Study On Biological Characteristics And Low Temperature-resistant Of Harmonia Axyrmonia On Different Geogryphic Populations

Harmonia axyridis Pallas is an important predatory insects to control pests on a variety of effects, it play an important role in biological control.Insect survival and reproduction are related to temperature, they have different adaptive strategies under different environmental conditions, than leading to its population appears geographical differentiation.In order to study the biological characteristics and the differences in low temperature capacity of Harmonia axyridis Pallas of different geographic populations, in laboratory conditions(temperature 25±1℃, relative humidity 65±5%, light L: D=16:8), Aphis craccivora Koch as feeder host, breeing and establish populations of Jilin, Henan, Guizhou. Research on the biological characteristics of the three population by the method of comparative, and tested the survival rate and reproductive characteristics after variable temperature refrigerated and thermostats refrigerated, the main results are as follows:1.By comparing the biological characteristics of three populations of Harmonia axyridis Pallas:(1) Adult size: there is not significant difference to female and male body length and width of the three population;(2) Development duration:the duration of egg is significantly increased with increasing latitude(F2,42=277.105, P<0.001), the larvae duration(9.01d) and pupae duration(4.47d)of Henan population is significantly higher than the other two populations;(3) Fecundity: the three populationa of Harmonia axyridis Pallas have a strong fecundity, preoviposition increased with increasing latitude, preoviposition is 13.65 d of Jilin population, is higher than Henan population(11.24d) and Guizhou population(8.29d); Jilin population egg laying amount by single female can reach 1223.53 eggs, is higher than the other two populations;(4) Life: female life of the three populations has increased with increasing latitude, life between male and female of Jilin populations have no significant differences, but the male life of Henan and Guizhou population were significantly higher than female life.2.Compared survival, fertility, feeding amount of the three population after variable temperature refrigeratd, the results showed that:(1)Survival rate: female and male survival rate of the three population increased with increasing latitude. Male and female survival rates of Jilin population were 70.88% and 63.73%, significantly higher than Henan population(64.21% and64.21%) and Guizhou population(51.80% and 48.38%);(2) Fecundity: females of three populations can lay eggs after treat by variable temperature refrigeratd, preoviposition increasedwith increasing latitude, but there was no significant difference among three population;(3)Feeding amount: consumption: continuous feeding 15 d after cold treatment, three populationscan usually can eat, daily feeding consumption is 219.04 of Jilin populations,is lightly lower than the Henan population(234.21) and Guizhou population(234.17), but there is not significant differences among populations daily food consumption.3.Test the survival rate, reproductive characteristics of the three populations after treatment by constant temperature refrigerated, The results showed that:(1) survival rate among populations: survival rate decreased with increase of the number of cold days; the survival rate of Jilin population was significantly higher than the other populations after treatment by 3℃; the survival rate of Guizhou population was significantly higher than the other populations after treatment by 6℃;(2)survival rate among populations: at the same period of low temperature treatment, the survival rate in 3℃ higher than 6℃of Jilin population, the survival rate in 6℃higher than 3℃of Henan population and Guizhou population;(3)fecundity among populations:there is not significant difference about egg laying amount and preoviposition period of three populations in same storage time and temperature.(4) fecundity in populations: there is not significant difference about egg laying amount and preoviposition period of the same populations in same storage time.