LINKS BETWEEN RETURN MIGRATION OF CROP PEST INSECTS AND BAT FORAGING BEHAVIORS AND BODY CONDITION
2013 Annual Report
1a.Objectives (from AD-416):
To quantify the timing and abundance of the late-season arrival of migrant crop pest insects, and their impact on foraging behaviors and body condition of Brazilian free-tailed bats.
1b.Approach (from AD-416):
Several species of crop pest insects (corn earworm, fall armyworm, cabbage looper and stink bugs) will be collected daily from pheromone traps and blacklight traps to identify return (i.e., southward) migration events in central TX (Uvalde and College Station). Bats returning to Frio Cave (near Uvalde) from nightly foraging flights will be netted, and fresh fecal pellets will be collected. The fecal pellets will be analyzed to determine the presence of several insect species in the diet of bats. Temporal changes in the fecal DNA will be correlated with daily insect collections and weather conditions. Changes in timing, locations, and altitudinal distribution of feeding activity of bats will be documented in relation to movements and availability of crop pest insects.
The goal of this project is to define the relationships between migratory behavior of key crop pest insects and the foraging activity and overall health of Brazilian free-tailed bats that prey on these insects. In FY 2013, male moths of five species of migratory crop pests (black cutworm, true armyworm, corn earworm, fall armyworm, and cabbage looper) were captured nightly in pheromone traps at Uvalde and College Station, TX. Captures of corn earworm moths were 10- to 100-fold greater than those of the other four migratory pest species. Significant peaks in bat foraging activity occurred from late August through mid-September despite extremely low captures of the five migratory pest species. Captures of the pest species increased, and bats foraged fewer hours yet gained weight on the day after passage of cold fronts. Overall, duration of bat foraging was inversely proportional to abundance of captured pest insects. The availability of various other insect species or predominantly more female moths migrating during the fall may explain much of the variability of the nightly foraging duration and weight gain of bats. Over the life of this project, the results have revealed valuable information on the interactions and inter-relationships between major crop insect pests and bats that consume these insects by the millions. This project expired in FY 2013.