Response characteristics of the descending interneurons in the honeybee (Apis mellifera) to stimulating light and their relation to the different horizontal direction of the stimulating light were studied with electrophysiological exocellular recording method. The light stimulus elicits strong on- and off-reponses and weaksustained response. The responses of descending interneurons depend on the intensity of the light; when the luminance gets higher, response becomes stronger. Based on the response characteristics of descending interneurons elicited by light stimuli with different projecting angles, the most sensitive range is approximately in an angle of 40 degrees.

Oostatic hormone is one of the key factors regulating the cyclicity ofovarian development in most insects. In housefly, Musca domestica vicina, when the first cycle oocytes are in vitellogeic stage or postvitellogenic stage, the second cycle oocytes cannot develop into vitellogenic stage, and there is no vitellin deposition in the second cycle oocyte. When semipurified oostatic hormone extracted from matureovary was injected into flies 12 hours after emergence with a doseage of one pair ovary/fly, oocyte development was obvious inhibited. Twenty-four hours after the injection, the revitell'ogenic development of oocyte was inhibited. When vitellogeninsynthesis was initiated, the injected oostatic hormone inhibited vitellogenin synthesis in the fat body, lowered vitellogenin titer in the haemolymph, and thus caused the detay of vitellin deposition in the oocyte. Vitellogenin uptake was not inhibited by the oostatic hormone. EDNH could restore the development of oocyte inhibited byoostatic hormone. Oostatic hormone is not species-specific.

With the method of probit analysis, we estimated the realized heritability (h²) of resistance to fenitrothion in the rice stem borer (Chilo suppressalisWalker). The results demonstrated that tolerant phenotypes in the observed popula-tion are lowly heritable (h²=0.277) and that the population has no potential forhigher increase in tolerance to fenitrothion. Under the circumstances of laboratory selection, the population has to propagate about 6-12 generations to acquire 10-fold resistance to fenitrothion, and it takes a longer time (16-35 generations) for thefield population to do so. Our results suggest that the risk to developing high resistance to fenitrothion is small and thus, fenitrothion should be considered as an effective chemical agent in the system of insecticide resistance management for the rice stem borer.

We have propagated Pseudaletis unipuncta granulosis virus (synergistic strain) in larvae of Pseudaletis separata and have conducted quantitative evaluation of the enhancement of the P. unipuncta granulosis virus-Ps (PuGV-Ps) on the NPVs of P. separata (Ps), Heliothis armigera (Ha) and Agrotis segetum (As). The results show the PuGV-Ps enhanced PsNPV, HaNPV and AsNPV infections in their original host insects. The high proportions (55%-85%, 30%-80%) of enhancement were observed in the PsNPV and HaNPV assays, and the median one (15%-35%) was obtained in the AsNPV-PsGV system. A synergistic factor (PuSF-Ps) has been isolated from the PuGV-Ps system using gel filtration technique. When PsNPV polyhedra were mixed with 250 ng PuSF-Ps, the value of enhancement increased by about 80%. The molecular weight of the synergistic factor was determined with Sephadex 150 column (1.6cm× 90cm) to be about 160k.

An investigation of long distance migration of the greenbug Schizaphis graminum (Rond ani) was conducted in Ningxia from 1971 to 1987, and the following relevant evidences have been obtained. When the immigration peak of the greenbug alates to spring wheat fields occurs, emergence of Mates from tlie local overwintering population in grassplots has ended; Mates carrying virus (BYDV) were captured in the fields in Ningxia m early spring, whereas none of the local overwintering aphids carried the virus; and incidence of BYDV in Ningxia in spring correlated closely with the abundance of the overwintering greenbug in south-easternwinter wheat region, but not correlated with Ningxia overwintering population abundance. It is concluded for the first time that there is a long distance migration of the aphid and the immigrant aphids are the main sources of the greenbug inNingxia in spring time. Regions which may be the source areas for the immigrant aphids to Ningxia are speculated. Ecological implications of the immigrant aphids, function of the southeasterly wind and the relevant problems to be studied in future are discussed.

Utilization of sugars by females of Sogatella furcifera (Horvath)(Homoptera: Delphacidae) from rice plants of different age groups of resistant Rathu Heenati (RHT) and susceptible Taichung Native 1 (TN1) was studied by measuring honeydew excretion, sugars in the honeydew, total sugar contents in rice bleeding sap, and changes of a-glucosidaSe activity in planthopper individuals. Insect feeding decreased with the increase of plant age of both RHT and TN1 varieties. Regardless of varietal susceptibility, total sugar content in rice bleeding sap increased with increase in plant age. Analysis of honeydew by high performance liquid chromato graphy (HPLC) revealed that quantities of sucrose and fructose were significantlytess in honeydew excreted on RHT than on TNI plants, indicating that S. furcifera ingested less but utilized well the phloem sap from RHT as compared with TN1.Glucosidase activity of S. furcifera after feeding on RHT was significantly lowerthan on TN1, and was positively correlated with changes in insect body weight,There may exist two independent mechanisms which control ingestion of food, and digestion and absorption of the ingested food in S. furcifera.

A laboratory evaluation of food consumption and utilization by larvaeof Mythimna separata (Walker) under different rearing densities (1, 15, 30larvae/jar) was made from the beginning of the fifth and sixth instar of larvae to the prepupal stage on the corn seedling. The food consumption, whether on daily or total basis increased with the larval density increased indicating that crowding may stimulate food intake of the larvae and hence enhance their damage on crops. This trend is also conspicuous in the amount of voided faeces. The growth, as measured by daily larval fresh weight was the highest at the density of 1 larva/jar, followed by 15 and 30 larvae/jar, due to the lower efficiency of approximate igestibility (AD) and lower efficiency in converting ingested food into body matter (ECI) in the higher rearing densities. Presumably, the lower AD and ECI should be the bases of the major reasons for the smaller size of M. Separata in the crowded conditions. It should, however be noted that all these difference would become insignificant as the period of larvae separating from the given rearing density become longer.

The foraging behavior of the lady beetle Propylea japonica to wards the cotton aphid Aphis gossypii was systematically examined. The results indicated that the foraging behavior of the lady beetle changed gradully at different aphicd dersities. When tile aphid density changed from low to high, the lady beetle switchedfrom active search to ambush search, and when the aphid density changed from high to low, the lady beetle switched from ambush to active search. Such behavioral change resulted from the integrated effect of the amount of food alreadly present in the gut and the encounter rate with aphids. We suggest that better control effect of the lady beetles on cotton aphids might be gaind by regulating their density ratio.

According to the population of Meriones unguiculatus, flea index and data of seven meteorological factors in Etuoke Banner and Etuokeqian Banner, Inner Mongolia Autonomous Region in 1975-1989, models of linear and curve regression between the flea index and the population of M. unguiculatus were obtained respec tively. The optimum regression subsets of multipic linear regression were conductedbetween the flea index and meteorological factors. And then, the model of standard regression was also obtained. The canonical correlation analysis explained such rela tions of the flea index and their hosts population to the meteorological factors. The conclusions are as follows: The population of M. unguiculatus was the main factoraffecting flea index. The meteorological factors exerted summing-up influence on the flea population, and yearly average relative humidity and temperature in the field were the two main factors with influence. Moreover, the flea index was influenced by the meteorological data greater than the population density of their hosts.

The ecological functions of chironomids on the development of lakeeutrophication were studied through examining the influence of chironomid larvae on nitrogen and phosphorous release in sediment. The results showed that chironomid larvae stimulated visible algal growth by increasing nitrogen and phosphorous release from sediment to overlying water. There is an important relationship between such an ecological function and the development of lake eutrophication.

In the present paper, three new genera and three new species fromXizang, China, are described. All the type specimens are deposited in ShanghaiInstitute of Entomology, Academia Sinica.

The present paper describes a new species of walking stick, whichwas collected from Longsheng of Guangxi Province. The type specimen is preservedin the Insect Collection of Beijing Forestry University. All measurements in descriptions are in mm.

The present paper describes a new record genus from China, NanatlkaYoung, 1986 and five new species of the family Cicadellidae, which were collectedfrom Yunnan and Sichuan Provinces. The type specimens are deposited in the Institute of Zoology, Academia Sinica.

Two new species of Seymnus Kugelann from China are described in the present paper. Type specimens are deposited in the South China AgriculturalUniversity, Guangzhou.

This paper deals with description of the eggs of thirteen species ofNoctuidae. The eggs were photographed with SEM from different aspects to showtheir shape and for the purpose of being used as taxonomic characters.

The present paper is a revision of the genus Topomyia of China.Totally 16 valid species, mainly from Yunnan and with a few from Guizhou, Guangxi, Xizang and Taiwan, including 3 new species, are mentioned. The 16 species, belonging to 2 subgenera, are as follows: baolini, bifurcata, hirtusa, inclinata, lindsayi, longisetosa, margina sp. Nov., svastti, sylvatica and zhangi of subgenus Topomyia and bannaensis sp. Nov., cristata, dulongensis sp. Nov., houghtoni, mengi and yanbarensis of subgenus Suaymyia. Keys for the identification of the above speciesare given. All types are deposited in the Institute of Epidemiology of Yunnan Province.Beijing 100850)Abstract The present paper is a revision of the genus Topomyia of China.Totally 16 valid species, mainly from Yunnan and with a few from Guizhou, Guangxi, Xizang and Taiwan, including 3 new species, are mentioned. The 16 species,belonging to 2 subgenera, are as follows: baolini, bifurcata, hirtusa, inclinata, lindsayi, longisetosa, margina sp. Nov., svastti, sylvatica and zhangi of subgenus Topomyia and bannaensis sp. Nov., cristata, dulongensis sp. Nov., houghtoni, mengi and yanbarensis of subgenus Suaymyia. Keys for the identification of the above species are given. All types are deposited in the Institute of Epidemiology of Yunnan Province.

The melanderi species-group established by Wheeler (1949) include 4species, Drosophila ordinaria Coquillet from southeastern Canada, Alaska and eastern USA; D. cameraria Hadiday from Europe; D. makinoi Okada from Japan and Korea, D. neomakinoi Gupta et Singh from India. The diagnoses of the melanderispecies-group are: 1. Secondary surstylus present; 2. Anal plates ventrally with modified teeth and setulae; 3. Hypandrial apodeme broader than long; 4. Anterior parameres completely separated from hypandrium. This paper deals with three new species of melanderi group. All specimens are collected in same place Deqen(Hengduan Mountains). This shows sympatray, implying the original area of melanderi group. All types are deposited in Kunming Institute of Zoology, AcademiaSinica.

This paper is the fourth part of a review on recent progress in insectmolecular biology. It summarizes the current understanding of the molecular basis underlying insecticide resistance conferred by enhanced detoxication (through activities of hydrolases, cytochrome P450, glutathione S-transferase) and by reduced target sensitivity (changes in AchE, sodium channel, GABA receptor). At least some of the molecular mechanisms of resistance, namely gene amplification, point mutation, and trans-acting regulatory element, have been proven correct.