ABSTRACT
Interaction between Musca domestica L. and its predator Muscina stabulans (Fallén) (Diptera, Muscidae): Effects of prey density and food source abundance. The objective of this work was to evaluate the influence of prey density and food source abundance on the predatory behavior of Muscina stabulans over M. domestica. Three predator/prey proportions were evaluated (1:1, 1:3 and 1:6), using 100 third instar predator larvae against second instar prey larvae. Each proportion was maintained using three different levels of food substrate (25, 50 and 100 g). The experiments were carried out in triplicate in BOD incubators (25ºC, UR 70% ± 10% and 12 h photoperiod). The mortality of the M. domestica larvae was 100% under all conditions, except in the 1:6 predator/prey proportion, at the 50g and 100g food substrate levels, where it was 99.99% and 99.22%, respectively. There was a significant increase in the development period of M. stabulans in relation to the increase in prey density and decrease in quantity of food substrate. An increase in the proportion of individuals and a reduction in the amount of resource slowed down larval development. Muscina stabulans pupal weight was proportional to the increase in prey density and the amount of food substrate. The proportion or the density influenced the survival of M. stabulans, with no difference in relation to the amount of food source and consequently in the interaction of the factors. There was no difference between the 1:1 and 1:3 predator-prey densities, with both differing from the 1:6 density.
ABSTRACT
To evaluate the population fluctuation of Coleoptera from a poultry farm in Pelotas, Rio Grande do Sul, Brazil, two sampling methods were used: a tube-type trap and a sandwich trap. The analyses of polynomial regression were applied independent of the type of sampling method used. The experiment was carried out for twelve months, from April 2002 to March 2003, in a broiler barn aviary at the Conjunto Agrotécnico Visconde da Graça/UFPEL. A total of 43.945 Coleopterans were captured from the following species: Alphitobius diaperinus, Carcinops troglodytes, Euspilotus rubriculus, Gnathocerus cornutus, Mezium americanum and Somotrichus unifasciatus. Among these, Alphitobius diaperinus was present in all months of the year, with larval population peak in February (235) and lowest capture in August (01). The adult population peak was in March (12,020) and the lowest capture in July (27). The remaining captured Coleopterans did not occur in all twelve months, however they also had population peaks in the months of February and March, which also were the months with the highest temperatures.
Para avaliação da flutuação populacional de Coleoptera, em granja avícola, em Pelotas, Rio Grande do Sul, Brasil, foram utilizados dois métodos de coleta: armadilha do tipo tubo e do tipo sanduíche, durante doze meses. A análise de regressão polinomial foi aplicada independentemente do tipo de método de coleta utilizado. O experimento foi conduzido durante 12 meses, de abril de 2002 a março de 2003, em um aviário de aves poedeiras do Conjunto Agrotécnico Visconde da Graça da Universidade Federal de Pelotas (UFPEL). Foram capturados 43.945 Coleopteros das espécies Alphitobius diaperinus, Carcinops troglodytes, Euspilotus rubriculus, Gnathocerus cornutus, Mezium americanum e Somotrichus unifasciatus. Entre esses Coleopteros, Alphitobius diaperinus esteve presente em todos os meses do ano, com pico populacional de larvas em fevereiro (235) e menor índice de captura em agosto (01), sendo que o pico populacional de adultos foi em março (12.020) e o menor índice de captura ocorreu em julho (27). Os outros Coleopteros capturados não ocorreram durante os 12 meses de captura, porém, eles também tiveram pico populacional nos meses de fevereiro e março, que foram os de temperatura mais alta.