Efficiency of Heterorhabditis Bacteriophora (Nematoda: Heterorhabditidae) on Anastrepha Serpentina Diptera: Tephritidae) Larvae Under Laboratory Conditions (Report‪)‬

The sapote fruit fly, Anastrepha serpentina (Wiedemann), sometimes called the tropical fruit fly, is an important species in Mexico because its larvae infest sapote (Calocarpum spp.), mammee [Pouteria sapota (Jacq.) Moore & Stearn], sapodilla (Achras zapota L.), willowleaf lucuma (Lucuma salicifolia Hbk.) and related fruits (Aluja 1994). Infestations in tree-ripe fruits frequently are so high that in parts of the country where these fruits are grown, especially in Veracruz, the growers do not allow them to mature on the trees, but pick them green and ripen them artificially to avoid infestation. Mammee tree is native to Central America and southern Mexico and it is becoming important as an exotic fruit in international commerce. For this reason, the sapote fruit fly is part of the pest management program of the National Campaign Against Fruit Flies (CNCMF, after its Spanish acronym) (Reyes et al. 2000). Unfortunately, its control is mostly based on the use of chemical insecticides, applied either on the foliage to control adults or on the soil to control larvae or newly emerged adults. Consequently, new control alternatives are being explored, such as natural products and biological control agents, which may at least partially substitute for the chemical insecticides. This is an important strategy due to the growing interest in organic agriculture. The entomopathogenic nematode Heterorhabditis bacteriophora (Poinar) is a natural soil dweller that parasitizes a number of insect species. Infection occurs through the insect's natural apertures such as the mouth, spiracles, or anus (Woodring & Kaya 1988). Once in the host hemocoel, the nematode releases its symbiotic bacterium Photorhabdus spp., which causes a rapid and lethal septicemia. This allows the growth and reproduction of the nematode for one or more generations. Due to its lethal efficiency, H. bacteriophora may become an important regulation factor for several insect populations whose larvae co-exist within the soil. This includes several species of fruit fly larvae (Tephritidae) whose susceptibility to nematode infection has been demonstrated previously (Beavers & Calkins 1984; Lindegren & Vail 1986; Lindegren et al. 1990; Lezama-Gutierrez et al. 1996; Gazit et al. 2000; Toledo et al. 2001, 2005, 2006). In this report we present evidence on the infectivity of H. bacteriophora to third instars of A. serpentina under laboratory conditions.