Criação e bioecologia de Atheloca subrufella (Hulst) (Lepidoptera : Phycitidae)

Abstract

Larvae of coconut moth, Atheloca subrufella (Hulst) (Lep.: Phycitidae), damage flowers and fruits of coconut, Cocos nucifera L., resulting in direct yield reduction. Thus, this work had three major objectives: to develop a feasible rearing methodology for all stages of this pest; to study the biology of A. subrufella reared at 18, 22, 25, 28, 30 and 32ºC and; to investigate the success of A. subrufella larvae colonizing coconut fruits related with the necrosis caused by the coconut mite, Aceria guerreronis Keifer (Acari: Eryophyidae). The rearing technique consisted of using green coconut fruits 10-12 cm of diameter and infested artificially with two to five larvae per fruit. Based on fertility life table parameters estimated for three successive generations, the best results were obtained with two and three A. subrufella larvae reared per fruit. The storage of egg and pupal stages at 12oC can be made upto five days without negative effect on egg viability and adult reproductive output, but storage periods over 10 days affected egg viability and adults’ performance. Developmental period of A. subrufella was reduced as temperature increases and marked effects were found at extreme temperatures of 18 and 32oC. The egg-adult period ranged from 19.3 to 59.8 days from 32ºC to 18ºC, respectively. Developmental viability from egg to adult was 25% at 18 and 32oC, and over 72% at the intermediate temperatures. The lower temperature threshold and thermal requirement for egg-adult period were 12.54oC and 362.75 degree-days, respectively. Basedon thermal requirement, A. subrufella can have 13 generations per year in the Zona da Mata and Sertão areas of Pernambuco State, Brazil. Data from field survey showed that only coconut fruits exhibiting necrosis caused by the coconut mite were infested with A. subrufella larvae. Moths of A. subrufella, however, exhibited similar oviposition preference on damage and undamaged coconut fruits. Neonate larvae and third instar larvae were not able to colonize undamaged coconut fruits. These results support the hypothesis that the necrosis in the coconut fruit caused by early infestation of the coconut mite is a key factor to A. subrufella larvae to colonize the mesocarp of the fruit protected by the fruit perianth. Therefore, the status of coconut fruit key pest of A. subrufella depends on fruit necrosis caused by the coconut mite.