Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/1998
Publication Date: N/A
Interpretive Summary: Fruit flies both destroy crops and, because of quarantines, hinder trade and economic growth throughout the tropics and subtropics. There is an increasing interest in discovering and preserving, or even cultivating, the natural enemies of pest fruit flies in the USA and elsewhere. However, very little is known about the predators, ants, beetles and other insects, of fruit flies; where they hunt and rest, what prey species they prefer, and how much they influence fruit fly numbers. Entomologists from the USDA- ARS in collaboration with Mexican colleagues studied where fruit fly larvae hide themselves in the soil to avoid predators while they complete development. At the same time fruit fly pupae were placed at various depths at sites with different soils and types of vegetation. In this paper they determined how effective predators were at destroying fruit flies under these different conditions and identified the natural enemies that inhabit the various sites. It is hoped that such knowledge will help create cultivation practices that encourage fruit fly predators to suppress pest populations.
Technical Abstract: In central Veracruz State, Mexico, tephritid fruit fly pupae are commonly attacked by ants, staphylinid beetles and other predators. It was found through excavations in 2 sites with different soil characteristics that Anastrepha spp. (Diptera: Tephritidae) larvae typically burrowed no more than 2 cm before pupating and rarely burrowed more than 5 cm. At 4 field sites pupae of the most commonly encountered local Anastrepha sp. (A. obliqua, ludens, and striata or fraterculus) were placed on the soil surface and at depths of 2.5 cm and 5 cm and were subsequently sampled daily for 10 days. Pupae on the surface invariably disappeared at a greater rate than those under the surface. There was no difference in the disappearance rate of pupae buried at 2.5 and 5 cm, suggesting that larvae would gain no benefit in terms of safety from predation by pupating at depths greater than those typically discovered during excavations of naturally buried pupae. The intensity of predation on the buried pupae differed considerably among the sites. At the end of the sampling period the proportion of pupae remaining ranged from 15-70%. The predators present and soil characteristics may have contributed to these differences. Predation was highest in a site with dry loose soil. It was lowest in sites with damp clay soils characterized by fine particle size and small inter-particle spaces.