Populational dynamics and effects of environmental temperature and rainfall on Astylus variegatus (Germar, 1824) and A. sexmaculatus (Perty, 1830) (Coleoptera; Dasytidae)

Abstract

Populational dynamics and effects of rainfall, maximum, minimum and average temperature on the movimentation of adults of A. variegatus, A. sexmaculatus were determined in Maria da Fé-MG, Brazil, during 1986. These species, mainly the first one, have become important as agricultural pests due to the damage caused by their larvae on seeds before germination. Since they were very attracted by the bright yellow collor Moericke traps were used for monitoring adult populations. The first insects were trapped on late January or early february and the populations increased very fast. Because they are polenofagous the infestation could be related to the flowering of corn planted in this place in rotation with potatoes. A small populational peak was observed in the first week of march and the acme occurred about seven days later when 886 adults of A. variegatus and 240 A. sexmaculatus were captured per trap during one week. Then the populations decreased and no more adults were observed after june. The study of Linear Multiple Regression between the climatic factors and the number of insects trapped showed that the maximum temperature was the variable more related to the movimentation of adults of both studied species.