Over the past two decades, several headspace collection techniques have been used to detect and identify volatile organic compounds (VOCs) emitted by plants, pests, air, and soil. Volatiles emitted ...by pests and infected plants are usually found at low concentrations. The important challenge is to be able to capture an exact collection of relative quantities of the relevant VOCs. Here we present an innovative headspace collecting device (HSCD) for sampling VOCs, which ensures an exact regulation of mass flow velocity and collected total gas volume allowing besides qualitative analysis of collected VOCs, an exact comparison of their relative quantities in plant or insect headspace samples. The HSCD possess six parallel odor collection systems each consisting of a digital mass flow detector and controller connected to a vacuum pump, which are mounted in a trolley suitcase, connected by tubes, and wired electrically. The programming of the channels, can be done by a digital control unit. Using the HSCD, VOCs emitted by the brown marmorated stink bug (BMSB), Halyomorpha halys , from its different developmental stages including egg, nymphal stages, nymphal exuvia, and adults were collected on thermal desorption tubes and analyzed using an automated thermal desorber connected to a gas chromatography-mass spectrometry system. Forty-five VOCs were identified in total, which mainly consisted of tridecane (4.36-69.33%), E -2-decenal (4.24-26.48%), 2-undecenal (0.63-50.03%), and E -4- oxo -2-hexenal (1.22-20.58%). The random forest analysis revealed three different chemical patterns among BMSB life stages samples. In conclusion, these results indicate that the new developed HSCD, a mobile, easy to use, and reliable instrument, has a high potential to sample relevant VOCs of a specific life stage of an insect both qualitatively and quantitatively. It was demonstrated that this information can be used for identifying specific chemical signatures, which fit to specific life stages of the BMSB, and may be used as biomarker for on-site detection of this pest e.g. in shipping containers or agricultural areas.
In Asia, Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae) is the predominant egg parasitoid of the brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae). Detections ...of adventive T. japonicus populations in North America since 2014, where invasive H. halys populations have impacted various specialty crops, spurred surveillance efforts to track T. japonicus, and yellow sticky cards (YSC) deployed in H. halys host trees have proven effective for this purpose. While T. japonicus exhibits positive behavioral responses to several olfactory stimuli associated with H. halys under laboratory conditions, these have not been evaluated for their potential utility to enhance surveillance of T. japonicus in the field. In northwestern Virginia, where both H. halys and T. japonicus are well-established, we examined the effect of baiting tree of heaven, Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae), with lures containing the H. halys aggregation pheromone and pheromone synergist on the abundance of H. halys egg masses and captures of T. japonicus in YSC. We also assessed the effect of baiting YSC with newly-laid H. halys egg masses or n-tridecane, a component of H. halys tarsal prints, on T. japonicus captures. Destructive sampling of pheromone-baited and nonbaited trees revealed no significant differences in H. halys egg mass abundance on foliage. Similarly, YSC deployed in pheromone-baited and nonbaited trees showed no significant differences in T. japonicus captures. Moreover, YSC augmented with H. halys egg masses or n-tridecane showed no increase in T. japonicus captures compared with nonbaited controls. The implications for surveillance of adventive T. japonicus are discussed.
The brown marmorated stink bug,
Halyomorpha halys
(Stål), native to China, Japan, and Korea, has emerged as a harmful invasive pest of a variety of crops in North America and Europe. The Asian egg ...parasitoid
Trissolcus japonicus
has been identified as the most promising agent for classical biological control of invasive
H. halys
populations. A 4-year study evaluated the fundamental and ecological host ranges of
T. japonicus
as well as its phenology and impact on
H. halys
populations in fruit orchards in its native range in northern China. In laboratory no-choice tests, developmental suitability of eight non-target host species for
T. japonicus
was demonstrated by the successful production of progeny on the majority (>85%) of non-target host species tested. In field-collected, naturally laid egg masses,
T. japonicus
was the most abundant parasitoid associated with
H. halys
and
Dolycoris baccarum
, but was also sporadically found in
Plautia crossota
. Furthermore, it was regularly reared from sentinel egg masses of
Menida violacea
,
Arma chinensis
, and
Carbula eoa
. The only species that did not support development in the laboratory and field was
Cappaea tibialis
. Besides the benefit of having a high impact on
H. halys
populations in Northern China, the risk assessment conducted in the area of origin indicates that native Pentatomidae in North America and Europe could be negatively impacted by
T. japonicus
. Whether the benefits of
T. japonicus
outweigh the possible risks will have to be evaluated based on the outcome of additional host range studies in the two invaded regions.
Accurate identification of parasitoids is crucial for biological control of the invasive brown marmorated stink bug,
Halyomrpha halys
(Stål). A recent work by Talamas et al. (2017) revised the ...Palearctic fauna of
Trissolcus
Ashmead, egg-parasitoids of stink bugs, and treated numerous species as junior synonyms of
T. semistriatus
(Nees von Esenbeck). In the present paper, we provide a detailed taxonomic history and treatment of
T. semistriatus
and the species treated as its synonyms by Talamas et al. (2017) based on examination of primary types, molecular analyses and mating experiments.
Trissolcus semistriatus
,
T. belenus
(Walker),
T. colemani
(Crawford), and
T. manteroi
(Kieffer) are here recognized as valid and a key to species is provided. The identification tools provided here will facilitate the use of
Trissolcus
wasps as biological control agents and as the subject of ecological studies.
In insects, tyramine receptor 1 (TAR1) has been shown to control several physiological functions, including olfaction. We investigated the molecular and functional profile of the Halyomorpha halys ...type 1 tyramine receptor gene (HhTAR1) and its role in olfactory functions of this pest. Molecular and pharmacological analyses confirmed that the HhTAR1 gene codes for a true TAR1. RT-qPCR analysis revealed that HhTAR1 is expressed mostly in adult brain and antennae as well as in early development stages (eggs, 1st and 2nd instar nymphs). In particular, among the antennomeres that compose a typical H. halys antenna, HhTAR1 was more expressed in flagellomeres. Scanning electron microscopy investigation revealed the type and distribution of sensilla on adult H. halys antennae: both flagellomeres appear rich in trichoid and grooved sensilla, known to be associated with olfactory functions. Through an RNAi approach, topically delivered HhTAR1 dsRNA induced a 50% downregulation in gene expression after 24 h in H. halys 2nd instar nymphs. An innovative behavioural assay revealed that HhTAR1 RNAi-silenced 2nd instar nymphs were less susceptible to the alarm pheromone component (E)-2 decenal as compared with controls. These results provide critical information concerning the role of TAR1 in olfaction regulation, especially alarm pheromone reception, in H. halys. Furthermore, considering the emerging role of TAR1 as target of biopesticides, this work opens the way for further investigation on innovative methods for controlling H. halys.
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•Cold storage extends the longevity of adult T. japonicus.•Storage at 13 & 18 °C did not cause sublethal effects on adult T. japonicus.•Cold storage of immature T. japonicus decreased ...survival.•Cold storage of immature T. japonicus at 8 & 18 °C did not affect sexes differentially.
Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae) has shown promise as a biological control agent for the invasive agricultural and nuisance pest, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae). In addition to the need for laboratory research colonies, the possibility for rearing T. japonicus for classical or augmentative releases necessitates investigation into efficient rearing protocols with control over timing of production. Cold storage is a means to slow insects’ metabolism and cold temperatures can be used to manipulate when and how many parasitoids are available for use. Conditions of cold storage (i.e., temperature and photoperiod), duration of exposure to cold, nutrition, age, and sex of parasitoids can all affect the success of a cold storage regime. We tested how these factors affected mortality, realized fertility of females, sex of progeny, and development time for cold-stored adult and immature T. japonicus using previously frozen H. halys egg masses. Rearing adult T. japonicus at 8, 13, or 18 °C (10:14 h L:D) significantly increased longevity compared to 23 °C (16:8 h L:D); however, for females reared at 8 °C, 10:14 h L:D, we found sublethal effects on realized fertility and sex of their progeny. Adults with access to food survived at greater levels than those without food. We found high mortality of cold-stored immatures in all the ages and cold storage conditions tested. Additionally, differences in T. japonicus emergence from fresh and frozen H. halys eggs was assessed. This work can be used to compare the costs and benefits of cold storage for T. japonicus and will assist forecasting the emergence and sex of adult parasitoids after T. japonicus are cold stored.
An adventive population of the exotic parasitoid wasp, Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae), discovered in Michigan in 2018, is a promising biological control agent of the ...invasive Halyomorpha halys (Stål) (Hemiptera: Pentatomidae). Following its discovery, field releases of Tr. japonicus were conducted over 2 yr in southern Michigan, to test how release size or release frequency impacts establishment. Sentinel eggs of H. halys and of the native Podisus maculiventris (Say) (Hemiptera: Pentatomidae) were used alongside yellow sticky cards to monitor parasitoids. In 2019 and 2020, 7,200 Tr. japonicus were released at 16 sites. Monitoring between 2019 and 2021 yielded only 49 individuals.The captures suggest reproductive activity and overwintering success in the field but do not allow for evaluation of best release methods. Parasitism by native parasitoids was below 7%, which is similar to other states and unlikely to provide sufficient control of H. halys. The placement of sentinel eggs or sticky traps either in the lower or middle canopy of trees did not influence parasitoid capture rates. Frozen and fresh H. halys sentinel eggs were attacked at the same rate, but more native parasitoids emerged from frozen eggs. We did not find signs of nontarget effects on P. maculiventris thus parasitism rates overall were very low.These results could indicate dispersal of Tr. japonicus from the release sites or slow population growth.The latter may be due to the relatively low densities of H. halys in Michigan or may stem from the small founding size of our laboratory colony.
We developed an agent-based stochastic model expressing stage-specific phenology and population dynamics for an insect species across geographic regions. We used the invasive pentatomid, Halyomorpha ...halys, as the model organism because gaps in knowledge exist regarding its developmental physiology, it is expanding its global distribution, and it is of significant economic importance. Model predictions were compared against field observations over 3 years, and the parameter set that enables the largest population growth was applied to eight locations over 10 years, capturing the variation in temperature and photoperiod profiles of significant horticultural crop production that could be affected by H. halys in the US. As a species that overwinters as adults, critical photoperiod significantly impacted H. halys seasonality and population size through its influence on diapause termination and induction, and this may impact other insects with similar life-histories. Photoperiod and temperature interactions influenced life stage synchrony among years, resulting in an order of magnitude difference, for occurrence of key life stages. At all locations, there was a high degree of overlap among life stages and generation. Although all populations produced F2 adults and thus could be characterized as bivoltine, the size and relative contribution of each generation to the total, or overwintering, adult population also varied dramatically. In about half of the years in two locations (Geneva, NY and Salem, OR), F1 adults comprised half or more of the adult population at the end of the year. Yearly degree-day accumulation was a significant covariate influencing variation in population growth, and average maximum adult population size varied by 10-fold among locations. Average final population growth was positive (Asheville, NC, Homestead, FL, Davis, CA) or marginal (Geneva, NY, Bridgeton, NJ, Salem, OR, Riverside, CA), but was negative in one location (Wenatchee WA) due to cooler temperatures coupled with timing of vitellogenesis of F2 adults. Years of the highest population growth in the mid-Atlantic site coincided with years of highest crop damage reports. We discuss these results with respect to assumptions and critical knowledge gaps, the ability to realistically model phenology of species with strongly overlapping life stage and which diapause as adults.
•Biological control of H. hays eggs was greater in corn than apple agroecosystems.•Corn had greater richness and abundance of predators than apple agroecosystems.•Wooded areas adjacent to crops and ...free of pesticide drift are natural enemy refuges.
Halymorpha halys is an invasive pest in the USA that inflicts damage to specialty crops, and conventional growers have increased use of broad-spectrum insecticides to manage this pest. The impacts of pest management programs on natural enemies of H. halys were examined in high vs. low intensity insecticide input agroecosystems in western North Carolina (USA). Apple orchards and corn fields, with their adjacent wooded habitats, served as the high and low-input environments, respectively. Sentinel egg masses and yellow sticky cards were deployed in these agroecosystems to compare predation and parasitism on H. halys eggs, and presence, abundance, and richness of natural enemies. A total of approximately 85% of all sentinel eggs deployed in apple orchards in both 2018 and 2019 produced a healthy stink bug nymph, higher than all other habitats. A total of 26.6% and 32.9% of eggs deployed in wooded habitats bordering corn exhibited mortality due to natural enemy attack in 2018 and 2019, respectively. Comparatively, eggs deployed in apple borders had 10.0% and 17.8% of total eggs killed by natural enemies, in 2018 and 2019, respectively. Corn agroecosystems generally had greater predation and parasitism of sentinel eggs, and greater richness and abundance of predators detected on yellow sticky cards compared to apple agroecosystems. Wooded habitats bordering crops serve as population reservoirs for H. halys, allowing for egg laying and dispersal into crops. If these areas are protected as refuge areas free from insecticide drift, such as from apple orchards, they can also harbor thriving natural enemy populations that could reduce populations of H. halys. Wooded areas free from harsh broad-spectrum insecticides are an important component for successful conservation and augmentative biological control in neighboring crops.
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