The flight ability and changes of flight muscle structures after flight of cotton bollworm (CBW) Helicoverpa arrnigera (Htibner) were systematically tested for thefirst time in China by applying flight mill, wind tunnel and electron-microscope. Based on these data combined with the results of the different diapause and cold hardiness conditions and characteristics of micro-morphology and molecular biolgical markers andCBW populations collected from different cotton regions in China, and division of theirresistance to insecticides, marine trapping data, sources analysis of pollens carried on the heads of CBW moths, as well as the labelling-release-recapture test in small scale, it was confirmed that CBW is a typical species possessing facultative migration ability, andthe CBW source of Liao River Valley Cotton Region, the most early maturing cotton region in Northeast China, might come from Yellow River Valley Cotton Region, and there might be frequent exchanges of CBW populations between neighboring cotton regions. The morphology and distribution of different kinds of olfactory sensilla on CBW antenna were observed. By using GC-EAG and GC-MS, the electro-physiological reactions of CBW to the extracts from different organs of a number of host plants were compared,and the components of volatile allelochemics in these extracts attractive to CBW mothwere determined. It was found that in cotton, most of the attactive allelochemics to CBW are terpenoids, in which the C10H16 terpenes possessing rather weak polarity can attract CBW moth to feed, while the sesquiterpenoids (C₁₅H₂₄) and other allelochemics possessing strong polarity can attract it to lay eggs. Methods for determining the components and contents of secondary metabolites in cotton plant suppressive to CBW, such as terpenoids, tannins and flavonoids were im-proved, the effects and interactions of different kinds of these metabolites on the development and reproduction of CBW were studied. Cross and back-cross methods were adopted to explore the genetic characteristic of resistance of cotton to CBW. On the other hand, artificial methods such as to spray the preparation of Bt transgenic Bacillus oiginally endogenous in cotton for promoting the resistance of cotton to CBW were tried. Finally, the factors causing the outbreaks of cotton bollowrom in China were analysed along four aspects, namely, the climate, nourishment, natural enemies and insecti- cide resistance. It could be said that the drought weather is the most important environmental condition of CBW cataclysm, the increasing fertility, especially the nitrogen fertility, is the main material basis making the CBW problem more and more important,and the unduly use of insecticides is the major man-made factor bringing about CBW population out of control.

The developmental duration of larvae and pupae and the dynamics of different geographical populations of cotton bollworm in Beijing region were investigated in the laboratory and field. The results indicated that there was no significant difference of larval development among geographical populations, but the diapause dynamics between south and north populations in the nature environment showed a great variation, and the dates for attaining 50% diapause rate of pupae in the populations from Hunan Province and Siehuan Province were 30 d and 22 d later than that of Beijing population. Based on the analysis on developmental dynamics of the populations, cold hardiness of cotton bollworm and climate environment, it was suggested that Beijing area would be the north boundary of ecological region for north population of cotton bollworm, and it was impossible for south population to finish yearly life history in north China.

The results of RAPD analysis of genetic variation among 17 geographicpopulations of cotton bollworm (CBW) showed that these populations could be divided into 4 distinct groups. (1)Sanya (SY) group, (2)Shache (3) group, (4)Hami (HM) group and (4)the rest (14 populations). The SY group had the longest genetic distance to the other groups and the 4th group had rather few genetic variations or much more gene similarity among populations. The genetic distance between Huanghe River Valley population and Liaohe River Valley population was the shortest. It was found by individual RAPD analysis that the individuals possessing the same genetic characteristicswere distributed disorderly in different geographic populations, indicating that there are frequent gene exchanges among populations from different ecological regions. Lastly, the reason of variation among geographic populations of CBW was discussed.

The populations of cotton bollworm, Helicoverpa arrnigera (Hubner), collected from Hami (HM), Xinjiang Uygur Autonomous Region and Hengyang (HY),Hunan Province in China, were crossed and backcrossed in the laboratory. The results showed that there was no significant difference in reproduction, hatching rate of eggsand reproductive duration between the F_l and F₂ moths of the two populations. The critical photoperiods for pupal diapause of HM, HY, HM♀× HY♂, HY♀×HM♂and (HY♀×HM♂)♀×HY♂ strains at 22℃ were 13 h 35 min, 11 h, 11 h 45 min, 11 h43 min and 11 h 9 min, respectively. The LT₅₀ values of diapause pupae of HM, HY,HM♀×HY♂ , HY♀×HM♂ ,HY♀×(HY♀×HM♂) ♂and (HY♀×HM♂)♀×HM ♂ at -15℃ were 159.74 h, 34. 2696 h, 100.65 h, 116. 75 h, 90.78 h and 135.58h, respectively, and the dominance degrees ID (HM♀×HY♂) and D (HY♀×HM♂)] were estimated to be 0.3998 and 0.5926. It indicated that the inheritance of cold hardiness in cotton hollworm is irrelevant to sex and controlled by multiple factors.

The characteristics of diapause termination for 13 populations of cotton bollworm, Helicoverpa armigera (Htibner), collected from various geographical regions in China, were investigated in the laboratory. The results showed that the developmental duration of diapausing pupae prolonged with the increase of latitude where the population was collected, for instance, that of Hengyang population (low latitude) and Hamipopulation (high latitude) were (15.6±4.9) days and (41.4±9.0) days at 30℃ respectively. The diapausing durations of the populatins from central and north China could besignificantly shortened by low temperature treatment, but it only played a slight role on the population from southern China. The developmental thresholds and effective accumulated temperatures of the vernalized diapause pupae of the populations from south,central, north and northwest China were 17.4℃ and 146.0 degree-day, 16.6℃ and 146.5 degree-day, 15.7℃ and 156.4 degree-day, and 15.7℃ and 167.7 degree-day, respectively.

The resistance levels to phoxim, cyhalothrin and endosulfan of cotton bollworm, Helicoverpa arrnigera (Hubner), collected from Jianyang of Sichuan Province, Wuxue of Hubei Province, Hengyang of Hunan Province, Nanjing of Jiangsu Province and Hangzhou of Zhejiang Province, were determined as 8.05-38.80, 2.86-290.00 and 5.87-19.83-fold, respectively in comparison with a susceptible cotton bollwormpopulation. The Jianyang population ? and Hangzhou population (S) were crossed and backcrossed in the laboratory. The results showed that the resistance levels in the F₁ to phoxim, cyhalothrin and endosulfan were 13.16 and 16. 69, 10.43 and 19.00, and 12.42 and 10.21-fold, and the degrees of dominance in heredity of resistance to the three insecticides were estimated to be-0.2220,-0.2147 and 0.0700, respectively. It indicated that phoxim or cyhalothrin resistance was incompletely recessive, and endosulfan resistance was controlled by the semi-recessive gene. The resistance levels of progenies of F₁ breeding to phoxim, cyhalothrin and endosulfan were 17. 66, 7.57 and 9.03fold, respectively, and that in F₁ backcross with the Hangzhou population were 8. 79, 3.00 and 6.61-fold, respectively. Based on the results mentioned above, it is suggested that the gene flow between the resistant and susceptible populations would significantly reduce the resistance levels to the three insecticides.

The resistance and rehabilitation of sensitivity to pyrethroids and the variation of acetylcholinesterase in cotton bollworm Helicoverpa armigera were studied by bioassay and biochemistry method. The results showed that the resistance of cottonbollworm to pyrethroids was unstable and the sensitivity to the insectcides increased with the time after withdrawal of stress. The rehabilitation of sensitivity in the first generation of cotton bollworm fed at the insectary was more rapid. The results of affinity tests between special inhibitors and acetylcholinesterase of the cotton bollworm confirmed that variation of acetylcholinesterase was taken place during the decrease of resistance to pyrethroids in cotton bollworm, and it might have a significant impact on the stability of this resistance.

The responses to deltamethrin and the changes of the detoxification enzymes were compared by bioassay and biochemical method between the susceptible and resistant strains of cotton bollworm Helicoverpa armigera. The results showed that the levels of resistance to deltamethrin were significantly high in the resistant cotton bollwormeither from the field or laboratory selection, and the ratios were 195.8 and 37 375-fold compared with the susceptible one, respectively. The hydrolase and mixed function oxidase might be the important enzymes to cause the high resistance of cotton bollworm todeltamethrin. The tests of inhibition by special inhibitors in vivo and in vitro indicated that there were high levels of acetyleholinesterase in the susceptible and resistantstrains. However, the affinity to the inhibitors between the two strains was significantly different, suggesting that acetylcholinesterase in the susceptible and resistant strains was changed differently. Consequently, the variation of acetylcholinesterase might also be an important factor affecting the resistance of insecticides even if it is a nerve toxin tocentral nervous system such as deltamethrin.

The methods of cross and back-cross between resistant and susceptible populations were used for exploring the inheritance mode of resistance to deltamethrin in the cotton bollworm Helicoverpa armigera (Htubner). The results showed that the degree of dominance of F_Rs and F_sR were 0.34 and 035, respectively. The difference between expectations and actual values of both backcross ratios of RS∶SS and SR ∶SS was significant at 1∶1, and the backcross plateaus were at 35%-45%, suggesting that the resistance of cotton bollworm to deltamethrin was controlled by the incompletely dominant genes. The anaphthylacetate esterase may be an improtant factor resulting the resistance of cotton bollworm to deltamethrin.

The nourishment of different parts of cotton plant, namely, the terminal leaf, bract, calyx, petal, anther, ovary, boll husk and boll heart, to cotton bollworm Helicoverpa armigera (Hubner) larvae and the distribution of terpenoid and tannin contents, the major secondary metabolites unfavorable to the larvae, in these cotton tissues were tested for exploring the relationship between feeding behavior of cotton bollworm larvae and the two kinds of allelochemicals in cotton. The results showed that the factthat the larvae preferred to feed on plant tip and bore into square and boll was closely related to the nutritive effect, mainly depended on the contents of terpenoids and tannins, of these organs on themselves. The tannin contents in terminal leaf gradually increased with the course of cotton's development, while there were significant drops ofterpenoid contents in terminal leaf in the 4th leaf, 6th leaf and early square stages, which were just the times the larvae damaged on cotton plant tip. The contents of secondary metabolites in outside parts of square and boll, such as bract, calyx, petal and boll husk, were higher than those in their inner parts, pollen, ovary and boll heart,etc. , and that in terminal leaf was intermediate. The terpenoids mainly presented in pigment glands, and tannins mainly scattered in the tissues of outer layer of cottonplants. It was indicated that certain feeding behavior of insect such as the feeding times and locations of cotton bollworm larvae is formed by its adaptability to the fluctuating contents of harmful secondary metabolites in host plant.

In this paper, the extracts of wheat flowers and wheat leaves (1 000 g and 3 200 g respectively) were drawn forth both by ethyl ether and steam distillation. The four samples were concentrated to two milliliters each by nitrogen. Activity of the extracts attracting cotton bollworm moths was tested by wind-tunnel and electroantennographic responses. In wind tunnel, the result showed that. (1) the volatile secondary metabolites from wheat flowers and wheat leaves possess attractive effect on cotton bollworm moths. The orientation rate were 45% to 72%, much higher than 22.2% of control, with significent difference by t test; (2)the orientation rates of females were higher than those of males; and (3) there were no significant difference between flowers and leaves. On EAG test, the result showed that antenna of cotton bollworm strongly responsed to the extracts of wheat flowers and leaves with significent difference to the control. EAG response of male was slightly higher than that of female, and the EAG response of cotton bollworm to wheat flower extract was slightly higher than to leave extract.

The volatiles of stem tip, square and flower of cotton, male flower and female filament of corn, celery, leaf and flower of peanut possessing attraction activities to cotton bollworm (CBW) Helicoverpa armigera (Htibner) were extracted onto TenaxTA or Tenax GR and collected with hexane separately. Electroantennography (EAG) was used to explore the electrophysiological responses of CBW to the tested volatiles,The amplitude values of receptor potential ranged from 0.1 to 1.2mV. The EAG responses of virgin female to the volatiles of square, flower and stem tip of cotton and flower and seedling of peanut increased with its age (1-10 days old). The mated females had significantly stronger EAG responses than the virgin females, suggesting that these plants emit some chemicals which are capable to promote the oviposition of females. The curves of dosage-EAG amplitude showed that mating can significantly reduce the threshold of female electrophysiological responses to the volatiles of stem tipand flower of cotton. The results of four-arm olfactometer tests indicated that the CBW moths were strongly attracted by these plant volatiles. The selective indices to cotton square, cotton tip, corn silk and peanut were 0.78, 0.61, 0.49 and 0.31 respectively.

The volatiles of carrot flower were absorbed on Tenax TA or Tenax GR and eluted with hexane. Electroantennography (EAG) was used to explore the electrophysiological responses of cotton bollworm (CBW) moths Helicoverpa armigera (Hubner) to the volatiles. The amplitude values of EAG ranged from 0.3 to 0.5mV. The results of combined gas chromatograph-electroantennograph (GC-EAG) and GC-mass spectrum(GC-MS)showed that there were five active components in the volatile oil,in which,four compounds were determined as 3-methyl-2-pentanol, myrcene, limonene, ocimene. The behavioral responses of CBW moths to the volatile oil were similar to natural carrot flower. The facts that the carrot flower and it's volatiles were only attaetive to 1-2 daysold moths, suggested that the carrot flower volatiles are semioehemicals solely associated with the feeding behavior of CBW.

Ultrastructure of the indirect flight muscle of cotton bollworm Helicoverpaarmigera (Htibner) moth was investigated with electron microscope. The polygonal,close-packed elliptical myofibrils consist of 4004800 myosin filaments. Thick and thin filaments form a hexagonal lattice with the thin filaments midway between the adjacentthick filaments with actin and myosin in 3: 1 ratio. The sarcomere length is about 2.043.5 gm and the mitochondria are estimated to be about 42.38-48.57% of the fiber's total volume. The development of myofibril and mitochondria had fulfilled after emergence, while the development of T-tubules is relatively slow, and they mature after the third day of moth eclosion and occupy 3. 31%-3.54%of the muscle volume in 5 day-old moth. No significant difference is found between flight muscle structures of experimental population and migratory moths collected on Bohai Sea where is about 80 Km away from the continent, but the mitochondria in migratory moth showed many cavitiesprobably caused by energy exhaustion of flight.

In this paper, the morphology and ultrastructure of genitalia of cotton bollworm Helicoverpa armigera were studied and compared with its sibling species (H. assulta and H. zea), the results indicated that: (1)In morphology, there was evident variation among individuals in the same population of cotton bollworm (CBW), but noobvious differentiation among the 17 geographic populations of CBW. The numbers of folding and large spines on vesica, and length/width of valve between CBW and its sibling species are partly overlap. (2)In ultrastructure, there was no obvious differentiation among individuals or geographic populations of CBW , but there were obvious differentiations between CBW and its sibling species in the aedeagus cornuti. The cornuti on aedeagus is a stable distinct character between CBW and its sibling species found newly by the authors.

The results of morphological comparisons and numerical analysis of morphological characters of cotton bollworm (CBW) Helicoverpa armigera and its sibling species indicated that there were evident variations among individuals in the same CBW population, but there were neither obvious geographic differentiations, nor stable varia-tions of geographic characteristics among different geographic populations. Nevertheless, there were significant correlations between the latitudes of CBW populations and their cucullus length, cucullus width, valve length/valve width, and valve length/cucullus width (_r=-0.612* ,-0.699*,0.693* and 0.691* , respectively). Even though,it should still be regarded that all the CBW populations in China belong to a single species, rather than different geographical species, by comparisons of CBW with orientaltobacco budworm and corn earworm which were obviously different from the former due to the morphological interruption.

Effects of reproductive organs of cotton, wheat, corn and soybean at low,medium and high rates of nitrogen fertiliser on development and fecundity of the cotton bollowm, Helicoverpa armigera (Hubner) were studied in the environment-simulated chamber (14L: 10D, (27±1)℃ and 60%-80%RH). The causes for those effects were further studied through analyses of C/N ratio in reproductive organs of the four namedplants. As rates of nitrogen fertiliser were increased, the C/N in all four plants was decreased, the order being soybean (0.5, 0.4 and 0.3, repectively), cotton (1.1,0.9 and 0.8, repectively), wheat (4.5, 4.0 and 3.8, repectively) and corn (5.2, 4. 2 and 4.2,repectively). Effects on the bollworm's development and survival took place mainly at young larval stage (1-3 instar), such as its developmental duration getting shorter and survival rate higher in all four plants with increase in rates of fertiliser; and the rates of development and survival were higher in plants with lower C/N's than in those with higher ones. With increase in rate of fertiliser oviposition in all four host plants were increased, and the indexes of population increase enhanced in host plants with higher C/N's, but enhanced first and then decreased in those with lower ones. Plants with medium C/N were more favourable for oviposition and population increase than thosewith C/N's either too high or too low. Effects on the bollworm's development and fecundity were resulted mainly from the difference in contents of carbohydrates and protein as well as their ratio in host plants.

Based on two years field trials, the morphological resistance of cotton lines to cotton bollworm Helicoverpa armigera (Htibner) were analysed. The results showed that the three indices, namely, the accumulated eggs, mean larval number and damagedsquare+boll number/100 plants, in the plots of cotton lines having red leaf, okra leaf, and frego bract were decreased by 28.1%, 31.45% and 36.0%; 19.0%, 25.4% and 28.4%; and 25.8%, 32.9% and 34.0% in comparison with the check plots, respectively. The larval number and damage of square and boll of those possessing high oil glanddensity, I.e. rich in terpenoid contents, were 45.1% and 51. 4% lower than the check plots ,respectively. There were coordinated action in those having both okra and red leaf, red leaf and frego bract or glabrous leaf and denser oil gland number characters, and thethree indices of these combinations were 48.3%, 55.2% and 57. 9%;52. 7%, 58.3% and 60.6%; and 29.9%, 54. 9% and 58. 3% lower than the checks respectively. The F₁ hybrids of the check separately crossed with red, okra or glabrous leaf lines had kept their own resistance to cotton bollworm in various degrees, while the bract of F1 crossed with frego leaf line turned normal and no resistance expressed. Possibly owing to the narrow condition of plot, the cotton lines without (outside flower) nectary glands did not show resistance.

Most of the individuals of rice brown planthopper, Nilaparvata lugens(Stal), were unable to feed and survive as well as develop on resistant rice varieties.After being forced to feed on resistant varieties for several generations, the abilities for brown planthopper to infest the varieties changed significantly. But the virulence shifted gradually. It seemed that there was a heritable accumulation from generation to generation. The course and rate of the shift of virulence differed from different resistant varieties as a result of their diversities in both resistant mechanism and genetic background.

The infestation of 3rd instar Nilaparvata lugens with different experiences was studied, and the following results were obtained. The experiences on resistant variety "Mudgo" could improve the honeydew excretion and survival of N. lugens on theBphl-carried varieties such as Mudgo, IR26, IR28, IR34, and also enhance the preferencefor the tested variety "Mudgo'; the experience of N. Lugens on resistant variety "ASD7", however, only contributed to the increase of honeydew excretion and survivalon the same variety, thus implying that the effects of experience were characterized by variety-dependence to some extent. It is still recognized that the amount of honeydew excretion was much less on Mudgo and ASD7 than on TN1 for N. lugens with the same experience on the resistant varieties.

Experiments showed that lowest survival rate, longest duration of nymphsand lightest weight of brachypterous female occurred in the 2nd generation of brownplanthopper (BPH) Nilaparvata lugens (Stal) on feeding on resistant rice varieties. There were no obvious differences in the survival rate, duration of nymphs andweight of brachypterous female between feeding on resistant rice varieties IR26、Mudgo.ASD7 after 3rd generation and feeding on susceptible variety TN1. The 2nd generation of BPH was found to be key generation adapting to the resistant rice varieties. In the variation of virulence of the brown planthopper, the lowest activities of alanine transaminase (ALT) and aspartic transaminase (AST) and the highest activities of superoxide dismutase (SOD) and catalase (CAT) were detected in the 2nd generation of the BPH feeding on resistant rice varieties.

Nilaparvata lugens (Stal), has two wing-forms, macropterous andbrachypterous. The brown planthopper (BPH) controlled by a pair of dominant genes,and coordinated by hormones excreted by endocrine which is affected by external factors, such as nymphal density and plant nutrients. The sensitive instars of BPH nymph for wing-form development are the Ist - 3rd instars in female and 1st - 5th instars in male respectively. The forewing length of BPH is affected by nymphal density. BPH feeding on rice plants at various stages have dfferent brachypterous ratios, tillering plants cause more brachypterous females than booting rice plants. There are no significant difference between the wing-form development and various BPH biotypes under various nymphal densities. The Zhejiang populations show low brachypterous ratios and have a negative correlation with nymphal density, belonging to the temperate type. The Philippine populations are almost brachypterous, however, the bracheypterous ratio of BPH males raise with the increase of nymphal density. The Guangxi population have a high brachypterous ratio,being similar to the tropical type. The results also indicate that the brachypterous ratios of males are the highest when the nymphal populations are at the medium (54-10 per tiller) or high (＞20 per tiller) densities.

The developments of wing pads and indirect flight muscles (IFM) in themacropterous and the brachypterous brown planthopper [Nilaparvata lugens (Stal)] were studied with paraffin method. The developmental differentiation of the IFMs occurred between the 8th and the 16th hour of the 4th nymphal instar, after which the IFMs of the macropterous nymph developed normally while the IFM development of thebrachypterous was suppressed. The wing pad developmental fferentiation was observed only at the 5th nymphal instar. The front wing pad cells of the brachypterous nymph proliferated slower than those of the macropterous and the development of hind wing pads of the rachypterous broke down. The wing dimorphism differentiation sensitive instar was inferred and compared between the male and female individuals.

Results of the present study indicate that the dominant biotype of the brown plantbopper (BPH) occurred in the 11 Provinces and Autonomous Region of China has changed from biotype 1 to biotype 2 except in Chengdu, Sichuan. Some individuals of BPH collected in early rice at Simao, Yunnam and Nanning, Guangxi were found to be the same as that of Bangladesh and Sri Landka. They could demage the varieties whichcontained the genes Bphl and bph2. Some local varieties and accessions are resistant to biotype 1 and 2 that should be extended for utilization. Most accessions of Oryzae officinalis Wall and the varieties (lines) derived from Ptb33 showed a broad spectrum resistance for cross breeding to control the demage by new biotypes.

A comparative study on development . Survival. Fecundity and innate capacity for population increase of the four geographic populations of brown planthoppers (BHP) (Nilaparvata lugens) was carried out in laboratory. The four populations were collected from Longzhou . Jiugongshan. Jianli, Xinhui in China. The results show: 1. After a longdistance migration, the Jiugongshan immigrant adult females need to be fed for 3.6 days to begin oviposition. Egg number laid per female is only 522, lower than that in second generation (714) . 2. In second generation, there is significant difference in the durationof the first and fifth instar nymphs among populations, but no significant difference in the second . Third, fouth instar that are key stages determining wing dimorphism, and no significant difference in longevity and oviposition period of adult females too. Egg number of Xinhui population is remarkably higher than those of the other three. At the same instar nymphs the generation specific survival rate of Jiugongshan population is lower than those of the other three. The innate capacity for population increase which can comprehensively reflect the information of development. Survival and fecundity changes slightly between 0.1874 to 0.1982. Furthermore, the reasons for the homogenieties and the heterogeneities above-mentioned are discussed.

Affected by a higher titer of juvenile hormone at the end of 5th nymphal instar and early stage after emmergence in vivo, the sexual maturation period of brachypterous adults of the brown planthopper was 40-50 hours earlier than that of macropterous adults. The percentage of successful mating of brachypterous females was higher and the mating ability of males was relatively stronger before 5-day age.Macropterous female adults did not mate at 1st. And 2nd. Day after emmergence. The mating ability of macropterous adults could surpass that of brachypterous adults gradually, the mating course of the experimental population lasted (70.38±41.77)s, and thepercentage of successful mating was 51.63%. Both males and females could mate repearly, and the percentage of successful mating was relatively higher during 0-4 o'clock and 10-14 o'clock in a day.

The effects of different high temperatures on the biological characteristics such as the duration of nymphal stadia, egg laying, preoviposition period and longevity, were studied. Developing periods of nymphs prolonged when temperature reached above 34℃. The numbers of egg deposited by female adults reduced when the 4th-instar nymphs were treated with higher temperatures, while egg deposition was reduced as female adults were treated with high temperatures at different day, especially one day after the emergence of the brachypterous form and three days after emergence of macropterous form. The life span of BPH was shortened when treated with high tempertures. A little effect of constant high temperature on the period of preoviposition of brachypterous form female adults was perceived but the period of preoviposition of macropterous form females was obviously prolonged when the 4th instar nymphs were reared under constant high temperatures. When treated with changing high temperatures, the preoviposition periods of both brachypterous and macropterous female adults were prolonged. Changing high temperatures have greater effect on the reproduction than constant high temperatures. Greater effect of high temperature treatment on themating of female adults than that of male adults was also observed. In conclusion, 34℃ was the critical temperature in both development and reproduction of BPH.

So far main evaluating method about effect of pesticides on natural enemies has been concentrated on their lethal rate resulted and rarely on their predation function. Impacts of three insecticides, shachong-shuang, methanidophos and buprofezin on the predation function of Pirata subpiraticus on brown planthopper were studied in this TR paper. Decrease rate of predation function, FD= [∑(D_t+S_t×FD_t,)] /TR×100 wast=l proposed as comprehensive evaluation of impact of insecticides to natural enemies,where D_t=death rate of natural enemy at t time, S_t=survival rate of natural enemy at ttime, FDt=decrease rate of predation function at t time and TR=duration of predation function recovery. The experimental results showed that 540 mg/L and 810 mg/L of shachong-shuang caused low death rates to the wolf spider, which are 12.63% and 27.57%, respectively, but had a great impact on its predtion function, which decreased65.41% and 81.3%, respectively, 100mg/L of methanidophos treatment showed 49.8% of death rate and 68.56% in the decrease of function. These two insecticides showed different affecting machanisms, the later had higher lethal toxicity and shorter duration of predation function recovery. For the third insecticide, buprofezin, both thelethal effect and function decrease of the spider could be ignored. The function recovery of the wolf spider needed about 7 d after shachong-shuan and me-thanidophos treatments. Moreover, the result of field experiment indicated that application of methanidophos would cause resurgence of planthoppers due to the decline of the function of natural enemies.

In this paper, a 32 channel, computer-monitored flight mill system fortesting the flight ability of small, weakly flying insects such as aphids was designed and presented. The flight mill construction, data collecting adapter and software design were described. The flight mill system is an optimal tool for studying small insects flight behavior. The flight ability of the bird cherry oat aphid (BCOA) Rhopalosiphum padi (Linnaeus) was tested with this flight-mill system. The results showed that the flight performance of the aphids varied with their ages. The. BCOA at 1 to 5-day old flew signifi- cantly longer than those at 7 to 9-day old. However, there was no significant difference in the average flight time among the BCOA with different ages, and the flight speed decreased with the increase of the aphid age.

The flight performance of laboratory-reared winged adults of the bird cherry oat aphid Rhopalosiphum padi (Linnaeus), was nvestigated with a flight-mill system at several temperature grades (8℃-30℃). The results showed that the temperature range of 12℃-20℃ was suitable for flight of the bird cherry oat aphid, the averageflight distance was 6.614-8.219km and the average time of flight was 5.074-7.003 h.At 15℃, the maximum flight distance and flight duration reached 26. 231km and 21.53h respectively. It was difficult for the bird cherry oat aphid to take off at 8℃, and both the flight distance and flight duration were short after take-off. At 23℃ and above, the aphid was easy to take off, but the flight distance and flight duration were becoming shorter gradually with the rise of temperature. At 30℃, the aphid stopped flying shortly after take-off. The flight speed increased with increase of temperature, the averagespeed was 0.781 km/h at 8℃ and 1.605 km/h at 30℃.

The contents of total phenolics, carbohydrates and the acidity in threewheat cultivars with different levels of resistance to the grain aphid, Rhopalosiphum padi (Linnaeus), were determined. The data indicated that a higher degree of wheat resistance to aphid was associated with a higher amount of phenolics, and some correlationwere found for carbohydrate content and acidity. In addition, aphids were analysed for their amylase and carboxylesterase activities, and it was found that aphids feeding on resistant wheat had higher activity of amylase and carboxylesterase, comparing with thosefeeding on susceptible variety.

Ten winter wheat cultvars (lines) with different degrees of resistance to wheat aphids were studied at seedling stage under the lab condition on the parameters of life table, resistant patterns and the content of some secondary substances in the plant tissues. The control capacity on Sitobion avenae F. (SA) andRhopalosiphurn padi L.(RP) and partial biochemical resistant mechanism have been revealed. The results showed the resistant patterns of cultivars to wheat aphid being 30% non-perference and70% antibiosis. The non-perference resistant cultivars made aphids crawling frequently and decreasing the colonial rate on wheat leaf greatly, but the colonial individuals and their growth rate and fecundity were as CK. The cultivars with different degrees of an-tibiosis resistance made SA and RP nymphal development prolonged by 2.1%-28.2% and 3.7%-13.9%, nymphal mortality increased 1.0-3. 6 and 1.0-2.25 times, average longivity shortened by 10.2%-96. 5% and 37.5%-97.1% and fecundity decreased by 3.4%-72.8% and 25%-97.2%, respectively. The result of biochemical analysis at seedling stage showed that there were significant differences in the contents of tannin and phenolic in plant tissues between the resistant and susceptible cultivars. The correlation between phenolic content and the resistant degree to SA was negatively significant(P＜0.05). The correaltion between phenolic content and the innate capacity for increase (r_m) of SA was also negatively significant. So, phenols in plant tissues seem to be one of the key resistant factors to SA. No correlation between phenolic content and the resistant degree to RP or rm of RP was found. There was no correlation between tannin content and the resistant degree to both wheat aphids.

In this study, the stylet penetration behaviours of Sitobion avenae F. and Rhopalosiphum padi L. on wheat cultivars with different degrees of resistance were recorded with EPG (Electrical Penetration Graph) technique. Results showed the specific wave patterns of aphid penetration on the four tested cultivars (Hongmanghong, Xiaobaidongmei, kok-1679 and L₁) were almost similar, but there were differences in thestart time, repeats and duration. The time for the first appearance of E₁ [N] and the rate of total duration of E₂ to total recording time (E₂ %) could be taken as the main physiological parameters aeeociated with the cultivars resistance. Based on the major wavepatterns' parameters, the cluster analysis was used to distigush resistant levels of the tested cultivars and the result was fit basically with the life table parameters in lab and the evaluation in field. In the end of this article, the possible location of the resistant factors, function in resisatant evaluation by EPG and factors affecting EPG recording were discussed briefly.

It is a common phenomenon of nature that insect shifts from one habitat to another by flight, while its seasonal long distance migration in space with air current occurs in a special environment. It is one of the unifications of insect and environment during the course of evolution. The fact that an insect migrates from A to B and finds a habitat in B is a random event, but the migration of an insect population complies with certain statistic regularity. Thus, the migratory insect gets the initiative adaptation to the environment by using a passive mode, the dispersion directed by air current.