Polyphagous Lepidopteran Pest Research Articles

Transcriptomic and proteomic elucidation of Z chromosome dosage compensation in Helicoverpa armigera.

Transcriptomic data have been used to study sex chromosome dosage compensation (SCDC) in approximately 10 Lepidoptera ZW species, yielding a consensus compensation pattern of Z It remains unclear whether this compensation pattern holds when examining more Lepidoptera ZW species and/or using proteomic data to analyse SCDC. Here we combined transcriptomic and proteomic data as well as transcriptional level of six individual Z genes to reveal the SCDC pattern in Helicoverpa armigera, a polyphagous lepidopteran pest of economic importance. Transcriptomic analysis showed that the Z chromosome expression of H. armigera was balanced between male and female but substantially reduced relative to autosome expression, exhibiting an SCDC pattern of Z . When using H. amigera midgut proteomic data, the SCDC pattern of this species changed from Z at transcriptomic level to Z = ZZ = AA at the proteomic level. RT-qPCR analysis of transcript abundance of six Z genes found that compensation for each Z gene could vary from no compensation to overcompensation, depending on the individual genes and tissues tested. These results demonstrate for the first time the existence of a translational compensation mechanism, which is operating in addition to a translational mechanism, such as has been reported in other lepidopteran species. And the transcriptional compensation mechanism functions to accomplish Z chromosome dosage balance between the sexes (M = F on the Z chromosome), whereas the translation compensation mechanism operates to achieve dosage compensation between Z chromosome and autosome (Z = AA).

Peritrophins are involved in the defense against Bacillus thuringiensis and nucleopolyhedrovirus formulations in Spodoptera littoralis (Lepidoptera: Noctuidae)

The peritrophic matrix (or peritrophic membrane, PM) is present in most insects where it acts as a barrier to mechanical insults and pathogens, as well as a facilitator of digestive processes. The PM is formed by the binding of structural PM proteins, referred to as peritrophins, to chitin fibrils and spans the entire midgut in lepidopterans. To investigate the role of peritrophins in a highly polyphagous lepidopteran pest, namely the cotton leafworm (Spodoptera littoralis), we generated Insect Intestinal Mucin (IIM−) and non-mucin Peritrophin (PER−) mutant strains via CRISPR/Cas9 mutagenesis. Both strains exhibited deformed PMs and retarded developmental rates. Bioassays conducted with Bacillus thuringiensis (Bt) and nucleopolyhedrovirus (SpliNPV) formulations showed that both the IIM− and PER− mutant larvae were more susceptible to these bioinsecticides compared to the wild-type (WT) larvae with intact PM. Interestingly, the provision of chitin-binding agent Calcofluor (CF) in the diet lowered the toxicity of Bt formulations in both WT and IIM− larvae and the protective effect of CF was significantly lower in PER− larvae. This suggested that the interaction of CF with PER is responsible for Bt resistance mediated by CF. In contrast, the provision of CF caused increased susceptibility to SpliNPV in both mutants and WT larvae. The study showed the importance of peritrophins in the defense against pathogens in S. littoralis and revealed novel insights into CF-mediated resistance to Cry toxin.

Role of the epsilon glutathione S-transferases in xanthotoxin tolerance in Spodoptera litura

Spodoptera litura, a polyphagous lepidopteran pest, demonstrates a remarkable capacity to adapt to varying host plants by efficiently detoxifying phytochemicals. However, the underlying mechanism for this adaptation is not well understood. Herein, twenty eplison glutathione S-transferase genes (GSTes) were characterized and their roles in phytochemical tolerance were analyzed in S. litura. Most of the GSTe genes were mainly expressed in the larval midgut and fat body. Exposure to the phytochemicals, especially xanthotoxin, induced the expression of most GSTe genes. Molecular docking analysis revealed that xanthotoxin could form stable bonds with six xanthotoxin-responsive GSTes, with binding free energies ranging from −36.44 to −68.83 kcal mol−1. Knockdown of these six GSTe genes increased the larval susceptibility to xanthotoxin. Furthermore, xanthotoxin exposure significantly upregulated the expression of two transcription factor genes CncC and MafK. Silencing of either CncC or MafK reduced the expression of GSTe16, which exhibited the largest change in response to xanthotoxin. Additionally, analysis of the promoter sequence of GSTe16 revealed the presence of seven CncC/Maf binding sites. Luciferase reporter assays showed that CncC and MafK enhanced the expression of GSTe16, leading to the increased xanthotoxin tolerance in S. litura. These findings provide insight into the functions and transcriptional regulatory mechanisms of GSTes, thereby enhancing our understanding of the role of GSTs in the adaptation of lepidopteran pests to phytochemicals.

Investigating the role of the ROS/CncC signaling pathway in the response to xenobiotics in Spodoptera frugiperda using Sf9 cells

Spodoptera frugiperda (fall armyworm, FAW) is an invasive polyphagous lepidopteran pest that has developed sophisticated resistance mechanisms involving detoxification enzymes to eliminate toxic compounds it encounters in its diet including insecticides. Although its inventory of detoxification enzymes is known, the mechanisms that enable an adapted response depending on the toxic compound remain largely unexplored. Sf9 cells were used to investigate the role of the transcription factors, Cap n′ collar isoform C (CncC) and musculoaponeurotic fibrosarcoma (Maf) in the regulation of the detoxification response. We overexpressed CncC, Maf or both genes, and knocked out (KO) CncC or its repressor Kelch-like ECH associated protein 1 (Keap1). Joint overexpression of CncC and Maf is required to confer increased tolerance to indole 3-carbinol (I3C), a plant secondary metabolite, and to methoprene, an insecticide. Both molecules induce reactive oxygen species (ROS) pulses in the different cell lines. The use of an antioxidant reversed ROS pulses and restored the tolerance to I3C and methoprene. The activity of detoxification enzymes varied according to the cell line. Suppression of Keap1 significantly increased the activity of cytochrome P450s, carboxylesterases and glutathione S-transferases. RNAseq experiments showed that CncC mainly regulates the expression of detoxification genes but is also at the crossroads of several signaling pathways (reproduction and immunity) maintaining homeostasis. We present new data in Sf9 cell lines suggesting that the CncC:Maf pathway plays a central role in FAW response to natural and synthetic xenobiotics. This knowledge helps to better understand detoxification gene expression and may help to design next-generation pest insect control measures.

Estimating the Cost of Production of Two Pentatomids and One Braconid for the Biocontrol of Spodoptera frugiperda (Lepidoptera: Noctuidae) in Maize Fields in Florida

The fall armyworm is a polyphagous lepidopteran pest that primarily feeds on valuable global crops like maize. Insecticides and transgenic crops have long been a primary option for fall armyworm control, despite growing concerns about transgenic crop resistance inheritance and the rate of insecticide resistance development. Global dissemination of the pest species has highlighted the need for more sustainable approaches to managing overwhelming populations both in their native range and newly introduced regions. As such, integrated pest management programs require more information on natural enemies of the species to make informed planning choices. In this study, we present a cost analysis of the production of three biocontrol agents of the fall armyworm over a year. This model is malleable and aimed towards small-scale growers who might benefit more from an augmentative release of natural enemies than a repetitive use of insecticides, especially since, though the benefits of using either are similar, the biological control option has a lower development cost and is more environmentally sustainable.

Comparative transcriptome analysis reveals key candidate genes mediating ovarian development in Spodoptera frugiperda fed on two host plants.

The fall armyworm (FAW), Spodoptera frugiperda, is a highly polyphagous lepidopteran pest, with its growth and adaptation affected by different host plants. However, little is known about the effects of host plants on ovarian development in this species. Thus, we evaluated the effects of feeding on corn (Zea mays L.) and goosegrass (Eleusine indica), on the ovarian development of S. frugiperda. Using various stages of S. frugiperda, we also evaluated the larval and pupal weights, number of eggs, and differentiation of ovarioles over time. Results showed that females fed on goosegrass had shorter ovarioles and laid less eggs than those fed on corn. Transcriptome analysis identified 3,213 genes involved in ovarian development in the fall armyworm. Of these, 881 genes were differentially expressed when fed on corn and goosegrass. The analysis also indicated that the hormone biosynthetic pathways may be involved in the reproductive system. In relation to the reproductive function, nine juvenile hormone (JH) biosynthetic genes, four 20-hydroxyecdysone (20E) biosynthetic genes, and four ovary-relevant functional genes were identified. The time course of the expression profiles of these hormone- and ovary development-related genes was measured by quantitative real-time PCR (qRT-PCR). In total, six of them showed a decreasing trend in the ovary of the FAW fed on goosegrass, while two genes showed an increasing trend. Our results showed that significant changes in the reproductive activity/ovary development in the FAW occurred in response to different diets. These results serve as bases for evaluating how optimal host plants and feeding preference affect ovarian development in the FAW.

Large genomic deletion linked to field-evolved resistance to Cry1F corn in fall armyworm (Spodoptera frugiperda) from Florida

The fall armyworm (Spodoptera frugiperda) is a highly polyphagous lepidopteran pest of relevant food and fiber staple crops. In the Americas, transgenic corn and cotton producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have controlled and reduced the damage caused by S. frugiperda. However, cases of field-evolved S. frugiperda resistance to Bt corn producing the Cry1F insecticidal protein have been documented in North and South America. When characterized, field resistance to Cry1F is linked to insertions and mutations resulting in a modified or truncated ABC transporter subfamily C2 (SfABCC2) protein that serves as Cry1F receptor in susceptible S. frugiperda. In this work, we present detection of a large genomic deletion (~ 8 kb) affecting the SfABCC2 and an ABC transporter gene subfamily 3 –like gene (SfABCC3) as linked to resistance to Cry1F corn in a S. frugiperda strain from Florida (FL39). Monitoring for this genomic deletion using a discriminatory PCR reaction in field-collected S. frugiperda moths detected individuals carrying this allele in Florida, but not in surrounding states. This is the first report of a large genomic deletion being involved in resistance to a Bt insecticidal protein.

Bio controlled efficacy of Bacillus thuringiensis cry protein protection against tomato fruit borer Helicoverpa armigera in a laboratory environment

Bio-pesticides that utilize beneficial microbial agents represent a new option that can potentially reduce reliance on chemical pesticides. To facilitate control of crop pests, this study includes both selection and characterization of Bacillus thuringiensis strains based on Cry gene content and toxicity evaluation. The result is an effective and non-hazardous polyphagous lepidopteran pest controller, Helicoverpa armigera. To achieve this objective, we selected ten soil bacteria samples selected from 10 different agricultural regions in Queretaro State, Mexico. Certainly, 65 and 130 kDa protein bands were observed in SDS-PAGE analysis of spore-crystal mixtures. Efficacy of bio-pesticides, 4 g/L effective water yielded maximum mortality; a mean of 64.88% of tomato fruit borer larvae were eliminated. The PCR sequences of bacterial strain were characterized and showed 98–99% similarity shows the distance from comparison of the 16S rRNA gene sequences of Bacillus thuringiensis.

Early Warning of Resistance to Bt Toxin Vip3Aa in Helicoverpa zea.

Evolution of resistance by pests can reduce the benefits of crops genetically engineered to produce insecticidal proteins from Bacillus thuringiensis (Bt). Because of the widespread resistance of Helicoverpa zea to crystalline (Cry) Bt toxins in the United States, the vegetative insecticidal protein Vip3Aa is the only Bt toxin produced by Bt corn and cotton that remains effective against some populations of this polyphagous lepidopteran pest. Here we evaluated H. zea resistance to Vip3Aa using diet bioassays to test 42,218 larvae from three lab strains and 71 strains derived from the field during 2016 to 2020 in Arkansas, Louisiana, Mississippi, Tennessee, and Texas. Relative to the least susceptible of the three lab strains tested (BZ), susceptibility to Vip3Aa of the field-derived strains decreased significantly from 2016 to 2020. Relative to another lab strain (TM), 7 of 16 strains derived from the field in 2019 were significantly resistant to Vip3Aa, with up to 13-fold resistance. Susceptibility to Vip3Aa was significantly lower for strains derived from Vip3Aa plants than non-Vip3Aa plants, providing direct evidence of resistance evolving in response to selection by Vip3Aa plants in the field. Together with previously reported data, the results here convey an early warning of field-evolved resistance to Vip3Aa in H. zea that supports calls for urgent action to preserve the efficacy of this toxin.

Enzymatic suppression activity of Alpinia galanga extract against polyphagous lepidopteran pest Spodoptera litura (Fabricius)

Plants produce a wide variety of metabolites in order to defend themselves against herbivore insects. To cope with the adverse effects of secondary metabolites, insects have also developed a variety of mechanisms including production of digestive and detoxifying enzymes. These enzymes provide benefit to insects by converting complex molecules into simpler form as well as help in detoxification of deleterious plant metabolites. The current study evaluated the effect of ethyl acetate extract of Alpinia galanga on digestive and detoxifying enzymes of Spodoptera litura (Fab). The larvae were fed on diet treated with different concentrations of the extract viz. 500, 1000, 1500, 2000 and 2500 ppm and the enzyme activity was observed after 48 and 96 hrs of feeding. The results revealed that the activity level of digestive enzymes viz. α-amylase, α and β-glucosidases, α and β-galactosidases and lipases decreased due to consumption of treated diet by the larvae. Similarly detoxifying enzymes viz. phosphatases and glutathione-S-transferases were also found to be suppressed. In conclusion, ethyl acetate extract of A. galanga exhibited enzyme inhibitory activity against S. litura.

First Report of Olepa ricini Fabricius, 1775 (Erebidae: Arctiinae: Arctiini) Feeding on Weed Plant Calotropis procera (Aiton) W.T. Aiton (Apocynaceae) from India

Calotropis procera (Apocynaceae) is a good host plant of several insect pest species. In this report, Calotropis procera is presented as a new host plant for a polyphagous lepidopteran pest, Olepa ricini Fabricius, 1775 for the first time from Indian region with 9±0.5 days adult longevity. Apart from this, complete list of other insects feeding on C. procera Aiton is also enlisted here.

Assessment of genotoxic and biochemical effects of purified compounds of Alpinia galanga on a polyphagous lepidopteran pest Spodoptera litura (Fabricius)

Keeping in view the increasing importance of botanical insecticides, the various metabolites from different plants are being investigated for insecticidal activity. Alpinia galanga, a medicinal plant belonging to family Zingiberaceae exhibits a wide range of biological activities. In the present study, purified compounds of A. galanga i.e. 1′-acetoxychavicol acetate and galangin were evaluated for their effect on detoxifying enzymes viz. esterases, acid phosphatases, alkaline phosphatses and glutathione-S-transferases as well as DNA damage of the Spodoptera litura (Fab.) larvae. DNA damaging potential of both the compounds was ascertained using comet assay. The purified compounds significantly changed the enzymatic profile of S. litura as well as induced genotoxic effects. Change in enzyme activity and damage to DNA may lead to genetic and physiological changes in insect and ultimately affect its fitness and survival.

Plant allelochemicals affect tolerance of polyphagous lepidopteran pest Helicoverpa armigera (Hübner) against insecticides

Cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), is a polyphagous lepidopteran pest distributed worldwide with a broad spectrum of host plants. However, the mechanism of H. armigera adaptation to various insecticides and defensive allelochemicals in its host plants is not fully understood. Therefore, this study examined the influence of consumption of plant allelochemicals on larval tolerance to methomyl and chlorpyrifos insecticides in H. armigera and its possible mechanism. Twelve plant allelochemicals were screened to evaluate their effects on larval sensitivity to methomyl. Of which flavone, coumarin, DIMBOA (2,4-Dihydroxy-7-methoxy-1,4-benzoxazin-3-one) and visnagin significantly reduced larval sensitivity to methomyl. Application of cytochrome P450 inhibitor piperonyl butoxide (PBO) significantly increased the mortality of methomyl-treated larvae. In contrast, PBO addition significantly decreased the mortality of chlorpyrifos-treated larvae. Moreover, allelochemical consumption enhanced the activities of glutathione S-transferase, carboxylesterase, cytochrome P450 and acetylcholinesterase in the midgut and fat body. The qRT-PCR analysis confirms that P450 genes, CYP6B2, CYP6B6 and CYP6B7 were induced by the four allelochemicals in the midguts and the fat bodies. In conclusion, the generalist H. armigera can take benefit of plant allelochemicals from its host plants to elaborate its defense against insecticides.

Effect of crude extracts and purified compounds of Alpinia galanga on nutritional physiology of a polyphagous lepidopteran pest, Spodoptera litura (Fabricius)

Secondary plant metabolites play an important role in providing protection to plants against herbivore insect pests. Keeping in view the increasing importance of biopesticides, the crude extracts from different plants are being investigated for insecticidal activities. Alpinia galanga, a medicinal plant belonging to family Zingiberaceae exhibits a wide range of biological activities. In the present study, crude extracts of A. galanga and its purified compounds i.e. 1′-acetoxychavicol acetate and galangin were evaluated for their effect on various nutritional parameters of Spodoptera litura (Fab.). All the extracts exhibited a significant influence on relative growth and consumption rates as well as efficiency of conversion of ingested and digested food. Ethyl acetate extract was found to be the most effective causing significant reduction in values of RGR, RCR, ECI and ECD of S. litura larvae in comparison to control larvae. The highest concentration of the ethyl acetate extract (2500 ppm) resulted in 44.95%, 10.99%, 38.08% and 37.04% decrease respectively in RGR, RCR, ECI and ECD in comparison to control. The purified compounds also showed inhibitory effects on various nutritional parameters. 1′-Acetoxychavicol acetate was found to be more effective in comparison to galangin.

Detection of sister-species in invasive populations of the fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) from Uganda.

The fall armyworm (FAW) Spodoptera frugiperda (J. E. Smith) is a species native to the Americas. This polyphagous lepidopteran pest was first reported in Nigeria and the Democratic Republic of São Tomé and Principe in 2016, but its presence in eastern Africa has not been confirmed via molecular characterisation. In this study, FAW specimens from western and central Uganda were identified based on the partial mtDNA COI gene sequences, with mtDNA COI haplotypes matching those identified in Nigeria and São Tomé. In this study, we sequence an additional partial mtDNA Cyt b gene and also the partial mtDNA COIII gene in Ugandan FAW samples. We detected identical mitochondrial DNA haplotypes for both the mtDNA Cyt b and COI partial genes, while combining the mtDNA COI/Cyt b haplotypes and mtDNA COIII haplotypes enabled a new maternal lineage in the Ugandan corn-preferred FAW samples to be identified. Our results suggested that the African incursions of S. frugiperda involved at least three maternal lineages. Recent full genome, phylogenetic and microsatellite analyses provided evidence to support S. frugiperda as likely consisted of two sympatric sister species known as the corn-preferred and rice-preferred strains. In our Ugandan FAW populations, we identified the presence of mtDNA haplotypes representative of both sister species. It is not known if both FAW sister species were originally introduced together or separately, and whether they have since spread as a single population. Further analyses of additional specimens originally collected from São Tomé, Nigeria and throughout Africa would be required to clarify this issue. Importantly, our finding showed that the genetic diversity of the African corn-preferred FAW species is higher than previously reported. This potentially contributed to the success of FAW establishment in Africa. Furthermore, with the additional maternal lineages detected, there is likely an increase in paternal lineages, thereby increasing the diversity of the African FAW population. Knowledge of the FAW genetic diversity will be needed to assess the risks of introducing Bt-resistance traits and to understand the FAW incursion pathways into the Old World and its potential onward spread. The agricultural implications of the presence of two evolutionary divergent FAW lineages (the corn and the rice lineage) in the African continent are further considered and discussed.

Selection and characterization of Bacillus thuringiensis strains from northwestern Himalayas toxic against Helicoverpa armigera.

In this study, we present the selection and the characterization of Bacillus thuringiensis (Bt) strains with respect to their cry/cyt gene content and toxicity evaluation toward one of the most important polyphagous lepidopteran pest, Helicoverpa armigera. Fifty‐six Bt isolates were obtained from 10 different regions of northwestern Himalayas, recording a total B. thuringiensis index of 0.62. Scanning electron microscopy revealed presence of bipyramidal, spherical, flat and irregular crystal shapes; SDS‐PAGE analysis of spore‐crystal mixtures showed the prominence of 130, 70, and 100 kDa protein bands in majority of the isolates; PCR analysis with primers for eight cry and cyt gene families and 13 cry gene subfamilies resulted in isolates showing different combinations of insecticidal genes. Strains containing cry1 were the most abundant (57.1%) followed by cyt2 (46.42%), cry11 (37.5%), cry2 (28.57%), cry4 (21.42%), cyt1 (19.64%), cry3 (8.9%), and cry7, 8 (7.14%). A total of 30.35% of the strains did not amplify with any of the primers used in this study. Median lethal concentration 50 (LC50) estimates of spore‐crystal mixtures of Bt‐JK12, 17, 22, 48, and 72 against second instar larvae of H. armigera was observed to be 184.62, 275.39, 256.29, 259.93 μg ml−1, respectively. B. thuringiensis presents great diversity with respect to the presence of crystal protein encoding genes and insecticidal activity. Four putative toxic isolates identified in this study have potential application in insect pest control. B. thuringiensis isolate JK12 exhibited higher toxicity against H. armigera than that of B. thuringiensis HD1, hence can be commercially exploited to control insect pest for sustainable crop production. The results of this study confirm the significance of continuous exploration of new Bt stains from different ecological regions of the world.

Inga laurina trypsin inhibitor (ILTI) obstructs Spodoptera frugiperda trypsins expressed during adaptive mechanisms against plant protease inhibitors

Plant protease inhibitors (PIs) are elements of a common plant defense mechanism induced in response to herbivores. The fall armyworm, Spodoptera frugiperda, a highly polyphagous lepidopteran pest, responds to various PIs in its diet by expressing genes encoding trypsins. This raises the question of whether the PI-induced trypsins are also inhibited by other PIs, which we posed as the hypothesis that Inga laurina trypsin inhibitor (ILTI) inhibits PI-induced trypsins in S. frugiperda. In the process of testing our hypothesis, we compared its properties with those of selected PIs, soybean Kunitz trypsin inhibitor (SKTI), Inga vera trypsin inhibitor (IVTI), Adenanthera pavonina trypsin inhibitor (ApTI), and Entada acaciifolia trypsin inhibitor (EATI). We report that ILTI is more effective in inhibiting the induced S. frugiperda trypsins than SKTI and the other PIs, which supports our hypothesis. ILTI may be more appropriate than SKTI for studies regarding adaptive mechanisms to dietary PIs.

CYP6B6 is involved in esfenvalerate detoxification in the polyphagous lepidopteran pest, Helicoverpa armigera

The cotton bollworm, Helicoverpa armigera, is a polyphagous pest that has a strong capacity to evolve resistance against various classes of insecticides. Cytochrome P450 enzymes have been suspected involved in pyrethroid metabolism and resistance in this pest. However, how many and which P450s are involved in pyrethroid metabolism is largely unknown. In this study, CYP6B6 and NADPH-cytochrome P450 reductase (HaCPR) from H. armigera were successfully co-expressed in Escherichia coli. Incubation of esfenvalerate with the recombinant CYP6B6-HaCPR monooxygenase complex revealed that CYP6B6 was able to transform esfenvalerate into 4′-hydroxy fenvalerate. Kcat and Km values for the formation of 4′-hydroxyfenvalerate by the E. coli-produced CYP6B6 were determined to be 1.65±0.11min−1 and 4.10±0.84μM respectively. Our results demonstrate that CYP6B6 has the ability to hydroxylate esfenvalerate, thus plays a role in fenvalerate detoxification.

Draft Genome Sequence of Enterococcus mundtii SL 16, an Indigenous Gut Bacterium of the Polyphagous Pest Spodoptera littoralis.

Insects are the most abundant and diverse animal class on Earth, and they are associated with an amazing variety of symbiotic microorganisms, which participate in many relationships with the hosts (Douglas, 2015). For example, the fungal symbiont (Leucoagaricus gongylophorus) of leaf-cutting ants produces diverse enzymes for the degradation of plant material (Kooij et al., 2016). Similarly, Bacillus pumilus isolated from the gut of wood boring Mesomorphus sp. (Coleoptera: Tenebrionidae) exhibits significant cellulolytic and xylose isomerase activities (Balsingh et al., 2016). The Lepidoptera, including moths and butterflies, is one of the most widespread and widely recognizable insect orders in the world. Although butterflies and moths play an important role in the natural ecosystem as pollinators and as food in the food chain, their leaf-chewing larvae are often problematic in agriculture, as their main source of food is live plants (Mithofer and Boland, 2012). The leafworm Spodoptera littoralis (Lepidoptera: Noctuidae) is a highly polyphagous lepidopteran pest found worldwide and also an important model system used in a variety of biological research. Recent extensive surveys of its microbiome reveal that Enterococcus mundtii is one of the predominant gut microorganisms of S. littoralis and present at high frequency (Tang et al., 2012; Chen et al., 2016; Teh et al., 2016). Particularly, a stable isotope labeling-based approach suggested that this phylotype was also highly metabolically active inside the host across life history of S. littoralis, indicating the significant role played by E. mundtii in host biology (Shao et al., 2014). Therefore, the symbiotic E. mundtii probably constitutes a key factor for the success of this generalist herbivore in adapting to different environments and food sources. The aim of this study was to produce a genome sequence of the strain SL 16, which would assist in understanding of the coevolution of the microbe and the insect host. The dataset has been submitted to NCBI Whole Genome Shotgun (WGS) projects and is reported here, providing an overview of the genome sequence and relevant features of gut symbiotic E. mundtii.

Polyphagy in an uncertain environment: Helicoverpa punctigera in inland Australia

We investigated potential primary hosts for Helicoverpa punctigera, a polyphagous lepidopteran pest which affects many crops, but also has many native hosts in non-cropping regions of inland Australia. The most common hosts are Asteraceae and Fabaceae, but there is little information on the relative importance of different species in these families for the population dynamics of H. punctigera in the inland. We tested three common hosts, one legume (Cullen cinereum) and two daisies, Rhodanthe floribunda and Polycalymma stuartii, for their suitability for survival and growth of early instar larvae. Survival was high on the flowers of all three species, and on the leaves of C. cinereum and R. floribunda, but low on leaves of P. stuartii. There were significant differences in growth rates, measured by head widths, in the order of C. cinereum > R. floribunda > P. stuartii, and flowers > leaves. They were strongly correlated with nitrogen content, measured by fresh weight. Field surveys of larval populations in western Queensland indicated that two legume species, C. cinereum and Cullen pallidum, were widely utilized and supported many larvae. Daisies were generally less widely used and/or had lower numbers of larvae. When C. cinereum or C. pallidum was found near daisies, the legume had more larvae if both the daisy and the legume were flowering, but this was reversed if only the daisy was flowering. The seasonality and habitats of the daisies and legumes are different. C. cinereum and C. pallidum (a new host record for H. punctigera) may be primary hosts of H. punctigera in inland Australia and key hosts for maintaining populations in flood plains. However the areas occupied by daisies can be more extensive depending on rainfall, and some species may be critical in generating outbreaks that affect cropping areas in southeast Australia.