Inheritance patterns for sex pheromone production in females, pheromone detection on male antennal olfactory receptor cells, and male pheromone behavioral responses were studied in pheromonally distinct populations of European corn borers from New York State. Gas chromatographic analyses of pheromone glands, single sensiflum recordings, and flight tunnel behavioral analyses were carried out on progeny from reciprocal crosses, as well as on progeny from subsequent F2 and maternal and paternal backcrosses. The data show that the production of the female pheromone blend primarily is controlled by a single autosomal factor, that pheromone-responding olfactory cells are controlled by another autosomal factor, and that behavioral response to pheromone is controlled by a sex-linked gene. F1 males were found to possess olfactory receptor cells that give spike amplitudes to the two pheromone isomers that are intermediate to those of the high and low amplitude cells of the parent populations. Fifty-five percent of the F1 males tested responded fully to pheromone sources ranging from the hybrid (E)'11-tetradecenyl acetate/(Z)-11-tetradecenyl acetate (E/Z) molar blend of 65:35 to the E/Z molar blend of 3.97 for the Z morph parents, but very few responded to the E/Z molar blend of 99:1 for the E morph parents. Data on the inheritance patterns support speculation that the Z morph is the ancestral and that the E morph is the derived European corn borer population.

Of 12 potential reproductive isolating barriers between closely related Z-and E-pheromone strains of the

Pheromone blend analyses of glands from individual female European corn borers,Ostrinia nubilalis (Hübner), from field-collected larvae or pupae associated with bivoltine flights in June and August and a univoltine flight in July have shown that: (1) a site in western New York has a bivoltine biotype utilizing (Z)-11-tetradecenyl acetate as its primary pheromone component (designatedZ), (2) two sites in central New York have mixed populations consisting of a bivoltine biotype utilizing theE pheromone isomer (designatedE) and a univoltine biotype utilizingZ, and (3) one site in central New York was found to have only the univoltineZ biotype. The combinations of voltine biotypes and pheromone strains found in New York support the existence of three European corn borer populations designated bivoltineE, bivoltineZ, and univoltineZ.

In New York state, there are three races of European corn borer moths, which are characterized principally by differences in voltinism and the sex pheromone communication system. One race is bivoltine, with females producing and males responding to a 99:1 EIZ isomeric ratio of~1l-14:0Ac's as the sex pheromone. Two races, one univoltine and one bivoltine, produce and respond to a 3:97 E 12 blend of~1l-14 :OAc·s. The races are referred to as BE, UZ, and BZ to denote these differences. Analyses by gas chromatography of field-collected females indicate that there is significant hybridization between the Z and E races when in sympatry, with hybrid females producing a 68:32 ratio of E/Zl1-14:OAc. Gene flow among the races was investigated using differences in triose phosphate isomerase (TPI) allozyme frequencies of moths from sites sampled across the state. The fixed nature of the Tpi-l allele in the BE race and increases in the Tpi-l allele frequencies in UZ populations in sympatry with the BE race support the hypothesis that gene flow following hybridization is unidirectional from BE populations into the Z populations. In addition, the TPI genotypes of the 10 hybrid females analyzed were consistent with hybridization occurring by E males mating with Z females.

The post-diapause development (PDD) time for univoltine European corn borers (ECB) under diapause breaking conditions averages approximately 44 days, whereas the PDD time for bivoltine ECB under the same conditions is approximately 15 days. This difference is the principal component of the life cycle that determines the number of generations possible in a summer. Previous workers have demonstrated some genetic control of differences in voltinism among populations, including apparent control by sex-linked (Z-linked) genes.In the present study allozymes of the enzyme, triose phosphate isomerase (TPI), were used as markers of the Z chromosomes in crosses of a bivoltine colony (Tpi-I) and a univoltine colony (Tpi-2). The F1 resulting from a cross of univoltine females (Z'W) and bivoltine males (Z'Z') consisted of hemizygous Tpi-I females (Z'W) with a mean PDD time of 19 days and heterozygous Tpi1npi-Z males (Z'Z') with a mean PDD time of 34 days. The F2 progeny consisted of Tpi-I females (Z'W) (mean PDD time = 15 days), Tpi-2 females (Z2W) (mean PDD time = 40 days), homozygous Tpi-1 males (Z'Z') (mean PDD time = 16 days), and heterozygous Tpi-Inpi-2 males (Z'Z') (mean PDD time = 25 days). The close correlation of TPI phenotypes and PDD times in these crosses, along with similar results for the maternal and paternal backcrosses of the F1 individuals, indicates that the PDD time is principally controlled by genes on the Z chromosome and that heterozygous males exhibit incomplete or partial dominance of these genes.o 1992 ~i l e y -~i s s , Inc.

In two races of European corn-borer moths (ECB), the E-race females emit and males respond to 99:l sex pheromone blend of (€)/(a-11-tetradecenyl acetates, whereas the Z-race females and males produce and respond to the opposite 3:97 pheromone blend of (€)/(a-11-tetradecenyl acetates, respectively. We previously have shown that female production of the final blend ratio i s under control of a major autosomal locus but that the sequence of male upwind flight responses to the blend i s controlled by a sex-linked (Z-linked) locus. This sex-linked control of behavioral responses in crosses of E and Z ECB now is confirmed by use of sex-linked TPI (triose phosphate isomerase) allozyme phenotypes to determine the origin of the sex chromosomes in F2 populations.F1 males from reciprocal E x Z crosses generate similar behavioral-response profiles in wind-tunnel studies, with moderate numbers responding to the Z pheromone and intermediate blends (35%-65% Z), but very few responding to the E pheromone. The F2 behavioral-response profiles indicate that they are composed of 1 :I mixtures of hybrids and paternal profiles. Analysis of TPI allozyme differences allowed us to separate male F2 populations into individuals whoseZchromosomes both originated from their grandfathers, and individuals who had one Z chromosome originating from each grandparent. With these partitioned F2s, the TPI homozygotes exhibited behavioral-response profiles very much like their grandfathers, whereas the TPI hybrids produced response profiles similar to their heterozygous F, fathers. These results demonstrate incontrovertibly that the response to sex pheromone in male ECB is controlled by a sex-linked gene that i s tightly linked to the TPI locus and therefore i s independent of the locus controlling pheromone blend production in females.Acknowledgments: The authors thank M.L. Hessney for rearing the insects used in these studies and J.P. Nyrop (Department of Entomology, NYSAES) and J. Barnard (Laboratory Director of Computer Services, NYSAES) for invaluable advice regarding statistical analysis. We are also indebted to M.R. Nolan and S. Kresovich (Germplasm Resources, National Clonal Repository, NYSAES) and N.F. Weeden (Department of Horticultural Sciences, NYSAES) for advice and encouragement regarding electrophoresis techniques.

For those arthropod species adapted for living below the soil surface, the soil is a refuge from the biotic and abiotic perturbations existing above ground. Convergent morphological, physiological, and behavioral adaptations of epedaphic, euedaphic, and hemiedaphic arthropods to selective aspects of subterranean existence are examined in light of overlapping ecological niches. The abiotic impact of the soil environment and its relationship to arthropod evolution, radiation, and ecology are discussed as well. Specific areas addressed include the invasion of land by marine arthropods, the impact of morphology on arthropod mobility, osmoregulatory/respiratory systems, and defensive strategies.

The synthetic female sex pheromone of the oriental beetle, Anomala orientalis Waterhouse, was evaluated in the field and in a sustained-/light tunnel. In a 2-wk period, >150,000 beetles were captured on three golf course fairways in Connecticut.Contrary to earlier reports that these beetles are most active during the warm, sunny portions of the day, we observed that peak activity occurs around sunset. Ten micrograms of either (Z)-7-tetradecen-2-one or an 89/11 (Z/E) blend on a rubber septum was found to be the minimum concentration with which no significant decrease in catch was observed in the field. There was no discrimination between Z and the blend at 1 J.'g and higher concentrations, but the E-isomer alone trapped significantly fewer beetles than either Z alone or the blend. These results are consistent with the /light tunnel data. The effects of temperature and light intensity on the mating behavior of A. orientalis also are discussed.