Feeding Behavior And Dispersal Capacity Of Harpactor Fuscipes(Fabricius)

Harpactor fuscipes?Fabrieius? is Hemiptera, reduviidae of predatory insects, mainly distributed in Guangdong, Guangxi, Yunnan, Fujian and other Southernareaof China.We found that it is dominant population of predators of tobacco pests, preying ontobacco cutworm Spodoptera lituraand tobacco aphis Myzus persicae,tobacco budworm Heliothis assulta and other kinds of tobacco pests, it can effective control these important pests. In this thesis, the biological characteristics andthe predation functional responses to important pest in tobacco S. lituraet al.were evaluated of H. fuscipes were investigated.Predation selectivity of Harpactor fuscipes for important pest M.persicae, S. litura and H. assulta in tobacco,feedingbehaviorcharacter parameters of Harpactor fuscipes?Fabricius?for Spodoptera litura, dispersal capacity of Harpactor fuscipes?Fabricius? evaluated under laboratory and the best amount of release of Harpactor fuscipes?Fabricius? in different densities of Spodoptera liturawere conducted. The results provide scientific basis for its further application in practice in near future. The main results were as follows:?1? Predation selectivity of Harpactor fuscipes for important pest in tobacco.The behavior response of a assassin bug, Harpactor fuscipes?Fabricius? to tobacco aphis, Myzus persicae, tobacco budworm, Heliothis assulta and tobacco cutworm, Spodoptera litura,was examined using the Y-tube olfactometer. The results showed that the bug adult was strongly attracted by three prey species, M. persicae,H. assulta and S. litura, the percentages of the bug adult that selecting 3^rd-instar larvae of H. assulta, S. litura and high-instar nymphs of M. persicae were up to 40.00%, 51.11% and 34.44%, respectively, and significantly higher than that of control. When selected high-instar nymphs of M. persicae, 3^rd-instar larvae of H. assulta and S. litura, the bug adult took14.53,13.44 and 9.38 minutes, respectively, and spended time of the bug selecting 3^rd-instar larvae of S.litura was significantly shorter than that of the bug selecting 3^rd-instar larvae of H. assultaand the nymphs of M. persicae. Moreover, among three prey species, the bug strongly preferred to select third-instar larvae of S. litura. These results would provide an important reference for artificially breeding H. fuscipes and widely application of the bug to control these important pests insafety production of agricultural products.?2?Feedingbehaviorcharacter parameters of Harpactor fuscipes?Fabricius?for Spodoptera litura.Harpactor fuscipes?Fabricius? has a strong ability of predation to important pest tobacco cutworm, Spodoptera litura. To learn predatory behavior is a successful key for effective selection predatory to the biological control. In this study, the Spodoptera litura-attacking behavior character parametersof H. fuscipesadults and 1^st-5^th instar larvaewas observed, including various stages of predatory behavior time allocation, first piercetime, the longest feedingtime, piercetime, feeding amount of H. fuscipes.The results showed that the proportion of timespend by starved adults and 1^st-5^th instar larvae of H. fuscipes wasfeeding>walking>resting>clearing. The time for starved adults to feed S. litura nymphs increased as the host nymphs developed. 4^th-instar and 5^th-larvae of H. fuscipes spent more time feeding than any other larvae instar. With the increasing larval instars, the time spent on walking decreased of H. fuscipes adults.With the increasing instars of H. fuscipes,first piercetime of H. fuscipes was decreased except H. fuscipesadults and 1^st-5^th instar larvae was feeding 1st-instar of S. litura. With the increasing instars of H. fuscipes, the longest feedingtime of H. fuscipes was decreased except H. fuscipesadults and 1^st-5^th instar larvae was feeding 4^th-instar of S. litura. With the increasing instars of H. fuscipes, feeding amount of H.fuscipes was increased except H. fuscipesadults and 1^st-5^th instar larvae was feeding 4^th-instar of S. litura. Feeding amount of H. fuscipesadults was the most of all instars.?3? Dispersal capacity of Harpactor fuscipes?Fabricius? evaluated under laboratory.In this study, horizontal and vertical walking capacity of H. fuscipes larvae(i.e.,1st through 5^th) and adults was examined using self-apparatus in the laboratory. The results showed that the horizontal walking distance of H. fuscipes increased as the assassin bug instar developed. Adults exhibited the greatest horizontal walking distances compared with larvae. Fifth instars exhibited the greatest horizontal walking distances and 1st-instar larvae was the shortest than any other larvae instars. H. fuscipes adults exhibited significantly greater walking distances compared with larvae instars. The average of horizontal walking speed of H. fuscipes increased as the assassin bug instar developed. Adults exhibited the greatest average of horizontal walking speed compared with larvae. Fifth instars exhibited the greatest average of horizontal walking speed and 1st-instarlarvae was the shortest than any other larvae instars. There was a significant difference in the average of horizontal walking speed H. fuscipes among the adults and larvae stages. A similar pattern was observed from vertical climbing tests with horizontal walking of H. fuscipes. The results of this study indicate that H. fuscipes adults and 5^th larvae have strong dispersal capacity. In the lab, the dispersal capacity of H. fuscipes increased as the assassin bug instar developed. These research results has important theoretical significance to formulate strategy of releasing the assassin bug to control these important pests.?4?The best amount of release of Harpactor fuscipes?Fabricius? in different densities of Spodoptera litura.A laboratory trial was conducted to examine thebest amount of release of H. fuscipes that 1, 2, 3 density 4^th-5^th instar larvae or adults of H. fuscipes were provided with second instar larvae of Spodoptera litura at the density of either5, 10, 15, 20, 25, or 30 larvae on a tobacco plant under greenhouse and caged conditions. The results showed that the number of second instar larvae of S. litura preyed by H. fuscipesincreased with the increase in prey density. The predatory quantity was affected by intraspecific interference. With the increasing of the density of H. fuscipes, the average predatory quantity per one H. fuscipesdeclined.While the number of Spodoptera litura at the density of either 10 larvae on a tobacco plant, release a assassin bug which is a 4^th-5^th instar larvae of H. fuscipes may result in a better production effects. While the number of Spodoptera litura at the density of either 15 and 20 larvae on a tobacco plant, release a assassin bug which an adult of H. fuscipes may result in a better production effects. While the number of Spodoptera litura at the density of either 25 larvae on a tobacco plant, release two 4^th-5^th instar larvae of H. fuscipesor an adult of H. fuscipesmay result in a better production effects. While the number of Spodoptera litura at the density of either 30 larvae on a tobacco plant, release two assassin bug which are 4^th-5^th instar larvae of H.fuscipes may result in a better production effects. These results would provide an theoretical basis for application of releasing the bug to control these important pests.