Long-Distance Migration in Helicoverpa zea What We Know and Need to Know

This paper identifies knowledge and knowledge gaps in biology and ecology, and migratory flight of corn earworm Helicoverpa zea (Boddie) The paper focuses on results from studies of corn earworm population dynamics and migration in Texas during a period of substantial irrigated maize Zea mays L production in the Lower Rio Grande Valley which prevailed before planted acres decreased due to drought expansive land development and the introduction of Bt corn Because overwintering survival of corn earworm in the U S is generally accepted to be limited to areas south of 40 degrees N latitude much of the maize-growing area in the north-central U S would not be infested by corn earworm if not for migration Overwintenng emergence contributes to infestations by corn earworm but it is difficult to separate the contributions of overwintering emergence and immigrants on local populations We emphasize three critical elements affecting the timing and extent of corn earworm migration period of emergence of adult corn earworm availability of fruiting maize as a host and availability of suitable atmospheric conditions for transport Knowledge of corn earworm migration will be especially useful in devising and utilizing novel control tactics in the northern tier of states where insecticides are applied extensively to control immigrant corn earworm in sweet corn seed corn, snap beans Phaseolus vulgaris L and other high-value crops This Is particularly important to the abundance geographical range and management of corn earworm relative to potential climate change and use of transgenic crops tolerant of drought and heat conditions