It was observed that testicular follicles from day 3 fourth instar nymph of the Oriental migratory locust Locusta migratoria rnanilensis cultured in TC199 or Grace's media were arrested at the stage of spermatocyte I. Addition of 10% FBS or locust testis homogenate could promote development to the stage of spermatocyte II.When cultured in media with 10% hemolymph from either the nymph of L. migratoria rnanilensis or the pupa of Antherea pernyi or Philosamia cynthia ricini, the follicles developed with massive production of spermatids and 20% sperms. Application of 20-hydroxyecdysone (20-E) and JH-I had no effect on the development in the latter case. Testicular follicles of day 3 third instar nymph, day 3 fourth instar nymph and day 0 fifth instar nymph implanted into male or female adult locusts ceased development, which was promptly recovered by injection of 20-E. By implantation, intact testis could proceed spermatogenesis and produce sperms spontaneously within 8 days without iniection of ecdysone. These results indicate that the insect hemolymph contains factor(s) that can promote the differentiation of spermatids and spermatogenesis, and the factor(s) seems to be non-species specific. The effect of ecdysteroid might not be direct, but spermatogenesis and normal differentiation of spermatids need both ecdysteroid and hemolymph factor(s), and the intact testismight have its own source of ecdysone.

Using a vital staining technique the difference of potency was observed in yolk deposition into the oocytes during vitellogenesis rjr the housefly Musca dornestica vacina. The potency of yolk deposition could be observed in vitellogenic folhces, but not in prey and postvitellogenic foliicles. The uptake of viteltogenin reached maximum during stage 6 of ovarian development (48 hours after adult eclosion) which was in coincidence with the high potency observed, while vitellogenin uptake into the ovary during the pre and post-vitellogenic stages of oogenesis was hardlydetectable. The potency of yolk deposition was significantly increased when the ovaries were incubated in the cultural medium containing JH lIl. The level of Na⁺K⁺ ATPase activity in ovarian microsomal fractions rose andfell in concert with the vitellogenic stages of oocyte development. Our results showed that the enzymic activity in previtellogenic flies 24 hours after eclosion was low; it rose and reached the peak in the ovaries of the flies 48 hours after eclosionand then decreased sharply to a very low level in the flies 72 hours after eclosion. When JH was injected into or topically applied on the body of the fly 32 hours after eclosion, the enzymic activity of microsomal fractions was found higher than that of the fly 36 hours after eclosion. However, when JH was injected into or topically applied on the body of the fly 44 hours after eclosion, the enzymic activity was found lower than that of the fly 48 hours after eclosion. When JH was added to a microsomal fraction prepared from ovaries 36 and 48 hours after eclsion, the enzymic activities were increased by 295% and 350%, respectively. When vitellogenicovaries were incubated in the medium with the presence of JH (10 μg/μl), the enzymic activity increased by 1.26 fold in the homogenate. We infer from our results that JH is related to the potency of yolk deposition and increase of Na⁺K⁺ ATPase activity so as to regulate the uptake of vitellogenin by oocytes.

We isolated from the smoky brown cockroach Periplaneta fuliqinosa a densonu cleosis virus (pfDNV) in 1990 and conducted back infection experiments according to Koch's hypothesis. The results of our study showed that the virus isolated from the dead cockroach could cause the same disease symptoms of other individuals of the same species from which the same virus could be isolated. The biophysical and biochemical properties of the virus were characterized. Purified viron is icosahedral spheroid and 20nm in diameter. Its nucleic acid is linear ssDNA with length 1.7/μmand molecular weight 1.7 X 10⁶ dalton. The structural protein is composed of 4 kinds of peptide with molecular weights 81K, 62K, 53K and 29K. According to the viral taxonomic principle, this virus belongs to densovirus in Parvoviridae. We nameit Periplaneta fuliqinosa densonucleosis virus or pfDNV. This virus might have potential value for control of the cockroach.

Melianoninol, melianone, melianol, meliandiol, meliantriol, vanillic acid, vanllin and toosendanin have been isolated from the fruits of chinaberry Melia azedarach.Melianoninol is a newly discovered compound. Their biological acivities toward the cabbage worm Pieris rapae were studied. It was found that the triterpenes melianone, melianol, meliandiol, meliantriol and toosendanin possessed strong antifeedant activities against the cabbage worm and only toosendanin showed considerable stomach toxicity to the test insect. The bio-activities of melianoninol, vanillic acid and vanillin were much lower than the other compounds.

The mosaic control with insecticides seems not suitable for insects such as aphids which reproduce by parthenogenesis and have low mobility in apterous form. In the present study we adopted another strategy by spraying unrelated insecticides at first and then exchanging or rotating the spraying in different areas in next terms.Since 1985, this strategy has been adopted to control the aphids on vegetables in Meilong, a suburban county of Shanghai. The aphids included Lip-phis erysimi pseu dobrassicae, Myzus persicae and Cavariella salicicoia. Based on bioassay and determination of a-Na esterase activity in single aphids, we found mosaic rotation of dimethoate and fenvalerate can delay the development of insecticide resistance in the above three species of aphids, as compared with continued use of dimethoate followed by continued use of fenvalerate to the point where control was impaired by resista nce.

Dendrolimus punctatus walker, just like D. Tabulaeforrnis, belongs to long-day type insect. The photoperiodic variation is the most important factor to determine the number of generations per year. The larvae of D. punctatus show typical oligopause, its diapause could be easily terminated in less strict conditions, especially in higher temperature. The results of our experiment also demonstrate that the larvae of D. punctatus the sensitive reaction to the duration of daylight received in the first instar. When larvae in early stadia were reared in the short-day condition, their growth and development usually show both temporary delay in the later instar and relative prolongation of whole larval stage. The larvae can only maintain their diapause in condition that the whole larval stage is under short-day photoperiod and optimal lower temperature. The oligopause type plays a key role in the differentiation of the life cycle in early autumn. The number of generations, especially the ratio between the second and third generations varies with the weather each year near 30°N region in China. Obviously, the fluctuation of ratio affects the population dynamics next year and thehigher ratio of third generation will cause more serious damage in forests with abundant pests.

We separated groups of worker and soldier castes from mature or immature colonies of Reticulitermes chinensis and transferred them into big vessels after sub stitute reproductives occurred and laid eggs; then observed the development and rowth of colonies regulated by substitute reproductives. The results showed that thenumbers of individuals in the separated colonies underwent great fluctuation during the substitute repreductive development, and the survival rate was about 61.5%. The substitute reproductive colonies would then develop faster and the numbers in creased after a period of recovery on the basis of better survivorship. The substitutereproductive colony developed earlier, and it developed as the development of normal colonies. In experimental conditions, a colony of 100 to 300 individuals can differentiate into winged adults in mature age in 2 to 3 years after the substitute reproductive lays eggs. In the field, the development and growth of a natural colony will not be disturbed by the replacement of reproductives because of the large number of individuals, and the annual flying activity will not stop either. The sub stitue reproductive colony can produce substitute reproductive once more, and then there may appear substitute reproductive in wing-pad form.

1. The average distance for fleas Neopsylla bidentatiforrnis and Citellophilustesquorurn sungaris to attack their hosts is less than 2 cm; the greatest distance does not exceed 10cm. Within effective attacking range, the number of blood suckingfleas is greater at short distance from their hosts than at long distance. 2. The frequency of host attack is higher in female fleas than in male, in sexually mature fleas than in newly emerged, in NeoFsylla bidentati/orrnis than in Citellophilus tesquorum sungaris, and on Mus musculus than on Citellus fauricus. 3.Within certain time after death of the host, a few fleas still （r） attack its corpse As the death time (x) prolonged the attacking fleas became fewer, and the relation may be expressed by the curve log logY=a- b·logX. 4. The time for fleas leaving from the host falls into a curve of partial distri bution which becomes more distinct when the temperature is higher. The rate for fleas leaving from the live host is as quick as from the dead host and it is almost identical for the two flea species. The average time for fleas to leave from theirhosts is negatively correlated to environmental temperature.

The structure of proventriculus of 14 flea species was studied by means of dis section, histological section and scanning electron microscopy. They include Tunga callida, Pulex irritans, Ctenocephalides felis felis, Xenopsylla cheopis, Vermipsyllaalakurt, Lentistivalius affinis, Neopsylla specialis specialis, Neopsylla dispar fuki enensis, Ctenophthalums eothenomus, Leptopsylla segnis, Macrostylophora euteles,Nosopsyllus wualis bo-seensis, Monopsyllus anisus, Syngenopsyllus calceatus. Theresults are summarized as follows. The external shape of proventriculus could be divided into four types: globular,ellipsoid, tubular and coho truncado. There are altogether twelve types of the apical shape of proventricular spines, I.e., (1) hooked, (2) curved and forked, (3)lobular, (4)acicular, (5) Spearhead, (6) flaring, (7)W-shaped, (8)big forked,(9) small forked, (10) sabre-shaped, (11) cone and (12) ligulate. There is a series of lateral teeth on the spines and the distribution ranges are one half, one-third,one-fourth, two-thirds or throughout the entire length of the spine. The proventri cular spines of the vector fleas of plague, Pulex irritans and Xenopsylla cheopis,have similar features: the spines being broad, long and strongly sclerotized; lateral teeth distributed densely and over one half of the spines. It seems that these structures favour the growth and aggregation of bacteria. However, the teeth are lacking in Verrnipsylla alakurt and Leptopsylla segnis. The proventriculus is absent in Tungs callida, a characteristic of the species.

Antennal sensilla of the ghost moths Hepialus baimaensis, H. renzhiensis and H. zhongzhiensis, were observed with a scanning electron microscope. The antennae of these three species each consists of two basal segments and 21-27 flagellar segments. The sensilla can be classified into types according to their morphology. Six types of sensilla found on the antennae of both sexes include sensilla trichodea, sen silla chaetica, sensilla basiconica, sensilla coeloconica, Bohm's bristles, and sensilla squamiformia. Moreover, sensilla campaniformia occur occasionally on male's only. The sensilla trichodea are further subdivided into two subtypes (designated A and B). Each flagellar segment possesses 2-3 sensilla sub-chaetica and 1-5 sensilla basiconica. There are two subtypes of sensilla coeloconica inciuding center pegs oflong and short pattern, the sensilla lack inward slantwise fringe pegs mainly distri buted on the flagellar segments. Bohm's bristles are distributed to the scape and pedicel segment. The general pattern of numbers and distribution of these sensilla is similar in all three species. The sensilla campaniformia have marked sexual dimor phism,

evelopmental rate, survival and age-specific fecundity of Cyrtorhinus lividipennis (REUTER), an important egg predator of the rice planthoppers, fed on eggs of white-backed planthopper (Sogatella furcifera Horvath), were determinedunder various constant temperatures from 17℃-33℃ and with different food. The developmental rate curve of this predator is in the shape of a sigmoid. The deve lopmental threshold and thermal constant were estimated to be 9.83℃ and 359.05day-degree, respectively. The generation survival (Y₁), the intrinsic rate of capacity of increase(Y₂) ,nd the total eggs laid per female (Y₁)were higher at 21℃-29℃, which can be described by following equations, Y₁= exp(-3.0031+0.5223X-0.0105X²), Y₂= -0.5971+0.0535X-0.0010X₂,and Y₃= exp(-12.0791+l.3869X-0.0278X²), whereX is the temperature in ℃. The optimum temperature for the population growth is 26.00℃ with a maximum finite rate of increase of 1.1044.On average, the number of eggs laid per female are 247.63±74.73, 237.25±18.62, 196.83±69.08 and 128.14±81.29, when fed with BPH egg, WBPH egg, BPHyoung nymph and WBPH young nymph, respectively. However, the developmental rate and longevity are not significantly affected by these prey. Egg hatchability is 59.83, 58.26, 44.35, and 46.96, respectively. Therefore, BPH egg is the best food of Cyrtorhinus lividipennis.

In Liaoning province there are 25 species of trombiculid mites belonged to 2 families, 3 subfamilies and 10 genera. A discussion on the ecological and geographi cal distribution of the mites has been conducted on the dominant species, commonspecies and rare species in four different kinds of geographical landscapes. 1. East Liaoning mountain ous area and hilly land of the peninsula: there are 22 species of trombiculids. The dominant species are Leptotrombidium (L.) orien tale and the rare species are L.(L.) apodemi, L.(L.) cricethrionis, L.(L.) linji,L(L.) gemiticulum, Neotrombicula talmiensis and Neoschoengastia (Ns.)gallinarum,etc. 2. Liaohe plain: There are 8 trombiculid species. The dominant species is Leptotrombidium (L.) palpale and the rare species are L.(L.) liaoji. 3. West Liaoning mountain ous region and hilly region: There are 8 trombiculid species. The dominant species is Neotrombicula gardellai and the rare species are Helenicula olsufievi and Chiroptella (Oudernansidium)muscae. 4. Loess hilly plateau and dry grassland: There are 2 common species of trom biculids, Walchia fragilis and Cheladonta ikaoensis.

This paper deals with the fatty acids in female midges of five species. They are Culicoides ebsoletus (Meigen), C. sinanoensis Tokunaga, C. nuiiangensis Liu,C. pulicaris (Linneaus) and C. punetatus (Meigen). The results showed that there were 12-14 major fatty acids in the female midges, of which the predominant ingredients were palmitoleic (C16:1), palmitic (Cl6:0), oleic (C18:1), and steraic(Cl8:0).Clustering analysis revealed that the Euclid distances between any two species of C.Obsoletus group was closer than that between C. obsoletus group and C. pulicarisgroup. The differences of the ingredients and contents among the five species are of some reference values to the taxonomy of Culicoides midges.