| The interaction between exotic species is one of the hot spots in biological invasion. The study on the interspecies relation between exotic species provide important evidence for the invasion process of the exotic species, prediction of the distribution areas and damages and propose reasonable prevention and controlling measures. Leptinotarsa decemlineata Say and Solanum rostratum Dunal are two invasive species with great harm have successfully invaded and sympatric distributed in Xinjiang. The former invaded earlier than the latter, and the latter is the former’s original host. In this study, we select L. decemlineata and S. rostratum as the main research objects, compared with sympatric distributed Solanaceous host plants such as potato. The investigation of sympatric distribution areas of two invasive species and comparison of L. decemlineata annual life history history, developmental duration, reproductive capacity, survival rate of overwintering generation, feeding and oviposition preferences on S. rostratum and on other Solanaceous host plants, explore the effect of S. rostratum invasion on distribution, life history and preferences of L. decemlineata, and discuss the potential damages of sympatric distribution of two species on potato production. The main results and conclusions are as follows:(1) In Xinjiang, L. decemlineata distributes in oasis, desert and desert grassland located in the area from Huocheng County to Mulei County in the northern Tianshan Mountain, mainly distributed in oasis and the main host plant is potato and Solanaceae plants. S. rostratum distributes in oasis, desert and desert grassland located in area from Shihezi city to Turpan city in the northern Tianshan Mountain. The areas from Urumqi city- Changji city are the sympatric distribution area of these two invasive species. Two sympatric distributed sites were found in each of oasis, desert and desert grassland in six sympatric distributed sites of two invasive species, which suggesting two species were co-existence in three different habitats in northern Xinjiang. In sympatric distribution areas, the mean number of L. decemlineata on per S. rostratum plants at S. rostratum flowering stage, in oasis is higher than the in desert and desert grassland(P<0.05). It reveals that the oasis is the most suitable habitat for the sympatric distribution and damage of the L. decemlineata, S. rostratum.(2) In the sympatric distribution areas of L. decemlineata, S. rostratum and potato, the phenology of S. rostratum begins 10d(2012) and 13-20d(2013) earlier than potato, and ends 30d(2012) and 13-19d(2013) later. It leads to the longer annual life history of L. decemlineata on S. rostratum than on potato 30-40d(2012) and 28-42d(2013), and more half generation per year on S. rostratum(two and a half generations / year). In spring, earlier appeared S. rostratum provide food source for overwintering L. decemlineata; in autumn, later wilted S. rostratum prolong the feeding time of L. decemlineata, postpone the overwintering beginning, shorten the overwintering duration in soil. Starvation tolerance of overwintering adults from S. rostratum plants was greater than that from potato plants before and after the winter(P<0.05). It suggests that S. rostratum can provide enough food for the overwintering L. decemlineata to enhance its starvation tolerance and improve the survival rate of overwintering adults. Generation overlapping frequency of L. decemlineata were 3-5 times(2012) and 4-8 times(2013) more on S. rostratum than on potato, suggesting that S. rostratum could increase the L. decemlineata overlapping generations, benefiting the rapid increase of populations.(3) The fecundity of the L. decemlineata was significantly different in five Solanaceae plants(P<0.01); and number of L. decemlineata eggs on S. rostratum were 1.5, 12, 12 and 25-fold larger than on potato, tomato, eggplant, S. nigrum. The survival rate and fecundity of L. decemlineata offsprings on S. rostratum were higher than on potato, tomato, eggplant, S. nigrum(P<0.05; P<0.05), while the developmental periods were shorter(P<0.05). L. decemlineata laid eggs on S. rostratum, most suitable for development and reproduction of L. decemlineata offspring that could increase their populations. The results support the preference- performance hypothesis of the plant-animal interaction.(4) The feeding preferences, feeding level and feeding leaf area of L. decemlineata have significant differences in five Solanaceae plants(P<0.01; P<0.01; P<0.01), especially the S. rostratum that means it has the strongest attraction for L. decemlineata.L. decemlineata eats the leaves and fruits of S. rostratum and it could directly reduce the fruit and seed production, and seed viability(P<0.05), reducing reproductive capacity of S. rostratum, leads to depression to further population expansion of S. rostratum.Invasion of S. rostratum promote the further invasion of L. decemlineata by providing food for L. decemlineata, expanding the distribution range, extending the life history, enhancing tolerance of starvation, increasing overlapping generations, shortening the breeding time and increasing the survival rate and fecundity. However, L. decemlineata reduces the reproductive capacity of S. rostratum in certain level by feeding on it. In S. rostratum and L. decemlineata sympatric areas, S. rostratum expanding the distribution range of L. decemlineata; In S. rostratum, potato and L. decemlineata sympatric areas, S. rostratum increasing the survival rate and fecundity of L. decemlineata, then benefit to disaster of L. decemlineata, increase the harm of L. decemlineata on potato production. Therefore, it would be an invasive antagonistic relationship between two invasive species, L. decemlineata and S. rostratum. |
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