Study On The Major Ecology And Control Strategy Of The Resseliella Citrifrugis Jiang

Resseliella citrifrugis Jiang, an important pest in pomelo garden in some areas of Fujian Province. In order to control the pest effectively, the major ecology and control technology were studied systematically in this paper. The research work mainly focused on the following aspects: spatial pattern of eggs, larvae, pupae and adult; the effects of temperature and host plants on the development, survivorship and fecundity of Resseliella citrifrugis Jiang; construction of experimental population life table of Resseliella citrifrugis Jiang at different temperatures; the relationship between the physical and chemical properties of several fruits and occurrence of Resseliella citrifrugis Jiang; the effect of soil moisture content on the pupation; construction of natural population life table of Resseliella citrifrugis Jiang on several host plants; at last control efficiency of several control technologies on population of construction of experimental population life table of Resseliella citrifrugis Jiang were evaluated. The results detail were as follows:The spatial distribution pattern of eggs and larvae at all densities were aggregated, the basic component of distribution was colony and individuals were mutually attracted in the harvesting period of host fruits. The spatial pattern of pupae was great aggregated negative distribution. The major spatial distribution pattern of adults of Resseliella citrifrugis Jiang was randomly and the basic component of distribution was colony. Based on the spatial distribution pattern the optimal theoritical sampling models of eggs, larvae and pupae were established.Temperature was one of main factors which affected on the development and reproduction of Resseliella citrifrugis Jiang. Mathemetic models describing the relations between development velocities and temperaturs were set up on three species of fruits for eggs, larvae and pupae of Resseliella citrifrugis Jiang. Temperature had a significant effect on experimental population increase of Resseliella citrifrugis Jiang when fed on different host fruits. The low temperature threshold of development of eggs, larvae and pupae of Resseliella citrifrugis Jiang were estimated to be 17.8℃, 20.2℃and 15.1℃respectively. The relation between indices of population trend and temperatures could be simulated as quadratic linear models when Resseliella citrifrugis Jiang was reared on different host fruits.Host plants had little effect on the development and survivorship of eggs, larvae and pupae of Resseliella citrifrugis Jiang but had a larger effect on the fecundity. The indices of experimental population trends of Resseliella citrifrugis Jiang fed on different host fruits were obviously different. The research results showed that Resseliella citrifrugis Jiang had the biological potential for explosion.Host plants had no effect on the pre-oviposition period of adult. However, the higher temperature could curtail the period of adult pre-oviposition.The pupa survivorship was influenced significantly by the time that the pupa was immersed in the water. Soil water content could affect the emergence rate of adult. The relation between the emergence rate of adult (Sa) and soil water content (Ws) was described as an equation Sa=﹣0.0002Ws2+0.0205Ws+0.3696.Resseliella citrifrugis Jiang preferred to the hardnesss of the same fruit. Usually the adult preferred the fruits which had a hardness of 50~70. Adult could lay more eggs in pomelo than in orange. There was a positive relation between the numbers of larvae and eggs in damaged fruits and the hardness of fruit peel.The natual population life tables of Resseliella citrifrugis Jiang reared on different fruits were constructed based on the systematically surveying data in the field. Indices of population trend of Resseliella citrifrugis Jiang populations in the orchards of pomelo, was 299.7, larger than those in orange orchards which was 208.2. The most important factor influencing indices of population trend was the factor"predator and others".The population dynamics of Resseliella citrifrugis Jiang was monitored with attractant traps was shown that occurrence peak and the population fluctuation of Resseliella citrifrugis Jiang varied with species and development periods of host plants.Several control measures including field sanitation, attractant trapping, and spraying commonly used insecticides were carried out and evaluated to against the Resseliella citrifrugis Jiang in the orchards. Field sanitation could debase the density of Resseliella citrifrugis Jiang effectively and reduce the damage rate of fruit. Attractant traps had a better control effect on Resseliella citrifrugis Jiang in the low density than in high density. The toxicities of 12 kinds of conventional chemical pesticides applied to control the Resseliella citrifrugis Jiang were determinated. Among 12 insecticides applied to control the Resseliella citrifrugis Jiang, avermectin had the highest toxicity to the adult. Trichlorphon ranked the second place. IPM practice, which contained field sanitation, attractant traps and chemical pesticides, could control the damage of Resseliella citrifrugis Jiang effetively on fruits. After IPM techniques were continuously carried out 8, 16 and 24 weeks the percent-undamaged fruit were 58.3%, 83.3% and 90.9% respectively.