BIOSYSTEMATICS OF THE GENUS EUXOA (LEPIDOPTERA: NOCTUIDAE) XV. SEX PHEROMONE CROSS ATTRACTANCY AMONG THE THREE CLOSELY RELATED SPECIES OF THE DECLARATA GROUP

Abstract

Can. Ent. 113: 235-243 (1981) Male release-recapture experiments show that under natural photoperiod there is no cross attractancy between species of the sympatric pairs E. declarata and E. campestris or E. declarata and E . rockburnei, but that there is between the parapatric pair, E. campestris and E. rockburnei. When the calling periods of E. declarata and E. campestris females are synchronized by photoperiod manipulation there is cross attraction between these two species as well. However, in mating discrimination tests between E. declarata and E. campestris the normally strong bias against interspecific mating is only partially overcome by synchronizing mating activity rhythms. The residual tendency for conspecific mating is more likely due to imperfect synchronization of mating rhythms or differences in close range courtship behavior than to differences in attraction pheromone. Males of all three species are attracted to the same synthetic attractants. The results are consistent with the hypothesis that the attraction pheromones of the three species in the declarata group are very similar and are unlikely to play a major role in reproductive isolation, which is probably effected primarily by differences in circadian rhythms of mating activity.

BIOSYSTEMATICS OF THE GENUSEUXOA(LEPIDOPTERA: NOCTUIDAE). XVIH. COMPARATIVE BIOLOGY AND EXPERIMENTAL TAXONOMY OF THE SIBLING SPECIESEUXOA RIDMGSIANA(GRT.) ANDEUXOA MAIMES(SM.)

“…However, reproductive isolation often results from the coaction of several isolating mechanisms and differences in timing of mating activity are known to act as an isolating mechanism in some species of Euxoa. In the sympatric species Euxoa declarata and Euxoa campestris, which have sex pheromones that are highly cross-attractive (Underhill et al 1981), reproductive isolation is achieved in both the field and in laboratory cages by a phase difference in mating periodicities of about 5.4 h (Byers and Hinks 1978;Teal et al 1978;Byers et al 1981). The approximately 2-h phase difference between the mating-activity periods of ridingsiana and maimes is, however, not enough to effect reproductive isolation because when males of either species are confined in cages with females of both species, about 25% of matings are interspecific.…”

BIOSYSTEMATICS OF THE GENUS EUXOA (LEPIDOPTERA: NOCTUIDAE): XVI. COMPARATIVE BIOLOGY AND EXPERIMENTAL TAXONOMY OF FOUR SUBSPECIES OF EUXOA COMOSA

“…The reduction in mating success (83.6% vs. 94.6%) is less pronounced than that (49.0% vs. 87.5%) found in crosses between sibling species of the Euxoa declarata group in an earlier study (Byers and Hinks 1978). In the declarata group the reduction was due to strong conspecific mating biases, based on differences in mating activity rhythms (Teal et al 1978;Byers et al 1981), which are largely, but not completely, overwhelmed under no-choice, laboratory conditions. Although there is also mating preference among the comosa subspecies, premating isolating mechanisms which function at close range i.e.…”

“…Druzhelyubova 1976, Poitout and Bues 1977) and adults of montane or northern populations of univoltine species often emerge earlier in the season than those at lower altitudes or latitudes (Iwao 1967;Milyanovskiy 1973). In the declarata group the reduction was due to strong conspecific mating biases, based on differences in mating activity rhythms (Teal et al 1978;Byers et al 1981), which are largely, but not completely, overwhelmed under no-choice, laboratory conditions. The length of period from eclosion to first oviposition varies considerably among Euxoa species.…”

“…For example if speciation were primarily the result of a premating isolating mechanism, such as temporal separation of reproductive activity, the rather slight genetic divergence involved would not likely affect hybridization success. This appears to be the case with the sibling species in the declarata group of Euxoa which produce vigorous and fully fertile hybrids (Byers and Hinks 1978;Byers et al 1981). On the other hand if considerable intraspecific differentiation of the genome were to occur in isolated populations, and particularly if incipient species in contact undergo reinforcement of reproductive isolation by developing postmating isolating mechanisms such as hybrid inviability (Udovic 1980), the extent of evolutionary divergence suggested by a reduction in hybridization success could be exaggerated.…”

Sex Pheromones of Two Leafminer Species, Antispila oinophylla and Holocacista rivillei (Lepidoptera: Heliozelidae) Infesting Grapevine in Italy

“…In addition Z7–14:Ald was recorded as an attractant for the heliozelid Antispila treitschkiella (Fischer von Röslerstamm) (Tóth et al 1992 ). The Z5–12:Ald was found as sex pheromone component in Gastropacha quercifolia (Linnaeus) (Bestmann et al 1993 ) and some noctuid moths in the genus Euxoa (Byers et al 1981 ; Underhill et al 1981 ).…”