Aspectos da bioecologia de Chrysomya albiceps (Wiedemann, 1819) (Diptera, Calliphoridae), em condições de laboratório

Abstract

The objective of this experiment was to know the major biological aspects of Chrysomya albiceps (Wiedemann) (Diptera, Calliphoridae) such as: The pos-embrionary development; the reproductive capacity and longivity of grouped or isolated couples and groups of virgin females; verification of the sex rate of offspring from females individualized after mating; estimate the days and time of preference of oviposition of isolated females and determination of the minimal temperature (base temperature) and the termic constant for the varions stages of pos-embrionary development of thls species under laboratory conditions. The colony of Chrysomya albiceps (Wiedemann) was established from larvae and adults colected in the Estação para Pesquisa Parasitológica W. O. Neitz area at UFRRJ and Seropedica District, Itaguaí, RJ. The biological aspects of this species were studied in climatized chambers regulated at 60 ± 10% relative humidity. The temperature and photophase conditions were conditioned to according to each experiment needs. The length and viability of larval and pupal stages of C. albiceps was 5,2 and 4,53 days; 95,75% and 94%, respectively. An effect of group was observed on the larvae at the first and second instar. The average weight of mature larvae was around 75 mg, varying from 12,2 to 120 mg. Only mature larvae wilh average weight higher than 42 mg have originated adults. The time of the developement from egg to pupa (isolated postures) was 6 days. The weight of mature larvae which originated males and females differed strongly (68,86 and 81,86, respectively). The emergence of males and females (isolated postures) occurred in the same day, 73% and 40% of males and females emerged in the morning and 27% and 60% of males and females emerged in the afternoon, correnpondingly. The sex ratio per generation was 0,5 and sex rate per female was 1,0. The ovoposition of grouped (clumped) pairs initiated on the fifth day pos-emergence, with a peak at 6th day (0,045g of mass of eggs/female, equivaling to 409 eggs and 391 larvae). The oviposition peak ocurred at 16th day, with 0,0265g of mass of eggs/30 females, with all infertile eggs. The egg production was highly inferior to whose observed on clumped pairs. Although, on isolated pairs, three gonodotrophic cycles were observed where the first cycle was more expressive with 65% of females ovoposinting, second cycle with 22,5% and the third cycle with 5%. Grouped pairs survived less than isolated pairs and the last, survived less than virgin females. This, probably, ocurred due an excessive energy use at sexual activities. The prefered time on the ovoposition corresponded to that the escotophase. The duration and the viability of the larval stage of C. albiceps under temperatures of 18; 22; 27 and 32°C were of 21,30; 10,61; 5,0 and 4,0 days and 76,5; 88,5; 98,5 and 99,5%, respectively; the weight of the mature larval at these temperatures were 45,16; 81,86; 84,35 e 70,53 mg, respectively. xxi The duration and the viability of the pupal stage under temperatures of 22, 27 and 32°C were of 9,36; 4,7 and 3,0 days and 98,8; 100 and 100%, respectively. The minimal temperature for the larvae stage, the pupal stage and the larvae/adult period were of 15,04; 17,39 and 15,38°C which corresponded to 65,67; 44,15 and 114,23 GD.