Aspectos biológicos e comportamentais de Conotrachelus humeropictus Fiedler, 1940 (Coleoptera: Curculionidae) e avaliação da bioatividade de extratos botânicos

Abstract

The Brazilian fruit industry scenario has taken on a large scale among the various agrobusiness productive segments in Brazil, mainly due to new consumption habits in the search for a healthier life. The North Region has become an important pole in this scenario, with fruits with promising economic potential such as açaí, graviola and cupuaçu, among others. The fruit of cupuaçu stands out for its flavor being quite consumed locally and in several states of Brazil and abroad. One of the major problems of this plant is the cupuaçu fruit borer, Conotrachelus humeropictus Fiedler (1940), a curculionid that can cause total loss in production. This study aimed to evaluate the biological and behavioral aspects of the insect and to detect botanical extracts that can be used in its control. The larvae were measured and weighed to determine the number of instars. To describe the behavioral aspects, the adults were monitored by means of filming and the analyzed images. Ethanolic extracts were prepared by cold maceration. The bioassays were performed in the laboratory and the tests followed with applications of the extracts on contact surface and test with a choice of 1%, 5% and 10% (m / v). The period of fourth instar larvae pre-pupae lasted for six days. In the pupae phase, pupation preference occurred in the 10 to 15 cm soil layer and the mean period of this phase was 60 (±11,34) days for males and 63 (±9,65) days for females. In adult studies, 395 adult insects were observed from 680 instar larvae and 58.08% viability. The sex ratio was 0.51, with a ratio of 1: 1, of males and females. The mean longevity was 427 days. To determine the rhythm of activity, mating, oviposition, time of tanatosis and feeding preference of the insect. The adult specimens were observed by means of filming and the images were analyzed for the description of the behavioral aspects by means of an etogram. The period of greatest activity of C. humeropictus was during the night, from 18:00, mainly for exploration and hiking. The resting act was the most frequent during the photophase. Mating occurred without following a careful sequence, as with most curculionids. No oviposition activity was observed on any of the tested substrates at any time. Females of C. humeropictus remained longer in tanatus when compared to males, with maximum average of 7 min and 59 s while males have a maximum average of 2 min and 40 s. For food preference with different substrates there was predilection for sugarcane, for the other substrates, beet, carrot and banana, there was no significant difference. When evaluating the effect of plant extracts of four known botanical species with potential insecticide Piper aduncum L., Piper hispidum Sw., Derris rariflora Benth., and Azadirachta. indica A. Juss., popularly known as monkey pepper, jaborandi, timbó and nim, respectively. Ethanolic extracts were prepared. The bioassays were performed in the laboratory and the tests followed with applications of the extracts on contact surface, topical application and repellent with a choice of 1%, 5% and 10% (m / v). The species of piperaceae were not efficient as insecticides for C. humeropictus like A. indica A. Juss. and D. rariflora Benth. which presented positive results, with mortality rate superior than 50% for the concentration of 5% and 10% concentration after 48 hours.