Potencial de fungos entomopatogênicos comerciais para o controle de Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae)

Abstract

Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) known as lesser mealworm is the main insect-plague of poultry houses. It causes nutritional losses, sanitary conditions, discomfort to birds and structural damage to production units. The objective of this study was to evaluate the potential of the entomopathogenic fungi Beauveria bassiana (IBCB 66 and Bb2), Metarhizium anisopliae (IBCB 425 and Ma2) and Isaria fumosorosea (If1) in different application methodologies on larvae and adults of A. diaperinus under conditions laboratory and semi-field. In the laboratory, the treatments consisted in the application of 1 mL of the suspensions of the isolates of entomopathogenic fungi (1 × 109 conidia.mL-1). Sterilized distilled water, distilled water sterilized with Tween® (0.01%) and chemical insecticide (cypermethrin+chlorpyrifos+piperonilabutoxide) were used as controls. Bioassay 1) The pathogenicity of the isolates was evaluated on larvae and adults of A. diaperinus and; Bioassay 2) the most promising isolates were incorporated into the poultry feed. The insects were transferred to the experimental units (UEs), being Petri dishes (Ø15 cm) for adults, and acrylic plates with 12 wells (Ø1 cm per well) for larvae, these were allocated in an incubator incubator (27 ± 2 ° C, RH 70 ± 10% and photoperiod of 14h). Each treatment consisted of eight replicates, with 12 larvae and 12 adults per replicate. In semi-field, the treatments that were promising were adopted in Bioassay 1 of the laboratory. As controls, the same ones used in laboratory bioassays were used. Bioassay 1) the application of 1.2 ml of the treatments on the surface of the contact UEs of the insects was tested; Bioassay 2) the incorporation of 10 mL of the treatments in medium to the litter. The UEs consisted of organizer boxes, translucent, with 19L of volume, supplied with 0.003 m3 of litter. These were allocated in an air conditioned room under conditions 27 ± 2 ° C, U.R. 70 ± 10% and photoperiod of 14h. Each treatment consisted of five replicates, with 20 larvae and 20 adults per replicate. The evaluations were performed after 10 days, for laboratory, and with seven and 10 days, for semi-field. The variable-response is mortality. In laboratory, in Bioassay 1, isolates BC2, IBCB 425 and IF1 were pathogenic to larvae of A. diaperinus, causing 40; 52.8 and 33.5% mortality, respectively. For adults, only IBCB 425 isolate was pathogenic, causing a 38.3% mortality. For both Laboratory Bioassay 2 and semi-field bioassays 1 and 2, these were considered to be non-significant. Although three isolates of entomopathogenic fungi (Bb2, IBCB 425 and If1) showed pathogenicity on larvae and adults of A. diaperinus, their virulence was considered low. Thus, it is suggested new studies with different isolates of the species used, as well as other fungi species in order to find an efficient isolate for the biological control of A. diaperinus.