Reproductive Isolation and Genetic Variation between Two “Strains” ofBracon hebetor(Hymenoptera: Braconidae)

• Published in: Biological control Vol. 9; no. 3; pp. 149 - 156
• Main Authors: Heimpel, George E., Antolin, Michael F., Franqui, Rosa A., Strand, Michael R.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-07-1997
• Subjects: biological control; Bracon hebetor; cryptic species; Heliothis virescens; Plodia interpunctella; Heliothis virescens; biological control; Bracon hebetor; Plodia interpunctella; cryptic species
• ISSN: 1049-9644; 1090-2112
• DOI: 10.1006/bcon.1997.0529

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.