Beauveria bassiana e acaricidas sintéticos avaliados em condições in vitro recomendados para a cultura do mamoeiro no controle de tetranychus urtcae koch

Abstract

The spider mite, Tetranychus urticae Koch, is considered one of the main pests of fruit in Brazil, among them, the Carica papaya culture has been heavily damaged by this arthropod. In papaya production are numerous challenges to the control of this pest. This work was prepared to contribute to the development of T. urticae management programs in papaya crop, with the following objectives: a) insulations prospect of dying insects fungal strains of Beauveria bassiana, aiming its use in the control of T. urticae; b) evaluate the efficiency in mortality of T. urticae in the egg, larva and protonymph in vitro when contaminated with fenpropathrin (0.5 g / L), abamectin (0.6 g / L), Milbemectin (0, 3 g / L), lime sulfur (7.0 g / L), three isolates of B. bassiana and distilled water control. In the 1st stage of the work was obtained 10 strains of B. bassiana, reisolated of dying insects found in high backlands of Paraiba, which are kept in culture media in UFCG. Of these, three (P21CZ, P22CZ and P29CZ), analyzing the results obtained in vitro, can be attributed to those with the highest germination potential for use in vitro bioenaios, in view of the control of T. urticae, and They were sent to the Selectivity of Laboratory Chemicals, UFERSA. In the 2nd stage of the work, to start bioassays fertilized females of T. urticae for sheet Canavallia ensiformis discs were transferred. When the mites reached in each bioassay, the desired stage, egg, larva or protonymph prefaced the bioassay. Each disc was sprayed with the treatments contaminated by manually pressurized spray then left for a period of 1 hour for drying, removing excess waste. Soon after drying were transferred to air-conditioned BOD chambers, where they were kept under controlled temperature conditions of 25 ± 1 ° C, photoperiod 12 hours and relative humidity of 60 ± 10%, to obtain biological data. The parameters evaluated were: duration and mortality of eggs, larvae, and protonymphs deutonymphs. The results of the three bioassays were subjected to analysis of variance and the means compared by Tukey test at 5% probability. Although the contaminated phase in the three bioassays have not been affected, there was cumulative mortality in the subsequent phases. The fenpropathrin insecticide caused 100% mortality in bioassays with egg and larva stage. The fenpropathrin chemical acaricides, milbemectin and abamectin were more efficient in all three bioassays with average values similar mortality. For directly treated larvae the abamectin, caused longer-term contact of the larvae. The isolated B. bassiana P22CZ, the concentration (2.5 x 106), had the highest mortality rate 63.8%. We observed a positive relation between increased exposure time of the mites to concentrations of isolated P29CZ and the highest concentration applied. The percentage of cumulative mortality by lime sulfur in the three bioassays, egg, larva and protonymph were low, with values of 8.8%, 7.5% and 25%.