Effects of insect cadavers infected by Heterorhabditis bacteriophora and Steinernema diaprepesi on Meloidogyne incognita parasitism in pepper and summer squash plants

Abstract

E. E. Del Valle, P. Lax, J. Rondán Dueñas, and M. E. Doucet. 2013. Effects of insect cadavers infected by Heterorhabditis bacteriophora and Steinernema diaprepesi on Meloidogyne incognita parasitism in pepper and summer squash plants. The effects of insect cadavers infected with three isolates of Heterorhabditis bacteriophora and one isolate of Steinernema diaprepesi on a population of Meloidogyne incognita in pepper (Capsicum annuum) and summer squash (Cucurbita maxima) were evaluated in greenhouse experiments carried out in Santa Fe (Argentina). Insect cadavers were obtained for the experiments from last instar larvae of Galleria mellonella and Tenebrio molitor that had been infected with entomopathogenic nematodes. Two six-day-old insect cadavers per pot were placed below the soil surface, and the soil was inoculated with 100 second-stage juveniles of M. incognita. Sixty days after inoculation, the following parameters were recorded for each plant: number of leaves; dry weight of aerial parts; numbers of galls, egg masses and eggs; and numbers of galls, egg masses and eggs g -1 of root fresh matter. In pepper, the only variable affected by the infected cadavers with respect to control was the number of eggs in the treatment involving T. molitor cadavers infected with the H. bacteriophora isolate Rama Caída. In summer squash, several treatments using infected cadavers resulted in a decrease in the numbers of galls and egg masses. Only the treatment involving G. mellonella cadavers infected with the H. bacteriophora isolate Rama Caída proved to be efficient in reducing the number of M. incognita eggs. Our results indicated that the application of insect cadavers infected with the entomopathogenic nematodes studied might reduce M. incognita damage in pepper and summer squash plants.