The olfactory system of male and female Spodoptera frugiperda (J. E. Smith) was studied by examining the morphology and distribution of antennal sensilla and determining the responses of both sexes to conspeciÞc female sex pheromone components and plant volatiles using electroantennography (EAG). Seven types of sensilla were observed on the ßagellum of the antennae: trichodea, chaetica, coeloconica, styloconica, auricilica, squamiformia, and basiconica. Only one type of trichodea sensilla was found on the antennae of both sexes, but these sensilla were more abundant on male than on female. EAG records of both sexes to 10-g stimulus loads of six pheromone components showed that (Z)-7-dodecenyl acetate (Z7Ð12: Ac) and (Z)-9-dodecenyl acetate (Z9 Ð12: Ac) elicited larger responses than those evoked by (Z)-11-hexadecenyl acetate (Z11Ð16: Ac), (Z, E)-9,11-tetradecadienyl acetate (Z9, E11Ð14: Ac), (Z, E)-9,12-tetradecadienyl acetate (Z9, E12Ð14: Ac), and hexane in female antennae. In the case of male antennae, (Z)-9-tetradecenyl acetate (Z9 Ð14: Ac) and Z9, E12Ð14: Ac evoked larger EAG responses than those elicited by Z7Ð12: Ac, Z11Ð16: Ac, Z9, E11Ð14: Ac, and hexane. The compounds that selectively evoked larger EAG responses from males than females were Z9, E12Ð14: Ac, and Z9 Ð14: Ac. Dose-response experiments showed that, at the lowest dose tested, Z9 Ð14: Ac and Z9, E12Ð14: Ac elicited larger EAG responses than Z9 Ð12: Ac and Z7Ð12: Ac in male antennae. At the highest doses tested, the diene elicited the largest EAG responses. In the case of female antennae, the dose, but not the pheromone component, had a signiÞcant effect. Male and female responses to 10-g stimulus loads of 16 plant volatiles showed that hexan-1-ol evoked larger EAG responses in comparison with those elicited by hexanal, (E)-3-hexenol, 2-carene, phellandrene, limonene, ␤-pinene, and hexane. The response of male antennae was signiÞcantly stronger than the female. Dose-response experiments showed that both sexes appeared to be most sensitive to alcohols, particularly at the highest dose tested.

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Nonirradiated males and females of Anastrepha obliqua (Macquart) were attracted to and landed more frequently on ripe fruits of Spondias mombin L. than on artificial fruit in wind tunnel bioassays. Porapak Q volatile extracts of S. mombin were also attractive and elicited landing on artificial fruit for both sexes. Combined gas chromatographic-electroantennographic detection (GC-EAD) analysis of volatile extracts showed that nine volatile compounds elicited repeatable antennal responses from females and males. The EAD-active compounds were identified by GC-mass spectrometry (MS) as follows: ethyl butyrate, isopropyl butyrate, hexan-1-ol, propyl butyrate, isobutyl butyrate, ethyl hexanoate, isopentyl butyrate, ethyl benzoate, and ethyl octanoate. In wind tunnel bioassays, males and females were attracted and landed more frequently on lures containing the nine-component blend of synthetic compounds than on unscented controls. Field cage bioassays showed that multilure traps baited with the nine-synthetic blend captured significantly more A. obliqua than traps baited with hydrolyzed protein or water.

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The reduction of domiciliary infestation by insect vectors, the key to controlling Chagas' disease, depends on identification of housing features associated with infestation. In this study, log-linear modeling was used to reanalyze data collected in 1964-1968 from 371 houses on characteristics potentially associated with infestation by the vector Triatoma dimidiata in a Costa Rican town with endemic Chagas' disease. A possible increased risk of infestation was observed for houses with a dirt floor (as compared with houses with another floor type) and for houses in poor sanitary condition (as compared with houses in good sanitary condition). A new risk factor for house infestation, the presence of roof tiles, was identified; the odds of infestation for houses with a tile roof were 2.4 times greater than the odds for houses with a galvanized metal roof. This significantly increased risk is probably due to the harboring of T. dimidiata in stacks of spare tiles next to house walls rather than to the tile roofs themselves.

We examined the interaction between an invertebrate iridescent virus (IIV) isolated from Spodoptera frugiperda (J.E. Smith) and the solitary ichneumonid endoparasitoid Eiphosoma vitticolle Cresson. In choice tests, parasitoids examined and stung significantly more virus infected than healthy larvae, apparently due to a lack of defense reaction in virus infected hosts. Parasitoid-mediated virus transmission was observed in 100% of the female parasitoids that stung a virus infected host in the laboratory. Each female parasitoid transmitted the virus to an average (AESE) of 3:7 AE 0:3 larvae immediately after stinging an infected larva. Caged field experiments supported this result; virus transmission to healthy larvae only occurred in cages containing infected hosts (as inoculum) and parasitoids (as vectors). The virus was highly detrimental to parasitoid development because of premature host death and lethal infection of the developing endoparasitoid. Female parasitoids that emerged from virus infected hosts did not transmit the virus to healthy hosts. We suggest that the polyphagous habits of many noctuid parasitoids combined with the catholic host range of most IIVs may represent a mechanism for the transmission of IIVs between different host species in the field.