Pheromone-mediated mating disruption in the millet stem borer, Coniesta ignefusalis (Lepidoptera: Pyralidae)

The millet stem borer, Coniesta ignefusalis Hampson (Lepidoptera: Pyralidae), is a major pest of pearl millet in the Sahelian region of Africa. The female sex pheromone has been identified and synthesised, and previous research had shown that the synthetic pheromone could cause high levels of reproductive communication disruption in small plots when released at rates of 640 mg/ha/day, using PVC resin formulation renewed every seven days to maintain efficiency. In the present research, in experiments in farmers’ fields in Niger, 86.8% (SE = 2.6%) communication disruption was achieved when polyethylene vials loaded with 0.5 mg pheromone at 400 dispensers/ha were used and replaced every 21 days. Polyethylene vials loaded with 80 mg pheromone gave uniform, zero-order release at approximately 0.05 mg/day at 27 °C. Experiments carried out on replicated 0.5 ha plots in farmers’ fields in Niger using a single application of these dispensers at 400 dispensers/ha resulted in at least 99% suppression of pheromone trap catches of male C. ignefusalis moths in treated plots relative to numbers in untreated plots for up to 3 months. However, sampling the central portions of these plots before and after harvest showed no significant differences in infestation, damage or yield loss between plots treated with pheromone and untreated plots. This may have been because of small plot size and the immigration of mated female moths into the treated plots which negated any reduction of mating of females within the treated plots. Comparisons of numbers of male C. ignefusalis moths in traps baited with the standard 0.5 mg monitoring lures and those baited with the 80 mg disruption dispensers showed catches in the latter were only 10-20% of those in the former; indicating high level communication disruptions in traps with high dose dispensers. Implications of using insect synthetic pheromones in the development of integrated management of C. ignefusalis in pearl millet cropping systems in the Sahel are discussed.     

A larval specific OBP able to bind the major female sex pheromone component in Spodoptera exigua(Hübner)

Odorant binding proteins(OBPs) in insects are postulated to solubilize and transport the hydrophobic odorants across the hydrophilic antennal lymph to the olfactory receptors(ORs) located on the dendrite membrane of the sensory neurons. OBPs in adult insects have been intensively reported, but those in larvae are rarely addressed. In our study, a full-length OBP c DNA, namely Sexi OBP13, was cloned by RT-PCR and RACE strategy from the heads of Spodoptera exigua larvae. The quantitative real-time PCR(q PCR) measurement indicated that Sexi OBP13 was highly expressed in larval head, but very low in other parts of larva and was not detected in any tissues of adult. The binding affinities of Sexi OBP13 to plant volatiles and female sex pheromone components were measured by competitive binding assays. Interestingly, Sexi OBP13 displayed a high binding affinity(Ki=3.82 μmol L–1) to Z9,E12–14:Ac, the major sex pheromone component of S. exigua, while low affinities to the tested host plant volatiles(Ki27 μmol L–1). The behavioral tests further confirmed that Z9,E12–14:Ac was indeed active to elicit the behavioral activity of the third instar larvae of S. exigua. Taken together, our results suggest that Sexi OBP13 may play a role in reception of female sex pheromone in S. exigua larvae. The ecological significance of the larvae preference to the adult female sex pheromone was discussed.     

甘肃大野口青海云杉种群的空间分布格局

为掌握青海云杉的空间分布特征和大面积遥感定量反演青海云杉结构提供关键参数,以及为青海云杉种群保护和祁连山水源涵养林的可持续经营提供基础数据,根据甘肃大野口1hm2青海云杉林大样地的调查结果,首次应用点格局方法开展青海云杉种群空间格局的研究,并且将研究区内树木分龄级计算,得到不同龄级的树木在不同尺度下的空间分布格局。首先,应用Weibull分布对样地内青海云杉的胸径分布进行拟合;然后分别采用点格局分析法和聚集指标测定法,对样地内各龄级的树木在不同尺度下的空间分布格局进行研究;最后应用纽曼A型分布对研究区内的青海云杉种群空间分布格局进行拟合。结果表明:青海云杉林胸径分布基本符合Weibull分布;研究区内种群密度较大,空间格局呈集群分布;幼树、小树、中树和大树在各研究尺度下均呈集群分布;青海云杉随着年龄的增长,聚集强度逐渐降低;研究区内青海云杉种群空间分布格局符合纽曼A型分布。集群分布的原因主要是自然和人为干扰、环境条件及青海云杉的生物学特性共同作用的结果。     

斜纹夜蛾信息素结合蛋白3基因的分子鉴定及进化分析

信息素结合蛋白(PBP)是大量存在于昆虫触角感器中的一类小分子蛋白,它特异性结合并运输性信息素组分到神经树突膜上的气味受体。通过设计简并引物并利用RT-PCR技术,从斜纹夜蛾雄虫触角扩增到1个长171bp的预期cDNA片段,测序后经比对表明是PBP3基因片段,将该基因命名为SlitPBP3。利用RACE技术进一步得到SlitPBP3的cDNA全长序列(GenBank登录号:GU082321),长568bp,编码164个氨基酸,具有PBP的典型序列特征。对基因组DNA的研究显示,该基因由3个外显子和2个内含子构成。2个内含子的位置和斜纹夜蛾的另2个PBP基因相同,具有保守性;其长度分别为124bp和73bp。进化分析显示,夜蛾科昆虫的PBP分为3个组,其中斜纹夜蛾的3个PBP被分在不同的3个组,因而可能具有不同的气味结合谱。     

性诱剂在杏园梨小食心虫防治中的应用

[目的]为性诱剂在杏园防治梨小食心虫提供依据.[方法]利用梨小食心虫性诱剂对新疆库车杏园梨小食心虫进行了使用方法、最佳自制诱捕器种类、1 hm2最适诱捕器数量及防治方法的研究.[结果]杏园梨小食心虫3个成虫羽化高峰期分别出现在4月下旬、6月中旬和8月下旬;在板式、管式、瓶式3种自制的诱捕器中,板式胶粘诱捕器的诱虫效果最好,其次是管式诱捕器,瓶式的较差;在发生量较小时诱捕器的数量以90枚/hm2为宜,但在实际推广应用中应随发生量的增大适当增加诱捕器数量;在防治试验中,迷向区的迷向率和防效分别为76.2;和77.78;,诱捕区的迷向率和防效分别为66.11;和90.75;,诱捕区的防治效果较好.[结论]在实际防治中使用诱捕器法为好.     

不同营养源对小菜蛾成虫嗅觉行为、触角电位反应和繁殖力的影响

采用行为测定仪、电生理等法,研究分别取食3种营养源(蔗糖水、红糖水和蜂蜜水)的小菜蛾成虫的嗅觉行为、触角电位反应、产卵量和产卵节律。结果表明,补充营养显著提高小菜蛾雌蛾对寄主植物成分——异硫氰酸丙烯酯的趋性,但不同营养源处理组间没有显著差异,同时发现补充营养不会显著影响雄虫对雌虫性信息素的触角电位反应;补充营养的雌成虫产卵量显著高于蒸馏水对照组,其中取食蜂蜜水的平均产卵量最大(106.7粒)。从产卵节律看,羽化后当天各处理组的小菜蛾均可产卵,其中取食蜂蜜水、蔗糖水和蒸馏水的3日龄雌成虫产卵量达到峰值,从4日龄起产卵量逐渐降低;取食红糖水的2日龄雌成虫产卵量达到峰值,从3日龄起逐渐降低;同时取食蜂蜜水、蔗糖水和红糖水小菜蛾产卵历期(13d、12d和11d)长于蒸馏水(7d)对照组。研究结果可为揭示小菜蛾成虫营养与其重要生命过程的关系提供科学依据。     

性诱剂对小菜蛾的诱集效果及药剂室内毒力测定

利用性诱剂对保定地区小菜蛾(Plutella xylostella L)的发生动态进行监测,筛选出适宜于保定地区使用的害虫性诱剂;采用浸虫法测定7种药剂对小菜蛾幼虫的室内毒力。结果表明,7种药剂对小菜蛾的室内毒力差异显著,其中1%甲氨基阿维菌素苯甲酸盐ME对小菜蛾幼虫毒力最高,处理48 h后的LC50为0.596 2 mg/L;通过对不同品牌的性诱剂比较试验,明确了中捷四方生物科技有限公司生产的小菜蛾橡胶反钟形诱芯对小菜蛾的诱集效果最好,适宜在保定地区使用。