Integration of Weeds Into Pest Management in Alfalfa Agroecosystems

Abstract

Weeds are often major limiting factors in crop production and they are eliminated through various control measures in modern agricultural systems. However, weeds can increase diversity and contribute to the stability of agroecosystems. They can also modify pest incidences by providing alternative hosts for pests and food sources, shelter and habitat for natural enemies. Because of their ecological aspects, weeds, when managed properly, could play an important role in pest management in organic farming systems. In this study, we assessed the effects of weeds on the incidences of alfalfa weevil, Hypera variabilis Hbst. (Coleoptera: Curculionidae), arthropod predators and forage yield in replicated weedy and weed-free plots in 1998 and 1999. The pest populations were sampled throughout the season using a sweep-net. Yield data were obtained using a I m(2) quadrate. The results showed that the weevil numbers were 20% higher in the weed-free plots than in the weedy plots in 1998. Arthropod predators were more abundant in the weedy plots. Forage yield was 14% and 16% higher in the weed-free plots than in the weedy plots in 1998 and 1999, respectively.