Author
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Byers, John |
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Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/30/2008 Publication Date: 6/27/2008 Citation: Byers, J.A. (2008). Active space of pheromone plume and its relationship to effective attraction radius in applied models. Journal of Chemical Ecology, 34:1134-1145. Interpretive Summary: Any lure’s chemical release rate that is attractive to flying insects has a specific effective attraction radius (EAR) that corresponds to the lure’s strength in causing insect orientation response. The EAR was defined as the radius of a passive sphere that would intercept the same number of insects as a pheromone-baited trap. Thus, the EAR is measured in the field by a ratio of catch on baited and unbaited traps and the unbaited trap interception area. The EAR serves as a standardized method for comparing the attractive strengths of lures that is independent of population density. In two-dimensional encounter rate models, a circular EAR (EARc) describes a key parameter affecting catch or influence by pheromone in models of insect mass trapping and mating disruption. However, the spherical EAR, as measured in the field, should be transformed to an EARc for appropriate predictions in such models. The EARc is calculated from EAR and FL, where FL is the effective thickness of the flight layer where the insect disperses. FL was estimated from catches of insects (comprising 42 species in the orders Coleoptera, Lepidoptera, Diptera, Hemiptera, and Thysanoptera) on traps at various heights above ground as reported in the literature. The EARc was further proposed as a simple but equivalent alternative to simulations of highly complex active-space plumes with variable response surfaces that have proven exceedingly difficult to quantify in nature. This hypothesis was explored in simulations where flying insects, represented as coordinate points, moved about in a correlated random walk in an area containing a pheromone plume, represented as a sector of active space composed of a capture probability surface of variable complexity. In this plume model, catch was monitored at a constant density of flying insects and then compared to simulations in which a circular EARc was enlarged until an equivalent rate was caught. This demonstrated that there is a circular EARc, where all insects entering are caught, which corresponds in catch effect to any plume. Thus, the EARc, based on the field-observed EAR, can be used in encounter rate models to develop effective control programs based on mass trapping and/or mating disruption for control of insect pests. Technical Abstract: Any lure’s semiochemical release rate that is attractive to flying insects has a specific effective attraction radius (EAR) that corresponds to the lure’s orientation response strength. The EAR was defined as the radius of a passive sphere that would intercept the same number of insects as a semiochemical-baited trap. Thus, the EAR is measured in the field by a ratio of catch on baited and unbaited traps and the unbaited trap interception area. The EAR serves as a standardized method for comparing the attractive strengths of lures that is independent of population density. In two-dimensional encounter rate models, a circular EAR (EARc) describes a key parameter affecting catch or influence by pheromone in models of insect mass trapping and mating disruption. However, the spherical EAR, as measured in the field, should be transformed to an EARc for appropriate predictions in such models. The EARc is calculated as (p/2EAR2)/FL, where FL is the effective thickness of the flight layer where the insect searches. FL was estimated from catches of insects (42 species in the orders Coleoptera, Lepidoptera, Diptera, Hemiptera, and Thysanoptera) on traps at various heights as reported in the literature. The EARc was further proposed as a simple but equivalent alternative to simulations of highly complex active-space plumes with variable response surfaces that have proven exceedingly difficult to quantify in nature. This hypothesis was explored in simulations where flying insects, represented as coordinate points, moved about in a correlated random walk in an area containing a pheromone plume, represented as a sector of active space composed of a capture probability surface of variable complexity. In this plume model, catch was monitored at a constant density of flying insects and then compared to simulations in which a circular EARc was enlarged until an equivalent rate was caught. This demonstrated that there is a circular EARc, where all insects entering are caught, which corresponds in catch effect to any plume. Thus, the EARc, based on the field-observed EAR, can be used in encounter rate models to develop effective control programs based on mass trapping and/or mating disruption. |
