| Semiothisa cinerearia Bremer et Grey (Lepidoptera:Geometridae), a phyllophagous insect which mainly damages some excellent street tree species such as Sophora japonica, Sophora japonica'Golden Stem',and Chinese pagoda tree. In recent years, the damage of Semiothisa cinerearia is increasing. We systematically studied biology, including morphologic characteristic, behavior, life history, population dynamics and happening regularity, including the effect of the temperature, humidity, photoperiod and different plants on the developmental periods of Semiothisa cinerearia; Identification of instars of larva is based on feeding in the lab and surveying in the field; the development threshold temperature (DTT) and effective accumulative temperature (EAT) of Semiothisa cinerearia were studied under five constant temperatures in the laboratory. The main results are stated briefly as follows:1,Morphologic characterThe morphological characteristics in every stage (egg, larva, pupa, adult) of Semiothisa cinerearia were studied and described.2,Behavior habitsThe egg-laying habits, feeding habits, pupation habits and adult habits and the adult life span of Semiothisa cinerearia were studied and described.3,Identification of instars of larvaThe body-length and head-width of different instars were measured. The results show that the larva has 7 instars. The average proportions of every two head-width of neighboring instars is 1.415.4,The life historySemiothisa cinerearia occurs 3 generations in Shenyang one year. It overwinters in soil to the depths of 3-5 cm by pupa.5,Field Population Fluctuation Patterns The mainly harmful period is from June to August. It had two peak in a year in Shenyang city, and the peak appeared in mid-June and late-July respectively. The population trends towards decrease after August. The old larva begin to pupate to overwinter in September.6,The effect of the temperature on the growth and development of Semiothisa cinereariIn the range from 20 to 30℃,the durations of various stages were shortened with the increase of temperature. At 32-33℃, adults and 1-5 instar larva mortality were higher. With the least square method, the DTT and EAT were calculated. The theoretical numbers of generations are predicated as 3.4-3.6 in a year in Shenyang, which was consistent with the records of reality.7,The effect of the humidity on the growth and development of Semiothisa cinereariCarry out five relative humidity (RH) 35%,45%,55%,65% and 75% in Climate incubator, with the temperature setted at 25℃, photoperiod of L:D=12:12.Under the 65% RH conditions, the durations of egg, larva, pupa, and generation were shorter. The durations of egg, larva and generation were the longest under the 35% RH.8,The effect of the photoperiod on the growth and development of Semiothisa cinereariEvery stage of Semiothisa cinerearia is dealt with 5 sorts of photoperiod of light to dark at 0:24,10:14,12:12,14:10,16:8 under the condition of 25℃,RH 65-75% indoor. The results showed that the eggs, larva and adults have the best state of survival rate at 14:10. The duration of larva development was the shortest when the L:D was 16:8, More longer under light, more faster for larva development. The percentage of moth emergence was the highest and the duration of pupae was the shortest in the 0:24 treatment.9,The effect of the plants on the growth and development of Semiothisa cinereariIn the process of breeding with the leaves of Sophora japonica,S.japonica Aurea,Robinia pseudoacacia, it is found that Semiothisa cinereari preferfed leaves of S.japonica Aurea than Sophora japonica's. In this paper, the eating capacity of every instar larva were recorded in detail.
|
PDF Full Text Request