The Sublethal Effects of β-Ecdysterone,a Highly Active Compound from Achyranthes bidentata Blume,on Grape Phylloxera,Daktulosphaira vitifoliae Fitch

Grape phylloxera, Daktulosphaira vitifoliae (Fitch) (Hemiptera, Phylloxeridae), is a very destructive insect pest of grapevines. Intercropping of Achyranthes bidentata Blume (f. Amaranthaceae) and Vitis spp. grapevines can be useful to control this pest. In the present study, the toxicity of 22 compounds, known to be present in A. bidentata, to grape phylloxera was evaluated. All treatments were toxic towards grape phylloxera but the degree of toxicity differed between treatments. Among the 22 tested compounds, several of which proved toxic towards grape phylloxera. However β-ecdysterone had higher toxic effects against grape phylloxera, with LC₅₀ values of 175.73 mg a.i. liter^-1. In addition, we assessed the sublethal effects of LC₁₀, LC₂₀ and LC₄₀ of β-ecdysterone on grape phylloxera. The fourth instar and adult developmental periods and total life span were significantly prolonged by LC₄₀ of β-ecdysterone. Fecundity decreased when grape phylloxera were exposed to LC₂₀ and LC₄₀ of β-ecdysterone. In addition, LC₄₀ of β-ecdysterone decreased the intrinsic rate of increase (r_m) and the finite rate of increase (λ) and prolonged the population doubling time (DT). The net reproductive rate (R₀) was significantly reduced by both the LC₂₀ and LC₄₀ β-ecdysterone treatments. Our results demonstrated that β-ecdysterone had higher toxic effects and significant sublethal effects on grape phylloxera, and showed potential control of grape phylloxera.     

Epistatic partners of neurogenic genes modulate Drosophila olfactory behavior

The extent to which epistasis affects the genetic architecture of complex traits is difficult to quantify, and identifying variants in natural populations with epistatic interactions is challenging. Previous studies in Drosophila implicated extensive epistasis between variants in genes that affect neural connectivity and contribute to natural variation in olfactory response to benzaldehyde. In this study, we implemented a powerful screen to quantify the extent of epistasis as well as identify candidate interacting variants using 203 inbred wild‐derived lines with sequenced genomes of the Drosophila melanogaster Genetic Reference Panel (DGRP). We crossed the DGRP lines to P[GT1]‐element insertion mutants in Sema‐5c and neuralized (neur), two neurodevelopmental loci which affect olfactory behavior, and to their coisogenic wild‐type control. We observed significant variation in olfactory responses to benzaldehyde among F₁ genotypes and for the DGRP line by mutant genotype interactions for both loci, showing extensive nonadditive genetic variation. We performed genome‐wide association analyses to identify the candidate modifier loci. None of these polymorphisms were in or near the focal genes; therefore, epistasis is the cause of the nonadditive genetic variance. Candidate genes could be placed in interaction networks. Several candidate modifiers are associated with neural development. Analyses of mutants of candidate epistatic partners with neur (merry‐go‐round (mgr), prospero (pros), CG10098, Alhambra (Alh) and CG12535) and Sema‐5c (CG42540 and bruchpilot (brp)) showed aberrant olfactory responses compared with coisogenic controls. Thus, integrating genome‐wide analyses of natural variants with mutations at defined genomic locations in a common coisogenic background can unmask specific epistatic modifiers of behavioral phenotypes.     

Revisiting the phylogeny of Wolbachia in Collembola

The endosymbiont Wolbachia has been detected in a few parthenogenetic collembolans sampled in Europe and America, including three species of Poduromorpha, two species of Entomobryomorpha, and two species of Neelipleona. Based on 16S rRNA and ftsZ gene sequences, most of the Wolbachia infecting parthenogenetic collembolans were characterized as members of supergroup E and showed concordant phylogeny with their hosts. However, the two neelipleonan symbionts form another unique group, indicating that Wolbachia has infected parthenogenetic collembolans multiple times. In this study, five parthenogenetic collembolan species were identified as hosts of Wolbachia, and four new Wolbachia strains were reported for four collembolan species sampled in China, respectively, including a neelipleonan strain from Megalothorax incertus (wMinc). Our results demonstrated that the Wolbachia multilocus sequence typing (MLST) system is superior to the 16S rRNA + ftsZ approach for phylogenetic analyses of collembolan Wolbachia. The MLST system assigned these Wolbachia of parthenogenetic collembolans to supergroup E as a unique clade, which included wMinc, supporting the monophyletic origin of Wolbachia in parthenogenetic collembolan species. Moreover, our data suggested supergroup E as one of the most divergent lineages in Wolbachia and revealed the discrepancy between the phylogenies of Wolbachia from parthenogenetic collembolans and their hosts, which may result from the high level of genetic divergence between collembolan Wolbachia, in association with the geographic differentiation of their hosts, or the possible horizontal transmission of Wolbachia between different collembolan species.     

粽管巢蛛和拟水狼蛛对稻纵卷叶螟和稻褐飞虱捕食作用研究

应用二次正交旋转组合设计方法建立粽管巢蛛和拟水狼蛛对稻纵卷叶螟和稻褐飞虱捕食作用的数学模型。结果表明，粽管巢蛛是稻纵卷叶螟的重要天敌，粽管巢蛛和拟水狼蛛均是稻褐飞虱的重要天敌。当稻褐飞虱密度较高时，随着蜘蛛密度的增加，由于蜘蛛之间的干扰作用，导致稻褐飞虱被捕食量下降。     

中国缺叉多距石蛾属六新种记述(毛翅目,多距石蛾科)

研究了中国毛翅目多距石蛾科缺叉多距石蛾属种类,并报道了其中亲缘关系较近的6新种,即端截缺叉多距石蛾Polyplectropus truncatufus sp.nov.,端突缺叉多距石蛾Polyplectropus convexus sp.nov.,斧端缺叉多距石蛾Polyplectropus dolabriformis sp.nov.,颚状缺叉多距石蛾Polyplectropus mandibuliformis sp.nov.,距枝缺叉多距石蛾Polyptectropus rectangulus sp.nov.,喙端缺叉多距石蛾Polyplectropus rostriformis sp.nov..新种模式标本保存在南京农业大学昆虫标本馆.     

Inheritance and expression of the cry1Ab gene in Bt ( Bacillus thuringiensis) transgenic rice

The inheritance and expression patterns of the cry1Ab gene were studied in the progenies derived from different Bt (Bacillus thuringiensis) transgenic japonica rice lines under field conditions. Both Mendelian and distorted segregation ratios were observed in some selfed and crossed F₂ populations. Crosses between japonica intra-subspecies had no significant effect on the segregation ratios of the cry1Ab gene, but crossing between japonica and indica inter-subspecies led to distorted segregation of the cry1Ab gene in the F₂ population. Field-release experiments indicated that the cry1Ab gene was stably transmitted in an intact manner via successive sexual generations, and the concentration of the Cry1Ab protein was kept quantitatively stable up to the R₆ generation. The cry1Ab gene, driven by the maize ubiquitin promoter, displayed certain kinds of spatial and temporal expression patterns under field conditions. The content of the Cry1Ab protein varied in different tissues of the main stems, the primary tillers and the secondary tillers. Higher levels of the Cry1Ab protein were found in the stems, leaves and leaf sheaths than in the roots, while the lowest level was detected in grains at the maturation stage. The content of the Cry1Ab protein in the leaves peaked at the booting stage and was lowest at the heading stage. Furthermore, the Cry1Ab content of cry1Ab expression in different tissues of transgenic rice varied individually with temperature. Received: 17 April 2001 / Accepted: 7 May 2001     

Control of Brennandania lambi (Acari: Pygmephoroidea) by freezing: evaluation of its efficacy and effects on mushroom growth and yield

Laboratory and field studies were conducted to evaluate freezing as a control measure against Brennandania lambi (Krczal) which infests cultivated mushrooms (Agaricus bisporus) in Shanghai primarily through contaminated spawn. Laboratory experiments showed that exposure of contaminated spawn at -10° C for 24 h killed all stages of B. lambi. These mites probably died due to the freezing of body tissues during sustained exposure at -10° C for 24 h. because the supercooling points for the egg, active larva, quiescent larva, non-gravid adult and gravid adult of B. lambi were respectively -11.34, -10.96, -11.43, -7.65 and -11.20° C, whereas the freezing points were respectively -6.68, -6.84. -6.56, -3.96 and -6.75 °C. Semi-field experiments showed that compost inoculated with B. lambi-infested spawn that had been exposed at -10 °C for 24 h had no mite infestation during spawn running and thus mycelium growth was normal. Laboratory and field experiments during 1989 to spring 1990 showed that freezing spawn had no effect on mushroom yield. Further field experiments in two farms during fall 1990 showed no effect of freezing spawn on yield in one farm and increased yield in the other farm. A field experiment during 1991 to 1992 also indicated that freezing spawn -10 °C for 24 h to 34 h had no effect on mushroom yield.     

Behavioral responses of the whitebacked planthopperSogatella furcifera (Homoptera: Delphacidae) on rice plants whose odors have been masked

In a two-choice test, moreS. furcifera females settled more often on exposed plants than on parafilm-masked ones, regardless of the susceptibility of rice varieties. This indicates that rice volatiles play an important role in the insect's short-range orientation to its host. The fact that more insects settled on exposed resistant Rathu Heenati (RHT) than to masked susceptible Taichung Native 1 (TN1) suggests that there must be certain common volatiles released by both varieties. Few females landed on masked plants of either RHT or TN1. This implies that the insect could not recognize at a distance that a plant was resistant or susceptible without olfactory stimuli.S. furcifera excreted less honeydew on masked plants than on exposed ones for both varieties and more on masked TN1 than on exposed RHT. The electronic monitoring of feeding behavior demonstrates that the insect made more frequent probes and had shorter phloem ingestion durations on exposed RHT than on exposed TN1 and on masked RHT than on masked TN1. Moreover, the insect had longer phloem ingestion durations on masked TN1 than on exposed RHT. These results suggest that volatile chemicals given off by resistant RHT plants have a negative effect on feeding.     

中国距水虻属四新种(双翅目,水虻科)(英文)

记述我国距水虻属Allognosta 4新种,基黑距水虻A.basinigra sp.nov.,彩旗距水虻A.caiqiana sp.nov.,大龙潭距水虻A.dalongtana sp.nov.,梁氏距水虻A.liangi sp.nov.。模式标本保存在中国农业大学昆虫博物馆。