Weeds sometimes play an important role in pest management systems and when specific weeds are not present, biological control of certain insects is often impossible. Weeds serve as food sources for alternative hosts of insect predators and parasites or for the parasites themselves. The implications of these relationships for weed and insect control and for crop production are in need of further investigation. (Source)
Weeds are major components of agro-ecosystems and they affect the biology of pests and beneficial insects in several ways; provision of flowers, presence of neutral insects, modification of crop microclimate, production of chemical stimulus, alteration of colonisation background, etc. (Source)
Certain weeds, can be regarded as important components of agroecosystems, which can complement existing insect pest management systems. Outbreaks of some insect pests are more likely to occur in weed-free than in weed-diversified crop systems. Moreover, crop fields with a dense weed cover and high diversity usually have more beneficial insects than do weed-free fields. Plants commonly considered weeds in many situations are considered desirable wild plants in this case. (Source)
Article: ResourceHome1 (permalink) Date: 24 January 2013; 8:54:11 PM AEDT