The Augmentative Biological Control Component in the Mexican National Campaign Against Anastrepha spp. Fruit Flies

The Mexican Government launched the National Campaign Against Fruit Flies in 1992, in order to create free and low prevalence areas of native fruit flies of economical importance belonging to the genus Anastrepha Schiner. The campaign uses an area-wide integrated pest management approach that includes the use of environment-friendly strategies to suppress or eradicate fruit flies, such as the application of selective toxic baits, the use of the sterile insect technique (SIT), and the release of the endoparasitoid Diachasmimorpha longicaudata (Ashmead). Fifty million parasitized pupae, produced in the Moscafrut facility in the State of Chiapas, are sent weekly via commercial flights to several states of the country (i.e. Michoacán, Sinaloa, Nayarit and Aguascalientes), in accordance with a national technical plan. In these areas the parasitoid releases are made by air or from the ground, and focused on Anastrepha spp. host trees located in marginal areas (including backyard orchards), with the objective of preventing fruit fly populations from moving into commercial orchards. Release densities fluctuate between 1500- 2500 parasitoids per hectare, depending on the ecological complexity of the area. Apparently, the effect of the releases has been similar in control areas, showing high rates in the percentage of parasitism reached in Anastrepha species (e.g. 33.5-64.7% in the State of Nayarit), and notable reductions in the flies per trap per day indices (e.g. 39% in the State of Michoacán and 41% in the State of Sinaloa). These data show the impact that augmentative area-wide releases of parasitoids can have on fruit fly populations. By carrying out these actions in association with other control measures, the presence of fruit flies inside commercial orchards was greatly reduced, and consequently, their control made easier.

KEYWORDS augmentative biological control, parasitoids, fruit flies, Anastrepha ludens, Anastrepha obliqua, Anastrepha striata, Anastrepha serpentina, Diachasmimorpha longicaudata, Mexico, area-wide management, grower associations