USDA-ARS, Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008, USA.
J Econ Entomol. 2011 Feb;104(1):14-20. doi: 10.1603/ec10303.
The pecan weevil, Curculio caryae (Horn), is a key pest of pecan [Carya illinoinensis (Wangenh.) K. Koch]. Current control recommendations are based on chemical insecticide applications. Microbial control agents such as the entomopathogenic nematode, Steinernema carpocapsae (Weiser) and the fungus Beauveria bassiana (Balsamo) Vuillemin occur naturally in southeastern U.S. pecan orchards and have shown promise as alternative control agents for C. caryjae. Conceivably, the chemical and microbial agents occur simultaneously within pecan orchards or might be applied concurrently. The objective of this study was to determine the interactions between two chemical insecticides that are used in commercial C. caryae control (i.e., carbaryl and cypermethrin applied below field rates) and the microbial agents B. bassiana and S. carpocapsae. In laboratory experiments, pecan weevil larval or adult mortality was assessed after application of microbial or chemical treatments applied singly or in combination (microbial + chemical agent). The nature of interactions (antagonism, additivity, or synergy) in terms of weevil mortality was evaluated over 9 d (larvae) or 5 d (adults). Results for B. bassiana indicated synergistic activity with carbaryl and antagonism with cypermethrin in C. caryae larvae and adults. For S. carpocapsae, synergy was detected with both chemicals in C. caryae larvae, but only additive effects were detected in adult weevils. Our results indicate that the chemical-microbial combinations tested are compatible with the exception of B. bassiana and cypermethrin. In addition, combinations that exhibited synergistic interactions may provide enhanced C. caryae control in commercial field applications; thus, their potential merits further exploration.
山核桃象鼻虫，Curculio caryae（Horn），是山核桃[Carya illinoinensis（Wangenh.）K. Koch]的主要害虫。目前的防治建议是基于化学杀虫剂的应用。微生物防治剂，如昆虫病原线虫 Steinernema carpocapsae（Weiser）和真菌 Beauveria bassiana（Balsamo）Vuillemin，自然存在于美国东南部的山核桃果园中，并已显示出作为山核桃象鼻虫替代控制剂的潜力。可以想象，化学和微生物制剂同时存在于山核桃果园中，或者可能同时应用。本研究的目的是确定两种用于商业山核桃象鼻虫防治的化学杀虫剂（即低于田间用量的carbaryl 和 cypermethrin）与微生物制剂 B. bassiana 和 S. carpocapsae 之间的相互作用。在实验室实验中，评估了在单独或组合（微生物+化学药剂）施用微生物或化学处理后，山核桃象鼻虫幼虫或成虫的死亡率。根据象鼻虫死亡率，评估了 9 天（幼虫）或 5 天（成虫）的相互作用（拮抗、相加或协同）性质。B. bassiana 的结果表明，在山核桃象鼻虫幼虫和成虫中，carbaryl 与 synergistic 活性，而 cypermethrin 则与 antagonism 活性。对于 S. carpocapsae，在山核桃象鼻虫幼虫中检测到与两种化学物质的协同作用，但在成虫中仅检测到相加作用。我们的结果表明，除了 B. bassiana 和 cypermethrin 之外，测试的化学-微生物组合是相容的。此外，表现出协同相互作用的组合可能在商业田间应用中提供增强的山核桃象鼻虫控制；因此，它们的潜在优点值得进一步探索。
