Heliothis Virescens Research Articles

Identification of Key Plant-Associated Volatiles Emitted by Heliothis virescens Larvae that Attract the Parasitoid, Microplitis croceipes: Implications for Parasitoid Perception of Odor Blends.

Herbivores emit plant-associated volatile organic compounds (VOCs) after feeding on plants. These plant-associated VOCs can be used by parasitoids to locate their hosts. It is hypothesized that certain compounds play key roles in the attractiveness of host-associated odor blends. The larval parasitoid, Microplitis croceipes (Hymenoptera: Braconidae) and its herbivore host, Heliothis virescens (Lepidoptera: Noctuidae), a major pest of cotton plant were used as model species to identify key compounds mediating attraction of parasitoids to hosts. Comparative GC/MS analyses of cotton-fed vs. artificial diet-fed hosts indicated that 12 of 17 compounds in the headspace of H. virescens larvae were exclusive to plant-fed hosts, and thus considered to be plant-associated. In order to identify key attractive compounds, a full blend of 15 commercially available synthetic compounds was modified by removing each of the 10 plant-associated compounds emitted by host larvae. In Y-tube olfactometer bioassays testing parasitoid responses to modified blends, 1-octen-3-ol, decanal, (E)-β-caryophyllene, α-humulene, α-farnesene, and β-pinene were identified as key compounds contributing to attractiveness of the natural blend of VOCs emitted by cotton-fed hosts. The results showed that while various host-associated compounds act in concert to serve as useful host location cues, only a fraction of the natural blend mediates attraction in parasitoids. Furthermore, the role of a compound is better assessed in the context of other compounds, and odor blends are better perceived as a whole rather than as individual components.

Molecular and functional characterization of cry1Ac transgenic pea lines

ABSTRACTTransgenic pea lines transformed with the cry1Ac gene were characterized at molecular (PCR, RT-PCR, qRT-PCR and immunostrip assay) and functional levels (leaf paint and insect feeding bioassays). The results showed the presence, expression, inheritance and functionality of the introduced transgene at different progeny levels. Variation in the expression of the cry1Ac gene was observed among the different transgenic lines. In the insect bioassay studies using the larvae of Heliothis virescens, both larval survival and plant damage were highly affected on the different transgenic plants. Up to 100 % larval mortality was observed on the transgenic plants compared to 17.42 % on control plants. Most of the challenged transgenic plants showed very negligible to substantially reduced feeding damage indicating the insect resistance of the developed transgenic lines. Further analysis under field condition will be required to select promising lines for future uses.

Gossypol toxicity and detoxification in Helicoverpa armigera and Heliothis virescens

Gossypol is a polyphenolic secondary metabolite produced by cotton plants, which is toxic to many organisms. Gossypol's aldehyde groups are especially reactive, forming Schiff bases with amino acids of proteins and cross-linking them, inhibiting enzyme activities and contributing to toxicity. Very little is known about gossypol's mode of action and its detoxification in cotton-feeding insects that can tolerate certain concentrations of this compound. Here, we tested the toxicity of gossypol and a gossypol derivative lacking free aldehyde groups (SB-gossypol) toward Helicoverpa armigera and Heliothis virescens, two important pests on cotton plants. Larval feeding studies with these two species on artificial diet supplemented with gossypol or SB-gossypol revealed no detectable toxicity of gossypol, when the aldehyde groups were absent. A cytochrome P450 enzyme, CYP6AE14, is upregulated in H. armigera feeding on gossypol, and has been claimed to directly detoxify gossypol. However, using in vitro assays with heterologously expressed CYP6AE14, no metabolites of gossypol were detected, and further studies suggest that gossypol is not a direct substrate of CYP6AE14. Furthermore, larvae feeding on many other plant toxins also upregulate CYP6AE14. Our data demonstrate that the aldehyde groups are critical for the toxicity of gossypol when ingested by H. armigera and H. virescens larvae, and suggest that CYP6AE14 is not directly involved in gossypol metabolism, but may play a role in the general stress response of H. armigera larvae toward plant toxins.

Pathogenicity and Infection Events of aBeauveria bassianaNative Strain in Tobacco Budworm,Heliothis virescens

Abstract. Pathogenicity of a native strain of Beauveria bassiana Vuill. (Ascomycota: Hypocreales) was evaluated on third-and fifth-instar larvae of tobacco budworm, Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae). Larvae were immersed in 1×108 conidia ml-1. After 72 hours, the percentage of each treated larval instar that died was 71 and 55%, respectively, while mortality of the nontreated check was 8 and 11%. The fungus was found across the cuticle and grew in the hemocoel 48 to 60 hours after inoculation of third-instar larvae and 60 to 72 hours for fifth instars. Fungal infection events also were studied in tobacco budworm larvae. The microscope and staining procedure showed mycelia grew as filamentous hyphae on the surface and penetrated the cuticle and spiracles; this phenomenon killed larvae. Inside the larvae, fungus grew as filamentous hyphae, but blastospores were not noticed. Results showed many young larval stages died and specific infection events in tobacco budworm compared to other ...

Registration of ‘Acala 1517‐16 B2RF’, a New Acala Cotton Cultivar with Insect and Herbicide Resistance

Insect pests and weeds cause significant yield losses in cotton (Gossypium hirsutum L.) production. The New Mexico Agricultural Experiment Station announces the release of an insect‐resistant and glyphosate herbicide‐tolerant Acala cotton cultivar, ‘Acala 1517‐16 B2RF’ (Reg. No. CV‐133, PI 678370), possessing Bollguard II (BGII or B2) and Roundup‐Ready Flex (RF) traits. Cotton with the B2 trait has an excellent season‐long in‐plant protection against pink bollworm [Pectinophora gossypiella (Saund.)], tobacco budworm (Heliothis virescens F.), American bollworm [Helicoverpa armigera (Hubner)], and glyphosate and an improved resistance to beet armyworm [Spodoptera exigua (Hübner)], soybean looper (Pseudoplusia includens Walker), and bollworm (H. zea Boddie). The new cultivar was selected as a progeny row derived from a backcross BC3F3 between a Monsanto B2RF donor and NM 970123 as the recurrent parent. Acala 1517‐16 B2RF was tested in 11 replicated field trials in New Mexico from 2007 to 2009, one field test in the High Plains of Texas, and nine locations outside of the Southwest region in 2009. Acala 1517‐16 B2RF had similar lint yield to ‘Acala 1517‐99W’ containing two Bt genes and two conventional cultivars ‘Acala 1517‐08’ and ‘PHY 72 Acala’. The most improved trait was its greater boll weight. In general, Acala 1517‐16 B2RF had similar fiber quality to the three checks in most of the tests, but its fibers were coarser than Acala 1517‐99W and finer than Acala 1517‐08 and PHY 72 Acala. This insect‐resistant and glyphosate‐tolerant Acala cotton cultivar is best adapted to the U.S. Southwest arid region of the Cotton Belt, where conventional Acala 1517 cultivars are grown.

Characterization and Growing Development of Spodoptera exigua (Lepidoptera: Noctuidae) Larvae Infected by Heliothis virescens ascovirus 3h (HvAV-3h).

Spodoptera exigua (Hübner) is a very serious worldwide pest capable of causing severe economic losses in numerous agricultural crops. The need for an effective, highly virulent, pathogenic microorganism for use as a biological control agent against S. exigua larvae is particularly important. Heliothis virescens ascovirus 3 h (HvAV-3h)-containing hemolymph with a titer of 9.58 × 10(12) genome copies per ml was used to inoculate S. exigua larvae per os with a 1.06 × 10(10) dosage per larva for the first- to second instar and 9.58 × 10(9) genome copies per larva for the third- to fifth instars. Intrahemocoelic injections were also used with a dosage of 1.53 × 10(9) genome copies per larva for third- to fifth instar. The postinjection mortality, body weight, and food intake of the S. exigua larvae were observed and recorded. The corrected mortality rates for the first- through fifth instar inoculated per os were 21.88 ± 0.98, 22.22 ± 4.00, 8.89 ± 4.01, 6.66 ± 3.33, and 8.89 ± 2.94%, respectively. The early instars were significantly easier to infect with virus compared to the later instar. The corrected mortality of the third, fourth, and fifth instars inoculated by injection was 96.58 ± 3.42, 98.83 ± 1.17, and 97.78 ± 2.22%, respectively. Compared to the healthy larval population, survival time of the diseased larval population was considerably extended. In addition, food intake was greatly reduced, and the body weight remained fairly constant in the third- and fourth instar. The body weight declined in the fifth instar corresponding to a reduction in food intake.

Disposable Polydimethylsiloxane (PDMS)-Coated Fused Silica Optical Fibers for Sampling Pheromones of Moths.

In the past decades, the sex pheromone composition in female moths has been analyzed by different methods, ranging from volatile collections to gland extractions, which all have some disadvantage: volatile collections can generally only be conducted on (small) groups of females to detect the minor pheromone compounds, whereas gland extractions are destructive. Direct-contact SPME overcomes some of these disadvantages, but is expensive, the SPME fiber coating can be damaged due to repeated usage, and samples need to be analyzed relatively quickly after sampling. In this study, we assessed the suitability of cheap and disposable fused silica optical fibers coated with 100 μm polydimethylsiloxane (PDMS) by sampling the pheromone of two noctuid moths, Heliothis virescens and Heliothis subflexa. By rubbing the disposable PDMS fibers over the pheromone glands of females that had called for at least 15 minutes and subsequently extracting the PDMS fibers in hexane, we collected all known pheromone compounds, and we found a strong positive correlation for most pheromone compounds between the disposable PDMS fiber rubs and the corresponding gland extracts of the same females. When comparing this method to volatile collections and the corresponding gland extracts, we generally found comparable percentages between the three techniques, with some differences that likely stem from the chemical properties of the individual pheromone compounds. Hexane extraction of cheap, disposable, PDMS coated fused silica optical fibers allows for sampling large quantities of individual females in a short time, eliminates the need for immediate sample analysis, and enables to use the same sample for multiple chemical analyses.

DIETARY SILVER NANOPARTICLES REDUCE FITNESS IN A BENEFICIAL, BUT NOT PEST, INSECT SPECIES.

Silver nanoparticles (AgNPs) have antimicrobial and insecticidal properties and they have been considered for their potential use as insecticides. While they do, indeed, kill some insects, two broader issues have not been considered in a critical way. First, reports of insect-lethal AgNPs are often based on simplistic methods that yield nanoparticles of nonuniform shapes and sizes, leaving questions about the precise treatments test insects experienced. Second, we do not know how AgNPs influence beneficial insects. This work addresses these issues. We assessed the influence of AgNPs on life history parameters of two agricultural pest insect species, Heliothis virescens (tobacco budworm) and Trichoplusia ni (cabbage looper) and a beneficial predatory insect species, Podisus maculiventris (spined soldier bug), all of which act in agroecosystems. Rearing the two pest species on standard media amended with AgNPs led to negligible influence on developmental times, pupal weights, and adult emergence, however, they led to retarded development, reductions in adult weight and fecundity, and increased mortality in the predator. These negative effects on the beneficial species, if also true for other beneficial insect species, would have substantial negative implications for continued development of AgNPs for insect pest management programs.

Water stress and kaolin spray affect herbivorous insects’ success on cotton

Ecological hypotheses of plant–insect herbivore interactions suggest that insects perform better on weakened plants and plants grown under optimal conditions are less damaged. This study tested the hypothesis that the colonization and oviposition rates by pests with different feeding strategies and levels of specialization are affected in different ways by two conditions commonly faced by commercially grown plants–water deficit and application of kaolin sprays, a reducer of abiotic plant stressors. We used four major pests of cotton as insect herbivore models. Three were chewing Lepidoptera: Alabama argillacea (Hub.), a monophagous pest on cotton; Heliothis virescens (Fabr.), which is polyphagous, but with cotton as a primary host; and Chrysodeixis includens (Walk.), which is polyphagous, with cotton as secondary host. The fourth pest was a sap-sucking species, the polyphagous whitefly Bemisia tabaci (Gen.). In both choice and no-choice trials, the three chewing pests oviposited significantly less upon water-stressed plants; the greatest effect was observed for C. includens (>90 % reduction in oviposition under choice and >58 % under no-choice conditions). In contrast, the sap-sucking B. tabaci exhibited statistically more colonization and oviposition on water-stressed plants. Application of kaolin sprays reduced colonization and oviposition by all herbivore species tested, irrespective of irrigation regime and feeding strategies.

Larval sensilla of the moth Heliothis virescens respond to sex pheromone components.

Female-released sex pheromones orchestrate the mating behaviour of moths. Recent studies have shown that sex pheromones not only attract adult males but also caterpillars. Single sensillum recordings revealed that larval antennal sensilla of the moth Heliothis virescens respond to specific sex pheromone components. In search for the molecular basis of pheromone detection in larvae, we found that olfactory sensilla on the larval antennae are equipped with the same molecular elements that mediate sex pheromone detection in adult male moths, including the Heliothis virescens receptors 6 (HR6) and HR13, as well as sensory neurone membrane protein 1 (SNMP1). Thirty-eight olfactory sensory neurones were identified in three large sensilla basiconica; six of these are considered as candidate pheromone responsive cells based on the expression of SNMP1. The pheromone receptor HR6 was found to be expressed in two cells and the receptor HR13 in three cells. These putative pheromone responsive neurones were accompanied by cells expressing pheromone-binding protein 1 (PBP1) and PBP2. The results indicate that the responsiveness of larval sensilla to female-emitted sex pheromones is based on the same molecular machinery as in the antennae of adult males.

Three toxins, two receptors, one mechanism: Mode of action of Cry1A toxins from Bacillus thuringiensis in Heliothis virescens

Insecticidal crystal (Cry) proteins from Bacillus thuringiensis (Bt) are highly active against Lepidoptera. However, field-evolved resistance to Bt toxins is on the rise. The 12-cadherin domain protein HevCaLP and the ABC transporter HevABCC2 are both genetically linked to Cry toxin resistance in Heliothis virescens. We investigated their interaction using stably expressing non-lytic clonal Sf9 cell lines expressing either protein or both together. Untransfected Sf9 cells are innately sensitive to Cry1Ca toxin, but not to Cry1A toxins; and quantitative PCR revealed negligible expression of genes involved in Cry1A toxicity such as cadherin, ABCC2, alkaline phosphatase (ALP) and aminopeptidase N (APN). Cry1Aa, Cry1Ab or Cry1Ac caused swelling of Sf9 cells expressing HevABCC2, and caused faster swelling, lysis and up to 86% mortality in cells expressing both proteins. No such effect was observed in control Sf9 cells or in cells expressing only HevCaLP. The results of a mixing experiment demonstrated that both proteins need to be expressed within the same cell for high cytotoxicity, and suggest a novel role for HevCaLP. Binding assays showed that the toxin-receptor interaction is specific. Our findings confirm that HevABCC2 is the central target in Cry1A toxin mode of action, and that HevCaLP plays a supporting role in increasing Cry1A toxicity.

Efficacy of Soybean's Event DAS-81419-2 Expressing Cry1F and Cry1Ac to Manage Key Tropical Lepidopteran Pests Under Field Conditions in Brazil.

Bacillus thuringiensis (Bt) event DAS-81419-2 (Conkesta technology) in soybean, Glycine max (L.) Merrill, expresses Cry1F and Cry1Ac proteins to provide protection from feeding by several lepidopteran pests. A total of 27 field experiments across nine locations were conducted from 2011 to 2015 in southern and central Brazil to characterize the efficacy of DAS-81419-2 soybean infested with Anticarsia gemmatalis Hübner (Lepidoptera: Erebidae), Chrysodeixis includens (Walker) (Lepidoptera: Noctuidae), Heliothis virescens (F.) (Lepidoptera: Noctuidae), and Spodoptera cosmioides (Walker) (Lepidoptera: Noctuidae) during vegetative (V4) and reproductive (R2 and R4) crop developmental stages. The efficacy of DAS-81419-2 was compared to that of a non-Bt isogenic variety managed with or without applications of commercial foliar insecticides for lepidopteran control. DAS-81419-2 soybean consistently experienced defoliation levels of 0.5% or less (compared with 20.05–56.74% in the non-Bt, nonsprayed treatment) and larval survival of < 0.1% in all four species across the vegetative and reproductive plant stages evaluated. The efficacy of DAS-81419-2 was significantly higher than commercial foliar insecticides applied to the non-Bt variety. DAS-81419-2 soybeans containing two highly effective Bt proteins are expected to be a more robust IRM tool compared to single-trait Bt technologies. The consistent efficacy of DAS-81419-2 soybeans across years, locations, and crop stages suggests that it will be a valuable product for management of hard-to-control key lepidopteran pests in South American soybean production.

Reduced stability and intracellular transport of dsRNA contribute to poor RNAi response in lepidopteran insects

ABSTRACTRNA interference (RNAi) has become a widely used reverse genetic tool to study gene function in eukaryotic organisms and is being developed as a technology for insect pest management. The efficiency of RNAi varies among organisms. Insects from different orders also display differential efficiency of RNAi, ranging from highly efficient (coleopterans) to very low efficient (lepidopterans). We investigated the reasons for varying RNAi efficiency between lepidopteran and coleopteran cell lines and also between the Colorado potato beetle, Leptinotarsa decemlineata and tobacco budworm, Heliothis virescens. The dsRNA either injected or fed was degraded faster in H. virescens than in L. decemlineata. Both lepidopteran and coleopteran cell lines and tissues efficiently took up the dsRNA. Interestingly, the dsRNA administered to coleopteran cell lines and tissues was taken up and processed to siRNA whereas the dsRNA was taken up by lepidopteran cell lines and tissues but no siRNA was detected in the total RNA isolated from these cell lines and tissues. The data included in this paper showed that the degradation and intracellular transport of dsRNA are the major factors responsible for reduced RNAi efficiency in lepidopteran insects.

Antennal-lobe tracts in the noctuid moth, Heliothis virescens: new anatomical findings.

As in other insects, three main tracts in the moth brain form parallel connections between the antennal lobe and the protocerebrum. These tracts, which consist of the antennal-lobe projection-neuron axons, target two main areas in the protocerebrum, the calyces of the mushroom bodies and the lateral horn. In spite of the solid neuroanatomical knowledge already established, there are still unresolved issues regarding the antennal-lobe tracts of the moth. One is the proportion of lateral-tract neurons targeting the calyces. In the study presented here, we have performed both retrograde and anterograde labeling of the antennal-lobe projection neurons in the brain of the moth, Heliothis virescens. The results from the retrograde staining, obtained by applying dye in the calyces, demonstrated that the direct connection between the antennal lobe and this neuropil is maintained primarily by the medial antennal-lobe tract; only a few axons confined to the lateral tract were found to innervate the calyces. In addition, these staining experiments, which allowed us to explore the arborization pattern of labeled neurons within the antennal lobe, resulted in new findings regarding anatomical arrangement of roots and cell body clusters linked to the medial tract. The results from the anterograde staining, obtained by applying dye into the antennal lobe, visualized the total assembly of axons passing along the antennal-lobe tracts. In addition to the three classical tracts, we found a transverse antennal-lobe tract not previously described in the moth. Also, these staining experiments revealed an organized neuropil in the lateral horn formed by terminals of the four antennal-lobe tracts.

Optimal Cotton Insecticide Application Termination Timing: A Meta-Analysis.

The concept of insecticide termination timing is generally accepted among cotton (Gossypium hirsutum) researchers; however, exact timings are often disputed. Specifically, there is uncertainty regarding the last economic insecticide application to control fruit-feeding pests including tarnished plant bug (Lygus lineolaris (Palisot de Beauvois)), boll weevil (Anthonomus grandis), bollworm (Helicoverpa zea), tobacco budworm (Heliothis virescens), and cotton fleahopper (Pseudatomoscelis seriatus). A systematic review of prior studies was conducted within a meta-analytic framework. Nine publicly available articles were amalgamated to develop an optimal timing principle. These prior studies reported 53 independent multiple means comparison field experiments for a total of 247 trial observations. Stochastic plateau theory integrated with econometric meta-analysis methodology was applied to the meta-database to determine the shape of the functional form of both the agronomic optimal insecticide termination timing and corresponding yield potential. Results indicated that current university insecticide termination timing recommendations are later than overall estimated timing suggested. The estimated 159 heat units (HU) after the fifth position above white flower (NAWF5) was found to be statistically different than the 194 HU termination used as the status quo recommended termination timing. Insecticides applied after 159 HU may have been applied in excess, resulting in unnecessary economic and environmental costs. Empirical results also suggested that extending the insecticide termination time by one unit resulted in a cotton lint yield increase of 0.27 kilograms per hectare up to the timing where the plateau began. Based on economic analyses, profit-maximizing producers may cease application as soon as 124 HU after NAWF5. These results provided insights useful to improve production systems by applying inputs only when benefits were expected to be in excess of the respective costs.

Identification and expression profiling of pheromone biosynthesis activating neuropeptide in Chlumetia transversa (Walker)

Insect neuropeptides (NPs) in the pyrokinin/pheromone biosynthesis-activating neuropeptide (PBAN) family are actively involved in many essential endocrine functions. These peptides are potential targets in the search for novel insect control agents. This is the first report on the cloning and sequence determination of Chlumetia transversa (Walker) PBAN (Ct-PBAN) using rapid amplification of cDNA ends. The open reading frame of Ct-PBAN was 588bp in length and encoded 195 amino acids, which were assembled into five putative neuropeptides (diapause hormone homolog, α-neuropeptide, β-neuropeptide, PBAN, and γ-neuropeptide). These peptides were amidated at C-terminus and shared the conserved pentapeptide motif FXPR (or K) L. Moreover, Ct-PBAN had high homology to PBANs in Helicoverpa zea (84.1%), Helicoverpa armigera (83.5%), Helicoverpa assulta (83%), and Heliothis virescens (82.6%). Phylogenetic analysis showed that Ct-PBAN was closely related to its orthologs in the family Noctuidae. In addition, real-time quantitative polymerase chain reaction assays showed that the expression of Ct-PBAN peaked in the female head and was also detected at high levels in 1-d-old adults. These results suggested that Ct-PBAN is associated with sex pheromone biosynthesis in female C. transversa and could be used for developing C. transversa control systems based on molecular techniques.

Development of cotton pests exhibiting different feeding strategy on water-stressed and kaolin-treated cotton plants

Consistent data demonstrate the positive response of sap-sucking insects to water-stressed plants, but there is a lack of information about the performance of chewing species, including whether their responses vary according to their feeding specializations. We tested the hypothesis that herbivores with distinct feeding strategies and host specialization will respond differently to two plant conditions, i.e. water deficit and kaolin treatment, where the latter is used to reduce abiotic and biotic plant stressors. We determined the development and reproduction of four major cotton pest species with different feeding strategies (chewing and sap sucking) and with specializations ranging from monophagous to polyphagous using well-watered or water-stressed cotton plants, which were treated or not treated with kaolin. Three chewing (lepidopteran) species, Alabama argillacea (Hub.), Heliothis virescens (Fabr.) and Chrysodeixis includens (Walk), as well as one sap-sucking species, Bemisia tabaci (Gen.), were used as models. The neonate larvae of all three chewing species exhibited lower survival when fed the leaves of water-stressed plants. In addition, the neonate larvae fed leaves from water-stressed and kaolin-treated plants did not complete their development or they exhibited low survival. Older larvae also exhibited significantly lower survival on kaolin-treated plants. The effects on life history traits were more obvious in monophagous chewing species compared with polyphagous species when fed leaves from water-stressed plants. The performance of B. tabaci was superior on water-stressed and untreated kaolin plants. Thus, water-stressed and kaolin-treated plants negatively affected all chewing species, whereas water-stressed plants only positively affected the sap-sucking species.

A Conserved Odorant Receptor Tuned to Floral Volatiles in Three Heliothinae Species.

Odorant receptors (ORs) play an important role in insects to monitor and adapt to the external environment, such as host plant location, oviposition-site selection, mate recognition and natural enemy avoidance. In our study, we identified and characterized OR12 from three closely-related species, Helicoverpa armigera, Helicoverpa assulta, Heliothis virescens, sharing between 90 and 98% of their amino acids. The tissue expression pattern analysis in H. armigera showed that HarmOR12 was strongly expressed both in male and female antennae, but not in other tissues. Functional analysis performed in the heterologous Xenopus expression system showed that all three OR12 were tuned to six structurally related plant volatiles. Electroantennogram recordings from male and female antennae of H. armigera closely matched the data of in vitro functional studies. Our results revealed that OR12 has a conserved role in Heliothinae moths and might represent a suitable target for the control of these crop pests.

Variability of Bacterial Communities in the Moth Heliothis virescens Indicates Transient Association with the Host.

Microbes associated with insects can confer a wide range of ecologically relevant benefits to their hosts. Since insect-associated bacteria often increase the nutritive value of their hosts' diets, the study of bacterial communities is especially interesting in species that are important agricultural pests. We investigated the composition of bacterial communities in the noctuid moth Heliothis virescens and its variability in relation to developmental stage, diet and population (field and laboratory), using bacterial tag-encoded FLX pyrosequencing of 16S rRNA amplicons. In larvae, bacterial communities differed depending on the food plant on which they had been reared, although the within-group variation between biological replicates was high as well. Moreover, larvae originating from a field or laboratory population did not share any OTUs. Interestingly, Enterococcus sp. was found to be the dominant taxon in laboratory-reared larvae, but was completely absent from field larvae, indicating dramatic shifts in microbial community profiles upon cultivation of the moths in the laboratory. Furthermore, microbiota composition varied strongly across developmental stages in individuals of the field population, and we found no evidence for vertical transmission of bacteria from mothers to offspring. Since sample sizes in our study were small due to pooling of samples for sequencing, we cautiously conclude that the high variability in bacterial communities suggests a loose and temporary association of the identified bacteria with H. virescens.

Tarsi of Male Heliothine Moths Contain Aldehydes and Butyrate Esters as Potential Pheromone Components.

The Noctuidae are one of the most speciose moth families and include the genera Helicoverpa and Heliothis. Females use (Z)-11-hexadecenal as the major component of their sex pheromones except for Helicoverpa assulta and Helicoverpa gelotopoeon, both of which utilize (Z)-9-hexadecenal. The minor compounds found in heliothine sex pheromone glands vary with species, but hexadecanal has been found in the pheromone gland of almost all heliothine females so far investigated. In this study, we found a large amount (0.5-1.5μg) of hexadecanal and octadecanal on the legs of males of four heliothine species, Helicoverpa zea, Helicoverpa armigera, H. assulta, and Heliothis virescens. The hexadecanal was found on and released from the tarsi, and was in much lower levels or not detected on the remaining parts of the leg (tibia, femur, trochanter, and coxa). Lower amounts (0.05-0.5μg) of hexadecanal were found on female tarsi. This is the first known sex pheromone compound to be identified from the legs of nocturnal moths. Large amounts of butyrate esters (about 16μg) also were found on tarsi of males with lower amounts on female tarsi. Males deposited the butyrate esters while walking on a glass surface. Decapitation did not reduce the levels of hexadecanal on the tarsi of H. zea males, indicating that hexadecanal production is not under the same neuroendocrine regulation system as the production of female sex pheromone. Based on electroantennogram studies, female antennae had a relatively high response to hexadecanal compared to male antennae. We consider the possible role of aldehydes and butyrate esters as courtship signals in heliothine moths.