Glutathione S-transferases (GSTs) constitute a multifunctional superfamily in which Zeta class is widely distributed in animals, plants, and bacteria. In mammals, Zeta GSTs show maleylacetoacetate isomerase (MAAI) activity and participate in phenylalanine and tyrosine metabolism. In this study, expressed sequence tags (ESTs) were searched for the predicted GST gene from Bombyx mori, BmGSTz1. A contig containing 1 239 bp was assembled on the basis of ESTs of BmGSTz1, which extended into 3′ and 5′-UTR (untranslated region). The contig of BmGSTz1 perfectly matched to the corresponding region of the silkworm genome sequence and had a poly (A) signal in its 3′-UTR. BmGSTz1 was composed of 4 introns and 5 exons, and the boundary between exon and intron conformed to the canonical GT-AG rule. TA cloning verified that the coding sequence (CDS) was 648 bp in length and encoded 215 amino acids. The putative molecular weight and isoelectric point of BmGSTz1 were 24.8 kD and 8.06, respectively. BmGSTz1 had relatively high similarities with GSTz1 from insects and mammalians. Phylogenetic analysis showed that BmGSTz1, DmGSTz1, AgGSTz1, ApGSTz1, and TcGSTz1 might be 1∶1∶1∶1∶1 orthologues. The RT-PCR and microarray data indicated that BmGSTz1 was expressed in various tissues in Day-3 5th instar silkworm larvae. The results of sequence analysis and expression characterization suggest that BmGSTz1 might have the MAAI activity. The data presented in this study provide useful information for further studying the function of BmGSTz1.

According to the homologous amino acid sequences in Caenorhabditis elegans and other insects, the full length cDNA sequences of 3 glycosyltransferase genes (named as Pxbre-3, Pxbre-4 and Pxbre-5) were cloned by RT-PCR and RACE-PCR from the midgut of 4th instar larvae of the diamondback moth, Plutella xylostella. The open reading frames of these genes were 1 383 bp, 1 230 bp and 1 041 bp, respectively. The deduced coding products had 460, 409 and 346 amino acids, respectively. These genes were homologous to the bre genes of Caenorhabditis elegans and had the predicted membrane-spanning regions and conserved motifs known to play key catalytic roles in glycosyltransferases. Thus, the three genes are inferred to code glycosyltransferases in P. xylostella. The mRNA expression of these three genes and Pxbre-2 was detected in different developmental stages (larva, pupa, and adult) of P. xylostella by real-time quantitative PCR, and the expression level was higher in pupa and adult. These results provide an important basis for investigating the possible involvement of glycosylphingolipid in resistance to Cry toxins in P. xylostella.

Aminopeptidase N (APN) and cadherin are key receptors of Bacillus thuringiensis Cry1A toxins in brush border membrane vesicles (BBMVs) of lepidopteran insects. Effects of RNAi-mediated silencing of an APN gene Haapn1 and a cadherin gene Ha_BtR on Cry1Ac toxicity were investigated by injecting dsRNAs of these two genes into the 4th instar larvae of Helicoverpa armigera in this experiment. Reduction of mRNA expression of Haapn1 (30%-49%) and Ha_BtR (30%-37%) was observed in the larvae injected respectively with Haapn1 dsRNA and Ha_BtR dsRNA (1 μg/larva) compared with the control larvae injected with elution solution (ES) only. Mortality of larvae injected with Haapn1 dsRNA was significantly lower than that of the control larvae injected with ES in treatments of 40 and 70 μg/cm² of activated Cry1Ac, but there was no difference in mortality of larvae injected with either Haapn1 dsRNA or ES in treatments of 100 and 170 μg/cm² of Cry1Ac protoxin. RNAi-mediated gene silencing by injecting Ha_BtR dsRNA had no effect on toxicity of both activated Cry1Ac and Cry1Ac protoxin. However, toxicity of both activated Cry1Ac and Cry1Ac protoxin against the 4th instar larvae injected with a mixture of Haapn1 dsRNA and Ha_BtR dsRNA was significantly reduced. These results further confirm that both Haapn1 and Ha_BtR are functional receptors of Cry1Ac in H. armigera, and both of them are involved in intoxication of Cry1Ac. Our results also suggest that mutations occurring in either Haapn1 or Ha_BtR may result in resistance to Cry1Ac in H. armigera.

In order to ascertain the insecticidal activity and probe into the insecticidal mechanism of Interruptin B, we studied its biological activity against the 3rd larvae of Plutella xylostella and Ostrinia furnacalis with leaf dipping method and the effect on the number of blood corpuscles in Spodoptera litura larvae by injection and blood cell count, and observed the cell proliferation inhibition of S. litura ovary cells (SL cells) using MTT method. Meanwhile, we observed its effect on the shape, density and the adherence rate of cells by inverted microscope. The results indicated that Interruptin B had the antifeedant and insecticidal activity against the 3rd instar larvae of P. xylostella and O. furnacalis. At 48 h post treatment, the AFC₅₀ values of Interruptin B against the 3rd instar larvae of O. furnacalis and P. xylostella were 108.56 g/mL and 143.88 μg/mL, respectively, while the LC₅₀ values were 346.23 μg/mL and 194.32 μg/mL, respectively. This compound also had strong inhibitive activity on the growth of S. litura larvae, its IC₅₀ values on SL cells at 24 and 48 h post treatment were 13.51 μg/mL and 4.11 μg/mL, respectively. Significant decrease of cell density were observed by microscope in the Interruptin B treated SL cells (P<0.05). The deformation rates of SL cells were 28.18%, 83.90%, 85.18%, 93.93% and 100%, and the adherence rates were 96.59%, 89.90%, 83.18%, 5.06 % and 1.09% at 3, 6, 12, 24 and 48 h post treatment, respectively. The deformation rate and adherence rate of SL cells treated with Interruptin B were significantly different from those in the control at 6-48 h post treatment (P<0.05）. The results show that Interruptin B possesses the antifeedant and insecticidal activity against P. xylostella and O. furnacalis, and can decrease the blood cells of the larvae of S. litura and the density of SL cells, and has strong inhibitive activity on the growth of S. litura larvae. In addition, it can inhibit cell proliferation, change the cell shape, and decrease the adherence rate of SL cells. These suggest that the insecticidal activity of Interruptin B is realized by affecting the cell activity of insects.

To study the species diversity pattern of carabids and its relation with environment factors in different ways of land use, systematic investigation of carabid beetles were conducted from May to October in 2009 by pitfall traps in Saibei Administrative Region, Hebei Province, Northern China. Carabid beetles caught from six habitats of different land uses, i.e., shrubmeadow, potato land, clover field, enclosed meadow, moderately grazed meadow and heavily grazed meadow, were identified and analyzed. The results showed that a total of 10 804 carabid beetles were collected, belonging to 10 genera and 18 species. Among all collected specimens, Pterostichus fortipes, Cymindis binotata and Carabus latreillei accounted for 67.5%, 7.53% and 7.06% of total specimens, respectively. The highest density of carabids was found in clover field, followed by potato field, and the lowest density in heavily grazed meadow. As to clover field, there was almost no disturbance, and the species richness, Margalef richness index, Shannon-Wiener diversity index and the evenness index of carabids were higher in clover field than other ones. The result of clustering analysis showed that the similarity of beetle community in different habitats accords with interference strength and land use patterns. Beetles seasonal activities were mainly from June to September, and peaked in July and August. Various species in different land use patterns have different seasonal trends. The number of carabid individuals increased with the plant biomass. Pterostichus fortipes mostly reached a peak in July when plants grow in luxuriance, except that the peak within the enclosed meadow appeared in August; Cymindis binotata peaked in 8-9 months. Canonical corresponding analysis indicated that the soil moisture, soil temperature, plant cover, plant biomass and plant height were important environmental factors in carabid community composed. The results suggest that the disturbance of different land uses influenced the environments where carabid beetles survived, and then influenced the species composition and quantity distribution pattern.

To investigate the genetic differentiation and gene flow among different populations of the Asian corn borer, Ostrinia furnacalis (Guenée), in China, we analyzed COⅡ sequences of mitochondrial DNA in 17 geographical populations. In the total 413 COⅡ gene sequences obtained, 34 variable sites and 35 haplotypes were observed. The mean haplotype diversity of all populations was 0.811, whereas it varied from 0.424 to 0.862 within population. The average gene flow (Nm) among the 17 populations was 2.02. The overall Fst value was 0.234. Molecular variance (AMOVA) analysis indicated that a high proportion of the total genetic variance was attributable to variations within populations (76.45%). The Tajima’s D value neutrality test results suggest that for the Asian corn borer, there might be no population expansion, so their population sizes were steady. The genetic distance was not significantly correlated with the geographical distance between populations. The phylogenetic tree revealed no obvious geographical pattern for the prevalence and distribution of the haplotypes.

In order to investigate the genetic variations of different geographical populations of Pieris rapae Linnaeus in China, the ribosomal DNA gene interval transcribed spacer 1 (ITS-1) sequences of 79 indididuals from 16 areas were determined and analyzed. Upon these gene sequence data and using Pieris canidia as the outgroup, we reconstructed phylogenetic trees by means of neighbor-joining and minimum evolution analyses, aiming to clarify their biogeographical divergence pattern. The results of the sequence variation analyses showed that the sizes of the ITS-1 of Pieris rapae range from 337 to 458 nucleotides in length. Aligned with the ClustalW software, the total 347 sites, which contain 281 conserved, 63 variable and 16 parsimonious informative, were obtained. Meanwhile, for the whole population of this study, the nucleotide diversity Pi and the Theta (per site) Eta were calculated to be 0. 014 and 0.041, respectively. Moreover, total 48 haplotypes were identified and the haplotype diversity 0.989 was obtained by the software DnaSP. Additionally, the fixation index (F_ST) 0.351 (P<0.05) was calculated by the analysis of molecular variance (AMOVA) software. The result of phylogenetic analysis indicated no pronounced correlation between their haplotypes and the geographical regions. Based on the phylogenetic trees, it is inferred that the Pieris rapae in China probably colonized first in the Liaoning, Inner Mongolia and Beijing, and then spread to other areas by transportation of their host plants and migration of their adults.

The genus Zhengitettix from China was reviewed, with six species recorded, including one new species, Zhengitettix triangularis sp. nov., which was collected from Yunnan, S.W. China. The new species is allied to Z. hainanensis Liang, 1994, but differs in: width of frontal ridge sulcus as wide as the width of basal segment of antenna; antennae inserted between the lower margin of eyes; hind process reaching one third of top part of hind tibia; hind wing reaching extending over the top of hind process; hind tibia black. A key to species of the genus is given.

Diapause is widespread in a variety of braconids, which are natural enemies for many pest insects. By regulating diapause of braconids, the following objectives can be achieved: increasing the shelf-life of braconid wasps, prolonging the time of prevention and control, and improving the braconids’ resistance ability and fecundity. These are important for production and application of braconids. This review summarized 2 545 literatures of diapause in the world since 1910. In total 37 species in Braconidae, belonging to 16 genera and 7 subfamilies, were reported for their clear diapause induction or diapause termination. Among them, the diapause characteristics of 23 species were described in detail. Majority of braconids diapaused in prepupae, followed by larval diapause, a small number of the braconids diapaused in adult. The diapause sensitive period varies in different species. Braconids have relatively long diapause duration, because most of them can be maintained for several months, and the longest one is up to 14 months. Photoperiod, temperature and host are major factors affecting the diapause of braconids. To some extent, humidity, parents and host plants can also affect the diapause process of braconids. Currently, the research of diapause in braconids is limited to biological observation, the physiological characteristics, hormone regulation, molecular regulation, etc. have not yet been studied, so there are many issues to be further explored.

To investigate the relationship between cellulase activity and host selection, Anoplophora glabripennis (Motsch.) larvae from four different host trees (Populus alba var. pyramidalis Bunge, Populus nigra var. thevestina (Dode) Bean, Populus simonii × Populus pyramidalis cv. opera Hsu and Salix matsudana f. lobato-glandulosa Fang et Liu) and adults fed on five different tree species were selected. The enzyme activities of endoglucanase andβ-glucosidase in the intestines of the insects were measured. The results showed that in the larvae, the activity of endoglucanase ranged from 1.36 to 2.71 μmol glucose/(g FW·h), and the activity of β-glucosidase ranged from 2.57 to 4.86 μmol glucose/(g FW·h). In the adults fed on different tree species, the activity of endoglucanase ranged from 4.08 to 9.27 μmol glucose/(g FW·h), and the activity of β-glucosidase ranged from 2.87 to 6.08 μmol glucose/(g FW·h). There are no significant differences in cellulase activities among the larvae from different host trees. However, the tree species which the adults fed upon has great effect on the activity of cellulase in the adults.

The egg parasitoids Trichogrammatoidea bactrae Nagaraja and Trichogramma confusum Viggiani are potential biological control agents for the diamondback moth (DBM), Plutella xylostella (L.). In this study, the olfactory response of two parasitoids to saturated hydrocarbons from host egg shells and adult scales of P. xylostella were measured using a Y-tube olfactometer. The results indicated that the percentages of mated females of T. bactrae entering the treatment arms of 2,6,10,14-tetramethyl-pentadecane, pentadecane and heptadecane were 80.65%, 68.75% and 66.67%, respectively, significantly higher than those entering the control arms, suggesting that these three compounds could stimulate an intensive search behavior by T. bactrae. However, the parasitoid did not respond to other 10 hydrocarbons. The percentages of mated females of T. confusum entering the treatment arms of 2,6,10,14-tetramethyl-pentadecane, pentatriacontane and pentadecane were 84.38%, 70% and 62.16%, respectively, significantly higher than those entering the control arms, revealing that T. confusum were significantly attracted by those three compounds. While the numbers of T. confusum entering the treatment and control areas had no differences in the tests with other 10 hydrocarbons. In the case of unmated males of T. bactrae and T. confusum, there was no significant difference in entering numbers of wasps between the treatment and control arms for all 13 saturated hydrocarbons.