We analyzed the life history characters related to rate of potential population growth for two genetically identical lines of Trichogramma kaykai Pinto and Stouthamer (Hymenoptera: Trichogrammatidae). These lines differed in that one was infected with parthenogenesis-inducing Wolbachia (W ), whereas the other was free of Wolbachia (W−) through antibiotic treatment. For both lines, the number of females emerging per day was the highest from eggs laid during the first 2 d of oviposition. Although adult longevity in W− was shorter than that in W , number of eggs reaching the prepupal stage, adult emergence, and female emergence were significantly higher for W− than for W . There were no significant differences in the number of mature ovarian eggs at emergence between W− and W . The values of mean length of generation (T) in W was similar to that in W−, but the values of net reproduction rate (R0) and intrinsic rate of natural increase (rm) in W were lower than those in W−. In most field populations, the W individuals form a small percentage (<5%) of the total population. The relative low growth rate caused by the Wolbachia infection may contribute to this low prevalence of the infection. Because differences in the relative population growth rates would soon result in the extinction of the infected population in the field, other factors must play a role in allowing the infection to maintain itself in the field.
Annals of the Entomological Society of America
Vol. 97 • No. 4
Vol. 97 • No. 4
life history characters
population growth rate