Eficiência da infectividade e mortalidade do fungo Beauveria Bassiana em adultos de Metamasius Hemipterus L. (Coleoptera Curculionidae).

Abstract

The species of the genus Metamasius (Coleoptera: Curculionidae) have a predominantly orange brown color with black spots and bands symmetrically distributed. Usually, males are smaller than females and found on all continents, mainly in the tropical region of the Americas. Considered a secondary pest, it is associated with several host plants such as sugar cane, banana, cotton, pineapple, among others. This insect pest has caused economic problems for sugar cane producers, limiting their productivity, quality of the raw material and percentage of sucrose. The indirect damages are caused by opening holes, which can serve as a gateway for phytopathogens and other opportunistic insects. In the absence of products registered for its control, one alternative is the use of entomopathogenic fungi such as Beauveria bassiana. The objective of this work was to determine different concentrations, to verify the most efficient and to evaluate the infectivity of the B. bassiana fungus in baits composed of sugar cane, green coconut shell, honey, conidia under laboratory conditions, in adults of Metamasius hemipterus L as a way to reduce the damages caused. The experiments were conducted under a temperature of 25 ± 1oC, 12 hours photo phase and 60 ± 10% relative humidity. For the efficiency test, 250mL plastic containers were used containing fragments of sugarcane treated in concentrations 1x106 and 1x108 con/mL and 5 adults of M. hemipterus and control sugarcane treated with distilled water plus Tween adhesive spreader 80 (0.01%). For infectivity, plastic containers containing vegetable sponges filled with 100g of the attractive and infectious compound (20 mL of distilled water containing 1x108 conidia and Tween 80 adhesive adhesive (0.001%)) and 5 adults of M. hemipterus and control with attractive compound added 20 mL of distilled water with Tween 80 adhesive spreader (0.01%). The fungus B. bassiana, when applied in the concentration of 1x108 con / mL, presented a statistically insignificant mortality, when compared to the lowest concentration 1x106 con / mL. Both concentrations showed efficiency in the mortality of M. hemipterus adults. For infectivity, the treatment using the fungus B. bassiana in the highest concentration, after 24 hours of exposure, was efficient in the mortality of adults of M. hemipterus. In view of the results, it can be concluded that the fungus B. bassiana presents itself as a promising agent for controlling this insect pest.