Criação de Rhynchophorus palmarum (LINNAEUS, 1758) (COLEOPTERA: CURCULIONIDAE) em dietas artificiais e controle utilizando fungos entomopatogênicos

Abstract

Among the insect-pests that cause economic damage to the culture of coconut (Cocos nucifera L.), the giant palm weevil Rhynchophorus palmarum (Linnaeus, 1758) (Coleoptera: Curculionidae) stands out for damage in different stages of development of the plant. This study aimed to: study the qualitative and quantitative biological parameters of R. palmarum in two artificial diets; and verify their susceptibility to entomopathogenic fungi. At the egg stage, it was determined the incubation period (days) and fertility (%). For the larval stage was calculated total viability and the viability for instar (%), duration of larval instars and the total duration of the larval period (days), the width of the head capsule (mm) and weight (g) of the larvae in two diets (A and B). Was determined the duration of the phases of pre-pupae and pupae (day), weight (g), viability (%) and the occurrence of deformation (%) in the pupa. After the emergence of adult R. palmarum, we calculated the sex ratio and observed the percentage of defective adults (%), weight (g) and length (mm) of males and females of two diets. After the formation of the couples were certain periods of pre-oviposition, oviposition and post-oviposition (days), total and daily fertility, longevity of males and females (days), and duration of the cycle (days). The absorbance of samples was calculated from adult R. palmarum from the artificial diets. The experimental design was completely randomized and all variables of the two artificial diets were submitted to analysis of variance (ANOVA) and means compared by t-test at 5% significance level. In a second experiment, the effect of different concentrations (107, 108 and 109 conidia.mL-1) of isolates IBCB 66, CPATC 032 and CPATC 057 of Beauveria bassiana (Balsamo) Vuillemin, isolated T9 Trichoderma harzianum Rifai and commercial product Boveril® on adult R. palmarum. The data of confirmed mortality were submitted to analysis of variance (ANOVA) using the Proc ANOVA of SAS, and the means compared by Tukey test at 5% probability. To determine percentage survival, confirmed mortality data were subjected to Log-Rank test using the Kaplan-Meyer method. Subsequently the values of LC50 and LT50 were estimated submitting mortality confirmed the Probit analysis. The diet A promoted a more viable larvae and pupae of R. palmarum. The percentage of deformed pupae in the diet B was higher in relation to diet A. The period oviposition of females from the diet A was 32.4 days. Regarding the lipid content of R. palmarum the adult male diet B, have the highest mean absorbance, while females diet B showed lower values. The commercial product Boveril® and isolated IBCB 66, CPATC 032 and CPATC 057 caused the confirmed mortality of 40, 36, 64 and 52% of R. palmarum adults, respectively, for the concentration 109 conidia.mL-1 did not differ concentration of 108 conidia.mL-1, where the isolated CPATC 032 caused mortality of 52% of the insects, which in turn did not differ isolated CPATC 057, which showed 44% confirmed mortality of adults. The isolated CPATC 032 showed higher virulence and lower LC50, estimating it in 1,11x109 conidia.mL-1; while the LT50 in concentrations 108 and 109 conídios.mL-1 was 17.61 days and 17.25 days, respectively.