Environmental Entomology · 1975 · 146 citations · 0 references
Life SciencesAgronomyEntomologyAgricultural EntomologyCrop ProductionInsect EcologyCrop Pest InsectsCrop-environment InteractionsInsect Population DynamicsInsect-plant InteractionsPest DynamicsYield EstimationCotton Insect PestsCotton PestsCotton PlantationsDefoliating PestsDefoliator DynamicsInsect Pest EcologyPest Impacts On YieldYield Response To Environment
A population model of cotton growth and development in response to weather, agronomic factors, and insect pests has been successfully used to examine cotton production in California. The impact of most arthropod pests on cotton yields is currently under investigation. Only the effects of defoliating insects, Spodoptera exigua (Hübner), Trichoplusia ni (Hübner), and Heliothis zea (Boddie), are reported here. The impact of moderate defoliation by S. exigua and T. ni populations causes only slight yield reductions. More important is the predation by S. exigua larvae on immature fruit (i.e., squares). Investigations on the interaction of plant age and developmental stage with defoliator damage (defoliation and predation on squares) indicates that the greatest yield reductions occur from attack early in the squaring period. The late season effects of H. zea are easy to measure and incorporate into the model.