Response of Tuta absoluta to endophytic fungal entomopathogens in tomato.

Abstract

Tuta absoluta is a leaf miner pest devastating tomato production. Use of broadspectrum pesticides to control this pest leads to the development of insecticide resistance, food contamination, poor health and environmental pollution. Recent knowledge of entomopathogenic fungi colonizing plants and, thus, antagonizing insect pests and plant diseases, sparked appreciable enthusiasm in using these capabilities. Therefore, this study aimed to assess the abilities of entomopathogens to endophytically colonize tomato plants, and to determine the ability of fungal species to modulate the behavior of T. absoluta. The two inoculation procedures (seed treatment and direct injection) allowed Metarhizium anisopliae and Beauveria bassiana strains to endophytically colonize tomato plants and thus have influenced the preference of T. absoluta oviposition. In Beauveria- and Metarhizium-colonized leaf mesophyll, damage by T. absoluta was significantly lower compared to control plants. This was attributed to the reduced number of eggs (7-8 plant-1 ) on fungus-colonized plants as opposed to 19 plant-1 on control plants in seed-treated assay. Reduced size of mines in Beauveria-injected plants has also contributed to the decrease in damage area by leaf miner larvae. The outcomes of this study suggest that seed inoculation is an effective method to be adopted by plant nurseries for commercial production of pre-colonised with entomopathogenic endophytes tomato plantlets.