argillacea (Hübner) on yields of cotton grown under rows spaced 0.38 m and 0.76 m at the irrigation area of Santiago del Estero, Argentina. The period evaluated was extended from first flower to first open boll. Treatments were T1 - without control of larvae, T2 - with control of larvae, T3 - control since first flower to the end of effective blooming, and T4 - with larval control since the end of effective blooming to first open boll. The effect of injuries on the crop was evaluated trough boll cotton yield. Larvae were sampled in a weekly basis and insects were present from the first flower until harvest. Populations of A. argillacea decreased crop yields in the two distances tested, by decreasing the weight or number of open bolls.     

Taxonomy and biogeography of the Nearctic Raphia Hübner (Lepidoptera,Noctuidae, Raphiinae)

The taxonomic status and biogeography of the North American Raphia species is reviewed using adult morphology, larval host plants, geographic phenotypic variation, and variation of mtDNA COI barcode sequences. Lack of diagnostic morphological differences, combined with relatively low mtDNA barcode divergences and clinal phenotypic variation in key geographic regions indicate that the six previously recognized species of North American Raphia are best interpreted as parapatric subspecies. Raphia frater abrupta Grote, stat. n., R. f. coloradensis Putnam-Cramer, stat. r., R. f. piazzi Hill, stat. n., and R. f. elbea Smith, stat. n., are accordingly revised to subspecies of R. frater Grote. Type locality restrictions are provided for Raphia abrupta and Raphia frater and a neotype is designated for Raphia frater var. coloradensis.