Efficacy of Native Iranian Entomopathogenic Nematodes Against Mediterranean Fruit Fly, Ceratitis capitata Wiedemann (Diptera: Tephritidae)

Abstract

The Mediterranean fruit fly, Ceratitis capitata, is a severe pest of orchards around the world and has recently invaded orchards in northern Iran. The soil-dwelling larvae of this pest are amenable to control by entomopathogenic nematodes (EPNs) but have been studied only in tropical orchards. To assess the biocontrol potential of Iranian strains of two EPN species, Heterorhabditis bacteriophora (boj) and Steinernema carpocapsae (z1), for control of C. capitata, we conducted a series of laboratory and a field experiment. the highly virulent nature of S. carpocapsae towards C. capitata larvae was apparent, demonstrating near 80% efficacy at a concentration of 25 infective juveniles (IJs) per cm² in loam soil, surpassing the 40% control exerted by H. bacteriophora. When tested at temperatures of 19, 25, and 30 °C, Steinernema carpocapsae caused the highest mortality at 25 °C (85%) and the lowest at 30 °C (58%), whereas control by H. bacteriophora was not affected by temperature (44–50%). Both EPN strains caused higher mortality in loam and clay loam soils than in sandy loam. Heterorhabditis bacteriophora produced significantly more IJ progeny from infected larvae than S. carpocapsae. Both S. carpocapsae and H. bacteriophora caused only moderate mortality of C. capitata pupae with 38 and 27%, respectively, at a rate of 50 IJs/cm². Under field conditions, both species caused significant mortality when sprayed at a concentration of 25 IJs/cm² on soil and tangerine fruits infested with C. capitata larvae, with 45 and 69% mortality for H. bacteriophora and S. carpocapsae, respectively. Our findings suggest that S. carpocapsae (z1) could be implemented as a biological agent in a C. capitata management program in temperate climate orchards.