NEUROETHOLOGY OF SEMIOCHEMICALLY MEDIATED HOST-FINDING AND ACCEPTANCE

Thomas C. Baker

The electrophysiological responses of insect antennae have been useful for helping to understand the relationship between host-related odorants and behaviors such as upwind flight to the source of the odorants. Whole antennal responses (electroantennograms, or EAGs) have been increasingly employed of late to help in the isolation and identification of behaviorally active components present in extracts or airborne emissions. Several examples of the utility of this technique will be discussed with regard to successful isolation and identification of active components of host-odor blends. The success of this technique depends on the EAG being coupled to GC recordings (GC-EAD) as well as on starting with behaviorally active extract coupled with discriminating behavioral assays. Single receptor neuron responses have also been increasingly used to help understand the relationship between receptor neuron tuning and how these receptor neurons project to the brain to be integrated for blend discrimination. Such studies, of which examples will be given, have helped reshape ideas about `generalist' and `specialist' receptors to where it now appears that olfaction of host-related odors is no different than that of sex pheromone odors in terms of the narrowness of receptor tuning as well as sensitivity.

KS1
Department of Entomology, Iowa State University, Ames, Iowa 50011, U.S.A

Behavioral Mechanisms of Mating Disruption

Peter Witzgall

Camouflage of natural plumes, competition between natural and synthetic plumes, imbalance of sensory input and sensory overload have been proposed as the behavioral and physiological mechanisms of mating disruption. Sensory adaptation or central habituation alone cannot explain communication disruption, as the males may use visual and tactile stimuli. False trail following or camouflage of calling females depend on assumptions that are hardly met in the field, i.e. sensorially largely unaffected insects, and a rather uniform distribution of synthetic pheromone in the latter case. Plume characteristics and stimulus concentrations are also expected to vary greatly within the crop, individual insects differ with respect to age and duration of exposure to disruptant. Quite obviously, the observed behavioral modifications cannot easily be attributed to distinct mechanisms; several mechanisms are assumed to synergize. The mechanisms of mating disruption derive from the disruptant chemicals - in relation to the pheromone composition of each species. Different chemicals, release rates and dispenser densities result in different behaviors. Behavioural studies on codling moth, Cydia pomonella, illustrate the limitations to asses insect behaviors in the field and to simulate the natural milieu in the laboratory.

IS 6
SLU, Box 44, 230 53 Alnarp, Sweden

THE EXPRESSION MOSAIC OF ODORANT-BINDING PROTEINS IN SILKMOTH ANTENNAE

R. Alexander Steinbrecht+, Rosario Maida+, Marina Mameli* and Jürgen Krieger*

As long as antibodies were available only against two moth odorant-binding proteins (OBPs), their antennal expression pattern was complementary and fairly simple. Meanwhile, four OBPs have been identified by molecular cloning in Bombyx mori and antisera have been raised against recombinant PBP (pheromone-binding protein), GOBP1 (general odorant-binding protein 1), GOBP2 and ABPX (antennal binding protein X). Serial sectioning of silkmoth antennae enabled us to label consecutive sections of individually identified sensilla with all four antisera. The emerging expression pattern is highly complex. Several labelling types were observed, which outnumber the variety of morphological sensillum types. Nevertheless, the long s. trichodea which all show identical physiological response patterns also represent a uniform labelling type. In the male silkmoth, these sensilla in addition to PBP also express GOBP1 and ABPX, however at a very low level, whereas in the female, these sensilla predominantly express GOBP2 an again GOBP1 and ABPX at lower levels. Short sensilla trichodea, whose function is still poorly understood, show the greatest variety of labelling types. Sensilla basiconica, which usually respond to plant odours, most often express GOBP1 and GOBP2 at about equal levels in both sexes.

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+ Max-Planck-Institut für Verhaltensphysiologie, D-82319 Seewiesen

* Inst. f. Physiologie, Univ. Stuttgart-Hohenheim, D-70599 Stuttgart

OLFACTORY RECEPTORS OF THE MALARIA MOSQUITO ARE SENSITIVE TO HUMAN SWEAT COMPONENTS.

J. Meijerink1, 2 & J.J.A. van Loon1.

Female mosquitoes of the species Anopheles gambiae Giles s.s. are one of the most important vectors of human malaria in Africa. It is generally assumed that they locate their human host by odours. These odours are detected by olfactory receptor neurons situated on the antenna.

Potential kairomones for female An. gambiae were identified from human sweat and tested for their sensory activity. Sweat freshly collected from the human forehead did not elicit electroantennogram (EAG) activity. However, sweat which was incubated at body temperature, evoked reproducible EAG responses and attracted female An. gambiae in a windtunnel bioassay. GC-MS analysis of the headspace composition of the incubated sweat revealed several components.

In order to reveal olfactory receptor neurons responsive to the identified sweat-borne components, studies were conducted at the single cell level. For other mosquito species the grooved peg sensillum is considered to house receptor neurons sensitive to host-odours. Indeed, incubated sweat elicited excitation of grooved peg receptor neurons. The same receptor neurons were excited by ammonia, implying that ammonia is causing a part of the attractiveness of the incubated sweat. However, most of the tested identified sweat-borne components did not elicit responses of grooved peg receptor neurons but evoked excitation of receptor neurons associated with the sensilla trichodea.

These data suggest that not only the grooved peg receptor neurons encode host-odours but that the sensilla trichodea might fulfil a function in host-seeking behaviour of female An. gambiae as well. The function of the different olfactory receptor neurons will be discussed.

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1Dept. of Entomology, Wageningen Univ. P. O. Box 8031, Wageningen, NL-6700 EH, The Netherlands, E-mail joop.vanloon@users.ento.wau.nl; 2Present address, Dept. of Ecology, Lund Univ., Sölvagatan 37, Lund, SE-22362, Sweden, E-mail jocelijn.meijerink@ekol.lu.se

THE NEUROETHOLOGY OF DISCRIMINATION BETWEEN HOSTS AND NON-HOSTS IN INSECTS

John A Pickett

At the ISCE meeting in Florida, 1993, we proposed that the basis of non-host avoidance by aphids involves responses mediated by olfactory neurons specific for compounds absent from hosts but present in non-hosts. This hypothesis is now finding wide acceptance and we add further examples from other taxa of phytophagous insects, including Coleoptera, and from carnivorous insects, including haematophagous Diptera and hymenopterous parasitoids. The semiochemicals involved in indicating host unsuitability are from diverse biosynthetic pathways, but include products of oxidative stress from both plants and animals.

IS 1

IACR-Rothamsted, Harpenden, Herts, AL5 2JQ, UK. E-mail: john.pickett@bbsrc.ac.uk

 

SENSORY PHYSIOLOGY INVOLVED IN SCARAB BEETLES HOST FINDING AND MATING

Walter Soares Leal

Insects primarily rely on their olfactory system to detect chemical cues from the environment and initiate the transduction of these chemical signals into neuronal activities, which ultimately lead to the appropriate behavioral responses. Scarab beetles possess sex pheromones-specific sensilla placodea, which are present in male and female antennae. Females perceive their pheromones with lower sensitivity than males not only because they have lower number of pheromone-specific sensilla, but also due to a higher threshold of the female detectors. Single sensillum recordings revealed that the pheromone-sensilla in Popillia japonica and Anomala osakana house two olfactory receptor neurons (ORNs) specific to either pheromone or behavioral antagonist. Morphological studies showed that each pheromone-sensitive sensillum in P. japonica houses a pair of ORNs, indicating that each chemical signal is independently detected by one of the paired dendrites. These dendrites branch and terminate near fine cuticular pores on the pheromone-sensilla. Male and female antennae also possess ORNs specific for the detection of floral and green leaf volatile compounds. Interestingly, the detectors for (Z)-3-hexenyl acetate had a threshold far below the sensitivity of the pheromone-detecting machinery. In order to gain a better understanding of the molecular basis of insect olfaction, we isolated, identified, and cloned the genes encoding pheromone- and odorant-binding protein in scarab beetles. The relationship between the pheromone structures and the primary sequences of the proteins suggest that OBPs play a part in the selectivity of the olfactory system by "filtering" chemical signals during the early olfactory processing (perireceptor events). In this presentation I will also discuss details of the structural biology of insect olfaction.

IS 2
Department of Entomology, University of California at Davis, Davis, CA 95616 USA; email: wsleal@ucdavis.edu

BIORATIONAL PESTICIDES : EVOLVING FRONTIERS

W. S. Bowers

The search for rational strategies with which to nourish burgeoning world populations, improve the public health and protect an increasingly degraded environment is the ultimate challenge to human ingenuity, the final frontier. Research in chemical ecology powerfully impacts these planetary imperatives.

Early methods of plant and animal protection relied upon the accumulation of indigenous knowledge derived largely by the accidental discovery of plant extractives toxic to pests or antibiotic to pathogens. Beyond this border of primitive knowledge the first frontier of scientific exploration of plant and animal protection began in the century just passed. During the twentieth century we saw the application of science to agriculture and public health provide for the first time in history occasional food surpluses and a public health stature heretofore undreamed. These successes, resulting directly from the development of organic pesticides employed in the control of noxious arthropods, nematodes and pathogens emphasize the prodigious benefits that may be achieved by the application of science to agriculture and public health protection.

Not without reason are biologists and chemists indicted for the global population explosion or were these early successes achieved without balancing costs. The extensive use of broad spectrum, indifferent toxicants highlighted their virtue/vice relationships by the hazards of a few pesticide residues left in the environment and the rapid development of pest resistance to even the most powerful toxicants. Nevertheless, population pressures insure there can be no return to the pastoral methods of yesteryear. The optimization of war gases or the mindless screening of industrial byproducts will continue to produce indifferent toxicants. However, future needs clearly command the development of selective, pest-suppressive methodologies that rationally perturb those discrete aspects of pest biology and behavior that have arisen from the divergent evolutionary changes that separate invertebrate and microorganism from human biology.

If the first frontier represented the application of synthetic toxicants to pest and disease control then a second frontier is clearly derived from the efforts of scientists probing the chemical ecology of earthlife. Their studies revealed the chemistry regulating the biology and behavior of plants, animals and microorganisms and illumined selective methods to interfere with pest biology. The application of this knowledge resulted in commercial products of plant and insect growth and behavior regulators, insecticides and antibiotics. Virtually without unwarranted side effects and environmentally benign these benefits of research in chemical ecology powerfully impact science and society.

Research in natural product chemistry historically investigated, characterized and cataloged the secondary chemistry of plants, insects and microorganisms, very often without uncovering their functions. Chemical ecological studies increasingly reveal secondary chemicals functioning in defense against herbivory, disease and competition. Moreover some plant defensive chemistry is apparently deployed only following induction by stresses such as herbivory or infection. Research is revealing the chemistry of the responsible inducing agents offering additional tools for product development. Although the discovery of induced natural antibiotics in animals is a subject of serious study for medical purposes, the induction in plants of chemistry defensive against herbivores and pathogens presents a exciting new frontier for investigation. Taken together with our advances in genomics and recombinant genetic manipulation we may confidently imagine a biorational revolution in agriculture and public health protection. That these frontiers continue is our challenge.


Dept. of Entomology - University of Arizona - Tucson, Arizona USA 85721

wbowers@ag.arizona.edu

ORGANIC SYNTHESIS IN CHEMICAL ECOLOGY: PAST, PRESENT, AND FUTURE

Kenji Mori

In 1973 when I began my pheromone synthesis, there existed almost no good methodology for assymmetric synthesis. It therefore took as long as 16 steps to construct the enantiomers of exo-brevicomin (1) from the enantiomers of tartaric acid. Now at present we have many fantastic methodologies for the synthesis of pure enantiomers. Recent examples of our synthetic works will be discussed such as the synthesis of the sandfly pheromone [9-methylgermacrene-B (2) and 3-methyl-a-himachalene (3)] and orobanchol (4), the germination stimulant. In pharmaceutical area, it is important to design and manufacture a useful drug. In the case of the Matsucoccus pine scale pheromones, we designed and synthesized 5, which was proved to be a strong pheromone mimic against M. josephi with no kairomonal activity against its predator Elatophilus hebraicus. Elucidation of the structure of new semiochemicals will continue to be pursued in the 21st century to necessitate their synthesis. Molecular design of useful pheromone mimics, however, may become very important in the coming century.
scheme

KS 4
Department of Chemistry, Faculty of Science, Science University of Tokyo, Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601 - Fax: 81-3-3235-2214

 

Induction of Plant Volatile Biosynthesis by Microbial Elicitors and Herbivores

Wilhelm Boland, Jürgen Engelberth, Thomas Koch, Dieter Spiteller

Plants are able to respond to herbivore damage with de-novo biosynthesis of a herbivore-characteristic blend of volatiles. The elicitors of volatile biosynthesis and their mode of action are largely unknown. One of the most potent protein elicitors is cellulysin, a cocktail of cell wall lytic enzymes from the fungus Trichoderma viride. The signal transduction, initiating volatile biosynthesis, proceeds via intermediates of the octadecanoid pathway, especially 12-oxo-phytodienoic acid (12-OPDA) and jasmonic acid (JA) both of which induce completely different pattern of volatiles. Ethylene is the first volatile to be released from damaged plants. Its biosynthesis is triggered by herbivory as well as by individual elicitors, but the mode of emission (burst or rhythmic) is different. Alamethicin (ALA), a voltage-gated, ion channel-forming peptide, is another potent elicitor of volatile biosynthesis [1]. ALA acts via depolarization of membrane potentials and simultaneously activates the octadecanoid and the salicylate signaling pathways. The up-regulation of the SA-pathway interferes with steps downstream of 12-OPDA and reduces the pattern of emitted volatiles to compounds characteristic for an 12-OPDA treatment. Ion channel-forming compounds were recently found in the regurgitant of lepidopteran herbivores suggesting that this mode of elicitation may be widespread in nature.

[1] Engelberth, J., Koch, T., Kühnemann F., Boland, W. (2000) Angew. Chem. Int. Ed. 39, 1860- 1862.

KS 5

Max-Planck-Institute for Chemical Ecology, Carl-Zeiss-Promenade 10, D-07745 Jena, Germany. Boland@ice.mpg.de

ASIAN LONGHORNED BEETLE PHEROMONE STUDY

Aijun Zhang, James Oliver, and Jeffery Aldrich

The introduction of Asian Longhorned Beetle (ALB), Anoplophora glabripennis (Coleoptera: Cerambycidae), into the U.S. poses a great economic threat to the nation's forests and shade trees. To aid in the detection and management of this invasive species, a study was initiated by USDA to determine if a sex pheromone is used for mate location. Two male-specific compounds from adult ALB volatiles were discovered by gas chromatographic-electroantennographic detection (GC-EAD) studies and identified as 4-(n-heptyloxy)butanal and 4-(n-hepyloxyl)butan-1-ol. The structures are unusual and have never been previously found in nature. The synthetic samples elicited the same antennal responses from both sexes and appeared to cause excitation of ALB females and males in preliminary wind tunnel trials. However, field tests conducted in 1999 in China did not verify this activity. Therefore, the exact function of these compounds in the beetles' behavior is still unknown.
OR 28
USDA, ARS, Insect Chemical Ecology Laboratory, Beltsville, MD 20705-2350, USA. E-mail: zhanga@ba.ars.usda.gov

OVIPOSITION STIMULANTS FOR PLUTELLA XYLOSTELLA AT THE SURFACE OF CRUCIFER LEAVES


J. Alan A. Renwick, Meena Haribal and Patrick R. Hughes

The diamondback moth, Plutella xylostella, is a global pest of brassica crops, and it can utilize a wide range of crucifers as host plants. Oviposition was previously thought to be stimulated primarily by glucosinolates, but chloroform washes of cabbage leaves have recently been shown to contain highly potent, non-polar stimulants. Systematic, bioassay-guided separation of extracts has resulted in the isolation and identification of two isothiocyanates, iberin and sulforaphane, that account for part of the stimulatory activity. However, a less volatile fraction that appears to be associated with waxes has the highest activity. Identification of the key compounds in this fraction is underway.
OR 41
Boyce Thompson Institute, Ithaca NY 14853, USA - jar14@cornell.edu

CHEMICAL ECOLOGY OF THE GENERALIST PREDATOR, ORIUS INSIDIOSUS (SAY) (HETEROPTERA: ANTHOCORIDAE)

Jeffrey R. Aldrich and Carolyn Lee Smith

The chemical ecology of Orius insidiosus was studied in the laboratory and in field plots of Bt-transgenic sweet corn. The objectives of the study were to examine the attractancy of plant-mediated chemicals to O. insidiosus as well as characterize attractant and arrestant pheromones produced by the insects themselves. 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 the field, the population of O. insidiosus varied throughout the season; early sweet corn plantings had the highest adult counts during the silking stages, while late plantings harbored the most adults during late whorl, tasseling, and fresh silk stages. 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, suggesting that females attract males with a pheromone.

OR 26
USDA-ARS Insect Chemical Ecology Laboratory, B-007, rm301, Beltsville, Maryland USA 20705; aldrichj@ba.ars.usda.gov

DETERMINATION OF GAS CHROMATOGRAPHIC AND MASS SPECTROMETRIC PROPERTIES OF A LARGE COLLECTION OF PHEROMONE-LIKE ACETATES

Alexsandro. A. da Silva1; Gulab. N. Jham1 and Athula. B. Attygalle

The majority of moth pheromones are mixtures of straight-chain unsaturated acetates bearing 12-20 carbon atoms. Monounsaturated acetates present in these mixtures are identified often by comparing their gas chromatographic retention times (Rt) obtained on several stationary phases of different polarities with those of authentic standards. Moreover, polyunsaturated pheromones can be identified by a random reduction to monoenes followed by the GC-MS analysis of the DMDS derivatives of the products (Attygalle et al 1996). Since only a few laboratories have access to authentic samples of all the isomers of monounsaturated acetates, and literature information on retention time and mass spectrometric data are rather incomplete, a compilation of an extensive information base containing such data would be invaluable to researchers interested in pheromone characterization. Hence, we have determined mass spectral fragmentation patterns and the retention times of 76 isomers of Z and E monoene acetates (19 dodecenyl, 23 tetradecenyl, 22 hexadecenyl, and 12 octadecenyl acetates) on three stationary phases of different polarity [DB1 (non-polar), Carbowax (polar) and DB 23 (highly polar)] coated on fused-silica capillary columns. Analytical data were obtained using a GC/MS (Shimadzu QP5000) system. Each standard (5 ng) was injected five times and data obtained (retention times, and relative abundances of mass spectral peaks) were statistically analyzed. A computation of averages and standard deviations showed excellent reproducibility under repetitive conditions. In general, best gas chromatographic separations were obtained on the DB 23 column. Although peaks for molecular ions were absent in all the spectra, a low-intensity peak (about 5%) at m/z (M+. - CH3COOH) allowed the mass determination. In most cases, specific intensity differences in many peak clusters in mass spectra together with the Rt values allow unambiguous determination of double bond position and configuration of these acetates.

Attygalle, A. B.; Jham, G. N.; Svatos, A.; Frighetto, T.; Meinwald, J.; Vilela, E.; Ferrara, F. A. (3E,8Z,11Z) -3E,8Z-11Z- Tetradecatrienyl acetate. A major component of sex pheromone of tomato pest Scrobipalpuloides absoluta. Bioorganic and Medicinal Chemistry, 4,305-314, 1996.


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Univercidade Federal de Viçosa

Departamento de Química, LPPN, Viçosa, MG, Brazil

2Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA e-mail: gulab@mail.ufv.br

IDENTIFICATION OF CHEMICAL DEFENSE SECRETION OF THE DUNG BEETLE CANTHON IMITATOR

A. Aliabadi1, R. J. Bartelt2 & D. W. Whitman3.

Dung beetles are not generally known to be chemically defended; however, Canthon imitator (fam.: Scarabaeidae; subfam.: Scarabaeinae), emits tiny droplets of a fetid-smelling liquid from two small glands on the posterior margins of the elytra when disturbed. We analyzed this secretion via GC/MS and found the chemical components of this foul-smelling emission included indole, m-cresol, phenol, and creosol. The beetles discharged their odorous secretion when attacked; bird, mammal, and reptile predators, refused to eat them.
OR 46
14160 Chemistry, Illinois Sta. Univ., Normal, IL 61790, USA, E-mail aaliab@ilstu.edu; 2USDA, ARS National Center for Agricultural Utilization Research, Bioactive Agents Research Unit, Peoria, IL 61604, USA, E-mail bartelrj@mail.ncaur.usda.gov; 34120 Biological Sciences, Illinois Sta. Univ., Normal, IL 61790, USA, E-mail dwwhitm@ilstu.edu. - #: (309) 438-7799 FAX: (309) 438-3722

BEHAVIORAL STUDIES OF gravid Aede aegypti MOSQUITOES EXPLOITING OVIPOSITION ATTRACTANTS AND STIMULANTS.

Álvaro E. Eiras, Eduardo S. Ivo & Adriana S. Gomes

Ovitrap (oviposition trap) has been used worldwide for detecting and monitoring populations of the yellow fever Aedes aegypti or Aedes albopictus mosquitoes. The addition of oviposition attractants in ovitrap, such as grass and hay infusions increase the effectiveness of the ovitrap. There are also evidences in laboratory that larval rearing water attracted gravid Aedes mosquitoes. However, the role of these infusions and larval rearing water as oviposition attractant and/or stimulant have not been described yet. Thus, we carried out for the first time, the behavioral sequences of gravid females A. aegypti exploiting oviposition sites with hay infusions and larval rearing water. We observed that there is a pattern of behavioral sequences during the pre-oviposition and oviposition period. Discrimination between oviposition attractant, and stimulant and how gravid female mosquitoes exploit baited ovitrap will be discussed.

OR 42

Depto de Parasitologia, Universidade Federal de Minas Gerais (alvaro@icb.ufmg.br)

 

A NEW CONTROL WAY RESULTED FROM STUDY OF EFFECTS OF THE NEEM EXTRACTS ON REPRODUCTION IN APRIONA GERMARI (COLEOPTERA, CERAMBACIDAE)

Boguang Zhao Xiaoping Li Xiaoping Cheng

The effects of neem extracts on their oviposition and egg hatch were investigated in the beetle (Apriona germari Hope), one of the most important forest pests in Asia. The branches of Broussonetia papyrifera Linn. were treated with neem extracts (Neem EC) as the beetle's food and host for egg laying. During 15 days' testing period the average egg number laid per day per pair beetles in treated group ( 7 pairs), which were fed on branches treated by neem extracts containing 50°¡10-6g/ml azadiractin, was 2.00°¿1.56 and that in the control group ( 7 pairs ) was 10.33°¿3.33. The two values were significant different examined by t-test. In the test with a dosage of the neem extracts containing 100°¡10-6g/ml azadirachtin, in the treated group ( 7 pairs ), the beetles began to die at the fifth day and all the beetles were dead at the eighth day, their average egg number laid per day per pair for the living beetle pairs, was 1.00°¿1.41 and that for the control group was 13.73°¿2.90. T-test shown differences between the two values were significant. The hatching rate of the eggs laid in the group of neem extracts containing 50°¡10-6g/ml azadirachtin, reached 33.3% at the nineteenth day. However, that of eggs laid by control beetles was 98.9% at the ninth day. During a 24 days' choice feeding test the branches were treated with a dosage of the neem extracts containing 100°¡10-6g/ml azadirachtin and the average food taken by the beetles in the treated group ( 7 pairs ) was 3.53°¿0.38g per pair per day and that on the control group ( 7 pairs ) was 3.42°¿0.60 g per pair per day. T- test shown that differences between the two values were not significant. Based on the above results a new way using trap trees treated with neem extracts to control the beetle species was put forward and discussed.
The project was supported by National Natural Science Foundation of China.
OR 24

Nanjing Forestry University Nanjing 210037, P. R. China bogusngzhao@yahoo.com

ATTRACTION AND INHIBITION OF ATTRACTION OF COFFEE BERRY BORER, Hypothenomus hampei. L. (COLEOPTERA: SCOLYTIDAE)

Olgar MARTINEZ-BORBON,1 Alfaro O. MORA,1 Guillermo R. MORA,1 A. Cam OEHLSCHLAGER,*2 Lilliana GONZALEZ,2 Romano ANDRADE2 and Leonardo ALVAREZ2

The coffee berry borer, Hypothenemus hampei, is the world's most serious insect pest of coffee affecting all growing areas except Hawaii and Costa Rica. Females are known to be attracted to methanol:ethanol mixtures and multiple funnel traps based on the Lindgren design are the most efficient traps reported. Field work in Nicaragua has optimized trapping of H. hampei and laid the foundation for a push - pull strategy with the discovery that green leaf volatiles are repellant to this scolytid. Contrary to published reports (Mathieu, et al., J. Appl. Entomol. 181-186, 1997) it was found that white multiple funnel traps are significantly more attractive to H. hampei than other colors such as red. Traps constructed from small funnels (bottomless drinking cups) with small cone angles are as effective as traps constructed from large funnels with large cone angles (Lindgren design). Lowering the number of funnels to a minimum of one does not decrease trap efficiency. H. hampei are equally attracted to methanol:ethanol mixtures from 97-40% methanol over a wide range of release rates (~200-1000 mg/d). Methanol:ethanol extracts of green coffee beans are no more attractive than the corresponding extraction solvent. Green leaf volatiles (Dickens et al. Experientia 48:523, 1990), especially (Z)3-hexenol, are highly repellant to H. hampei, MCH (3-methylcyclohex-2-en-1-one) and verbenone are mildly repellant and alpha-pinene exhibted no attractive or repellant activity. H. hampei management via alternating trap and repellant sites within infested plantations is an obvious extension of this work.

OR 44


1Institute de Café de Costa Rica, Barvra, Costa Rica, 2ChemTica Internacional, S. A., Apdo. 159-2150, San José, Costa Rica, www.chemtica.com

 

TERMITE SEX PHEROMONE IDENTIFIED AFTER SOLID PHASE MICROEXTRACTION FROM TERGAL GLANDS OF FEMALE ALATES OF CORNITERMES BEQUAERTI (ISOPTERA, NASUTITERMITINAE).

Christian BORDEREAU1, Eliana M. CANCELLO2, Etienne SEMON3, Annie COURRENT1, Brigitte QUENNEDEY 1

Sex pheromones in termites generally are emitted by females after the dispersal flight of alates and secreted by abdominal sternal or/and tergal glands. Until now only 2 compounds, dodecatrienol and n-tetradecyl propionate, have been identified as termite sex pheromones. We have studied Cornitermes bequaerti, one of the most abundant and economically important termite present in Brazil. In this species, the sex pheromone is emitted by females from glands located at the anterior part of tergites 8-10. Cold anesthesized female alates oberved under a stereomicroscope were artificially induced to expose their tergal glands thanks to forceps. A Supelco Polydimethylsiloxane/Divinylbenzene fiber for solid phase microextraction was rubbed on the surface of tergal glands. Controls were carried out by rubbing tergites and intertergal membranes 2-4. Comparison by GC analysis of compounds present on glandular and non glandular surfaces allowed to point out a specific compound of tergal glands. By GC-MS, this compound was identified as (3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol (dodecatrienol). Bioassays have shown that synthetic dodecatrienol induced sexual behavior in males. It is thus concluded that dodecatrienol, already known as a sex pheromone and a trail-following pheromone of several species of termites also is the major component of the sex pheromone in the mandibulate Nasutitermitinae C. bequaerti. It is the first time that a termite sex pheromone is directly isolated from the surface of its glandular source.

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1 Université de Bourgogne, C.N.R.S, U.M.R 5548 " Développement, Communication chimique ", 6 Bd. Gabriel, 21000 Dijon, France

2 Museu de Zoologia da USP _ CP 42694, CEP 04299-970, Sao Paulo, SP, Brazil

3 I.N.R.A. Laboratoire de Recherches sur les Arômes, 17 Rue Sully, 21034 Dijon, Franc

Close-Range sex pheromone of Lygocoris pabulinus (L.). identification of female- specific compounds as possible attractants

Falko P. Drijfhout1, Astrid T. Groot2, Teris A. van Beek1, J. Hans Visser2 and Aede de Groot1

Males of the green capsid bug, Lygocoris pabulinus, exhibit a specific courtship behavior, a vibration of the abdomena. When legs of female bugs are offered to males, it elicits this vibration behavior. In order to determine which compounds are involved in this close-range communication between females and males, extracts from the legs from females and males were analyzed. The female extracts were attractive in the close-range bioassays. The extracts contained several hydrocarbons such as n-alkenes, n-alkanes and some methylalkanes. Female extracts contained more (Z)-9-pentacosene and male extracts contained more (Z)-9-heptacosene. Without these hydrocarbons the extracts were less active in the vibration bioassay. These hydrocarbons were also found on the body of green capsid bugs and were deposited on different substrates by females.

Groot, A.T., Visser, J.H., Geerts, R., Drijfhout, F.P., and van Beek, T.A., 1998, Proc. Exp. Appl. Entomol. 9:191-195.

OR 1
1 Laboratory of Organic Chemistry, Phytochemical section, Wageningen University, Dreijenplein 8, 6703 HB Wageningen, The Netherlands

2 Plant Research International, Wageningen UR, P.O. Box 16, 6700 AA Wageningen, The Netherlands

Biologically active volatiles in Australian sexually deceptive orchids

Florian P. Schiestl1, Rod Peakall1, Fernando Ibarra2 & Wittko Francke2

Flowers of sexually deceptive orchids mimic the sex pheromones of their pollinator species. Pollination occurs when the male attempts to copulate with the flower. We investigated the "pseudopheromones" of orchids in the genus Chiloglottis and Arthrochilus which are pollinated by male thynnine wasps (Hymenoptera: Tiphiidae). Female thynnines are flightless and call for males by releasing sex pheromones from a low perch. We examined floral odors and their detection by the males using gas chromatography with electroantennographic detection (GC-EAD). Gas chromatography _ mass spectrometry was used to identify odor compounds. In the spring-flowering Chiloglottis trapeziformis, one peak elicited electroantennographic reactions in pollinator-males. This peak was found in the labella as well as in the sepals of the flowers. C. valida, which occasionally shares the same pollinator species, produces the same active compound, in labella and sepals. In the autumn-flowering C. trilabra and C. reflexa, two compounds were found to elicit electroantennographic responses, with the main compound having the same retention time in both species. In C. trilabra, both the labellum and sepals are attractive to pollinators and both produce the same active compounds. In odor samples of Arthrochilus huntianus labella, two compounds elicited electroantennographic responses in the pollinator males. One compound had the same retention time as the main active compound of C. trilabra. Chemical identifications are currently being done. Our results suggest that the mimicry of the pollinators' sex pheromone in the investigated Australian orchids requires only a few compounds. Supported by the FWF Austria and the Australian Orchid Foundation.

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1Division of Botany and Zoology, The Australian National University, Canberra, ACT, 0200, Australia; Email: florian.schiestl@anu.edu.au; 2 Institute of Organic Chemistry, University of Hamburg, Germany

FEMALE-PRODUCED SEX PHEROMONE OF THE PREDATORY BUG Geocoris punctipes

Francisco de Assis Marques1,2, J. Steven McElfresh1, and Jocelyn G. Millar1

A compound identified from volatiles produced by adult female Geocoris punctipes attracted male bugs, and stimulated males to investigate nearby moving objects of the appropriate size in their search for females. The compound was identified as (E)-2-octenyl acetate, a relatively common component of the volatile semiochemicals produced by a number of heteropteran species. This compound comprised a significant proportion of the female volatiles, whereas it was detected in only trace amounts in volatiles collected from live males. Other components in the extracts from adults of both sexes included (E)-2-hexenyl acetate, (E)-2-octenal, and several saturated hydrocarbons, but these components were not part of the attractant. These compounds plus (E)-2-hexenal, (E)-4-oxo-2-hexenal, and (E)-2-decenal were found in extracts of homogenized adults, whereas the cast skins from late instar nymphs contained (E)-2-octenal, (E)-4-oxo-2-octenal, (E)-2-octenoic acid, and several saturated hydrocarbons.

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1 Department of Entomology, University of California, Riverside CA, 92521, USA

2 Current address: Department of Chemistry, Federal University of Paraná, P.O. Box 19081, Curitiba, 81531-990, Brazil. Email: tic@quimica.ufpr.br

Testing the possibility of population control by mass trapping of Ips duplicatus in a forest island using time-series data

Fredrik Schlyter1 Qing-He Zhang1, Guang-Tian Liu2

The possibility of effective population control of bark beetle populations by mass trapping in a forest landscape has been since long been questioned. Even the scientific experimental testing on landscape scale of the hypothesis of population reduction by mass trapping is a logistic nightmare and establishment of proper treatment/control areas is not always manageable.

We would like to suggest a possible work-around by analysing time series of tree mortality data, in our example helped by an island effect, good long-term records, and a very competitive synthetic pheromone.

The successful development of a synthetic pheromone (ipsdienol and E-myrcenol), dispensers, and dose-response of wick-dispensers is briefly described. In the 3000 ha forest reserve, surrounded by grassland, 70 traps have been employed for 2 years catching >1 million beetles/year. The long-term tree mortality has since 1984 been oscillating around 500 (200 _900) trees for 16 years, in spite of intensive conventional management. After the first year of mass trapping mortality was down to 70 trees.

Data of preliminary nature for 2000, including some sites using push-and-pull with non-host volatiles on forest edge combined with mass trapping, will be presented with an aim to provoke discussion.

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Dept. of Plant Protection Sciences, Swedish Univ. of Agricultural Sciences, P. O. Box 44, SE-230 53 Alnarp, Sweden, 2Baiyinaobao Natural Preserve, 025375 Inner Mongolia, P. R. China