The cotton aphid, Aphis gossypii Glover, predation rate of convergent lady beetle, Hippodamia convergens Guerin-Meneville, was determined by assigning a single predator randomly to each of four prey density treatments...The cotton aphid, Aphis gossypii Glover, predation rate of convergent lady beetle, Hippodamia convergens Guerin-Meneville, was determined by assigning a single predator randomly to each of four prey density treatments in the laboratory. Prey densities included 25, 50, 100, and 200 aphids per Petri dish arena. Predation response was recorded at 1, 4, 8, 16, 24, and 48 h after assigning predators to their prey treatments. Rate of consumption increased through time, with all 25 aphids consumed during the first 4 h of the experiment. At the highest density, adult lady beetle consumed on average 49, 99, 131, 163, 183, and 200 aphids within 1, 4, 8, 16, 24 and 48 h, respectively. Predators showed a curvilinear feeding response in relation to total available time, indicating that convergent lady beetles have the potential to suppress larger populations of aphids through continuous feeding by regulating their predation efficiency during feeding. The analysis of age-specific mortality in absence of prey revealed that lady beetles could survive for an extended period of time （more than 2 weeks） without prey. The ability of a predator to survive without prey delays or prevents the rebound of pest populations that is a significant factor in natural biological control. A two-year field sampling of 10 cotton arthropod predator species showed that spiders （27%） were the most dominant foliage dwelling predators in the Texas High Plains cotton followed by convergent lady beetles （23.5%）, hooded beetles （13.5%）, minute pirate bugs （11%）, green lacewings （9.5%）, bigeyed bugs （7.5%）, scymnus beetles （3%）, soft-winged flower beetles （2%）, damsel bugs （1.5%）, and assassin bugs （1.5%）. A field cage study showed that one H. convergens adult per plant released at prey density of one aphid per leaf kept the aphid population below economic threshold for the entire growing season.展开更多
为筛选出对棉蚜高效的药剂品种,选用了6种杀虫剂对棉花苗期棉蚜进行田间药效评价。试验结果表明:20%氟啶虫酰胺悬浮剂和50 g/L双丙环虫酯可分散液剂对棉蚜的速效性和持效性均较好,药后1 d仿效即可达到>88%,药后14 d防效仍能保持在>...为筛选出对棉蚜高效的药剂品种,选用了6种杀虫剂对棉花苗期棉蚜进行田间药效评价。试验结果表明:20%氟啶虫酰胺悬浮剂和50 g/L双丙环虫酯可分散液剂对棉蚜的速效性和持效性均较好,药后1 d仿效即可达到>88%,药后14 d防效仍能保持在>95%;20%吡虫啉可分散液剂速效性好,但持效性较差,持效期仅有7 d;20%环丙氟虫胺悬浮剂速效性和持效性均表现一般;50%吡蚜酮水分散粒剂对棉蚜防效最差。20%氟啶虫酰胺悬浮剂75 g a.i./hm^(2)、50 g/L双丙环虫酯可分散液剂7.5 g a.i./hm^(2)或12 g a.i./hm^(2)均可有效防治苗期棉蚜。展开更多
文摘The cotton aphid, Aphis gossypii Glover, predation rate of convergent lady beetle, Hippodamia convergens Guerin-Meneville, was determined by assigning a single predator randomly to each of four prey density treatments in the laboratory. Prey densities included 25, 50, 100, and 200 aphids per Petri dish arena. Predation response was recorded at 1, 4, 8, 16, 24, and 48 h after assigning predators to their prey treatments. Rate of consumption increased through time, with all 25 aphids consumed during the first 4 h of the experiment. At the highest density, adult lady beetle consumed on average 49, 99, 131, 163, 183, and 200 aphids within 1, 4, 8, 16, 24 and 48 h, respectively. Predators showed a curvilinear feeding response in relation to total available time, indicating that convergent lady beetles have the potential to suppress larger populations of aphids through continuous feeding by regulating their predation efficiency during feeding. The analysis of age-specific mortality in absence of prey revealed that lady beetles could survive for an extended period of time （more than 2 weeks） without prey. The ability of a predator to survive without prey delays or prevents the rebound of pest populations that is a significant factor in natural biological control. A two-year field sampling of 10 cotton arthropod predator species showed that spiders （27%） were the most dominant foliage dwelling predators in the Texas High Plains cotton followed by convergent lady beetles （23.5%）, hooded beetles （13.5%）, minute pirate bugs （11%）, green lacewings （9.5%）, bigeyed bugs （7.5%）, scymnus beetles （3%）, soft-winged flower beetles （2%）, damsel bugs （1.5%）, and assassin bugs （1.5%）. A field cage study showed that one H. convergens adult per plant released at prey density of one aphid per leaf kept the aphid population below economic threshold for the entire growing season.
文摘为筛选出对棉蚜高效的药剂品种,选用了6种杀虫剂对棉花苗期棉蚜进行田间药效评价。试验结果表明:20%氟啶虫酰胺悬浮剂和50 g/L双丙环虫酯可分散液剂对棉蚜的速效性和持效性均较好,药后1 d仿效即可达到>88%,药后14 d防效仍能保持在>95%;20%吡虫啉可分散液剂速效性好,但持效性较差,持效期仅有7 d;20%环丙氟虫胺悬浮剂速效性和持效性均表现一般;50%吡蚜酮水分散粒剂对棉蚜防效最差。20%氟啶虫酰胺悬浮剂75 g a.i./hm^(2)、50 g/L双丙环虫酯可分散液剂7.5 g a.i./hm^(2)或12 g a.i./hm^(2)均可有效防治苗期棉蚜。
