Bionmics And Ecological Characteristics Of Two Lepidopotera Pests On Caragana Korshinskii Kom

Caragana korshinskii is one of the most important plant species for the vegetation restoration and ecological reconstruction in desert and semi-desert areas in the northwest of China. It has also the value integrated exploitation and utilization. In recent years, two Lepidoptera pests, Neolycaena tengstroemi (Erschoff) andChiasmia saburraria Richardsi(Prout), were newly found in Ningxia when a pest survey on Caragana korshinskii Kom was conducted in Luoshan national nature reserve. These two pests on the host plants Caragana korshinskii Kom can cause harm to the host plant during the larvae period when they outbreak, and the growth of host plant can be damaged severely, and even the host plant will be killed at the end. However, the information about biology and ecology of Neolycaena tengstroemi and Chiasmia saburraria richardsi was limited in China and worldwide. In this paper, we have conducted systematic researches on the biology and ecology of Neolycaena tengstroemi and Chiasmia saburraria richardsi. The main results were showed as follows:1. The morphology, life history and biology behavior of Neolycaena tengstroemi and Chiasmia saburraria richardsi were investigated systematically through the combination method of field investigation and lab rearing. The biology characteristics of these two peats had been first systematically revealed.Neolycaena tengstroemi (Erschoff) has only one generation per year in Ningxia. This butterfly begins to survive summer and winter as an egg which is dispersed on the foliar mud of the branch of the host plant Caragana korshinskii Kom. The eggs of pest begin to hatch in late march the following years, while the host plants start to generate. Duration of the larvae period is from late March to mid-May. In early May, the last instar larva begins crawling down to litter layer or the surface soil around the host plant root to pupae. The prepupal period is four days, and the pupal stage is about 15 days, the larvae pupate at the beginning of May. The adults emerge in the late May, and it can fly to 3 meters, but it fly relative slowly, the peak quantity of adults emerge at the beginning of June, however adults can be still seen at the beginning of July. The adults start to oviposit in the first days of June, and eggs stage is about 295 days.Chiasmia saburraria richardsi (Prout) have two generations per year in Ningxia. And two generations are overlapping, coterminous, and this phenomenon of generation overlapping is very severity. It begins to overwinter as a pupa which is deep between 10cm and 30cm in the soil from the late August, overwintering adults emerge in mid-May with the peak of emergence in mid-June. Two days after emergence, adults can mating and lay eggs. The eggs and larvae of the first generation emerge in the late May, the last larvae of the first generation begin to pupate in the late July, the duration of pupa period is about 10 days, the pupa of the first generation come into the eclosion period, the eggs and larvae of the second generation emerge in the late July. The last larvae of second generation begin to pupate in late August, and the duration of pupal period is about 160 days which is much longer than the first generation.2. The distribution and damage degree of Neolycaena tengstroemi and Chiasmia saburraria richardsi were studied. The eggs and larvae of Neolycaena tengstroemi are mainly distributed on the branches of the host plant Caragana korshinskii, mostly from 0 to50cm, and the pupa is distributed in the litter layer and the surface of soil around the root of Caragana korshinskii, mostly from 0 to 30 cm. The larva of Chiasmia saburraria richardsi is also mainly distributed on the branches of the host plant Caragana korshinskii, mostly from 0 to 30 cm, and the pupa is distributed in the soil around the root of Caragana korshinskii, mostly far from 0 to 30 cm and deep between 10 and 30 cm.3. The ecology of Neolycaena tengstroemi and Chiasmia saburraria richardsi were investigated systematically. The study was made mainly on the spatial distribution patterns and sampling techniques of Neolycaena tengstroemi and Chiasmia saburraria richardsi. Eggs and larvae of Neolycaena tengstroemi and larvae of Chiasmia saburraria richardsi are all spatially aggregated in their distribution range, and fit the negative binomial distribution. The theoretical sampling limit formula and sequential sampling decision-marking mode of eggs and larvae of Neolycaena tengstroemi and larvae of Chiasmia saburraria richardsi were established based on the information from the spatial pattern. Moreover, the optimal sampling was determined for investigation, prediction and controlling of these two pests.