Two ribozymes, ribozyme N-1 and ribozyme N-2, were chemically synthesized, which are designed for blocking the expression of polyhedrin gene of Autographa californica nuclear polyhedrosis virus (AcNPV). In vitro, they are able to specifically and effectively cleave the target mRNA fragments which were transcripted from part of polyhedrin gene. Results showed that the percentage of cleavage was increased when the temperature or time of incubation was increased or higher concentration of ribozyme was used. Ca²⁺, Mn²⁺ can substitute Mg²⁺ as the neces sary divalent cation for the cleavage reaction by ribozyme.

Noctuids-sensitive parasporal crystals were dissolved and protoxins were activated with trypsin or gut juice of larva of Prodenia litura and Bomhyx mori. Toxic polypeptide produced by digestion of B. mori gut juice or trypsin was toxic only to B. mori, whereas toxic polypeptide pro duced by gut juice of P. litura was toxic to both P. limra and B. mori. Coleoptera-sensitlve δ-endotoxins of 70 Kd and 50kD could not be degraded completely by trypsin or gut juice of Mythimna separata. SDS-PAGE and chromatography showed that the 130 Kd protoxin was degraded to P. litura- specific toxins of 70 Kd and 75 Kd by P. litura gut juice, B. mori-specific toxins of 62 Kd and 65 Kd by B. mori gut juice and B. mori-specific toxins of 65 Kd and 68 Kd by trypsin. WhenP. litura-specific polypeptides of 70-75 Kd were subsequently treated with B. mori gut juice,the resulting polypeptides of 62-64 Kd were no longer toxic to P. litura but acquired B. moritoxicity. Reversely, protoxin treated first with B. mori gut juice or trypsin and then with P.Litura gut juice, resulting 62-65 Kd polypeptides were toxic only to B. mori. It was shown that the action of proteases of B. mori gut juice was similar to trypsin but different from proteases of P. litura gut juice.

Newly molted male and female 5th-instar larvae of gypsy moth, Lymantria dispar, were separately infected with a LDMNPV suspension of known concentration: 1.3× 10⁴-10⁶ PIB,/ml.The experimental results demonstrated that sublethal doses of LDMNPV not only caused dif ferent mortalities of male and female larvae,but also affected their pupal number and sex ratio which was in favor of male. The EM pictures of ultrasection showed that fat body,trachea, ganglia, brain, ovary and prothoracic gland of female moth were infected by LDMNPV. Little data about brain, ovary and prothorcic gland infected by NPV is available. Polyhedra existed in nuclei of infected cells display strong reaction with antibody of LDMNP using immunogold-labelled technique.

Adipokinetic and hyperglycemic hormones have been discovered in several insects, but no approach has been made to homopterans. In this study, crude extract of adipokinetic hormone was isolated from an aphid, Macrosiphum sp., and its biological activities were tested. Infecuon of the crude extract equivalent to 20 mg aphids mto Schistocerca gregaria and Pertptaneta americana caused increases of lipid and sugar levels in haemolymph by 131.03% and 60.43%, respectively. The results showed that the extract had a much higher adlpokinetic activity than hyperglycemic effect. The activities could be suppressed by treatment with endopeptidase, pyroglptamyl aminopeptidae or high temperature.

The body colour variation in cotton aphids (Aphis gossypi) of the natural population developed from zygotes on different host plants and of the population raised from aphids reared individually in the laboratory were investigated. Results showed that the body colour of the aphids would remain unchanged as the new-born aphids during their whole Ide within each generation whatever the populations, the individuals, the hosts and the nutritional conditions may be. But among the successive generations,the body colour changed gradually from green to yellow with rising temperature and from yellow to green with decreasing temperature. X² test demonstrated that there was no correlation between the body colour variation and the nutrients, the host plant, the light and the culturing condition. The variation only correlated to temperature. This is in accord with the phenomenon that under different environmental con dititms the same genotype expresses differently to give rise body colour polymorphism. However, a few dark yellow colour aphids found on the host plant Hibiscus syriacus dis played no change in colour with temperature during their development and transformation to migratory form. It seems there exists a genetic polymorphism of body colour among the aphids. This was proved by the results of observation on embryo development and analysis of karyotype of the insect.

A comparative study was conducted for the first time to test the cross immune reaction between rabbits sensitized by bites of lxodes sinensis and Haernaphysalis bispinosa. When H. Bispinosa fed on the rabbits which had been attacked for three times previously by I. Sinensis,its body weight increased by 143.12±32.67 mg. But when it fed on the controlled rabbits notattacked previously by ticks the body weight increased by 181.30± 44.35 rog, which showed significant difference in comparison with the former case. The homogenates of I. Sinensis and H. bistnnosa snowed 24 and 22 proteins and protein subunits respectively in the SDS-PAGE patterns. The main bands of I. Sinensis were 6 and their molecular weights were 142, 105, 94,66/65, 64 and 58 KD. The main bands of H. bispinosa were 5 and their molecular weights were 215, 114, 105, 66/65 and 52 KD. The number of protein bands of H. bisplnosa and I.Sinensis were recognizable by the sera of rabbits attacked by H. bispinosa and by I. Sinensis,and they both contained an immunoblot, the common antigen band identified which is a 105KD protein band. It is concluded that the immune response of the rabbits attacked by these two ticks stimulates the production of antibodies which show cross immune reactions and the 105 KD protein may serve as the antigen common in both ticks.

The content of protein and activities of carboxylesterase (CarE) and polyphenol oxidase in larval stage of the massonpine caterpillar Dendrolimus pinctatus Walker showed positive correlation with age increase in instars. After treatment with fenvalerate, the content of protein and activity of Care increased during exciting stage but reduced to normal level during inhibitory stage. The activity of polyphenol oxidase showed less change. The activity of Dnase increased with age from third to fifth instar, but decreased in the sixth instar. The activity of Rnase showed negative correlation with the increase of larval instars. After applying fenvalerate, theactivity of Dnase began to drop and that of Rnase rose during exciting stage, but dropped to normal level during inhibitory stage. The results showed correlations among protein, nuclease and Care with insecticide tolerance, except polyphenol oxidase. Based on the results of toxicity test, it is clear that the insecticide tolerance of massonpine caterpillat increased with larval instars. The lethal dosage of fenvalerate to larvae in fifth instar is 2.8 times That to larvae in third instar and that to larvae in sixth instar is 2.3 times that to larvae in fourth instar. It will be rational to carry out chemical control before larvae in fourth instar.

The primary follicles cannot grow further, and stop at N stage when adults are decapitated soou after emergence in diapausing Culex ptpiens pallens. The primary follicles begin ro develop about 24 hours after being decapitated in the 5-day old diapausing adults. Thus the role played by neuroendocrine of the head in regulation of folliaular development is conspicuous.The corpora allata (CA) of diapausing mosquitoes are characterized by their small size, little cytoplasm, no vacuole and being inactive, so there is no indication of juvenile hormone (JH).Synthesis and secretion. The primary follicles of diapausing ovary can develop when they are uansplanted into the abdomen of reproductive mosquitoes, but they fail to grow in diapauslng mosquitoes. ZR 515 (JHA) and JH extracted from haemolymph of reproductive mosquitoes can trigger diapausing follicles to develop.

The pink bollworm Pecdnophora gossypiella is an important pest of cotton in Central China. It breeds three generations a year and its mature larva passes over winter. The life tables of its natural population were constructed from 1978 to 1988 in Jianghan Plain and the average values of demographic constants of the first, second and third generation were determined as follows: The survival rates were 3.23 ±1.07, 4.01±1.83, and 1.46±1.09; and the exponential equations were Y₁= 61.66 e0.58x Y₂=142.47e^-0.73x and Y₃=146.68e^-0.80x, where x=stage of development, the type of curve appeared to fit in with type A of Price(1975), which gave over 80% self mortality from egg to the mature larva in each generation. The population trend indices were 1.12, 2.03 and 0.45. The second generation had the highest index in each year which caused eventually heavy damage to the cotton bolls and resulted in a rapid increase of population density of the third generation. The average and maximal numbers of eggs produced per female moth were 34.8/253, 50.66/235 and 30.79/293. Sex percentage of the female moths were 54.6%,54.8% and 51.1%. The natural instananeous rate of population increase r were 0.0390, 0.0430 and 0.0026. Net replacement rate R were 4.39, 4.43 and 2.04. Mean length of a generation Twere 38, 37 and 276 days. Finite rate of increase were 1.0398, 1.0411 and 1.0026 times. Population doubling time t were 18,17 and 267 days respectively. The population fluctuation was essentially affected by the self mortality of the intrusive borers in each generation and the overwintering Iarvae, which could be called as the key stages of pest mortality relevant to population density.

Adult flight capabilities of three major rice stem borers, Tryporyza incertulas, Chilo sup=pressalis and Sesarnia inferens were determined with flight mill and computer system. The results show that the moths of T. incertulas and C. suppressalis have similar flight capability. Normal flights took place within four days after emergence, and they had no conspicuous pre-repro ductive period and calling and mating could occur whithin 24 hours after emergence. Motlhs within one day after emergence in the second phase of ovarian development had the strongest flight capability. The cumulative flight distance of a female moth was determined to be over 32 kilometers. Female moths showed longer flight duration while most of the male moths made irregular interval flights affected easilty by physical conditions. Flights of thse two species were closely related to calling, mating and ovipositlon behaviours, showing typical mating flight syndrome. Though most flights in the field were trivial, the longest dispersal distance could be over 100 kilometers. The moth of S inferens had the strongest flight capability among the three rice stem boreres and the flight distance of female and male moths were over 32 and 50 kilometers, respectively. Normal flight could occur during the first six days of adult life. The pre-reproductive period were two to three days. Adults in the second phase of ovarian development made the longest flights. Thler flight capability declined with the development of the ovaries. This species has flight capability of long distance dispersal and possesses physiological and behavioural bases of migration flight.

This paper deals with the habitat niche of planthoppers and their predators on rice plant and studied the relationship between the habitat niche and the predation effect in the coexistence system containing two insect pests and five species of predators. The results showed that in the system investigated the magnitude of positive main effect of predation on brown planthop pers (Nilaparvata lugens) varied with species in a diminishing order as follows. Clubiona japonlcole, Paederus fuscipes, Tetragnalha praedon ia, and Ummeliata insecticeps; while Pirata subpira ticus exhibited the highest negative effect. The sequence of intensity of positive main effect on rice leaf rollers (Cnaphalocrocis medinali;) was C.japonicola, T. praedonia and P. fuscipes.H had been found that P. subpiraticus, U. insecticeps and Bianor hotingchiehi mainly preyed on planthoppers, T. praedonia on rice leaf rollers and C.japonicola was important for thecontrcl of the both pests. These were consistent with their habitat niche (niche width). Under a certain prey density, the predation effect of the predators reached a maximum when there was a good biological order (I.e. optimal proportion of various species). The results from experiments using addition and exclusion methods in&cared that increase in predator density could not increase the number of prey taken in a coexistence system with a defined density in each species. It is believed to be due to the interactions between inter-species and intra species.

The threshold temperature and thermal constant of various stages of the meadow moth(Loxostege sticticalis L.) were determined in the laboratory. The threshold temperatures for egg, larva, pupa, adult and whole generation weere 14.3℃, 12.7℃, 11.6℃, and 10.5℃, and thermal constants for them were 30.5, 190.7, 158.3, 96.7 and 531.2 day-degrees, respectively. Although the calculated values of threshold temperature were snmewhat different from the values actually measured, the number of predicted generation based on above results were consistent with those actually observed in various geographic regions in China. According to the computation of thermal constants, the generation number of meadow moth occurred annually appeared decreasing with the increasing of latitude. There was annually 1generation in the areas northern to the annual isotherm line of 0℃, 2-3 generations to 0-8℃,and 3-4 generations to 8-12℃. Analysis of population dynamics of the meadow moth in various regions revealed that this insect caused damage mostly in the 2-3 generation region bythe first generation occurring from May to July.

For 6-8 months each year from 1983 to 1988, we made investigations on the fauna of Tabanidae and its vertical distribution on the southern slope of Taibai Mts. A total of 46 species in 5 genera were obtained, which included 7 species of Chrysops belonging to the subfamilyChrysopinae, 3 species of Atylotus, 6 species of Hybornitra, 5 species of Haernatopota and 25 species of Tabanus in the subfamily Tabaninae. According to the the vegetation, climate and elevation above sea level, the southern slopeof Taibai Mrs was divided into 8 vertical zones. Among these zones, the number of species of the tabanids was highest in the Pinus-Qurcus forest (1000-1500 m), ie. 42 species accounting to 91.3% of the total species discovered, the second came the evergreen broad-leaf and deciduous forest (600-1000 m), in which 36 species were found according to 78.3% of the total, and the third was in the mixed forest (1500-2000 m) where 24 species according to 52.2% were found.In places below 600 m or above 2000 m less species had been discovered. The fauna of Tabanidae investigated could be considered as a transitional zone for Palaeartic to Oriental, the Palaeartic fauna is prominent, the zone in 600-2000m to be the tran sitional center, while that of 1000-1500m to be the division line between the two regions in Qinling Mountains.

Three species of fleas in Ceratophyllidae were studied. They include Syngenopsyllus cacceatus, Macrostylophora euteles and Monopsyllus anisus. The lateral, dorsal and ventral sides oftheir phallosomes were observed with light and scanning electron microscopes. There are a pair of C-sclerite and a pair of iverticulum at the base of aedeagal pouch in S. calceatus. In M. euteles there is a pair of aubergine-shaped sclerite. The apex of the aedeagal crochet is divided into dorsal and ventral lobes. The anterior end of the aedeagal apoderne is different from its specialized posterior end. The paxillus of these three species is in the shape like ox horn and protrudes anteriorly, the taxonomic characteristics in these three species are discussed, his suggested that the penis rods slide between the median and lateral laminae during copulation.

The compound eye of the peach fruit moth, Carposlna niponeis Wals. Measures 0.54 mm by 0.50 mm in size and each of them contains about 1500 ommatidia arranged in a density about 330 per square millimeter. The clear zone is about 64% of the ommatidum. The retinula cell is enlarged at the distal end of the clear zone where the nucleus is located. The ommatidiun and its periphery from the distal surface to the proximal are divided into 10 layers as revealed in examination of the fine structures in the present work.