Ormia depleta: Laboratory maintenance, strain identification, and evaluation of Aphis nerii as a banker species.

摘要

Ormia depleta (Wiedemann) is a tachinid fly used in the biological control of Scapteriscus spp. mole crickets. Several changes to the current method of rearing O. depleta in the laboratory were attempted. Manipulations of temperature, humidity, and photoperiod during the pupal and adult stages showed that the percentage of gravid females was higher at 23°C than at 27°C and at 70% relative humidity than at 85%, but photoperiod did not have a significant effect. A diet of melezitose did not increase the fecundity of flies compared to a melezitose-free diet. Increasing the number of planidia used to inoculate host mole crickets increased the number of pupae produced, but reduced the survivability of those planidia and the mean weights of the pupae produced. Larger host mole crickets were also found to produce larger pupae. Acheta domesticus was tried as a factitious host and found to be unsuitable. Although pupae were produced, they were small and few in number. Dissections of hosts with developing larvae showed that the larvae in Acheta developed slowly and apparently had trouble emerging from the host. Identification of two Brazilian strains of O. depleta was performed by gas chromatographic analysis of cuticular hydrocarbons. The results indicated that, using the model used in this experiment, the strains could be identified with 80% confidence. An evaluation of the honeydew of Aphis nerii on its milkweed host indicated that it is an adequate carbohydrate source for O. depleta, but further study is needed in this area before any recommendations can be made.