Color Variations Investigation Of Harmonia Axyridis And The Influence Of Temperature And Food On Color Mottle Differentiation Of Propylea Japonica

Harmonia axyridis(Pallas) and Propylea japonica(Thunberg) are an important predator insects, which both are more common type of stain insects. And this type of multi- pigmentation phenomenon is greatly influenced by non-genetic factors, which mainly related to climate variations and geographic distribution. The Color variations diversity of Harmonia axyridis and the main factors of pigmentation diversity of P. japonica ware investigated In The Current Study. At the same time, the biological characteristics of various types of P. japonica, including its predation on aphid as well as heat resistance and tolerance to starvation, has been studied. The results of current study are expected to provide important technical guidance and theoretical significance on protection and utilization of natural enemies.The main results are summarized as follows:1. Investigation of the color variations of H. axyridis and phylogenetic analysis of 19-spot H. axyridis based on their COI geneThe results indicated that the frequency of yellow background was higher than that of black background in the five different provinces. There were 11 different colored speck populations in the samples from Helanshan area, which showing the yellow background, and among them, the 19-spot ladybeetle was the most abundant population, accounting for 28.77% of all the yellow background samples. Meanwhile, when comparing the frequencies of different spot occurred in the yellow background samples, the No.3 spot was the highest of 84.43%, while the frequency of No.? spot was the lowest of 28.77%. The phylogenetic relationship analysis showed that among the populations of H. axyridis, all the 19-spot ladybeetle are higher homologous to each other, except the populations from Yunnan province. The results indicated that the key factors that influence the formation of different color of H. axyridis was more likely to be other factors than genes.2. The effects of food on the pigmentation differentiation of P. japonicaSince using corn leaf aphid turning to bean aphid continuous feeding P. japonica as well as using bean aphids turning to corn leaf aphid continuous feeding of P. japonica, tests showed that after two generations, the population of the ancora, feliciae, dionea and tessellate can form a relatively stable rate of pigmentation differentiation, and different feeding food led to different ratio of various pigmentation of P. japonica. Ancora in the two populations have accounted for a very high proportion, of which the ratio of ancora feeding on bean aphids is about 40%, and feeding on corn leaf aphid is about 35%; tessellate account for a very small proportion of the population, about 5 %. Thus it can be seen that, the ancora ladybug populations feeding on two foods is the advantages of pigmentation type. Results indicated that foods have a certain influence on the formation of P. japonica pigmentation, which is an important factor in the formation of different proportions of pigmentation.The research of developmental periods of each pigmentation shows that different pigmentation types have no difference in egg and larva, however, there are differences in the pre-pupal and pupal stage, so we can infer that pre-pupae may a critical stage leading to the formation of different phenotypes of P. japonica. Among them, by comparison with the development duration of each phenotype, ancora are the shortest. Generally speaking, each development duration of each pigmentation feeding on bean aphid is less than P. japonica feeding on corn leaf aphid in the whole, indicating that bean aphid is more suitable for the nutritional needs of growth and development of P. japonica.3. The effect of temperature on the phenotypes differentiation of P. japonicaTemperature is an important factor of P. japonica forming pigmentation. The percentage of tessellate is significantly higher than other spots type at 15 ? condition, while it disappears with a sharp decline at 35 ?; and the ratio of ancora increases with increasing temperature gradually, which percentage is significantly higher than other type of pigmentation at 30 ? and 35 ?. It revealed that tessellate are more accommodate to low temperatures, whereas ancora might have a strong heat resistance.Comparing with the ratio of each type of pigmentation of P. japonica at the same temperature, the results indicated that it easily lead to pigmentation differentiation of P. japonica with significant proportion at 15 ?, 30 ? and 35 ?; while when it is at 20-25 ?, the percentage difference of each pigmentation variation of P. japonica is relatively small. Generally speaking, high temperature will significantly influence the pigmentation differentiation of P. japonica.4. Predation of P. japonica each type of stain resistance, heat resistance and hunger studyResults show that, the voracity and daily food consumption of biomass of ancora female were higher than dionca significantly in 24 h, which was about 53.32 and 17.01 mg respectively. There were not significant differences between every pigmentation females in the daily gain and feeding of efficiency; the feeding effectively of tessellate males was significantly higher than the other three types, which was 14.41%. Overall, the voracity, consumption of biomass, weight gain and feeding efficiency of females of these phenotypes are larger than those of males. However there was no difference in starvation resistance among four phenotypes of P. japonica. Heat resistance test results showed that the heat resistance of ancora is slightly better than the other phenotypes; moreover, after high temperature treatment of 2-3 hours, the mortality of each phenotype increased dramatically.