CRIS Project Accomplishments

Semiochemically Mediated Enhancement of Native Beneficials and Suppression of Key Pest Insects
(Project 1275-22000-155-00D)

View project information in ARS National Programs database

Asian Longhorned Beetle (Specific Project: 1275-22000-155-03S)

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The Asian longhorned beetle (ALH) (Coleoptera: Cerambycidae: Anoplophora glabripennis) attacks and kills healthy deciduous trees, and now has footholds in New York City and Chicago. The threat of this beetle to U. S. forests is considered the most critical issue for APHIS in the last 20 years; its escape from containment areas could be catastrophic. To date, detection of ALB infestations is based solely on visual surveys. An attractant lure to bait traps for the ALB is needed to more efficiently detect beetle infestations and to intercept future ALB introductions.

Gas chromatography-electroantennogram detector (GC-EAD) systems were constructed in ICEL and in the APHIS quarantine facility, Methods Development Center, Otis, MA. Logs infested with ALB from sites in New York City and Chicago, Illinois, were transported to the quarantine facility, and aeration extracts were prepared from ALB males and females separately. Two compounds not detected from females were consistently detected in samples from ALB males in May 1999, and antennae from both sexes of the beetle were found to be especially sensitive to these male-specific compounds by GC-EAD. Identification and synthesis was accomplished prior to the natural July emergence of ALB in China. The male-specific compounds are volatile dialkyl ethers (4-(n-heptyloxy)butanal and 4-(n-heptyloxy)butan-1-ol) of a type heretofore unknown from insects. In preliminary tests in the quarantine laboratory these compounds appeared to stimulate flight and walking in both sexes. However, July 1999 field tests in China failed to demonstrate attraction to the aldehyde and/or the alcohol, with or without a mixture of six host volatiles. Laboratory and field observations indicate that ALB males are territorial and that males recognize females upon antennal contact. In the summer of 2000, laboratory Y-tube bioassays demonstrated that walking male and female ALBs are significantly attracted to a 1:1 blend of 4-(n-heptyloxy)butanal and 4-(n-heptyloxy)butanol (10 [g each).

Pink Hibiscus Mealybug (Specific Project: 1275-22000-155-03S)

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In recent years the pink hibiscus mealybug (Homoptera: Pseudococcidae: Maconellicoccus hirsutus) reached the West Indies from its native region of Africa, and is an impending threat to fruit, vegetables, and ornamentals in the U.S. At the urging of APHIS, about 1 year ago the ICEL entered into an effort to isolate and identify the sex pheromone of M. hirsutus. Late last season this pest was detected in California, even before the expected entry of the pest into Florida, so there is now heightened urgency to identify and synthesize its pheromone. Once PHM females mate they stop releasing sex pheromone; therefore, virgin females are needed for pheromone isolation and identification. To this end, a method was devised to chemically inhibit PHM male development. The chemical formulation and protocol for this technique were supplied to collaborators at the ARS laboratory in St. Croix, Virgin Islands, enabling ~2000 virgin females to be cultured per host pumpkin. Aeration sampling of virgin PHM females was accomplished in quarantine at the ARS facility in Newark, DE, using infested host material shipped from St. Croix. PHM males significantly responded by GC-EAD to a pair of relatively minor compounds in the aeration blends from females. One of these EAD-active compounds has been identified, synthesized, and tested in the field. In the preliminary field tests in the Virgin Islands, the single known synthetic pheromone component attracted wild PHM males at the lowest dose tested (10[g/trap) equivalently to traps baited with 20 live virgin PHM females. At the highest dose tested (10mg/trap), captures of PHM males were significantly inhibited relative to unbaited control traps. Efforts are proceeding to identify the second EAD-active compound and, concurrently, to conduct additional field tests of the known component in the Virgin Islands, the Imperial Valley of California where PHM was detected in 1999, and Puerto Rico.

Lygus Bug

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Tarnished plant bugs, Lygus lineolaris (Heteroptera: Miridae), feed on the flowers and meristematic tissue of hundreds of plants, including many agriculturally important species. These plant bugs, along with a complex of stink bugs (Pentatomidae; see below), have always been difficult to control. The advent of reduced tillage practices intensified this problem. Furthermore, the Bt-endotoxin expressed in various transgenic crops is ineffective against these pests. Pheromones would be useful for monitoring and possibly intercepting bugs immigrating into crops, and female Lygus bugs have long been known to produce a sex pheromone. However, identification of the pheromone for L. lineolaris has eluded chemical ecology researchers for decades. Recent GC-EAD studies of the tarnished plant bug and the cross-pheromonally active mirid species, Adelphocoris lineolatus, have led to identification of compounds believed to be part of the pheromone attractive to L. lineolaris males. We are continuing our efforts to identify the presumably missing components of the pheromone.

Brown Stink Bugs

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Euschistus spp., including several common brown-colored stink bugs (Heteroptera: Pentatomidae), are part of a complex of pentatomid bugs that severely damage innumerable commodities worldwide by flying into fields late in the season, and inflicting damage before they are detected. As with mirid bugs, synthetic stink bug pheromones are needed to track migrations, and to possibly suppress populations by trapping out immigrant females or directing them to trap crops for destruction by limited insecticide application. ICEL research on Euschistus pheromones has resulted in the first commercially available pheromone for monitoring stink bugs (methyl 2E,4Z-decadienoate). Researchers at the University of Florida have developed a trap that captures stink bugs (and various other insects) purely due to visual cues. Collaborative research with the UFL demonstrated that inclusion of methyl 2E,4Z-decadienoate lures in these traps increased the captures of E. servus ~10 fold versus unbaited traps-an efficiency that may significantly suppress populations of this pest in peach and pecan orchards. A trapping scheme is being developed to harvest predatory stink bugs in early spring for augmentative biological control programs using these traps (see below), and capture and destroy brown stink bugs later in the season using the same traps with the Euschistus pheromone. Ultimately it is envisioned that the pheromones of other phytophagous stink bugs will be included in the trapping program as new pheromones are identified (ongoing ICEL research) and commercialized.

Southern Green Stink Bug

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The southern green stink bug (SGSB), Nezara viridula (Heteroptera: Pentatomidae), is a serious agricultural pest worldwide. Its host range includes soybean and other field crops, a variety of fruits and nuts, and many vegetables. Earlier research in the ICEL and elsewhere showed that sexually mature N. viridula males release an attractant pheromone, the major components of which are (Z)-a-bisabolene (1-methyl-4-(1,5-di- methyl-(Z)-1,4-hexadienyl)-cyclohexene) and trans- and cis- 1,2-epoxides of (Z)-a-bisabolene. However, pheromone-trapping efforts for the SGSB in the field have thus far employed only blends of the epoxides, with marginal success. Recent GC-EAD analyses in ICEL using the antennae of female SGSBs as well as antennae of the parasitoid fly, Trichopoda pennipes (Diptera: Tachinidae), indicate that (Z)-a-bisabolene is at least as active as the epoxides. Racemic (Z)-a-bisabolene and the trans- and cis-1,2-epoxides of (Z)-a-bisabolene have been freshly synthesized to pursue this line of research. In addition, another line of research has been initiated using N. viridula; namely, exploring the possibilities to control Heteroptera by transgenic modifications of the insects or their bacterial symbionts (“paratransgenesis”). Research by Dr. Alfred Handler (ARS, Gainesville, FL) has demonstrated that the SGSB is susceptible to the so-called piggyBac transposable element originally found in Lepidoptera. Currently we are in the early stages, in collaboration with Dr. Handler’s laboratory, of generating a genomic library for N. viridula, and discussing strategies for future research along these lines. Simultaneously, we have been collaborating with Dr. Phyllis Martin (ARS, Beltsville) on isolation of the symbiotic bacterium found in the gastric caeca of Nezara as a potential target for transgenic modifications that could be lethal to the insect under certain conditions such as hot summer temperatures. To date, we have isolated and successfully cultured a gram-negative bacterium (probably a Yokenella sp.) from the mid-gut caeca of N. viridula that is apparently the host-specific symbiont of the SGSB.

Spined Soldier Bug

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Hardware and protocols were tested to enable individual growers and insectary operators to mass-produce predatory spined soldier bugs (SSBs), Podisus maculiventris (Heteroptera: Pentatomidae: Asopinae), for augmentative biological control. Using pheromone-based technology, an average of 1775 female SSBs (potentially as many as 1.6 million offspring) were captured each year during 2-3 weeks in early spring. Augmentation of SSB (~5 nymphs/plant) significantly suppressed the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Coleoptera: Chrysomelidae). Pheromone-mediated augmentation using porous nursery cages and pheromone dispensers (Soldier Bug Attractors®; Sterling International, Inc., http://www.rescue.com/) was less labor-intensive than earlier methods, and resulted in significantly improved potato yield. Success of this predator augmentation/conservation technique against the CPB suggests that the approach will work as well or better against less formidable pests.

Minute Pirate Bugs

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Orius insidiosus (Heteroptera: Anthocoridae), is an important generalist predator in a multitude of agroecosystems, including open-air agriculture (e.g. field crops, vegetables, and fruit orchards) and greenhouse operations. The phenology and chemical ecology of this predator was studied in the laboratory and in sequentially planted field-plots of Bt-sweet corn. Olfactometer tests determined that adults were significantly more attracted to leaves, silk, and pollen than to a control. In tests comparing one corn plant sample to another, silk attracted significantly more O. insidiosus adults (females more so than males) than other plant parts. In laboratory choice tests, an arrestant-type pheromone produced by virgin and mated females elicited responses in both sexes. In field tests, synthetic blends mimicking volatiles from adults were tested in traps to examine their attractiveness to the predator. Male adults were significantly more attracted to a blend consisting of (2E,7)-octadienal (female-specific)and (E)-2-octenal (from both sexes) than to a control, indicating that females attract males with a pheromone.

Tachinid Flies

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"Though often little noticed, these flies have an important role in controlling phytophagous Insecta" (Arnaud 1978). Previous ICEL research has shown that tachinids usually exploit the pheromones of Heteroptera as host-finding kairomones, and recent GC-EAD analyses indicate that, in general, tachinids are 5-10 times more sensitive to the pheromones of bugs than are the bugs themselves. We found that geographically isolated populations of Trichopoda pennipes (Diptera: Tachinidae) give dramatically different antennal responses to pheromone extracts of N. viridula and certain native host species. This is the first experimental verification that kairomone-strains of tachinids exist. These data help explain why T. pennipes introduced into Hawaii from Florida failed to parasitize N. viridula, and T. pennipes fails to attack the squash bug, Anasa tristis (Coreidae), in California although A. tristis is the most common host of this parasitoid in the northeastern U.S. In the future, electrophysiological screening of parasitoids prior to classical biological control introductions could avoid inevitable failures. Additional studies of tachinid chemical ecology showed that a species (Euclytia flava) attracted to pheromones of the spined soldier bug and certain other indigenous species, when given a choice, prefers to oviposit on exotic hosts. Thus, invasive species may be more vulnerable to native parasitoids than are native host species yet go unrecognized as potential hosts.

Multi-colored Asian Ladybird Beetle

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The Asian lady beetle, Harmonia axyridis (Coleoptera: Coccinellidae), became established in the U.S. in the 1980’s, either accidentally or as a result of importation from Asia for aphid control, and is now abundant in much of the country. The propensity of adults to enter houses in the fall has become a serious concern to homeowners. DEET (N,N-diethyl-3-methylbenzamide) repels H. axyridis adults, but this compound is unsuitable for use on buildings because it dissolves paint. Two natural compounds (camphor and menthol) were found that significantly repelled H. axyridis adults over short distances in laboratory bioassays and in preliminary experiments on the external walls of buildings. Combined with an effective trap for H. axyridis adults (collateral research by Dr. Russell Mizell, University of Florida), a repellent formulation suitable for building surfaces could lead to an effective “push/pull” protocol to protect houses from overwintering H. axyridis adults.

Yellowjackets

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Yellowjackets are increasingly a health hazard and nuisance in urban and suburban America, especially the German yellowjacket Vespula germanica (Hymenoptera: Vespidae). Heptyl butyrate is an effective attractant for the western yellowjacket, V. pensylvanica, but is ineffective for Vespula spp. in the eastern U.S. ICEL research on eastern yellowjackets showed that the main pest species (including the German yellowjacket) use (E)-2-hexenal with either a-terpineol or linalool as a kairomone to find prey, probably because this chemical mixture mimics the odor from damaged leaves associated with potential prey. We continue to test combinations and new formulations of these compounds at BARC, and have promising new leads for yellowjacket attractant blends.

Bruchins

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Pea weevil (Coleoptera: Bruchidae: Bruchus pisorum) oviposition on pods of specific genetic lines of pea (Pisum sativum) stimulates cell division at the sites of egg attachment. As a result, tumor-like growths of undifferentiated cells (neoplasms) develop beneath the egg. These neoplasms impede larval entry into the pod. This unique form of induced resistance is conditioned by the Np allele, and mediated by a newly discovered class of natural products that we have identified from both cowpea weevil (Callosobruchus maculatus) and pea weevil. These compounds, which we refer to as “bruchins,” are long chain a,w-diols, esterified at one or both oxygens with 3-hydroxypropanoic acid. Bruchins are potent plant regulators, with application of as little as 1 femtomole (0.5 picogram) causing neoplastic growth on pods of all of the pea lines tested. The bruchins are the first natural products discovered with the ability to induce neoplasm formation when applied to intact plants.

1275-22000-134-00D - Discover, Synthesize, Develop Attractants and Behavior-Modifying Chemicals to Manage Insects.

View project information in ARS National Programs database

Mediterranean Fruit Fly

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Various true fruit flies (Diptera: Tephritidae) more or less continuously invade the U.S. mainland and threaten our fruit industry. Foremost among these pests is the Mediterranean fruit fly (medfly), Ceratitis capitata, for which ~200,000 attractant-baited traps a year are deployed in California alone for early detection of invaders. For more than 35 years, trimedlure, a mixture of sixteen regio- and stereoisomers of tert-butyl esters of 4- and 5-chloro-2-methylcyclohexane-1-carboxylate has been widely used as an attractant to monitor and detect male (but not female) medflies. (-)-Ceralure B1, (ethyl (1R,2R,5R)-5-iodo-2-methylcyclohexane-1-carboxylate), an analog of trimedlure has been synthesized in a highly regio- and stereoselective manner. This unique nine step synthesis generates (-)-ceralure B1 on a multi-gram scale in 15% overall yield. Preliminary estimates suggest that this compound is at least 7-10 times more active than trimedlure. To our knowledge this molecule is by far the most potent attractant for the medfly thus far reported-a level of activity that may make (-)-ceralure B1 useful for eradication of medfly incursions by male annihilation.

Melon Fruit Fly

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Cuelure, 4-(p-hydroxyphenyl)-2-butanone acetate, a derivative of raspberry ketone, 4-(p-hydroxyphenyl)-2-butanone, is highly attractive to male (but not female) melon flies, Bactrocera cucurbitae, and certain other Bactrocera spp. (Diptera: Tephritidae). However, both raspberry ketone and cuelure have limitations because neither compound is sufficiently attractive to achieve eradication of melon fly populations by male annihilation, in part because of low volatility. Ongoing research in ICEL is exploring mechanical and derivatization methods to increase the volatility of raspberry ketone.

Arthropod Repellents

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Globalization and increased travel continues to spread disease vectors and subject people to biting arthropods and disease. For example, west Nile fever (transmitted by Culex pipiens; Diptera: Culicidae) made its U.S. debut in New York City in 1999; the Asian tiger mosquito, Aedes albopictus (Culicidae; a potential vector of dengue and Japanese encephalitis), is established and spreading in the U.S.; and reports of Lyme disease (transmitted by the deer tick, Ixodes scapularis) have increased dramatically since the first recognized U.S. cases in 1975. Moreover, disease organisms are becoming resistant to drugs, vaccines are lacking for many diseases (e.g. dengue and malaria), and drugs used to treat exotic diseases often have serious adverse side effects. Thus, the demand for arthropod repellents is increasing, yet public and military acceptance, usage compliance and confidence in DEET (by far the mainstay of repellents) has suffered because of concerns about health risks associated with the compound. The ICEL has a long history of working with the DoD on arthropod repellents. Most recently, a new, more efficient method for quantitative evaluation of candidate repellent compounds using human test subjects has been developed. Using this new methodology, stereoisomers of 1-[3-cyclohexen-1-ylcarbonyl]-2-methylpiperidine, the racemate of which was previously shown to equal or exceed the arthropod repellency of DEET (N,N-diethyl-3-m-toluamide), were synthesized and tested. The stereoisomers differ significantly (but in the same relative pattern) in repelling Anopheles stephensi and Aedes aegypti (Culicidae), mosquito vectors of yellow fever and malaria. This is the first demonstration, to our knowledge, of differential repellent activity of a compound based on chirality.

1275-22000-133-00D - Modifying Chemicals with Enhanced Biological Potency

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Siberian Moth

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The Siberian moth, Dendrolimus superans sibiricus (Lepidoptera: Lymantriidae), is the most destructive defoliator of coniferous forests in northern Asia. Recent outbreaks of the moth caused defoliation of more than 1 million ha of fir and larch forests in Siberia, Russia. Populations of this species do not yet occur in the North America, but the moth is potentially a threat to forests here. A blend of Z5,E7-dodecadienal and Z5,E7-dodecadienol was found to be a potent attractant for male Siberian moths. This sex attractant will be used for monitoring around U.S. ports of entry to provide a first line of defense against this potentially devastating exotic pest.

Rosy Russian Gypsy Moth

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The rosy Russian gypsy moth, Lymantria mathura (Lepidoptera: Lymantriidae), is another forest pest that has the potential to invade the U.S. via egg masses deposited on Russian ships and containers. Research was undertaken to isolate and identify the pheromone of this moth for monitoring at ports of entry and, if necessary, to track the spread of this pest. Two compounds, Z,Z,Z-3,6,9-nonadecatriene and Z,Z-(9S,10R)-9,10-epoxy-3,6-nonadecadiene, were identified from abdominal tip extracts of female moths based on GC-EAD responses and dose response curves. Single cell recordings showed that only one of the monoepoxide enantiomers (S,R) was active. In field tests, both the (S,R)-monoepoxide and the racemate were active. This type of pheromone system is more typical of those found in the families Arctiidae, Noctuidae and Geometridae, rather than Lymantriidae. Additional (racemic) material has been stockpiled for tests in the summer of 2000.

1275-22000-137-00D - The Colorado Potato Beetle: Biology, Behavior and Nutrition

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Colorado Potato Beetle

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The Colorado Potato Beetle (CPB) is known to develop resistance to varied management strategies; thus, a need exists for discovery and development of biorational, environmentally-friendly alternative control procedures. Field tests conducted in Maine with a collaborator, Dr. A. R. Alford (Development of an attractant for management of the Colorado potato beetle - 1275-22000-137-15G and Development of attractant technology for management of Colorado potato beetle - 1275-22000-137-21G), at the University of Maine demonstrated the effectiveness in the field of CPB attractant blends discovered by us. Our results demonstrate the potential usefulness of attractants in CPB management.

CPB is known to develop resistance to varied management strategies; thus, a need exists for discovery and development of biorational, environmentally-friendly alternative control procedures. Receptors neurons for specific glycoalkaloids in adult CPB were discovered and characterized. This knowledge may aid in the bioassay and discovery of feeding deterrents for use in management of pestiferous CPB populations (Development of an attracticide for the Colorado potato beetle - 1275-22000-137-20S).

Synthetic attractants and repellants for CPB were characterized and tested in laboratory behavioral bioassays and field tests. Strategies for management of CPB using attractants and deterrents were evaluated in the field. A laboratory behavioral bioassay was developed which showed blends of specific chemicals that were attractive to the CPB and its predators. The discovery of attractants and deterrents for CPB and its predators provides tools for manipulation of the insects for management of pestiferous population using biorational, environmentally friendly, behavioral chemicals.

1275-22000-180-00D - Sustainable Management Systems for Insect Pests of Shade Trees in the Mid-Atlantic Region

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Gypsy Moth

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Developed improved survey for the Gypsy Moth, control and evaluation technology for insect pests of shade trees in the mid-atlantic region that uses reduced-risk tactics that are inherently safe for man and the environment. Specific objectives include the development of gypsy moth management tactics for non-forest areas, the development of reduced-risk integrated pest management components, systems for insect pests of shade trees and developing Entomopthora maimaiga for the "slow the spread" program (STS).