Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 6/1/1997
Publication Date: N/A
Interpretive Summary: Bollworm infestations in cotton often occur earlier or increase more rapidly than expected from local population cycles, and may be due to bollworm moth flight from distant regions. Information is needed to positively identify migrant moths, and to predict the distance and distribution of their flights from known habitats. Bollworm moths were self-marked in the Lower Rio Grande Valley of southern Texas and northeastern Mexico with: 1) distinctive citrus pollen while feeding on citrus nectar in February and March; and 2) distinctive clubmoss spores not present naturally in Texas that were mixed in a feeding attractant/ stimulant solution sprayed on mature corn in June. Marked moths were captured in traps throughout south-central Texas as far as 661 km from the nearest commercial citrus production area in February and March, and 230 km from the area treated with clubmoss spores in June. Forecasts based on estimated insect flight trajectories and local minimum air temperature accurately predicted numerous dates of capture of marked bollworms. Predictions of bollworm moth flight could be used to alert growers of probable infestations by bollworms from regions outside their local production areas. Further, these results support efforts to strategically manage bollworms within a large area rather than on single farms.
Technical Abstract: Research was undertaken to validate estimates of long-distance flights of adult male bollworm, Helicoverpa zea, using a network of pheromone traps in northeastern Mexico and south-central Texas. Captured bollworm moths were examined for external contamination of citrus pollen and internal contamination of Lycopodium clavatum spores. Moths contaminated with citrus pollen were captured throughout the network of pheromone traps as far as 661 km from the nearest location of commercial citrus production in the Lower Rio Grande Valley (LRGV) during February and March. Moths which consumed a feeding attractant/stimulant mixture with Lycopodium clavatum spores were captured as far as 230 km north of treated corn fields in the LRGV in June 1996. Estimated nightly insect flight trajectories from Weslaco (LRGV) and local minimum air temperatures were well correlated with capture events of citrus pollen-contaminated bollworms in February and march 1994 (chi-square=60.556; 3 df; P<0.0001). Results show that probabilities of capture events can be estimated for specific recipient locations, and suggest that the insect flight trajectory method can be applied to other dates and source areas. These findings strongly support a need to suppress dispersal of bollworm moths that jeopardizes the effectiveness of pest (and pest resistance) management on an areawide basis.