Feeding preference of the larvae of Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae) and Ravinia belforti (Prado e Fonseca) (Diptera: Sarcophagidae) concerning different diets.

tion, two with the 4th, three with the 5th, and one with the 6th generation). The tests were done in a 15cm diameter Petri dish containing a layer of 1cm of pure agar (2g for 20ml of water) so the larvae could move. Nine 2cm circular holes, were opened in the agar eight being equally distant from the central hole (Fig.). We dropped melted agar in the newly opened holes, which after getting cold, formed a thin layer that sealed the space between the glass and the agar. Thus, preventing the larvae from escaping from the hole under the agar layer. In the four holes indicated by letter “A” (Fig.) were placed the diets to be tested (mashed fish, minced meat with 24 hr of environmental exposure, recent human faeces and mashed aged banana). The holes “B” remained empty and in the central hole designated as “C” recently hatched larvae were placed. For each test a newly prepared Petri dish was used. The testing dishes with the larvae of C. megacephala and R. belforti were kept in a chamber with temperature of 27oC, 80±10% UR, for a period of 6 hr. Afterwards, the larvae were counted in each hole containing the diets. The experiments were carried out from May to October 1993. The results obtained were statistically analyzed through the adherence test of χ2 at 1% probability. The Table shows that 69% of the larvae of C. megacephala and 47% of the R. belforti were found in the holes containing mashed fish, indicating that this particular diet is highly attractant to the larvae of these flies. It has been demonstrated that adult flies of C. megacephala are attracted to fish. It has been proved not only by faunistic surveys (AX Linhares 1981 Rev Bras Entomol 25: 189-215, JM d’Almeida, HS Lopes 1983 Arq Univ Fed Rur Rio de J 6: 38-48), but also in studies about the preference for ovipositional substrates. In addition, meat is an attractive diet for the C. megacephala larvae but less attractive than fish (Table ). The larvae of C. megacephala were not attracted to faeces or banana (1.2% and 0.5 % respectively). When these diets were used as baits to attract flies and as ovipositional substrates, they proved to be ineffective (d’Almeida, Lopes 1983 loc. cit., JM d’Almeida 1988 Mem Inst Oswaldo Cruz 83: 201-206). Nevertheless, KR Norris 1965 (Ann Rev Entomol 10: 47-68) reports that faeces is a good environment for rearing C. megacephala. The Sarcophagidae R. belforti, is frequently bred in human and animal faeces (JM d’Almeida 1989 Mem Inst Oswaldo Cruz 84: 257-264, HS RESEARCH NOTE