Optimisation of the parasitism rate of <i>Diachasmimorpha longicaudata</i> (Hymenoptera: Braconidae) in <i>Ceratitis capitata</i> (Diptera: Tephritidae)

Fruit flies are the most serious problem in fruit production worldwide, causing severe losses in production and fruit quality. The use of parasitoids, especially <i>Diachasmimorpha longicaudata</i> (Ashmead) (Hymenoptera, Braconidae), is an important tool for suppressing the fruit fly population. The objectives of this study were to determine the exposure time, density, and ideal larval instar of <i>Ceratitis capitata</i> (Wiedemann) (Diptera: Tephritidae) and to verify whether the parasitoid's previous experience affects its interaction with the host insect and the influence of these factors on the parasitism rate. In three bioassays, fly larvae were placed in 'parasitism units' to test different methods of exposure to female parasitoids. The variables included the previous experience of the female parasitoid with oviposition, the exposure time (30, 60, 120, 240, and 480 min) of the larvae to the parasitoid and the number (5, 10, 15, and 20) and instar (second and third) of the fly larvae. The flies and parasitoids that emerged were quantified, and the parasitism rate and sex ratio of the parasitoids were calculated. The results of the present study indicate that to increase the parasitism rate of <i>D. longicaudata</i>, third-instar larvae of <i>C. capitata</i> must be grouped into parasitism units of 20 larvae and exposed to a single female of the parasitoid for 8 h.