ChileanJAR

The biological control program of Sítobíon avenae Fab started in Chile in 1975, with the introduction of new species of Coccinelidae and Hymenoptera. From 1981, Aphidíus erví has been the maln parasitoid affecting S. avenae populations. During three years, the amount of embryons in S. avenae females was recorded and related with the presence or absence of parasitoids larvae, by dissection of specimens collected in the field. This study, stáblished evidence that the aphid's stage at parasitation was the direct cause of its reduction in numbers and of the aphid's mortality, before attainining its reproductive periodo