Learning the Language of Insects- and How to Talk Back - Entomology

these redundant pairs mght send theiraxons to the same discrete centers in themacroglomer ular complex in the antennallobe of the brain There would be fourmajor centers in the antennal lobe7 onereceiving inputs from cells responsive to themajor component only7 and three other centersreceiving Inputs from particular redundantpairs of receptor cells that reflect thebehavioral redundancy found earlier byLinn and Roe10fs~In collaboration with Bill Hansson at the4University of Lund7 Sweden7 we have nowbegun to see if such redundant-pair-specificcenters exist7 by recording from the cells' and finding out which compounds they aretuned to, then dying the cells with cobalt,(and s~lver-intensifying them to follow themdown to their areas of arborization inthe macrog~omerular complex (MGC)(Hansson et a1 1992) So far7 we have foundthat cells specific for the major componentdo in fact send their axons only to onemajorsubcompartment of the macroglomerularcomplex It will be exciting to see if theother subcompartments that are found inthe MGC are there for the purpose of receivlnginputs from par ticular redundantpairs of minor components.Natural noise does appear to have hadan effect on the ability of insects to communicate>and now by artificially addingselected types of noise we know we can affectplocesses such as mating and oviposition?even feeding The use of pheromonesfor disrupting mating has become commerciallyacceptable? even desirable Forinstance, by placing controlled-release dispensersof three-component oriental fruitmoth pheromone into the environment> thesuccess rate of males locating calling femalescan be reduced to then California> peach growershave accepted this control measure> and apattern that has occurred is that after threesuccessive years of using pheromones, themoth populations plummet to the pointwhere often no control intervention isnecessar ye Included among other species forwhich commercially available disruptantshave been successful are the tomato pinwoImmoth7 the pink bollworm moth7 andgrape berr y moth (Rldgway et a1 1990).Does the pheromone disruption-emittednoise work by confusing males? causingthem to fly upwind7 locate the inappropriatesynthetic sources, and waste timeinvestigating them instead of mating? Ordoes it work by adapting (habituating) themales' pheromone-specific pathways tohampe~ their sensory capabilities? There isevidence that it is a little of both, since pinkbollworm males have been observed underfield conditions visiting disruptant hollowWinter 1993fibers However> evidence for the adaptation-habituationmechanism as a contributingfactor comes from the experimentsof Hollis Flint and coworkers in Arizona(Flint & Merkle 1984) They showed thatwhen noise in the form of the correct SO: SOpheromone blend of the two pink bollwormpheromone components was broadcastinto fields7 traps emitting this sameratio were completely shut down to maleattraction, as were traps emitting a differentseries of blend ratios of the same twocomponents When they used a 9:l ratio ofthese components with which to disruptcommunication7 however, they found thatdisruption again was profound across allsignaling frequencies, including the naturalblend However, this time traps emitting afrequency artificially enriched with thecomponent that predominated in the disruptionblend did manage to capture a smallbut significant number of males., This blendwould never have attracted males in a noisefreeenvironment7 because it is such an extremeoff-ratio. This odd result showed thatmales could be made to fly upwind to a badblend as if it were an optimal one byartificially compensating for the adaptationEnriching the blend with the componentto which the adaptation hadselectively occurred brought back an illusionof the correct balance to the odor"Finally> the steps involved in learning thelanguage of insects must include communicationwith other scientists We musteffectively use our language to pass on ourknowledge about the insects to our colleaguesand to transmit our insights aboutpossible evolutionar y patterns or about theprospects for applying our knowledge forpest management purposes. The insects do7indeed, oftentimes seem to be trying to tellus something, Once we learn what it is7 wemust not be lazy and let their message die byfailing to publish or talk about our findings.The important feature of communicationbetween insects and ourselves is that wemust understand that we are the channel,,The old axiom "publish or perish" isfamiliar to everyone,, But actually7 the importantaspect of this statement for thoseinvolved in insect communication researchis publish, or else the language of insectswill perish,, Their words will not merelyhave fallen on deaf ears7 but even moretragically, they will have ended up in a mutehuman channel.References CitedAcree, T. E , R. Nishida & H. Fukami. 1985.Odor thresholds of the stereoisomers ofmethyl jasmonate J Agric Food Chem 33:425427Baker, T,, C. 1989,, Origin of courtship and sexpheromones of the oriental fruit moth and adiscussion of the role of phytochemicals in theevolution of lepidopteran male scents pp,401418, In C,, H, Chou & G,, R, Waller[eds,], Phytochemical ecology: allelochemicals,mcotoxins, and insect pheromones andallomones, Academia Sinica, Taipei, R, O,,C,1990,, Upwind flight and casting flighc complementaryphasic and tonic systems used forlocation of sex pheromone sources by malemoths, pp 18-25, In K, D~ving, led,,], IS01X, Proceedings 10th International Symposiumon Olfaction and Taste, GCSIAS Oslo,Baker, T. C. & R" T" Cadi. 1979, Courtshipbehavior of the Oriental fruit moth (Grapholithamolesta): experimental analysis andconsideration of the role of sexual selection inthe evolution of courtship pheromones in theLepidoptera, Ann, Entomol, Soc, Am, 72:173-188,Baker, T. C. & K. F. Haynes. 1989. Field andlaboratory electroantennographic measurementsof pheromone plume structure correlatedwith oxiental fruit moth behaviour,,Physiol Entomol, 12: 263-2 79,,Baker, T. C", R., T., Cadi & ,J,. R. Miller:. 1980.Oriental fruit moth pheromone componentemission rates measured after collection byglass-surface adsorption, J, Chem, Ecol,. 6:749-758,Baker, T. C.> M,, A. W~llis, K. F. Haynes & I? L,,Phelan, 1985. A pulsed cloud of pheromoneelicits upwind flight in male moths, Physiol,Entomol 10: 257-265,Baker, T. C.,, B, S. Hansson, C. Lofstedt & J.Lofqvist. 1988" Adaptation of antennalneurons in moths is associated with cessationof pheromone-mediated upwind flight, Proc,Natl, Acad,, Sci, U,S,.A,. 85: 9826-9830,,Bentley, D. & R. R,. Hoy. 1974. The neurobiologyof cricket song, Sci Am 231: 33-44,Bjostad, L. B. & W, L. Roelofs. 1987., Sex pheromonebiosynthesis in lepidopterans: desaturationand chain shortening, pp,. 77-120,, In G,,D, Prestwich & G, L, Bloomquist [eds,], Pheromonebiochemistry, Academic, New York.,Card6> A,, M., T. C. Baker & Ro I.Cadi. 1979.Identification of a four-component sex pheromoneof the female oriental fruit moth,Grapholita molesta (Lepidoptera: Tortrici-dae),, J,, Chem, Ecol,, 5: 42 3427,Conner7 W. E.,, T" Eisner, R. K. Vander Meer, A.Guer~ero, D. Ghuingelli & ,J. Meinwald..1980. Sex attractant of an arctiid moth(Utethesia ornatrix): a pulsed chemical signal,.Behav, E~ol,, Sociobiol,, 'E 55-63,Eisner, 1. 1970. Chemical defense againstpredation in arthropods, pp,, 1,57-217,, In E,,Sondheimer & J,, B, Simeone [eds,]? Chemicalecology Academic, New York,,Flint, H. M" & ,J. R. Merkle. 1984. The pinkbollworm (Lepidoptera: Gelechiidae): alterationof male response to gossyplure by releaseof its component Z,Z-isomer., J,, Econ,, Entomol,77: 1099-1104,,Hansson, B. S,, & T. C. Baker. 1991. Differentialadaptation rates in a male moth's sex pheromonereceptor neulons,, Naturwiss '78: 517-520,