Crotolária é agente indireto no controle de Aedes aegypti (Diptera: Culicidae)?

Abstract

Aedes aegypti Linnaeus, 1762 (Diptera: Culicidae) is native species from African continent and currently has a wide geographical distribution. In Brazil, this species found favorable conditions to reproduce, forming large populations. Aedes aegypti adult feed on floral nectar and fruit juice, the blood repast made by females for the maturation of eggs. In the blood repast the females are able to transmit, besides the dengue, other arboviruses like chikungunya, zika and yellow fever. According to empirical knowledge, crotalaria plants attract dragonflies, the main natural predator of A. aegypti. Therefore, this study aimed to verify if Crotalaria spectabilis is a food source for A. aegypti, attracting its predators, especially dragonflies. This study was carried out in two areas of 100 m2 with monoculture of C. spectabilis in municipality of Missal, PR. To verify if A. aegypti visit C. spectabilis flowers, observations were performed in 10 newly opened flowers during two consecutive days in each area. These observations were carried out from 7:00 to 14:00 h, five minutes per hour in each flower. Captures active using entomological net were realized during a day in each area, from 8 to 15 hours, 10 minutes per hour. Representatives of one individual from each species of all arthropods collected were transfixed mounted on pins and identified at the family level. In order to analyze the number of dragonflies that foraged the C. spectabilis plants, the individuals were counted in 10 minutes sessions per hour from 11:00 to 15:00 h during three days in each area. In total, 14,985 arthropods were collected foraging on C. spectabilis (306 in area 1 and 14,679 in area 2) belonging to 10 orders and 41 distinct families. No A. aegypti individuals were observed visiting C. spectabilis flowers. 22 dragonflies were recorded in area 2 foraging on the evaluated culture. These results show that C. spectabilis is a food source and a local search for prey for arthropods. However, there was no relationship between the cultivation of this plant and the biological control of A. aegypti.