Associations of Wheat with Pea Can Reduce Aphid Infestations

Increasing plant diversity within crops can be beneficial for pest control. In
this field study, the effects of two wheat and pea associations (mixed
cropping and strip cropping) on aphid populations were compared with
pure stands of both crops by observations on tillers and plants. Pea was
more susceptible to infestations than wheat. As expected, the density of
aphid colonies was significantly higher in pure stands during the main
occurrence periods, compared with associations. Additionally, flying beneficials,
such as not only aphidophagous adult ladybirds but also parasitoid,
hoverfly and lacewing species that feed on aphids at the larval stage,
were monitored using yellow pan traps. At specific times of the sampling
season, ladybirds and hoverflies were significantly more abundant in the
pure stand of pea and wheat, respectively, compared with associations.
Few parasitoids and lacewings were trapped. This study showed that increasing
plant diversity within crops by associating cultivated species can
reduce aphid infestations, since host plants are more difficult to locate.
However, additional methods are needed to attract more efficiently adult
beneficials into wheat and pea associations.