Pecan weevil, Curculio caryae (Horn) (Coleoptera: Curculionidae), is a major fruit pest of pecan, Carya illinoinensis (Wangenh.) K. Koch. The majority of economic damage results from larvae feeding on the kernel. Pecan fruit were collected at three sites to describe oviposition activity related to location on the fruit, cluster size, and determine the likelihood of multiple females ovipositing in the same fruit. Results indicated that oviposition was primarily at the distal (stigma) end of the fruit, although feeding punctures seemed to occur without respect to fruit location. Infestation of a fruit cluster rarely resulted in all fruit in the cluster being infested; in fact, one or two fruit were the most common infestation level, regardless of cluster size. Infestation by larvae typically occurred at greater frequency in larger clusters and less frequency in single fruit clusters than the infestation rate across all cluster sizes, suggesting that more fruit produced a greater concentration of volatile compounds attractive to females. Multiple punctures in the shuck were frequently observed, but multiple punctures of the testa were rare when infestation was moderate but increased when infestation was high. This indicated that feeding by adult weevils was not affected by earlier feeding, but deep penetration of the fruit leading to oviposition was inhibited by a previous penetration of the testa. In orchards with the majority of the crop infested, fruit were identified with larval development up to the third instar, combined with eggs. Evidence suggests an oviposition-marking pheromone produced by the host or female weevil deters other females from using the fruit for reproduction, but will not avert multiple oviposition episodes when non-infested fruit are sparse.
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1 December 2009
Oviposition Characteristics of Pecan Weevil
Michael W. Smith,
Phillip G. Mulder
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