Efficacy of Steinernematid Nematodes (Rhabditida: Steinernematidae) on the Suppression of Anastrepha ludens (Diptera: Tephritidae) Larvae in Soil of Differing Textures: Laboratory and Field Tria

摘要

The efficacy of the entomopathogenic nematodes, Steinernema carpocapsae (Weiser 1955} All strain and S. riobrave (Cabanillas, Poinar & Raulston), against last instar of Anastrepha ludens (Loew) was determined in different soil types. Larvae were exposed to entomopathogenic nematodes in sandy loam, loam, and clay texture soils. Higher rates of larval mortality were observed in sandy loam and loam than in clay. S. carpocapsae showed LC~(50) values of 35.15 and 18.32 infective juveniles (IJs)/cm~2 in sandy loam and loam soils, respectively. The nematode S. riobrave showed LC_(50) values of 14.55 and 10.31 Us/ cm~2 in sandy loam and loam, respectively. In field conditions of sandy loam soil, S. carpocapsae reduced adult emergence by 64%, whereas S. riobrave reduced adult emergence by only 14% compared with the control using the higher IJ concentration. These results suggest that soil type is a critical factor that must be taken into account when selecting the nematode species and planning fruit fly biological control strategies.