| P.canaliculata is native to the Amazon basin of South America.It has been introduced into China's Taiwan and Guangdong provinces since the 1980 s.It has been flooded in the south of the Yangtze River due to poor man-made management and wild proliferation.Because it likes to eat crops and has a large amount of reproduction,it has become a vicious aquatic animal that harms crops in China and other Asian countries.In 2003,it was listed by the State Environmental Protection Administration as the first blacklist of 16 alien species invading China.In this paper,we studied the winter hatching rate of P.canaliculata and the fertility of different habitats,and learned the breeding characteristics and influencing factors of different snails in different seasons and habitats,further determined the key areas of prevention and control and formulated appropriate control strategies.Research indicates: 1.Winter fertility of P.canaliculata in GuilinIn the middle of December 2017,the egg stalks of P.canaliculata in Guilin,Guangxi,were collected and placed at room temperature for hatching experiments.The length,width and weight of the eggs mass and egg diameter were measured.Meanwhile,the total number of eggs and incubation rate were recorded.The correlations between incubation rate and these factors were analysed,respectively.The results showed that the number of egg per egg mass in winter was 48-608,and the mean(mean±SD,the same below)was 214.14±10.45.The egg diameter was 2.31~3.32 mm,and the mean was 2.69±0.018 mm.The incubation rate was 0~93.94%,and the mean was 29.21%±3.12%.Among them,the hatched eggs accounted for 82.18% in winter(December-February)and 17.82% in spring(March),respectively.The results indicated that the eggs produced by P.canaliculata in winter mainly adopt winter hatching strategy.The incubation rate of P.canaliculata was significantly positively correlated with the total number of eggs(r=0.365,P=0.000),and negatively correlated with the egg diameter(r=-0.248,P=0.013).The number of eggs was the key to the incubation rate.The winter incubation rate was related to temperature(r=0.607,P=0.002).The incubation amount decreased with time in spring.2.Summer fertility of P.canaliculata in different regions of GuangxiWe collected the egg stalks of P.canaliculata in six habitats(rice field,waste field,ditch,pond,river,swamp)in Guilin,Laibin and Beihai,Guangxi,from July to August 2018.The length,width and weight of the eggs mass and egg diameter as well as the total number of eggs were measured.The correlations between incubation rate and these factors were analysed,respectively.The results showed that the number of egg per egg mass in summer was 48~1041,and the mean was 256.19±155.67.The number of eggs in the pond habitat was the highest,and the mean was 395.61±213.33.The number of eggs in waste field was the lowest,mean(SD)was 168.39±55.47;The egg diameter was 1.72~2.72 mm,mean was 2.17±0.17 mm,and the diameter of the ditch habitat was the largest and the mean was 2.32±0.13 mm.The diameter of the egg in the rice field is the smallest,and the mean was 2.07±0.16 mm.The comparison between the number of eggs and the diameter of the egg is: Laibin>Guilin>Beihai,The comparison of the number of eggs in habitat is: pond > river > swamp > ditch > paddy field > waste field,the comparison of egg diameter diameter in habitat: ditch > pond > swamp > river > waste field > rice field.It is indicated that the fertility of P.canaliculata in Guangxi in the summer is not related to latitude.The habitats with high water surface height or food are rich,and the number of eggs is larger and the diameter of the eggs is larger.There were significant differences in egg number and egg diameter between different regions and habitats(P<0.01),indicating that there were significant differences in prevention and control results under different prevention and control efforts.The above results indicated that the summer fertility of P.canaliculata was significantly higher than that of winter,and the egg mass produced in winter was difficult to hatch in winter.Therefore,the winter egg mass can effectively reduce the breeding base of the second year.In summer,the fertility of P.canaliculata in Guangxi is quite different,mainly related to the effectiveness of artificial prevention and control in the area.The prevention and control of P.canaliculata in the Beihai area is relatively strong,and the prevention and control of the Laibin is weak.The high-hazard areas of the snails such as the Laibin and Guilin should be strengthened.The prevention and control efforts.The fertility of P.canaliculata in rice fields,waste field and other habitats in Guangxi is well controlled,but the fertility of P.canaliculata in freshwater habitats that are diverted into farmland is still high,and the fertility varies greatly between habitats.It is necessary to wipe out P.canaliculata of the fresh water before the water is diverted into the field,and to artificially prevent and control P.canaliculata in the freshwater habitat around the farmland. |
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