Comparison of two laboratory cultures of Psyttalia concolor (Hymenoptera: Braconidae), as a parasitoid of the olive fruit fly

Life-history trials were conducted in the laboratory on two cultures of Psyttalia concolor (Szépligeti) (Hymenoptera: Braconidae) reared on olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae). The tested cultures (A and B) had similar histories except that Culture A was maintained in Kenya for four years. Results showed that parasitoids from both cultures preferentially searched on olive fruit containing 8 to 10-day-old (second and third instar) olive flies, and reproduced most successfully when third-instar fly larvae were available. The mean longevity of adult female P. concolor was a negative function of temperature. Females from Culture B lived significantly longer at 15, 22, 25, and 32 °C than females from Culture A. For both cultures, adult female longevity was significantly longer when the parasitoids were provided with honey than when provided water alone, or nothing; the presence of hosts significantly reduced longevity, suggesting an energetic cost for reproduction. The parasitoids produced an average of 28.7 ± 4.1 and 22.2 ± 5.1 offspring per female in Cultures A and B, respectively. The results are discussed with respect to use of biological control agents held under different rearing conditions, and the potential of P. concolor for use as a biological control agent for olive fruit fly in California.