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 × 107, 1 × 108 and 1 × 109 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.
ABSTRACT
The aim of the present study was to evaluate the interactions between Chrysoperla externa (Hagen, 1861) and the eggs and first-instar larvae of Helicoverpa armigera (Hübner 1805) infected by entomopathogenic fungi. The H. armigera eggs and larvae were treated with sterile distilled water + 0.01% Tween 80 (T1, control), Beauveria bassiana (Bals.) Vuill (T2), Metarhizium anisopliae (Metsch.) Sorok (T3), or Metarhizium rileyi (Farlow) Samson. (T4) at different concentrations (1 × 107, 1 × 108, and 1 × 109 con. mL-1). For each treatment, a single third-instar C. externa was offered prey (a combination of 80 eggs and 50 first-instar H. armigera larvae) at 0, 24, and 48 h after inoculation. Ten trials were completed for each treatment, and the entire experiment was repeated three times. Neither the concentrations of fungi nor the application method affected consumption by C. externa. Because all the predator larvae reached the pupal phase, with 100% viability in adults, these results suggest that entomopathogenic fungi and C. externa are compatible and that the simultaneous use of these biological control agents is possible for managing H. armigera.
