Maintenance of non-crop plants in pepper crops is not sufficient to favor soil-borne entomopathogenic fungi

The main focus of conservation biological control strategies are on the populations of predators and parasitoids, but entomopathogenic fungi also require favorable environmental conditions for the conservation of their propagules and for their establishment in the soil of agroecosystems. Although non-crop plants provide favorable conditions for beneficial arthropods, little is know about the influence of these plants in the establishment of entomopathogenic fungi, which are known as natural enemies of insects. The objective of this study was to evaluate the effect of non-crop vegetation on the virulence, abundance and occurrence of entomopathogenic fungi in the soil of chili pepper crops. Soil was sampled in three areas, each one containing two chili pepper plots in different treatments: (1) chili pepper monoculture and (2) chili pepper crop whit non-crop plants strips between the lines and in the edges of the plots. Soil samples were collected at 20 sites selected in each plot at a depth of 20 cm, with a soil core sampler. The samples were individually placed in plastic bags and in laboratory were divided into 200 ml plastic vials. Subsequently, in each vial were added four Tenebrio molitor L. (Coleoptera: Tenebrionidae) larvae as "live-baits" for entomopathogenic fungi in soil. Larval mortality was evaluated every 48 hours. In two sampled areas T. molitor larvae in contact with the soil of the areas with non-crop plants had shorter survival than the larvae in contact with the soil from chili pepper monoculture. The occurrence of entomopathogenic fungi was higher in soil samples from chili pepper crops with non-crop plants. The most frequent fungi were Metarhizium sp. and Fusarium sp. with very low occurrence of Beauveria sp. This research indicates that the maintenance of non-crop plants into the agroecosystems as single strategy is not sufficient to benefit the community of entomopathogenic fungi in cultivated soils.

Key-words: conservation biological control, entomopathogens, ecosystem services