Selectivity of Entomopathogenic Fungi to Chrysoperla externa (Neuroptera: Chrysopidae)

SIMPLE SUMMARY: Agricultural crop systems have adopted integrated management as a model of success in pest control; however, chemical control is still prioritized. The use of pesticides incorrectly and excessively has provided a reduction in natural enemies, selection of resistant populations and resurgence of pests. Chrysoperla externa is a predator found in several regions in Brazil that preys on different pest insects. Entomopathogenic fungi Beauveria and Metarhizium also stand out for causing epizootics on pests. Both predators and entomopathogens can simultaneously act as pest control; thus, verifying the selectivity of entomopathogenic fungi to predators increases the potential for biological control through synergism and conservation of natural enemies in the agroecosystem. Considering the control potential of these different biological control agents, in this study we evaluated the selectivity of Beauveria bassiana, Metarhizium anisopliae and Metarhizium rileyi to the larvae of this predator. The results provide evidence that the biological development of larvae of C. externa is not influenced by the entomopathogenic fungus. These species of fungi can be recommended, aiming at a management of populations of arthropod pests, with low effect on C. externa when it is present in the agrosystem. ABSTRACT: We aimed to evaluate the selectivity of entomopathogenic fungi to larvae of Chrysoperla externa (Neuroptera: Chrysopidae). For this purpose, Beauveria bassiana (strain ESALQ PL63), Metarhizium anisopliae (strain ESALQ E9) and Metarhizium rileyi (strain UFMS 03) were assessed at different concentrations (1 × 10(7), 1 × 10(8) and 1 × 10(9) conidia mL(−1)). The control treatment consisted of distilled water and Tween80 0.01. The treatments were applied with a Potter spray tower using two different methodologies: direct application (DA) and dry film (DF). Up to 96 h after application, no treatment provided a larval mortality above 3%. After 120 h, only B. bassiana induced significant mortality in all instars, with rates of 26%, 17% and 10% for first, second and third instar larval periods, respectively. There was no difference regarding to the application method or concentration of conidia. The percentage of individuals that revealed changes in the length of the larval and pupal periods varied among different treatments with entomopathogenic fungi and control treatments, application methodologies and concentrations. Despite B. bassiana revealing a higher mortality than M. anisopliae and M. rileyi on larvae of C. externa, these three entomopathogenic fungi may be used in association with C. externa for sustainable pest management.