Glutamate-gated chloride channels (GluCls) or inhibitory glutamate receptor (IGluR) is the major action targets of avermectins. However, people have little knowledge of IGluR in insects currently. In this preliminary experiment, RNA interference (RNAi) technology was used to study the function of the IGluR in Plutella xylostella. The results showed that the most suitable injection volumes of double strand RNA (dsRNA) for the 2nd and 3rd instar larvae were 50.6 nL and 71.3 nL, respectively. The results of quantitative real-time PCR (qRT-PCR) showed that the post transcriptional level of IGluR in the 2nd instar larvae decreased by 32.67% at 36 h after RNAi and that in the 3rd instar larvae decreased by 49.30% at 24 h after RNAi. The susceptibility of larvae after RNAi to abamectin revealed that the mortality of the larvae injected with the dsRNA of IGluR was significantly lower than that of the control. The results suggest that the IGluR in P. xylostella is a potential target site for abamectin, and these results would lay the foundation for further elucidation of the target resistance mechanism of P. xylostella to abamectin.

To illustrate the effects of low-dose ⁶⁰Co-γ radiation on the development, phototactic behavior and sex pheromone titer in Helicoverpa armigera (Hübner), we examined the emergence rate, the deformity rate and longevity of H. armigera adults under five doses of radiation, and determined the rate of phototaxis and sex pheromone titer of H. armigera by phototactic behavior trial and pheromone extraction method. The results indicated that (1) there were no effects of ⁶⁰Co-γ radiation on adult emergence, deformity and longevity of the moth except for the irradiation of 20 Gy, under which the emergence rate was remarkably decreased by 16.67% (female) and 20.00% (male), and the deformity rate was increased by 10.00% (both female and male). (2) Both in photophase and scotophase, the rate of phototaxis and sex pheromone titer were increased. The biggest jump of the rate of phototaxis occurred in 3-day-old females in photophase (28.33%±3.33%-91.67%±4.41%), while that of sex pheromone titer occurred in 5-day-old females in scotophase (36.27±4.26 ng-59.13±4.63 ng), indicating that this dose irradiation (50 Gy) probably promoted the occurrence of phototactic behavior and the production of sex pheromone, while the radiation at five doses had no significant effects on phototaxis. (3) There was a declining trend following an increasing trend of the rate of phototaxis and sex pheromone titer as age increased. The biggest jump of the rate of phototaxis occurred in females in photophase and males in scotophase both after radiation (91.67%±4.41%-3.33%±1.67%), while that of sex pheromone titer occurred in females in scotophase after radiation (71.00±5.22 ng-3.63±1.47 ng). (4) There were no obvious differences in the emergence rate, the deformity rate, longevity and the rate of phototaxis between females and males in most treatments. This research may provide some theoretical basis for exploring the changes in phototaxis and physiological and biochemical characteristics of H. armigera, and also offer new ideas on taking advantage of physical and chemical communication for integrated management of H. armigera.

In order to reveal the infection characteristics of bacterial endosymbionts Wolbachia and Cardinium in natural populations of Sogatella furcifera (Horváth) and the relationship between Wolbachia and bacteriophage WO, we used PCR method to detect the infection rates and tissue distribution of these bacteria and phage in various S. furcifera populations which were collected from nine localities in seven provinces and regions of China. The results revealed that the double infection of Wolbachia and Cardinium was a common event in this insect with each population tested having a high infection rate. For Cardinium, the infection rate was nearly 100%, but for Wolbachia, the infection rates of females and males were quite different, nearly 100% in females while ranged from 22.2%-95.0% in male adults. In addition, by comparing the detection results using different DNA extraction methods and DNA polymerase, we found that the rough DNA extraction method has evident disadvantages in surveying the endosymbiont infection. Wolbachia and Cardinium existed not only in the germinal tissues of S. furcifera but also in non-reproductive tissues/parts such as head, thorax, legs and wings. Meanwhile, these two endosymbionts exhibited different change patterns during the adult stage, particularly in males. There existed an obvious negative correlation between the infection rates of Wolbachia and the rates of bacteriophage WO detected from uninfected individuals in males. The lower Wolbachia infection rate in males might be caused by the transition of WO phage from lysogenic to lytic type under the induction of certain factors. The results of this study will shed light on further understanding of the reproductive manipulation and underlying mechanisms of Wolbachia and Cardinium, their vertical transfer, interrelationship and their potential utilization.

To study the insecticidal activities and active ingredients of Cacalia tangutica, the methanol extracts of C. tangutica against Musca domestica and Aedes albopictus were bioassayed with feeding method and dipping method. The active ingredients of C. tangutica were isolated and identified. Results indicated that the methanol extracts from different parts of C. tangutica showed highly insecticidal activities against adult M. domestica and the 4th instar larvae of A. albopictus. Nine compounds (stigmasterol, friedelin, 7-hydroxy-8-methoxycoumarin, umbelliferone, daphnetin, daphnetin-8-O-β-D-glucopyranoside, quercetin, kaempferol and β-daucosterol) were isolated and identified from extracts of leaves and flowers of C. tangutica. Among them, friedelin, quercetin and kaempferol were firstly isolated from this plant. At 48 h after treatment, the corrected mortalities of adult M. domestica caused by friedelin, quercetin and kaempferol at the dosage of 500 μg/g were 88.33%, 69.90% and 77.04%, respectively. At 72 h after treatment, the corrected mortalities of the 4th instar larvae of A. albopictus caused by friedelin, quercetin and kaempferol at the concentration of 50 μg/g were 88.49%, 72.22% and 71.06%, respectively. The studies suggest that C. tangutica would be a promising control agent on medical insects and deserves a further study.

In order to explore the effects of temperature on the population growth of Comstock mealybug, Pseudococcus comstocki, the life table of the experimental population of P. comstocki at six different temperatures (17℃, 20℃, 23℃, 26℃, 29℃ and 32℃) was constructed. The results showed that the generation duration decreased with the temperature increasing from 17℃ to 29℃. The longest generation durations of females and males were 121.27 d and 89.64 d at 17℃, respectively, while the shortest were 52.10 d and 36.01 d at 29℃, respectively, and the relationship between the development and temperature could be simulated by the Logistic model. The developmental threshold temperature and the effective accumulated temperature of females were 8.69℃, and 1 020.90 day-degrees, and those of males were 10.27℃ and 659.04 day-degrees, respectively. At 26℃, the survival rate and population trend index were the highest, being 81.94% and 322.27, respectively. The temperature of 26℃ was the most suitable for the population growth. While at 17℃and 29℃, the survival rates were 64.85％and 67.23％, and the population trend indexes were 69.91 and 42.19, respectively. At 32℃, growth retardation appeared in the 1st instar nymphs. It is concluded that high and low temperatures are not suitable for the population growth of P. comstocki and high temperatures have stronger effects than low temperatures.

The environmental heterogeneity is an important mechanism underlying the formation and maintenance of bio-geographic pattern. The spatial pattern of grasshopper species is the result of longterm adaptation in nature, reflecting the co-evolution mechanisms with which grasshoppers adapt to the habitats. Through field survey from July to August, 2009, by using the GIS and S-PLUS 8.0, we developed the GAM model for the relationship between nymph and adult adundance of Oedaleus asiaticus and topographic indices in the upper reaches of Heihe River on the northern slope of the Qilian Mountains. The topographic indices included elevation, direction, slope, position, profile and plane. The results showed that the structure and D² values of models were different for O. asiaticus nymphs and adults, so was the model stability in modeling, indicating their differences in response to the gradients of topographic indices. The gradient analysis in this model showed that the locust nymphs and adults were distributed in a wide range of environments, in different gradients of elevation, direction, slope, position, profile and plane, and in all land positions. However, it does not mean that the distribution of locust nymphs and adults is equally affected by each factor, or has a uniform distribution probability in the whole environmental range. The GAM modeling indicated that the distribution of locust nymphs and adults were mainly controlled by the elevation. With the elevation increasing, the abundance of locust nymphs and adults showed an upside-down “V” trend, but the upper limit of elevation for distribution of the locust nymphs was higher than that of adults. Adults had higher abundance in the whole regions, but they were mainly located in the region where the profile is less than 0, while the nymphs mainly concentrated in the south and southwest slopes, which was consistent with the actual observation results. The heterogeneity of O. asiaticus in selecting habitats made the spatial pattern of locust nymphs and adults in the same terrain obviously different.

The invasive Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) biotype Q (hereafter referred to as Q) was first detected in China in 2003, it gradually displaced the well-established biotype B (hereafter referred to as B) and has become the dominant whitefly in China by 2008. The goal of the current study was to provide insight into the rapid invasion of B. tabaci Q and the domination of B. tabaci Q over B in China. In this study we used 11 microsatellite loci to analyze and compare the genetic structure of one Q and 11 B introduced populations collected in China in 2003 with those of two native Q populations from Spain, one invasive Q population and one native B population from Israel, and five introduced B populations from Spain, the USA, and Australia. The results revealed that the first B. tabaci Q population in China was probably introduced from the western Mediterranean region rather than from the eastern Mediterranean region. The 11 B. tabaci B populations in China, however, might be the progeny of multiple primary introductions from the source region or represent secondary spread from an invaded region. Chinese B had greater genetic diversity than B from Spain, Australia, and the USA, suggesting that Chinese B might have more than one source. Both the first-introduced Chinese Q population and the well-established B populations have not experienced a substantial decrease in genetic diversity relative to their source populations, suggesting minimal bottleneck or founder effects. Genetic diversity for the invasive Q population was greater than the B populations in China, which might contribute to Q’s strong ecological adaptability to the new environments in the introduced regions and thus might explain why it has rapidly spread and displaced the well-established B populations in China.

Encarsia formosa Gahan (Hymenoptera: Aphelinidae) is the dominant parasitoid of important whitefly species, such as Trialeurodes vaporariorum Westwood and Bemisia tabaci (Gennadius). Most of the Aphelinidae species are small and morphologically similar, and this makes them hard to be identified accurately. In this study, a pair of SCAR (sequence characterized amplified region) primers (EFZZF/EFZZR) which are specific to En. formosa was developed by using other five common Aphelinidae species and four biotypes of B. tabaci as the control. The fragment amplified by these primer pairs was 287 bp in length. Species specificity test showed that all En. formosa specimens were detected with no cross reactions with other aphelinid species, including En. sophia (Girault & Dodd), Eretmocerus hayati Zolnerowich & Rose, Eretmocerus sp., Er. mundus Mercet, Amitus hesperidum Silvertri, or whitefly species including four biotypes (B, Q, ZHJ-1, and ZHJ-2) of B. tabaci as well as T. vaporariorum and Aleurocanthus spiniferus (Quaintanca). Even at the concentration of 7.812 ng/μL DNA, equal to 1/1 600 of a whole female adult of En. formosa, the 287 bp DNA fragment could be detected in all replicates. The technique developed here would be useful for rapid and precise species identification, determination of the host spectrum and more effective utilization of En. formosa.

The mutation of the gene methuselah (mth) in Drosophila chromosome 3 leads to a 35% increase in average lifespan of adults and enhances their resistance to various forms of stress, such as starvation, high temperature, and paraquat, a superoxide-generating drug. The gene methuselah (mth) encodes a family B G protein-coupled receptor (GPCR) Mth and its endogenous ligand is Stunted, a small peptide encoded by the sun gene. The sun gene knockout or overexpression of peptide antagonists of Mth receptor also extends life span of fruit flies. Mth receptor characterized by a signature seven-trans-membrane configuration is thought to be the first GPCR associated with the control of animal ageing. The unique ectodomain of Mth receptor makes contact with multiple ligands. Its biological functions include maintaining the balance of homeostasis and metabolism and participating in the regulation of lifespan, stress response, male germline stem cell population, sensorimotor function, etc. At present, researches of Mth receptor are still in the initial stage. Its working mechanism is of great significance to reveal how GPCR participates in lifespan control. Moreover, it may help us develop new drugs to extend life. Therefore, the structure, function, ligand and signal transduction pathway of the Drosophila Mth receptor were mainly summarized in this article and the outlook for the practical research value of its signal pathway were also reviewed.

The ecological processes and mechanisms of alien species invasion are important parts of invasion biology. The case study of ecological processes and mechanisms of invasion of the important alien species is of significance to the construction of invasion biology discipline and the management of the invasive species as well. The case study of the alien species in China, however, was rather scarce till the present. The systematic study of an important alien whitefly, Bemisia tabaci biotype Q, in China during the past 10 years has provided an excellent chance for us to analyze the ecological processes and mechanisms of the alien species invasion. In this article, the ecological processes of B. tabaci biotype Q in China during the past 10 years are traced, the characteristics of its invasion processes are summarized, the invasion mechanisms of the pest is analyzed from the viewpoint of genetic structure of invasive populations, biological factors and human activities, and the future research directions of invasion biology of B. tabaci biotype Q are also prospected. We conclude that there are three main characteristics of the invasion processes of biotype Q in China: the introduction was cryptic, the spread speed was fast, and the damage was severe. The mechanisms of invasion of biotype Q in China are associated with the genetic basis of the introduced populations, the ecological factors and a variety of human activities. Among them, the wide application of insecticides, which is beneficial to the displacement of biotype B by Q, might be the most important factor involved in the successful invasion of biotype Q in China.

【Aim】 To select the suitable reference genes in Plutella xylostella after exposure to Bt toxin by quantitative real-time PCR. 【Methods】 Eight candidate reference genes, including 18S ribosomal RNA (18S rRNA), beta actin gene (ACTB), elongation factor 1 gene (EF1), glyceraldehyde-3-phosphate dehydrogenase gene (GAPDH), ribosomal protein L32 gene (RPL32), ribosomal protein S13 gene (RPS13), ribosomal protein S20 gene (RPS20) , and β-tubulin gene (TUB), were chosen. The stability of these candidate reference genes was investigated using three softwares (geNorm, NormFinder and BestKeeper). Then, the expression of aminopeptidase N2 gene (APN2) was analyzed by using different reference genes. 【Results】 Based on the results of geNorm analysis RPS13 and EF1 were the most suitable reference genes in P. xylostella after exposure to the Bt toxin Cry1Ac, while based on the results of the NormFinder and BestKeeper analysis RPS13 and RPL32 were the most suitable reference genes. Using new reference gene (EF1) or traditional reference gene (RPL32) for normalization, similar expression levels of APN2 were observed, whereas normalization with the unstable reference gene (18S rRNA) might lead to erroneous interpretations. 【Conclusion】 This work is contributable to the solid foundation for future gene expression studies in the diamondback moth, and may also serve as a resource to screen reference genes for expression studies in other insects.

【Aim】 To explore the components of the alarm pheromone of Tyrophagus putrescentiae. 【Methods】 The extracts were extracted from T. putrescentiae mites with hexane. Biological activity of the extracts was assayed by observing the behavioral response of the mite to the extracts. The components of the extracts were identified by GC-MS. 【Results】 T. putrescentiae had intensive alarm response to the extracts, which consist of neryl formate, Z-citral, and E-citral based on GC-MS data. 【Conclusion】 This experiment proved the existence of alarm pheromone in T. putrescentiae and established the foundation for its further research.

In order to evaluate the control effects of Aenasius bambawalei Hayat on the 3rd instar nymphs and female adults of Phenacoccus solenopsis Tinsley, the parasitic functional response of A. bambawalei to P. solenopsis, and the density effect of A. bambawalei were determined under the laboratory conditions of 25±1℃, RH 70%±5% and 14L∶10D. The results showed that the response of A. bambawalei fitted Holling type Ⅱ model and was affected by the densities of host and parasitoid. When the densities of the 3rd instar nymphs and female adults of P. solenopsis were higher than 15 and 10 individuals per container, respectively, the increase rate of parasitism by A. bambawalei began to decrease. Taking the ration of instant attack rate to parasitizing time (α/T_h) as an evaluation index, the parasitizing efficiency was 21.1307 for the 3rd instar nymphs, which was higher than that for female adults (6.2506). Additionally, there was a stronger intraspecific interference in the parasitic functional response of A. bambawalei. The number of parasitized hosts decreased with the increasing density of A. bambawalei. The relationship between searching efficiency (E) and density (P) of A. bambawalei could be well simulated with the model E=0.2931P^-0.6240 for the 3rd instar nymphs, and with the model E=0.0944P^-0.4840 for female adults. This study provides essential data and methods for the research and application of A. bambawalei for biological control of P. solenopsis.