Egg parasitoids of the exotic invasive brown marmorated stink bug, Halyomorpha halys (Stål), were investigated using lab-reared fresh (live) and frozen (killed) lab-reared sentinel egg masses ...deployed for 72h on foliage in three habitats-woods, orchard, and soybean field-in Maryland, USA, in summer 2014. Four native hymenopteran species, Telenomus podisi Ashmead (Scelionidae), Trissolcus euschisti (Ashmead) and Tr. brochymenae Ashmead (Scelionidae), and Anastatus reduvii (Howard) (Eupelmidae), developed and emerged from H. halys eggs. One exotic parasitoid, Trissolcus japonicus (Ashmead), emerged, providing the first known occurrence of this species in North America. Native parasitoids emerged from frozen eggs significantly more often than from fresh eggs (89.3% of egg masses and 98.1% of individual eggs), whereas the exotic Tr. japonicus did not show a similar difference, strongly suggesting adaptation to H. halys as a host by Tr. japonicus but not by the native species. Parasitoids were habitat-specific: all three Trissolcus species were significantly more likely to occur in the woods habitat, whereas Te. podisi was found exclusively in the soybean field. Further investigations are required to elucidate evolving host-parasitoid relationships, habitat specificity, and non-target effects of Tr. japonicus over the expanded range of H. halys in North America.
The striped cucumber beetle, Acalymma vittatum (F.) (Coleoptera: Chrysomelidae), is a key pest of cucurbits in eastern North America, rapidly colonizing young plantings and vectoring bacterial wilt ...of cucurbits. Its aggregation pheromone has been identified and synthesized stereospecifically, but has not been field tested to date. Here, we present field bioassays of this pheromone, using mixed vittatalactone made with a novel and cost-efficient semispecific synthesis. This mixture of eight stereoisomers of (2R,3R)-vittatalactone proved highly attractive to both sexes of striped cucumber beetle, using two different trap types and a pilot attract-and-kill combination with watermelon containing the diabroticine feeding stimulant cucurbitacin-E-glycoside, under field conditions in cucurbit vegetable plantings. Availability of mixed vittatalactones could enable highly effective and specific management of striped cucumber beetle.
We describe a novel and straightforward route to all stereoisomers of 1,10-bisaboladien-3-ol and 10,11-epoxy-1-bisabolen-3-ol via the rhodium-catalyzed asymmetric addition of trimethylaluminum to ...diastereomeric mixtures of cyclohex-2-enones 1 and 2. The detailed stereoisomeric structures of many natural sesquiterpenes with the bisabolane skeleton were previously unknown because of the absence of stereoselective syntheses of individual stereoisomers. Several of the bisabolenols are pheromones of economically important pentatomid bug species. Single-crystal X-ray crystallography of underivatized triol 13 provided unequivocal proof of the relative and absolute configurations. Two of the epoxides, (3S,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol (3) and (3R,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol (4), were identified as the main components of a male-produced aggregation pheromone of the brown marmorated stink bug, Halyomorpha halys, using GC analyses on enantioselective columns. Both compounds attracted female, male, and nymphal H. halys in field trials. Moreover, mixtures of stereoisomers containing epoxides 3 and 4 were also attractive to H. halys signifying that the presence of additional stereoisomers did not hinder attraction of H. halys and relatively inexpensive mixtures can be used in monitoring, as well as control strategies. Halyomorpha halys is a polyphagous invasive species in the U. S. and Europe that causes severe injury to fruit, vegetables, and field crops and is also a serious nuisance pest.
The reported male-produced aggregation pheromone of the brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), identified as a mixture of ...(3S,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol and (3R,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol, offers new opportunities for its management. We found that black pyramid traps deployed along crop borders in Maryland and West Virginia, containing lures with both stereoisomers of this reported aggregation pheromone combined with methyl (E,E,Z)-2,4,6-decatrienoate (MDT) lures, attracted more adult and nymphal H. halys than either the aggregation pheromone or MDT alone. In season-long totals, combined lures acted synergistically by catching 1.9–3.2 times more number of adults, and 1.4–2.5 times more number of nymphs, than expected from an additive effect of the lures deployed individually. There were no significant differences in patterns of male and female captures. MDT alone was not significantly attractive to adults during most of the growing season, but became increasingly attractive to adults and especially nymphs in autumn. Mixed-isomer lures containing eight stereoisomers of 10,11-epoxy-1-bisabolen-3-ol, including the two active stereoisomers, were as effective at catching adults and nymphs with or without MDT as were lures loaded only with the two active stereoisomers in the natural ratio ((3S,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol: (3R,6S,7R,10S)-10,11-epoxy-1-bisabolen-3-ol) of 3.5:1. These results identify a combination of semiochemicals that is attractive season-long for detection, monitoring, and potential control of this polyphagous invasive pest of North America and Europe.
BACKGROUND
Colorado potato beetle Leptinotarsa decemlineata (Say); Coleoptera: Chrysomelidae is a widespread key pest of potatoes and other solanaceous crops of the temperate Northern Hemisphere. Its ...evolution of multiple pesticide resistance is a continuing threat if chemical control is relied upon for pest management. An integrated approach including semiochemicals and other non‐pesticidal tactics is essential to sustainable management. In addition to the known volatile aggregation pheromone produced by male adult beetles that is attractive to both females and males, there is a yet‐unidentified female‐produced sex pheromone. Using caged ‘bait plants’ in the field in Maryland, USA, we tested the attraction of male and female beetles to groups of male‐only, female‐only, larvae, and uninfested bait plants.
RESULTS
Results of five field experiments demonstrate that the female‐produced sex pheromone is attractive to male beetles, whereas the male‐produced pheromone is attractive to both females and males. Male attraction increased with higher densities of females on bait plants, but female attraction did not change with female density on bait plants.
CONCLUSION
This is the first study to demonstrate male attraction to the female sex pheromone in the field, and to our knowledge, the first to demonstrate a beetle species using bidirectional communication between males and females. Use of semiochemicals for monitoring and management of Colorado potato beetle should consider male‐, female‐, as well as plant‐produced volatiles as important tools for pest manipulation in potato integrated pest management. Published 2021. This article is a U.S. Government work and is in the public domain in the USA.
In five field experiments, Colorado potato beetle males were attracted to conspecific males and females, whereas females were only attracted to males. The yet‐unidentified female pheromone is equally important as the male pheromone in attracting males. Both pheromones show promise for manipulating Colorado potato beetle movement in sustainable pest management.
Striped cucumber beetle, Acalymma vittatum (F.) and spotted cucumber beetle (Diabrotica undecimpunctata howardi Barber) are key pests of cucurbits. Pesticide applications directed against cucumber ...beetles can jeopardize bee pollination which is essential to crop yield. Alternative selective tactics, including behavioral control for managing cucumber beetles, are needed in order to improve pest management. The striped cucumber beetle pheromone vittatalactone is attractive to both male and female adults, and also to spotted cucumber beetles. We tested the response of both species to different doses of synthetic vittatalactone, and to different trap types, in field trapping experiments in Maryland. Both species showed strong dose–response in May–June and October 2020. Among 12 trap types tested during a 2-wk experiment in June, using 1 mg mixed vittatalactone, sticky panel traps caught the most of each species, with vittatalactone-baited traps exceeding unbaited traps by >8 fold for striped and >2 fold for spotted, and with significant response to yellow versus clear color absent in striped, but strong in spotted. Among nonsticky traps, those with yellow or yellow-green exceeded those without these colors for both beetle species, and a ground-placed boll weevil trap captured the most striped cucumber beetles. Bucket-style traps caught excessive nontarget bumblebees (Bombus spp.) if yellow, and a few beetles, if all green. Results allow field monitoring with a choice of sticky or nonsticky traps and suggested lure loading of 1 mg mixed vittatalactone, containing ∼90 µg active isomer. These findings contribute to the development of multispecies behavioral monitoring and control as a component of cucurbit IPM.
Molecular gut‐content analysis enables detection of arthropod predation with minimal disruption of ecosystem processes. Most assays produce only qualitative results, with each predator testing either ...positive or negative for target prey remains. Nevertheless, they have yielded important insights into community processes. For example, they have confirmed the long‐hypothesized role of generalist predators in retarding early‐season build‐up of pest populations prior to the arrival of more specialized predators and parasitoids and documented the ubiquity of secondary and intraguild predation. However, raw qualitative gut‐content data cannot be used to assess the relative impact of different predator taxa on prey population dynamics: they must first be weighted by the relative detectability periods for molecular prey remains for each predator–prey combination. If this is not carried out, interpretations of predator impact will be biased towards those with the longest detectabilities. We review the challenges in determining detectability half‐lives, including unstated assumptions that have often been ignored in the performance of feeding trials. We also show how detectability half‐lives can be used to properly weight assay data to rank predators by their importance in prey population suppression, and how sets of half‐lives can be used to test hypotheses concerning predator ecology and physiology. We use data from 32 publications, comprising 97 half‐lives, to generate and test hypotheses on taxonomic differences in detectability half‐lives and discuss the possible role of the detectability half‐life in interpreting qPCR and next‐generation sequencing data.
There have been notable and significant advances in elucidating the chemical ecology of the invasive
Halyomorpha halys
(Hemiptera: Pentatomidae), brown marmorated stink bug. This highly destructive ...and polyphagous pest is originally from Korea, China, and Japan, but was accidentally introduced into North America and Europe. Prior to its invasion into these regions, little was known about its chemical ecology. However, since then, researchers have identified and synthesized its aggregation pheromone, documented its synergism with the pheromone of another Asian stink bug,
Plautia stali
, developed monitoring traps of various designs, and lures with reliable attractants have become commercially available. Furthermore, plant volatiles have been shown to have attractive, neutral, and repellent effects on attraction and retention of
H. halys
, and
H. halys
-derived volatiles have been shown to play a role in recruiting natural enemies. Finally, management strategies based on pheromone-based technology have been evaluated, including insecticide applications based on a cumulative threshold of adult captures in pheromone-baited traps, and the use of intensively baited trees in an attract-and-kill strategy to manage this pest. This review summarizes the available literature on the chemical ecology of
H. halys
and concludes with several research areas that should be explored in future research.
Trissolcus japonicus (Ashmead) is an Asian egg parasitoid of the brown marmorated stink bug, Halyomorpha halys (Stål). It has been under study in U.S. quarantine facilities since 2007 to evaluate its ...efficacy as a candidate classical biological control agent and its host specificity with regard to the pentatomid fauna native to the United States. A survey of resident egg parasitoids conducted in 2014 with sentinel egg masses of Halyomorpha halys revealed that Trissolcus japonicus was already present in the wild in Beltsville, MD. Seven parasitized egg masses were recovered, of which six yielded live Trissolcus japonicus adults. All of these were in a wooded habitat, whereas egg masses placed in nearby soybean fields and an abandoned apple orchard showed no Trissolcus japonicus parasitism. How Trissolcus japonicus came to that site is unknown and presumed accidental.
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