Reproductive Isolation and Genetic Variation between Two “Strains” ofBracon hebetor(Hymenoptera: Braconidae) |
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Authors: | George E Heimpel Michael F Antolin Rosa A Franqui Michael R Strand |
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Institution: | aDepartment of Entomology, University of Wisconsin, Madison, Wisconsin, 53706;bDepartment of Biology, Colorado State University, Fort Collins, Colorado, 80523, f1 |
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Abstract: | Bracon hebetorSay(Hymenoptera: Braconidae) is known primarily as a parasitoid of pyralid moth larvae infesting stored grain. In the 1970s, a parasitoid identified asB. hebetorwas released for control ofHeliothis/Helicoverpaspp. (Lepidoptera: Noctuidae) on the island of Barbados. Because life-history traits of this parasitoid differed from those reported forB. hebetorfrom the United States, we conducted a series of laboratory experiments to determine whether this parasitoid was (i) a population ofB. hebetorthat attacks noctuids in the field or (ii) a different species fromB. hebetor.We confirmed thatHeliothis virescens(F.) was a more suitable host for the Barbados strain than forB. hebetor.However, a stored-grain infesting pyralid,Plodia interpunctella(Hübner), was a more suitable host for the Barbados strain than wasH. virescens.Reciprocal crosses between the Barbados strain andB. hebetorshowed that the two populations were reproductively isolated. No mating was observed during a series of 30-min observations of reciprocal crosses, and the crosses produced only male offspring. Examination of each female's spermatheca confirmed that females were not fertilized. Sequence analysis of a 517-bp fragment of the mitochondrial 16S rRNA gene revealed that two populations ofB. hebetorfrom our laboratory were identical but differed in sequence by 2% from the Barbados strain. Collectively, our results indicate that the Barbados strain is a distinct species fromB. hebetor. |
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Keywords: | Bracon hebetor Plodia interpunctella Heliothis virescens cryptic species biological control |
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