|Rodriguez Del B, L|
Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/20/2001
Publication Date: 3/1/2004
Citation: Cortez, E., Vargas-Camplis, J., Coleman, R.J., Rodriguez Del B, L.A., Leyva, J.L. 2004. Evaluation of Catolaccus grandis for boll weevil control in northeastern Mexico. Southwestern Entomologist. 29:69-75 Interpretive Summary: The boll weevil, Anthonomus grandis, is the most important insect pest attacking cotton in northeastern Mexico and South Texas. Suppression of boll weevil populations with chemical insecticides is costly and disrupts beneficial insects' ability to control secondary pests such as worms, aphids, and whiteflies. There is an urgent need to develop non-chemical or chemical-restricted technology for eliminating boll weevil reproduction. The potential of mass rearing and releasing the parasitic wasp, Catolaccus grandis, for managing boll weevil has been demonstrated in several regions of the U.S. cotton belt. A cooperative study was conducted to validate this control approach in two areas in Northeastern Mexico. We monitored causes of boll weevil mortality in release fields and insecticide-treated fields. The primary cause of mortality in release fields was due to the effects of parasitism by Catolaccus grandis. The study showed the importance of achieving high mortality of boll weevils during the early season infestation period which resulted in slower population increase and lower overall densities of boll weevil and percent damaged fruit. Releases of the parasitic wasp in Northeastern Mexico has potential for controlling boll weevils and thus reducing insecticide applications for boll weevils and their deleterious effect on predators and parasites of other insect pests.
Technical Abstract: We established boll weevil cohorts in check and release fields and constructed life tables to assess the mortality of boll weevil immatures assignable to Catolaccus grandis and other agents. Field sites in Mexico were at Estacion Cuauhtemoc, Tamaulipas and Ebano, San Luis Potosi during late summer of 1999. Results from the release sites indicate that Catolaccus grandis was the main mortality factor of boll weevil, primarily of third instar larvae. Seasonal average mortality of third instars was higher at the Cuauhtemoc release plot (72.4%) than at the Ebano release plot (64.3%). However, mortality due to C. grandis parasitism was much lower at Cuauhtemoc than that recorded at Ebano during the crucial early period of boll weevil infestation and establishment, and the effect of the parasitoids was not sufficient to prevent high damage in the release plot at Cuauhtemoc. In contrast, the higher mortality occurring at Ebano during the early infestation period (> 70%) may have resulted in a slower population increase and lower overall densities of boll weevil and percent damaged fruit; even though after one insecticide spray reduced the parasitoid activity. At Ebano, satisfactory control of boll weevil was observed in the release field while the check required 11 insecticide applications for boll weevil control. In the check plot at Cuauhtemoc, early season insecticide applications for boll weevil control caused sufficient natural enemy mortality resulting in the need for controlling Spodoptera exigua. Use of C. grandis augmentation technology in Northeastern Mexico shows potential for reducing boll weevil populations as well as minimizing effects of pesticide impact on natural enemy populations that maintain other pest species below economic thresholds.