Evaluation of Catolaccus grandis (Hymenoptera : Pteromalidae) for boll weevil(1) control in Northeastern Mexico

摘要

Boll weevil cohorts were exposed in check and release fields to assess the mortality of boll weevil immatures assignable to Catolaccus grandis (Burks) and other agents through life table analyses. Field sites in Mexico were at Estacion Cuauhtemoc, Tamaulipas and Ebano, San Luis Potosi during late summer of 1999. Results indicated that Catolaccus grandis was the main boll weevil mortality factor, primarily of third-instar larvae. Seasonal average mortality of third instars was higher at the Cuauhtemoc release plot (74.1%) than at the Ebano release plot (64.3%). However, overall mortality due to C grandis parasitism was much lower at Cuauhtemoc than at Ebano during the crucial early period of boll weevil infestation and establishment, and the effect of the parasitoids was not sufficient to prevent severe crop damage in the Cuauhtemoc release plot. In contrast, higher mortality occurring at Ebano during the early infestation period ( > 70%) may have resulted in a slower population increase, lower overall weevil densities and percentage damaged fruit. 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 to control Spodoptera exigua Habner.