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Zeuzera leuconotum Butler(Lepidoptera: Cossidae) is one of the most damaging pests on forestry in northern China in recent years.Because its larvae cause damage by tunneling into tree trunks,it is very difficult to control by cutting off the damaged branches or applying insecticides.In order to find a pollution-free and efficient controlling method,we have already begun a series of studies on the sex pheromone of the pest.It is necessary to know the character of calling behavior and the circadian rhythm of sex pheromone production and release by female Z.leuconotum. In this paper,the female moth calling behavior and characters were investigated through observation in the insectariums under the condition of(19—32)℃,75%—85% RH and 14L∶10D photoperiod.And the circadian rhythm of sex pheromone production and release by the female moth was researched in detail by determining the electrophysiological(EAG) responses.The crude extracts of sexual pheromone were prepared by the two methods.One of the methods was to directly extract pheromone from female sexual gland by hexane,and another was to collect pheromone from air in the bottle which filled with a female moth.The Former reflected the sex pheromone production,and the latter reflected the sex pheromone release. The results showed that the calling behavior of all female moths occurred during the scotophase.Some females(43.3%) called on the first night after eclosion and called mainly during the second half of the scotophase.Calling varied with age of female.The percentage of females calling increased from 1 to 2-d-old and decreased from 3 to 6-d-old gradually.The percentage of 2-d-old females calling was the biggest(86.7%,average),significantly bigger than 1 or 4,5,6-d-old females(P0.05).The old females(5 to 6-d-old) called earlier than younger in the scotophase.The calling peak occurred in 4-6 h of scotophase. The EAG response of males to different extracts reflected that only a few females could produce and release sex pheromone on the first night after eclosion.The sex pheromone production and release of females varied with age,which regulation was the same as that of calling.The sex pheromone production and release of 2-d-old females were the highest,significantly higher than those of other age females(P0.05).The sex pheromone production of the female gland increased with the time into scotophase,but very slowly from the onset to 4 h,and sharply from 4 to 5h,and peaked.After the peak,the production decreased greatly during 6 to 8h.At 4 h into scotophase,sex pheromone release began to increase,and quickly reached the peak.In a word,there was a circadian rhythm in the production and release of sex pheromone by Z.leuconotum.The peak of production occurred on 5 h into scotophase,but that of release occurred on 6 h of entering scotophase. In the field test,it was found that the percentage of males trapped by using 2-d-old virgin females had the same regularity as mentioned above.Therefore,it was confirmed that the calling behavior,sex pheromone production and release of Z.leuconotum were synchronized.

To find the optimum mixture ratio of larch(Larix gmelinii) and birch(Betula platyphylla),seven forest types were set in Inner Mongolia,including pure larch stand,pure birch stand,and five mixed stands with various tree proportions.Each forest type had three stands as replicates.Species richness and diversity of plant and insect populations were investigated and analyzed by traditional community investigation and manual collection.For the plant community,88 species were recorded and the dominant communities included Compositae,Rosaceae,Ranunculaceae,Papilionaceae,Ericaceae and Pinaceae.The dominant populations were Carex chingannensis Litw.,Lolium perenne L.,Fragaria orientalis Lozinsk.,Equisetum palustre L.,Geranium dahuricum DC.,Galium boreale L.while the rare populations included Heracleum moelledorffi,Ligularia fischeri,Pedicularis rubens and Viola acuminate.For the insect community,147 species were recorded.Lymantria dispar L.,Loxostege sticticalis L.,Chilo suppressalis(walker),Sidemia spilogramma Rambur,Chrysomelidae,Muscidae,Staphylinidae,Eusilpha sp.,Nitidulidae,Ips subelongatus Motschulsky were found as the dominant populations while Tomicobia seitneri(Ruschka)and Sipyloides sipylus were classified as rare speices.As the birch mixture in mixed forests increased,the species richness of plant and arthropod first increased and then decreased and peaked in L70B30 forests.The diversity of them had similar pattern as species richness.The distribution status of plant and insect populations along the gradient of birch mixture was also examined by the application of canonical correspondence analysis(CCA).The explaining environmental factors included mixture proportion(quantified by the mixture of birch),canopy closure,stand slope and soil organic matter(%).The results showed that the distribution of plant communities was well reflected by the CCA analysis.34.1% and 37% of the plant-environment relation was explained by axis 1 and 2,respectively.Birch mixture(BM) had significantly negative correlation with axis 1 while the canopy closure(CC) had a significantly positive correlation.In terms of the insect diversity,axis 1 and 2 explained 34.8% and 28.1% of the insect-environment relation while BM and CC also had similar correlations with axis 1 and 2.The results showed that most populations were significantly affected by the mixture status and canopy closure,which was also significantly decided by the composition status of canopy layer.In addition,the stand slope can also change their distribution status.These results also indicated that the diversity of plants and insects was highest when the mixture ratio of larch and birch was between 5 ∶ 5 and 7 ∶ 3,which should be the optimum mixture ratio in thinning practices.The present study is to provide theoretical base to improve the forest management,including how to quantify and control the thinning intensity.Generally,the relation of diversity and forest ecosystem stability was considered as positive which meant that the stability will increase with the diversity level.Therefore,the present study provides a new way to improve the health level of boreal forests in northeastern China.The forest manager could carry out various practices to transform the simple structure of forests,especially for the man-made forests and to keep and increase the forest health in this area.

Trabala vishnou gigantina Yang(Lepidoptera: Lasiocampidae) is one of the most important defoliators in China.Larvae of T.vishnou gigantina feed on tender leaves primarily causing damage to the crown layer.In the last few years,the use of single species plantations combined with poor management and a lack of adequate monitoring and early warning has allowed populations of this pest to erupt and cause serious damage in Hippophae rhamnoides L.forest stands in Wuqi County,Shaanxi Province,China. Spatial distribution is one of the most important properties of insect populations.It provides dynamic information about insect populations,describes individual associations,and allows the prediction of variations in spatial distribution patterns.Geostatistical methods provide very powerful tools for explaining the spatial distribution of many species.These methods allow both the direct measurement of spatial distribution of organisms and tracking of changes in distribution over time because the exact location of the species has been documented at a specific point in time. To further investigate spatial distribution and effectively control this pest species,spatial distribution patterns of T.vishnou gigantina pupae were analyzed using geostatistical methods in pure H.rhamnoides forests with different slopes and densities.Results show high levels of pupating occurred mainly in mid-August.Also,males pupated 3.7 days earlier than females.Pupae were also widely distributed on southeastern facing shady slopes,and on west and north facing sunny slopes.Pupae gathered mainly at heights of 30—75 cm on trees.Analysis of isotropic variograms indicated T.vishnou gigantina pupae spaced themselves 95.609,47.379,79.238,and 42.415 m apart in densely forested shady slopes,open forests on shady slopes,densely forested sunny slopes,and open forests on sunny slopes,respectively,while the intensity of local spatial continuity was 0.760,0.561,0.649,and 0.407,respectively,in the above stands.Also,semivariogram analysis revealed the Gaussian model had the best fit to T.vishnou gigantina pupae distributional patterns in dense forests,implying an intense spatial aggregation pattern,while the linear model fitted best with the open forest,implying a random distribution.As the maps with Kriging interpolation described,T.vishnou gigantina pupae exhibited an edge effect and an obvious directional distribution;the pupae had a clustered distribution at the edge of the plantation and occurred in point locations scattered inside the plantation.Numbers of clustered plaque gradually declined toward the center of the forested area.This was reflected in the tendency of the pupae to cluster together on a spatial scale,and in the direction of their proliferation. Currently,T.vishnou gigantina infestations are most commonly controlled using chemical pesticides.However,H.rhamnoides is an economically and ecologically important plant,so residues need to be considered when spraying pesticides.Based on the spatial distribution characters,we suggest picking the pupa manually on the sunny slopes and especially on the edges of seabuckthorn plantations at a height of 30—75 cm to limit reproduction of this pest species.Research results demonstrate the spatial distribution patterns of T.vishnou gigantina pupae in pure H.rhamnoides forests,providing a theoretical basis and practical guidance for controlling populations of this insect pest.This research will provide a meaningful foundation for integrated pest management.

We studied biological characteristics and habitat requirements of Parnassius imperator in Yagou,Yongjing County.We also analyzed population trend and key factors responsible for its fluctuation.Our research methods included for example transect survey,observation at sample plots,indoor breeding,etc. 1)P.imperator is an endemic species to China.It is univoltine in Yongjing County,and overwinters in egg stage on rocks nearby host plants Corydalis adunca(also endemic to China).Eggs hatch in mid-March the following year.The larvae stage includes 4 instars and last for 52 days.Duration of the larva period is from late March to late June.The pupae stage lasts about 47 days,and larvae pupate in early May.Adults emerge at the beginning of May and can fly fast.Peak quantity of adults ranges from mid-July to mid-August,however adults can still be found in late September.The egg stage lasts about eight months. 2)P.imperator is a dominant species in Yagou,Yongjing County.Adults like to stay and fly in valley with bare rocks and shrubs,larvae are found on sunny and semi-sunny slopes.Geographic distribution of P.imperator and its host plant C.adunca overlaps in China.This explains their close co-evolutionary relationship. 3)Two subspecies of P.imperator.P.imperator gigas Kotsch,occured in Yongjing county and P.imperator regulus(Bryk et Eisner) in Hezuo city. 4)Extremely abnormal climate,for example,Strong cooling,frost or snow,is the main factor that affects the population decline of P.imperator.Human disturbance is afnother threat affecting survival of P.imperator. 5)Conversation measures should focus on conservation of habitats of Parnassius sp.,and reduction of human disturbance to support survival of the population in Yagou.We also stress the need for long term population monitoring and research on impact of climate chang and habitat loss.

Bursaphelenchus xylophilus (Pine wood nematode, PWN) is a serious pest in pines that changes the original biological and geographical distribution as well as the structure and function of the natural ecosystems. The nematode and associated pine wilt disease have great impact on the stand growth of Masson pine forests in China. The growth rule of individual forest factors after the PWN invasion was analyzed using “the technique of censusing every individual” and “quadrat method”. The results showed that the invasion of PWN in 1996 had significant impact on the diameter growth of the pines, but PWN only seldom affected the height growth of the pines. Based on this, the paper also established the grey forecast and grey-Markov combination models of the growth of Masson pines attacked by PWN. This series of models had a high simulation accuracy and could be applied to predict stand description factors in Masson pine forest, no matter whether it was attacked by PWN or not.

According to the international methods of pest risk analysis and urban forestry characteristics in Beijing, a quantitative risk assessment system in Beijing for three primary non-indigenous pests was proposed. This system was used to analyze three major non-indigenous species, Dendroctonus valens, Hyphantria cunea, and Apriona swainsoni. The results show that the risks of these three pests in the Beijing area were 2.46, 2.30, and 2.02, which were all highly risky. Based on the result and extensive risk communications, combined with the management experience of the Beijing Forest Protection Station, the authors proposed some effective control measures to prevent the invasion of the three pests into Beijing.