Date of this Version
Beckers, Martin & Wagner in Journal of the Kansas Entomological Society (2011) 84(3).
The tachinid fly, Ormia ochracea Bigot 1889, is a major parasitoid of field crickets in North America. The fly ranges from Florida to California, and it has also been introduced to Hawaii. Across this range, O. ochracea uses at least 6 different Gryllus species as hosts for its larvae (Cade, 1975; Walker, 1986; Walker and Wineriter, 1991; Zuk et al., 1993; Wagner, 1996; Hedrick and Kortet, 2006). O. ochracea finds it hosts by eavesdropping on male mating songs (Cade, 1975). The fly deposits up to 3 planidial larvae (Adamo et al., 1995a) directly on the male and these larvae burrow into the cricket to continue development. After 7– 10 days, the larvae emerge from the host and kill it during this process (Adamo et al., 1995b). Interestingly, the fly also deposits approximately 6 planidial larvae (Adamo et al., 1995a) on the ground around the male cricket. These larvae wave their heads while standing on the ground (Cade, 1975) and snap forward with their anterior end when touched (pers. obs.), suggesting that they wait for a host to pass by to cling onto rather than actively searching for a host (Allen et al., 1999). Possible hosts targeted by these larvae could be the singing male, passing males, females approaching the singing male for mating (Martin and Wagner, 2010), or even juvenile crickets (Vincent and Bertram, 2009a). In contrast to the planidia deposited directly on the cricket, the potential of incidental infestations by the surrounding larvae is poorly understood. We measured the survival of planidial larvae of O. ochracea in a dry and a damp environment to estimate how long the larvae survive and pose a potential threat to passing crickets.