Boyle Sean M, Salom Scott, Schultz Peter, Lopez Lorena, Weber Donald C, Kuhar Thomas P
Department of Entomology, Virginia Polytechnic Institute and State University, 170 Drillfield Dr., Blacksburg, VA 24061, USA.
Department of Entomology, Virginia Polytechnic Institute and State University, Hampton Roads Agricultural Research and Extension Center, 1444 Diamond Springs Rd., Virginia Beach, VA 23455, USA.
Environ Entomol. 2023 Oct 16;52(5):779-786. doi: 10.1093/ee/nvad079.
The squash bug, Anasa tristis (De Geer) (Hemiptera: Coreidae), is a serious pest of cucurbit crops across the United States. Conventional growers commonly use broad-spectrum insecticides to manage squash bugs, however organic growers lack these effective chemical tools and must rely on alternative management strategies. Biological control of A. tristis is largely understudied, specifically the potential of natural enemy, Hadronotus pennsylvanicus (Ashmead) (Hymenoptera: Scelionidae), as an augmentative biological control agent. For this reason, we performed early-season field releases of H. pennsylvanicus on organic farms in southeastern Virginia to test if this would improve A. tristis egg parasitism. We chose organic vegetable farms growing summer squash (Cucurbita pepo L.) as release sites and nearby Virginia Tech Agricultural Research Extension Centers (AREC) as no-release sites. Parasitoids were reared in the lab and deployed as parasitized egg masses (2-3 females wasps/plant) in June 2020 and 2021. Before parasitoid deployment, host eggs collected from release and no-release sites displayed low levels of H. pennsylvanicus parasitism in 2020 (<21%) and 2021 (<8%). In both years, the percentage of A. tristis eggs parasitized within 2 weeks post deployment was significantly greater at release sites (60%) than at no-release sites (~14%). High rates of H. pennsylvanicus parasitism (>72%) were further observed at release sites 4, 6, 8, and 10 weeks following parasitoid deployment. Our study demonstrates that releases of lab-reared H. pennsylvanicus can increase A. tristis egg parasitism rates and subsequently decrease successful nymph hatch rates in early summer squash plantings.
南瓜缘蝽（Anasa tristis (De Geer)，半翅目：缘蝽科）是美国葫芦科作物的一种严重害虫。传统种植者通常使用广谱杀虫剂来防治南瓜缘蝽，然而有机种植者缺乏这些有效的化学工具，必须依靠替代管理策略。对南瓜缘蝽的生物防治在很大程度上尚未得到充分研究，特别是天敌宾夕法尼亚强胸缘蝽（Hadronotus pennsylvanicus (Ashmead)，膜翅目：缘蝽小蜂科）作为一种增殖性生物防治剂的潜力。因此，我们在弗吉尼亚州东南部的有机农场进行了宾夕法尼亚强胸缘蝽的早期田间释放，以测试这是否会提高南瓜缘蝽卵的寄生率。我们选择种植夏南瓜（Cucurbita pepo L.）的有机蔬菜农场作为释放地点，并选择附近的弗吉尼亚理工大学农业研究推广中心（AREC）作为非释放地点。寄生蜂在实验室饲养，并于2020年和2021年6月作为寄生卵块（约每株2 - 3只雌蜂）进行投放。在投放寄生蜂之前，2020年（<21%）和2021年（<8%）从释放地点和非释放地点收集的寄主卵显示出较低水平的宾夕法尼亚强胸缘蝽寄生率。在这两年中，投放后2周内被寄生的南瓜缘蝽卵的百分比在释放地点（约60%）显著高于非释放地点（约14%）。在投放寄生蜂后的第4、6、8和10周，在释放地点进一步观察到了高寄生率（>72%）。我们的研究表明，释放实验室饲养的宾夕法尼亚强胸缘蝽可以提高南瓜缘蝽卵的寄生率，并随后降低初夏南瓜种植中若虫的成功孵化率。
