Location: Pest Management and Biocontrol Research
Title: Detection and monitoring of pink bollworm moths and invasive insects using pheromone traps and encounter-rate models Authors
Submitted to: Journal of Applied Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 11, 2014
Publication Date: August 1, 2014
Citation: Byers, J.A., Naranjo, S.E. 2014. Detection and monitoring of pink bollworm moths and invasive insects using pheromone traps and encounter-rate models. Journal of Applied Ecology. 51(4):1041-1049. Interpretive Summary: The pink bollworm is one of the most destructive pests in agriculture. An ongoing eradication program has nearly exterminated this pest from the southwestern USA and portions of northern Mexico. However, the continued threat of reinvasion from Mexico and other parts of the world requires improved methods to detect and monitor for this pest. We developed a computer model to simulate the ability of attractive traps to detect populations of the pink bollworm. The simulation showed that the probability of detection increased as the number of traps or pink bollworm moths increased. Additional predictions of detection using modified predator-prey equations provided similar results but were much simpler to use. These equations can be used to predict the number of traps needed to detect the pest at a given population level, as well as the population level that is present given a particular number of moth captures on traps. Furthermore, these predictive equations are adaptable to other pest species or monitoring methods. These findings will aid regulatory agencies and eradication programs in optimizing detection efforts for the pink bollworm and other invasive insect species.
Technical Abstract: The pink bollworm moth, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), is one of the most destructive pests in agriculture. An ongoing eradication program using a combination of sex pheromone monitoring and mating disruption, irradiated sterile moth releases, genetically-modified Bt cotton, and local insecticide applications have all but exterminated the pink bollworm from the southwestern USA and portions of northern Mexico. However, the continued threat of reinvasion from Mexico reinforces the need to improve pheromone-based monitoring. Invasions from other parts of the world such as India, where resistance to single-gene transgenic Bt cotton has evolved, further heightens the need for better monitoring strategies. The mean flight height and standard deviation (SD) of the vertical flight distribution of pink bollworm males were estimated from transparent sticky cylinder traps baited with synthetic pheromone at several heights above ground. An effective attraction radius (EAR) of a standard pheromone lure was estimated from male moth catches on the pheromone-baited sticky traps and many similar blank traps. The circular EARc was estimated from the spherical EAR and SD. The EAR of a pheromone lure for pink bollworm was 1.03 m and the EARc was 2.61 m. The mean flight height of males was 0.82 m and the vertical flight distribution SD was 0.26 m. A computer program simulated male moth movement and capture on various numbers of traps of EARc distributed over an area of 1-100 km^2. The simulated catch results were comparable to predictions using the EARc with modified encounter-rate equations of Royama and Rogers. The encounter-rate equations were solved for initial populations of male moths in the regions and Poisson statistics were used to calculate population confidence limits. The encounter rate models and Poisson methods can be used to determine levels of pheromone trap densities that are likely to detect and estimate low population levels of resident or invasive pink bollworms and many other pest insect species.