Control Effect Of A Series Of Physical Control Methods On Pomacea Canaliculata

Pomacea canaliculata is widely distributed in lots countries and regions and seriously harms local agricultural production and ecological environment.At present,the common prevention and control of P.canaliculata mainly depends on chemical control and followed by biological control.But if only using chemical or biological methods on the prevention and control of P.canaliculata,there will be lots of problems such as serious environmental pollution,management difficulty and high cost.On-going physical prevention and control methods generally are the techniques by collecting the snails and their egg massed and then destroying them together,irrigating and setting up interception network at water gap,using attractant to gather adult snails,and so on.Although these measures have advantages of little harm to environment,easy application,convenient management and low cost,it can assist the chemical and biological measures well to reduce the damage of the snails.However,at preseant,less is known about the actual effects and its related quantitative study on these physical measures,For this point,we designed different physical methods involving inserting bamboo,soaking egg mass,putting attractants and setting up interception network,and so on.The effect results of above physical methods to control P.canaliculata are obtained:1.The bamboo slips inserted in the paddy fields can lure the P.canaliculata to spawn on them and the quantity of egg masses tended to decrease in the rice reviving stage,jointing stage and heading stage.High trapping efficiency can be obtained by inserting the bamboo slips at the position of 1 m far from paddy ridge,with the distance of 1 m between slips,30-50 cm high above the paddy water.Specially,in the area with high density of P.canaliculata,the 30 cm distance between bamboo slips should be used to obtain efficient trapping of egg masses.2.The hatching of P.canaliculata egg masses can be influenced by being soaked at daytime and draining off water at night.If the mass is one-day old,the date of that the first egg hatches will be postponed,the duration of hatching will be extended first and then be shorten,the rate of hatching will reduce when increasing the times of the mass being soaked.The result shows that if egg masses are under 4 days old,the more times they are soaked,the more adverse effect the hatching will get.If egg masses are older than 4 days,after being soaked once,the date of that the first egg hatches doesn't have significant difference compared with the control group,the duration of hatching reduces,but the hatching rate decreases more slowly than that in control group.When egg masses are 7 days old,the duration of hatching reduces as the water-soaked times of egg masses increase,but the hatching rate has no difference with the control group.In practical application,when egg masses are fresh,if they are soaked as long as possible,they would experience the greatest damage3.Among the different kinds of food attractants put in the water boxes,fruit peel can attract P.canaliculata in the shortest time.Lettuce leaves can gather a large amount of P.canaliculata in the first 60 minutes.In other group of experiments,newspaper can hardly attract P.canaliculata in the first 60 minutes,and after 60 minutes,the P.canaliculata came to eat newspaper gradually.For the leaves of banana is tough and have a poor taste,it can hardly attract P.canaliculata in any time.When the depth of water is 0 cm,all the four kinds of attractants can attract most of the P.canaliculata.When the depth of water is 15 cm,fruit peel can attract the most P.canaliculata.When the depth of water is 30 cm,newspaper can gather most P.canaliculata.When the P.canaliculata is of high density of 0.81 /L in each box,the feeding rate of lettuce leaves and newspaper is higher than that of the other two attractants.When the P.canaliculata density is 0.40/L in each box,the feeding rate of lettuce leaves is high than that of the other levels of density.When the P.canaliculata density is 0.20/L in each box,fruit peel has the highest feeding rate.4.Interceptions placed at different location have different effect on restricting P.canaliculata.When the interception is set at the water inlet,the number of P.canaliculata intercepted is significantly higher than that when the interception is set at the water outlet.The smaller aperture interceptions,the better intercepting effect they have.Interceptions with aperture at 0.5 cm can intercept P.canaliculata of each size level.Interceptions with aperture at 1.5 cm can intercept all the P.canaliculata of large size and part of medium and small size.Interceptions with aperture at 2.5 cm can only intercept few P.canaliculata.At low temperature,the number of P.canaliculata on the soil surface is significantly lower than that in the puddle and soil layers when the soil is not covered by water.Burying screen meshes in the soil and puddle can gather some P.canaliculata.The number of P.canaliculata gathered by screen meshes buried in puddle is significantly higher than that buried in the soil.