Ecology Adaptability Of Drosophila Suzukii (Matsumura) (Diptera:Drosophilidae)

Drosophila suzukii (Matsumura) (Diptera:Drosophilidae) is an important fruit fly and widely distributed in Asia, Europe and North America. D. suzukii heavily threatening soft fruits production in recent years. In order to understand the occurrence, distribution and damage of D.susukii population, we have carried out research on the ecology adaptability of this pest. And these results provide theoretical basis for forecasting and control this pest.The research results are achieved as follows:1?The effects of temperatures on growth and developmental of D.suzukii were examined at 15,19,23 and 25? by feeding with artificial diet. The results showed, D.suzukii were completely growth and developed in the range of 15-25?. The longest development duration of egg-adult was 35.34±0.36d(15?), while the shortest was 13.21±0.12d (23?). The lowest eclosion rate was 70.37%(15?) while the highest was 94.87%(25?). The relationship between development rate (1/days) and temperature conformed to the S curve model. The development threshold temperature and effective accumulated temperature of egg-adult were 9.26±2.33? and 196.62±38.76 day-degree, respectively.2?The cold resistance of D.suzukii was studied by measuring the supercooling point of Beijing and Yunnan populations.The results showed, the variation of supercooling point at different developmental stages of D.suzukii was examined.The supercooling point of different day-old female adults was found no significant difference, otherwise the different day-old male adult was significantly different. The range of supercooling point of female and male adult were -17.27?-18.89? and -17.59?-21.09? respectively in Beijing population, and the range of supercooling point of female and male adult were -16.11?-17.90? and -16.94?-19.96? respectively in Yunnan population. The supercooling point of 3-5 day-old mated female adults, unmated female adults, mated male adults were significantly different between two populations. We speculated that the cold tolerance of Beijing population was stronger than Yunnan population.3?Field populations of D. suzukii were monitored with sugar-vinegar traps placed in Beijing Haidian District during July 2014 to August 2015. The results showed that the population dynamics trend were similar among different altitudes in all monitoring sites. The population peak was observed from mid-July to early August. By dissecting the ovaries of female adults, we found D.suzukii would enter reproductive stage with the increasing of altitudes in the spring in all monitoring sites after one month -terminate diapause stage. The non-diapaused ovary appeared in early June. Less than 50% females were observed with non-diapaused ovaries before mid-June, while more than 50% from mid-June to mid-September. The proportions of females with non-diapaused ovaries were at low levels from late September to next May. D.suzukii entered diapause stage with the decreasing of altitudes. So D.suzukii overwintered with reproductive diapause. Trapping results showed that we trapped male adults in early spring and then female adults which indicated D.suzukii overwintered as male and female adults.4?The ripe wild fruits were collected at fixed time interval in natural mountains, and cultured for 3 weeks under the condition of 25? and R.H.70%. Thereafter the fruits were checked daily and number of D. suzukii emerged were recorded. Totally 16 wild fruit species were collected, within which D. suzukii emerged from half of them. The wild hosts of D.suzukii included Rubus corchorifolius, Prunus pseudocerasus, Ampelopsis humulifolia, Morus alba, Solanum lyratum, Rhamnus globosa, Lonicera maackii and Berberis poiretii. Raspberry(R. corchorifolius), wild cherry (P. pseudocerasus), A. humulifolia and mulberry (Morus alba) were more suitable wild hosts. The broad host range of D.suzukii implies an important reason for this pest's fast spreading and outbreak.The preliminary physiological mechanism of D. suzukii to detect hosts was explored in the present study. The sensilla on the antennae and maxillary palp of male and female D. suzukii were observed by scanning electron microscope technology. Results showed that there were three types of sensilla on flagellum of the antennae, including sensilla basiconica, sensilla coeloconica and sensilla trichodea. Only sensilla basiconica and sensilla chaetica were observed on the maxillary palp. Sexual dimorphism in structure, distribution and numbers of all the sensilla was not observed. Large and small subtypes of sensilla basiconica were further distinguished. The average length of large and small sensilla basiconica was 12.11 and 9.91?m, respectively. A number of large horizontal-bar shape pores (d=0.250?m) were distributed on the surface of large sensilla basiconica, while numerous small pores (d=0.027?m) on the surface of small sensilla basiconica. Large sensilla basiconica, a unique type of sensillum not yet observed in other Drosophila species, was only distributed on the flagellum of D. suzukii. Functioning as an olfactory sensillum, large sensilla basiconica might be evolved as a specific type of sensillum for D. suzukii to smell volatiles emitted by healthy and fresh fruits.