Butler Casey D, O'Neil Robert J
Department of Entomology, Purdue University, Smith Hall, 901 W. State St., West Lafayette, IN 47907-2089, USA.
Environ Entomol. 2008 Aug;37(4):964-72. doi: 10.1603/0046-225X(2008)37[964:VAPPOI]2.0.CO;2.
The generalist predator, Orius insidiosus (Say), is an important natural enemy of the soybean aphid, Aphis glycines Matsumura. Soybean thrips, Neohydatothrips variabilis (Beach), serve as an important prey resource for O. insidiosus in soybeans, sustaining the predator's population before the arrival of the soybean aphid. Although generalist predators can forage on a broad range of prey, they may show distinct preferences for particular prey, attacking prey at levels disproportionate to their relative numbers. To assess the preference of O. insidiosus for soybean aphid and soybean thrips, attack rates of nymphal and adult O. insidiosus were measured in the laboratory. For both adults and nymphs, the number of prey attacked increased as more prey were provided. For nymphs, the total number of prey attacked increased as the predator matured. In general, the number of prey attacked by adult predators was relatively constant as the predator aged. Both O. insidiosus nymphs and adults displayed a preference for soybean thrips, by disproportionately attacking soybean thrips over soybean aphid regardless of the relative densities of the two prey. We discuss implications of this preference on O. insidiosus life history characteristics and the potential impact on O. insidiosus-prey dynamics in the field.
多食性捕食者暗黑赤眼蜂（Orius insidiosus (Say)）是大豆蚜（Aphis glycines Matsumura）的重要天敌。大豆蓟马（Neohydatothrips variabilis (Beach)）是暗黑赤眼蜂在大豆田中的重要猎物资源，在大豆蚜到来之前维持着捕食者的种群数量。尽管多食性捕食者可以捕食多种猎物，但它们可能对特定猎物表现出明显的偏好，攻击猎物的水平与其相对数量不成比例。为了评估暗黑赤眼蜂对大豆蚜和大豆蓟马的偏好，在实验室中测量了暗黑赤眼蜂若虫和成虫的攻击率。对于成虫和若虫来说，提供的猎物越多，被攻击的猎物数量就越多。对于若虫来说，随着捕食者成熟，被攻击的猎物总数增加。一般来说，成年捕食者随着年龄增长，被攻击的猎物数量相对稳定。暗黑赤眼蜂的若虫和成虫都表现出对大豆蓟马的偏好，无论两种猎物的相对密度如何，都会不成比例地攻击大豆蓟马而不是大豆蚜。我们讨论了这种偏好对暗黑赤眼蜂生活史特征的影响以及对田间暗黑赤眼蜂-猎物动态的潜在影响。
