Natural enemy movement between adjacent sorghum and cotton fields

摘要

Major pests in commercial cotton affect both the quantity and quality of cotton yield. However, existing populations of natural enemies and a variety of chemicals are available to protect the cotton crop. Because neither natural nor chemical controls are acceptable as 'stand-alone' solutions, an integrated approach to pest control in cotton is needed. Using predator conservation as a foundation, better pest control may be realized by using grain sorghum as a source for natural enemies in cotton. There is some evidence to indicate that neighboring cotton fields alread receive some benefit from close association with grain sorghum, but the specifics of this relationship are not yet known. Using fluorescent dust markers, we further explored predator movement between cotton and grain sorghum. Results indicate that predators move between cotton and sorghum in both directions throughout cotton maturation, but that cotton receives more immigrant predators from sorghum than it loses by emigration. Further, the strength of predator migration changed with sorghum phenology, with the greatest benefit to cotton coming during the soft dough stage of sorghum growth. Correlating data on predator habitat in both crops with strength of migration indicated that predatory arthropods moved in response to low prey levels and high temperatures. Results indicate that adjacent plantings of grain sorghum can contribute to pest control in cotton, but that predator movement may be sensitive to synchrony of crop phenology and local environmental conditions.