Effects of photoperiod and temperature on the developmental duration and diapause in Dolycoris baccarum (Heteroptera: Pentatomidae) from Hohhot, Inner Mongolia, China.

The shield bug, Dolycoris baccarum (L.) (Heteroptera: Pentatomidae), is widely distributed across Asia and Europe. At high latitudes, it overwinters, as adult in diapause, which then becomes the insect source for the following year. To fully understand the developmental duration and diapause characteristics of D. baccarum, the effects of photoperiod and temperature were studied in a population from Hohhot, Inner Mongolia, China. The results indicated that the developmental duration was significantly prolonged at temperatures of 20 or 25 °C, with a prolonged light period; however, when the light period was prolonged to 16L:8D and 18L:6D, the developmental duration was shortened significantly. Furthermore, the developmental duration was also shortened significantly with increasing temperature, when the photoperiod was 12L:12D for short days and 16L:8D for long days. All individuals entered diapause under short-day conditions of 10L:14D and 12L:12D at a temperature of 20 °C; however, the diapause rate decreased significantly under 14L:10D and 16L:8D photoperiods, and the diapause rate decreased significantly at a temperature of 25 °C with prolonged photoperiod. Interestingly, when the photoperiod was fixed at 12L:12D, the diapause rates at different temperatures (20, 25, 28, and 30 °C) exceeded 95%; while the effect of temperature on diapauses was nonsignificant under this photoperiod, it was still sensitive to the photoperiod; at a photoperiod of 16L:8D, the effect of temperature on the diapause rate was noticeable, and the diapause rate decreased significantly with increasing temperature.

Metabolic Response of Peach Fruit to Invasive Brown Marmorated Stink Bug (Halyomorpha halys Stål.)'s Infestation.

The brown marmorated stink bug (BMSB; Halyomorpha halys Stål.) is a highly destructive and polyphagous invasive pest that poses a serious threat to more than a hundred reported host plants. In the current study, the metabolic response of peach fruit of two cultivars-'Maria Marta' and 'Redhaven'-to BMSB infestation was studied using high-performance liquid chromatography (HPLC) and mass spectrometry (MS). In general, a strong phenolic response to BMSB infestation in peach flesh in the injury zone was observed, with flavanol content increasing by 2.4-fold, hydroxycinnamic acid content by 5.0-fold, flavonol content by 3.2-fold, flavanone content by 11.3-fold, and dihydrochalcones content by 3.2-fold compared with the undamaged tissue in the cultivar 'Maria Marta'. The phenolic response in the 'Redhaven' cultivar was even stronger. Consequently, the total phenolic content in the injured flesh also increased, 3.3-fold in 'Maria Marta' and 6.9-fold in 'Redhaven', compared with the uninjured flesh. Infestation with BMSB induced the synthesis of cyanidin-3-glucoside, which is not normally present in peach flesh. In comparison, the phenolic response was lower in peach peel, especially in the cultivar 'Maria Marta'. The study showed that both peach cultivars reacted to BMSB infestation with an increase in phenolic content in the peach flesh, but in a limited area of injury.

Protective Geometry and Reproductive Anatomy as Candidate Determinants of Clutch Size Variation in Pentatomid Bugs.

AbstractMany animals lay their eggs in clusters. Eggs on the periphery of clusters can be at higher risk of mortality. We asked whether the most commonly occurring clutch sizes in pentatomid bugs could result from geometrical arrangements that maximize the proportion of eggs in the cluster's interior. Although the most common clutch sizes do not correspond with geometric optimality, stink bugs do tend to lay clusters of eggs in shapes that protect increasing proportions of their offspring as clutch sizes increase. We also considered whether ovariole number, an aspect of reproductive anatomy that may be a fixed trait across many pentatomids, could explain observed distributions of clutch sizes. The most common clutch sizes across many species correspond with multiples of ovariole number. However, there are species with the same number of ovarioles that lay clutches of widely varying size, among which multiples of ovariole number are not overrepresented. In pentatomid bugs, reproductive anatomy appears to be more important than egg mass geometry in determining clutch size uniformity. In addition, our analysis demonstrates that groups of animals with little variation in ovariole number may nonetheless lay a broad range of clutch shapes and sizes.

Distribution and prevalence of viral genomes in Italian populations of the invasive brown marmorated stink bug Halyomorpha halys.

Halyomorpha halys (Stål), the brown marmorated stink bug, is a highly invasive insect species that causes significant agricultural losses, especially to orchard fruits, vegetables, herbaceous and ornamental plants. It is also a nuisance pest that seeks shelter in indoor spaces during the winter months. Harnessing the H. halys virome can result in new environmentally sustainable approaches to contain its populations and its relatated agricultural damages. In this study, RNA-Seq data were used to explore the virome associated to ten field populations collected in the Lombardy region in Northern Italy. We identified six complete viral genomes, three of which were previously unknown, belonging to the orders Reovirales, Articulavirales, Ghabrivirales, Durnavirales, and Picornavirales. The prevalence of the six viruses was evaluated by Real-time reverse transcription-quantitative PCR on eighty individuals. Halyomorpha halys ifla-like virus 2 turned out to be the most geographically widespread virus, as it was found in more than 50% of the analyzed insects and in nine out of the ten sampling locations. Moreover, in some individuals, this iflavirus was found in association with each of the other viruses in various combinations that involved up to four viruses. Further studies on such virus-virus interactions and their relationships with the insect host may open the possibility to exploit these naturally occurring viruses as specific and targeted biocontrol agents of H. halys.

First report of Colletotrichum fioriniae infections in brown marmorated stink bugs, Halyomorpha halys.

An epizootic caused by fungal pathogens occurred among Halyomorpha halys, brown marmorated stink bugs, while they were overwintering, with infections also occurring after overwintering. We report that one of the two pathogens responsible was Colletotrichum fioriniae (Marcelino & Gouli) Pennycook; a species well known as a plant pathogen and endophyte and which has only previously been reported naturally infecting elongate hemlock scales, Fiorinia externa. To prove pathogenicity, H. halys adults challenged with conidia died from infections and the fungus subsequently produced conidia externally on cadavers.

Determination of the Absolute Configuration of the Male-Produced Sex Pheromone of the Stink Bug Pellaea stictica, (2R,4R,8R)-2,4,8,13-Tetramethyltetradecan-1-ol by Stereoselective Synthesis Coupled with Enantiomeric Resolution.

In a previous study, we reported the identification and synthesis of a male-specific sex pheromone component of the stink bug, Pellaea stictica, as the alcohol 2,4,8,13-tetramethyltetradecan-1-ol (1). To establish the correlation between the stereochemistry of the pheromone and its bioactivity, it first was necessary to determine its absolute configuration. For this purpose, a series of syntheses were designed to: (a) furnish a mixture of all possible stereoisomers; (b) a narrowed down group of diastereomers, and (c) one specific enantiomer. A crucial step in the syntheses involved a coupling reaction between two key intermediates: a phosphonium salt and an aldehyde, through a Wittig olefination. Nuclear magnetic resonance data of a mixture of the synthetic pheromone diastereomers and further comparison of GC retention times with that of the natural product by gas chromatography suggested that the methyl branches at C2 and C4 were in a syn relationship, reducing the possibilities to only four of the eight possible stereoisomers. Employing GC analysis, chiral derivatization reagents and synthetic (8R)-2,4-syn-1 it was possible to confirm the configuration of the methyl branch at C8 as R, reducing the number of possible stereoisomers to two. After enantioselective synthesis of (2R,4R,8R)-1, the absolute configurations of all methyl branches of the natural compound were confirmed as R, fully identifying the male-produced sex pheromone of P. stictica as (2R,4R,8R)-2,4,8,13-tetramethyltetradecan-1-ol.

Identification of Zingiberenol and Murgantiol as Components of the Aggregation-Sex Pheromone of the Rice Stink Bug, Mormidea v-luteum (Heteroptera: Pentatomidae).

Mormidea v-luteum (Lichtenstein, 1796) feeds on commercial crops, such as rice and ryegrass, causing damage that slows growth and reduces productivity. With the aim of developing an eco-friendly control technique, we investigated the compounds involved in chemical communication in this species. The volatiles produced by a group of seven males or females allocated to different aerated glass chambers were collected for 24 h and analyzed by gas chromatograph/mass spectrometry and gas chromatography/Fourier transform infrared spectroscopy. The analyses showed six male-specific compounds, identified as two isomers of zingiberenol (compounds 1 and 2), three isomers of murgantiol (3, 5 and 6) and sesquipiperitol (4). Compounds 1 and 5 were the major components and were produced in a ratio of 6:4. The absolute stereochemistry of the two isomers of zingiberenol was established as (1S,4R,1'S)-1 and (1R,4R,1'S)-2 by chiral gas chromatography. Stereochemistry was not determined for all the other molecules. To confirm the attractiveness of these chemicals, bioassays were performed in a Y-tube olfactometer, first using crude extracts and, subsequently, synthetic compounds. Male volatiles were attractive to both sexes, demonstrating an aggregation pheromone. In bioassays with synthetic compounds, (1'S)-zingiberenol was highly attractive to both males and females. However, when (1'S)-murgantiol was tested, only females were attracted. Interestingly, when a mixture of zingiberenol and murgantiol isomers was tested, it was attractive to both sexes, with females more attracted to the mixture than to zingiberenol alone; males did not distinguish between treatments. Thus, the bioassay data suggest that the molecules have different functions in chemical communication of this species: zingiberenol acts primarily as an aggregation pheromone, while murgantiol plays a role as a sex pheromone.

Trichoderma harzianum Strain T22 Modulates Direct Defense of Tomato Plants in Response to Nezara viridula Feeding Activity.

Plant growth-promoting fungi belonging to genus Trichoderma are known to help plants when dealing with biotic stressors by enhancing plant defenses. While beneficial effects of Trichoderma spp. against plant pathogens have long been documented, fewer studies have investigated their effect on insect pests. Here, we studied the impact of Trichoderma root colonization on the plant defense responses against stink bug feeding attack. For this purpose, a model system consisting of tomato plant, Solanum lycopersicum cv Dwarf San Marzano, Trichoderma harzianum strain T22 and the southern green stink bug, Nezara viridula, was used. We firstly determined stink bug performance in terms of relative growth rate and survival on tomato plants inoculated by T. harzianum T22. Then, we evaluated relative expression of plant defense-related genes on inoculated plants induced by stink bug feeding. We found evidence that T. harzianum T22 affects tomato defense responses against N. viridula nymphs leading to reduction of growth rate. Our results also showed that T. harzianum T22 enhances plant direct defenses by an early increase of transcript levels of jasmonic acid marker genes. Yet this effect was time-dependent and only detected 8 h after herbivore induction. Taken together, our findings provide better understanding on the mechanisms underlying tomato induced resistance against herbivorous stink bugs.

Attraction of Brown Marmorated Stink Bugs, Halyomorpha halys, to Blooming Sunflower Semiochemicals.

The polyphagous invasive brown marmorated stink bug, Halyomorpha halys, reportedly discriminates among phenological stages of host plants. To determine whether olfaction is involved in host plant stage discrimination, we selected (dwarf) sunflower, Helianthus annuus, as a model host plant species. When adult females of a still-air laboratory experiment were offered a choice of four potted sunflowers at distinct phenological stages (vegetative, pre-bloom, bloom, seeding), most females settled onto blooming plants but oviposited evenly on plants of all four stages. In moving-air two-choice olfactometer experiments, we then tested each plant stage versus filtered air and versus one another, for attraction of H. halys females. Blooming sunflowers performed best overall, but no one plant stage was most attractive in all experiments. Capturing and analyzing (by GC-MS) the headspace odorants of each plant stage revealed a marked increase of odorant abundance (e.g., monoterpenes) as plants transitioned from pre-bloom to bloom. Analyzing the headspace odorant blend of blooming sunflower by gas chromatographic-electroantennographic detection (GC-EAD) revealed 13 odorants that consistently elicited responses from female H. halys antennae. An 11-component synthetic blend of these odorants attracted H. halys females in laboratory olfactometer experiments. Furthermore, in field settings, the synthetic blend enhanced the attractiveness of synthetic H. halys pheromone as a trap lure, particularly in spring (April to mid-June). A simpler yet fully effective sunflower semiochemical blend could be developed and coupled with synthetic H. halys aggregation pheromones to improve monitoring efforts or could improve the efficacy of modified attract-and-kill control tactics for H. halys.

De novo formation of an aggregation pheromone precursor by an isoprenyl diphosphate synthase-related terpene synthase in the harlequin bug.

Insects use a diverse array of specialized terpene metabolites as pheromones in intraspecific interactions. In contrast to plants and microbes, which employ enzymes called terpene synthases (TPSs) to synthesize terpene metabolites, limited information from few species is available about the enzymatic mechanisms underlying terpene pheromone biosynthesis in insects. Several stink bugs (Hemiptera: Pentatomidae), among them severe agricultural pests, release 15-carbon sesquiterpenes with a bisabolene skeleton as sex or aggregation pheromones. The harlequin bug, Murgantia histrionica, a specialist pest of crucifers, uses two stereoisomers of 10,11-epoxy-1-bisabolen-3-ol as a male-released aggregation pheromone called murgantiol. We show that MhTPS (MhIDS-1), an enzyme unrelated to plant and microbial TPSs but with similarity to trans-isoprenyl diphosphate synthases (IDS) of the core terpene biosynthetic pathway, catalyzes the formation of (1S,6S,7R)-1,10-bisaboladien-1-ol (sesquipiperitol) as a terpene intermediate in murgantiol biosynthesis. Sesquipiperitol, a so-far-unknown compound in animals, also occurs in plants, indicating convergent evolution in the biosynthesis of this sesquiterpene. RNAi-mediated knockdown of MhTPS mRNA confirmed the role of MhTPS in murgantiol biosynthesis. MhTPS expression is highly specific to tissues lining the cuticle of the abdominal sternites of mature males. Phylogenetic analysis suggests that MhTPS is derived from a trans-IDS progenitor and diverged from bona fide trans-IDS proteins including MhIDS-2, which functions as an (E,E)-farnesyl diphosphate (FPP) synthase. Structure-guided mutagenesis revealed several residues critical to MhTPS and MhFPPS activity. The emergence of an IDS-like protein with TPS activity in M. histrionica demonstrates that de novo terpene biosynthesis evolved in the Hemiptera in an adaptation for intraspecific communication.

Habitat visualization, acquisition features and necessity of the gammaproteobacterial symbiont of pistachio stink Bug, Acrosternum heegeri (Hem.: Pentatomidae).

Plant-sucking stinkbugs are especially associated with mutualistic gut bacterial symbionts. Here, we explored the symbiotic relationship of a pistachio stinkbug, Acrosternum heegeri Fieber by histological, fluorescence in situ hybridization (FISH), real-time PCR and molecular phylogenetic techniques. Furthermore, the effects of the symbiont on the resting/wandering behaviors of the newborn nymphs, pre-adult survival rates, and stage compositions were investigated. Transmission electron microscopy and real-time PCR analyses showed that a rod-shaped gammaproteobacterium was persistently located within the posterior midgut crypts. Molecular phylogenetic and FISH techniques strongly suggested that this symbiont should be placed in the genus Pantoea of the Enterobacteriales. Scanning electron microscopy confirmed the presence of the bacterial cells on the egg surface which the surface sterilization of the eggs resulted in the successful removal of the symbiont from the eggs. Symbiotic and aposymbiotic A. heegeri showed no significant differences in the wandering behaviors of the first nymphal stages, while the symbiont-free insects suffered retarded growth and lower survivability. Together, the results highlight the habitat and acquisition features of Pantoea symbiont and its contribution in A. heegeri biology that might help us for better pest management in the future.

Kairomones from Euschistus heros egg masses and their potential use for Telenomus podisi parasitism improvement.

Telenomus podisi Ashmead (Hymenoptera: Scelionidae) is the most important egg parasitoid of Euschistus heros (Fabricius) (Hemiptera: Pentatomidae), and its successful parasitism is related to their searching ability to find suitable hosts under a complex chemical environment using host-reliable cues. Thus, the objective of this study was to elucidate chemical substances on the external layer of E. heros eggs and report its potential kairomonal activity on T. podisi. We tested female wasps in olfactometer system to synthetic compounds obtained from a chemical identification of E. heros egg masses. The synthetic blend was also evaluated in parasitism tests under laboratory and semi-field conditions. We identified 31 substances from egg surface extracts, including monoterpenes, aldehydes and alkanes. Among those compounds, a synthetic solution including camphene, ß-pinene, limonene and benzaldehyde-induced chemotaxic behaviour on the wasps and increased the parasitism on E. heros eggs, either in laboratory or semi-field test, suggesting its potential use to T. podisi manipulation and parasitism improvement.

Male-Produced Aggregation Pheromone of the Sloe Bug, Dolycoris baccarum L. (Hemiptera: Heteroptera: Pentatomidae).

The sloe bug, Dolycoris baccarum L. (Hemiptera: Heteroptera: Pentatomidae), is a Palearctic species and an important polyphagous pest. Previous studies have reported that male D. baccarum produce an aggregation pheromone, to which conspecific adults of both sexes respond. We used solid-phase microextraction (SPME) to collect volatiles released by sexually mature virgin males and females, and identified potential components of the male-produced aggregation pheromone. Analysis of the SPME samples by gas chromatography-mass spectrometry (GC-MS) revealed three male-specific components, α-bisabolol, trans-α-bergamotene, and ß-bisabolene, at a ratio of 100:10:3. A field trapping experiment showed that (±)-α-bisabolol alone attracted D. baccarum adults, and it was synergized by trans-α-bergamotene, but not (S)-ß-bisabolene. However, neither trans-α-bergamotene nor (S)-ß-bisabolene was attractive individually. A binary blend of (±)-α-bisabolol and trans-α-bergamotene in a 10:1 ratio was less attractive than caged live males, suggesting that further study is necessary to determine the absolute configuration or steroisomeric composition of the natural pheromone components. This is the first report of α-bisabolol and trans-α-bergamotene as semiochemicals among Pentatomidae, and the first to identify α-bisabolol from insects.

An IDS-Type Sesquiterpene Synthase Produces the Pheromone Precursor (Z)-α-Bisabolene in Nezara viridula.

Insects use a wide range of structurally diverse pheromones for intra-specific communication. Compounds in the class of terpenes are emitted as sex, aggregation, alarm, or trail pheromones. Despite the common occurrence of terpene pheromones in different insect lineages, their origin from dietary host plant precursors or de novo biosynthetic pathways often remains unknown. Several stink bugs (Hemiptera: Pentatomidae) release bisabolene-type sesquiterpenes for aggregation and mating. Here we provide evidence for de novo biosynthesis of the sex pheromone trans-/cis-(Z)-α-bisabolene epoxide of the Southern green stink bug, Nezara viridula. We show that an enzyme (NvTPS) related to isoprenyl diphosphate synthases (IDSs) of the core terpene metabolic pathway functions as a terpene synthase (TPS), which converts the general intermediate (E,E)-farnesyl diphosphate (FPP) to the putative pheromone precursor (+)-(S,Z)-α-bisabolene in vitro and in protein lysates. A second identified IDS-type protein (NvFPPS) makes the TPS substrate (E,E)-FPP and functions as a bona fide FPP synthase. NvTPS is highly expressed in male epidermal tissue associated with the cuticle of ventral sternites, which is in agreement with the male specific release of the pheromone from glandular cells in this tissue. Our study supports findings of the function of similar TPS enzymes in the biosynthesis of aggregation pheromones from the pine engraver beetle Ips pini, the striped flea beetle Phyllotreta striolata, and the harlequin bug Murgantia histrionica, and hence provides growing evidence for the evolution of terpene de novo biosynthesis by IDS-type TPS families in insects.

Comparative Mitogenomic Analysis of the Eurydema Genus in the Context of Representative Pentatomidae (Hemiptera: Heteroptera) Taxa.

The family Pentatomidae, the largest within the superfamily Pentatomoidae, comprises about 5,000 species; many of which are economically important pests. Although the phylogeny of Pentatomidae species has been studied using various molecular markers, their phylogenetic relationships remain controversial. Recently, mitochondrial genomes (mitogenomes) have been extensively employed to examine the phylogenetics and evolution of different insects, and in this study, we sequenced complete/near-complete mitochondrial genomes from five shield bug species of Eurydema to gain a better understanding of phylogenetic relationships in the Pentatomidae. The five mitogenomes ranged in length from 15,500 to 16,752 bp and comprised 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), 2 ribosomal RNAs (rRNAs), and a control region. We compared mitogenomic characteristics of the Pentatomidae and constructed phylogenetic trees using Bayesian inference and maximum likelihood methods. Our results showed that gene arrangements, base composition, start/stop codons, gene overlaps, and RNA structures were conserved within the Pentatomidae and that congeneric species shared more characteristics. Saturation and heterogeneity analyses revealed that our PCGs and PCGRNA datasets were valid for phylogenetic analysis. Phylogenetic analyses showed consistent topologies based on BI and ML methods. These analyses strongly supported that Eurydema species belong to the tribe Strachiini, and formed a sister group with Pentatomini. The relationships among Eurydema species were shown to be consistent with their morphological features. (Strachiini + Pentatomini) was found to be a stable sibling of the clade comprising Cappaeini, Graphosomini, and Carpocorini. Furthermore, our results indicated that Graphosoma rubrolineatum (Heteroptera: Pentatomidae) belongs to the Pentatominae and not the Podopinae.

Nosema maddoxi sp. nov. (Microsporidia, Nosematidae), a Widespread Pathogen of the Green Stink Bug Chinavia hilaris (Say) and the Brown Marmorated Stink Bug Halyomorpha halys (Stål).

We describe a unique microsporidian species that infects the green stink bug, Chinavia hilaris; the brown marmorated stink bug, Halyomorpha halys; the brown stink bug, Euschistus servus; and the dusky stink bug, Euschistus tristigmus. All life stages are unikaryotic, but analysis of the consensus small subunit region of the ribosomal gene places this microsporidium in the genus Nosema, which historically has been characterized by diplokaryotic life stages. It is also characterized by having the reversed arrangement of the ribosomal gene (LSU -ITS- SSU) found in species within the "true Nosema" clade. This microsporidium is apparently Holarctic in distribution. It is present in H. halys both where it is native in Asia and where it is invasive in North America, as well as in samples of North American native C. hilaris collected prior to the introduction of H. halys from Asia. Prevalence in H. halys from mid-Atlantic, North America in 2015-2016 ranged from 0.0% to 28.3%, while prevalence in C. hilaris collected in Illinois in 1970-1972 ranged from 14.3% to 58.8%. Oral infectivity and pathogenicity were confirmed in H. halys and C. hilaris. Morphological, ultrastructural, and ecological features of the microsporidium, together with a molecular phylogeny, establish a new species named Nosema maddoxi sp. nov.

Rapid differentiation and asynchronous coevolution of male and female genitalia in stink bugs.

Despite claims that genitalia are among the fastest evolving phenotypes, few studies have tested this trend in a quantitative and phylogenetic framework. In systems where male and female genitalia coevolve, there is a growing effort to explore qualitative patterns of evolution and their underlying mechanisms, but the temporal aspect remains overlooked. An intriguing question is how fast male and female genitalia may change in a coevolutionary scenario. Here, we apply a series of comparative phylogenetic analyses to reveal a scenario of correlated evolution and to investigate how fast male and female external, nonhomologous and functionally integrated genitalia change in a group of stink bugs. We report three findings: the female gonocoxite 8 and the male pygophore showed a clear pattern of correlated evolution, both genitalia were estimated to evolve much faster than nongenital traits, and rates of evolution of the male genitalia were twice as fast as the female genitalia. Our results corroborate the widely held view that male genitalia evolve fast and add to the scarce evidence for rapidly evolving female genitalia. Different rates of evolution exhibited by males and females suggest either distinct forms or strengths of selection, despite their tight functional integration and coevolution. The morphological characteristics of this coevolutionary trend are more consistent with a cooperative adjustment of the genitalia, suggesting a scenario of female choice, morphological accommodation, lock-and-key or some combination of the three.

Biology, Ecology, and Management of an Invasive Stink Bug, Bagrada hilaris, in North America.

The painted bug, Bagrada hilaris, native to eastern and southern Africa and Asia, was detected in California in 2008, and it has spread rapidly throughout several southwestern US states. A polyphagous insect, it is particularly damaging to the billion dollar cole crop industry. B. hilaris frequently causes damage when it migrates to newly planted crops from weedy hosts. Feeding produces circular or star-shaped chlorotic lesions that become necrotic, and infested plants may be distorted. Currently, no reliable sampling methods for B. hilaris exist, nor are there effective natural enemies in the United States. Therefore, management has relied on multiple applications of insecticides and cultural practices such as removal of weedy hosts, destruction of crop residues, timing of planting, and use of transplants. Several pyrethroid and neonicotinoid insecticides are most effective for controlling the insect. Reliable sampling methods and further development of integrated pest management strategies to manage this invasive pest are urgently needed as its range continues to expand.

Volatiles Mediating Parasitism of Euschistus conspersus and Halyomorpha halys Eggs by Telenomus podisi and Trissolcus erugatus.

This study identified chemicals found on the eggs of two stink bug species, one native to western North America, Euschistus conspersus, and an invasive species from Asia, Halyomorpha halys. The responses of two scelionid egg parasitoids, Trissolcus erugatus and Telenomus podisi, toward natural stink bug egg volatiles, and synthetic reconstructions of egg volatiles, were tested in bioassays. A compound, methyl (2E,4Z)-2,4-decadienoate, previously identified as the major component of the male-produced aggregation pheromone of E. conspersus, was the major volatile identified from extracts of E. conspersus eggs. In contrast, for H. halys, the sesquiterpenoids that compose the male-produced aggregation pheromone of this species were not detected on eggs, whereas the presence of hexadecanal, octadecanal, and eicosanal was detected. In laboratory olfactometer tests, both Tr. erugatus and Te. podisi females were attracted to extracts of E. conspersus eggs, and to synthetic methyl (2E,4Z)-2,4-decadienoate. However, female Tr. erugatus and Te. podisi wasps were repelled, both by extracts of H. halys eggs and by a blend of the aldehydes identified from H. halys eggs. A follow-up field study, using hexane-washed and intact E. conspersus as sentinel eggs, showed that the parasitoids Trissolcus erugatus and Gryon obesum emerged from these eggs. Sentinel hexane-washed eggs treated with 3 ng of methyl (2E,4Z)-2,4-decadienoate were parasitized more by these two species than were hexane-washed or unwashed eggs, whereas hexane-washed eggs treated with a comparable dose of the C16,18,20 aldehyde mixture were avoided by these parasitoids. In a further field experiment, Trissolcus basalis was the primary parasitoid found in sticky traps baited with methyl (2E,4Z)-2,4-decadienoate, indicating that this species was attracted to, but either did not oviposit or develop in the E. conspersus sentinel eggs in the previous experiment.

Identification and Synthesis of the Male-produced Sex Pheromone of the Stink Bug, Pellaea stictica.

Stink bugs are major pests of a wide variety of agricultural crops worldwide. The species Pellaea stictica is a Neotropical stink bug found in several South American countries. Chromatographic analyses of volatiles released by adults of this species showed that males produce a sex-specific compound, and bioassays with a Y-tube olfactometer showed that the compound was attractive only to females, confirming that it is a sex pheromone. Gas chromatography coupled to mass spectrometry and Fourier transform infrared analyses of the natural compound and several derivatives suggested that the structure was an alcohol with a saturated carbon chain and several methyl branches. After synthesis of two proposed structures, the pheromone of P. stictica was identified as a novel compound, 2,4,8,13-tetramethyltetradecan-1-ol. Laboratory bioassays showed that the synthesized mixture of stereoisomers of 2,4,8,13-tetramethyltetradecan-1-ol was as attractive to P. stictica females as the natural pheromone.