The vegetational diversity favors biological control through the coexistence of generalist predators

Abstract

This study evaluated how the vegetation diversity affect the coexistence of generalist predators
and favors the biological control. An experiment was carried out in the laboratory, where the
larvae of the predators Cycloneda sanguinea and Chrysoperla externa were released together
or individually in kale plants infest with aphids and planted in monoculture or intercropped with
coriander. The predators in both cropping systems reduced the population growth of aphids,
especially in the intercrop. However, the predators interfered in the predation rate of each
other, due to differences in their foraging patterns. Chrysoperla externa acted as intraguild predator
of C. sanguinea, mainly when the density of aphids in the plants was low. The presence
of coriander, reduced the frequency of these negative interactions. The increase of vegetation
diversity enabled the coexistence of these generalist predators, because once it reduced the
negative interactions between them, favoring biological control.