橘小实蝇的发生特点与综合防治技术

橘小实蝇(Bactrocera dorsalis)在福建省寄主范围很广,并严重为害寄主。它的主要为害期是每年的4-11月。生产实践中采用综合治理与农业防治技术有效地控制其为害。     

湿度对橘小实蝇及寄生蜂存活与发育的影响

研究外来入侵害虫橘小实蝇及其寄生蜂在不同湿度条件下的存活与发育能力,以预测其在福建的适生分布区。结果表明:在25℃条件下,不同相对湿度对切割潜蝇茧蜂成蜂种群寿命影响大小依次为75%>95%>55%>35%,其中75%相对湿度下种群平均寿命最长,采用二次曲线模型并求得最适相对湿度为75.2%;不同相对湿度对橘小实蝇种群寿命的影响大小依次为75%>55%>95%>35%,采用二次曲线模型并求得最适相对湿度为68.7%,二者可能具有相似的分布区域。同时,从存活曲线分布的情况来看,切割潜蝇茧蜂在不同湿度下的存活曲线分布较橘小实蝇更集中,表明橘小实蝇对湿度的变化表现出更强的敏感性。同时,湿度低于35%时,不能交配并繁殖后代;处于较高湿度时,对其后代体形大小没有显著影响。     

长柄俑小蜂寄生橘小实蝇蛹的功能反应

长柄俑小蜂寄生橘小实蝇蛹的功能反应符合功能反应模型HollingⅡ型,其方程为:Na=1.5324TrN0/(1 1.5324ThN0)。每只寄生蜂在24 h内最大寄生量为17.57只橘小实蝇蛹。寄生1只寄主蛹所需的时间为1.37 h;瞬时攻击率(功能系数)为0.6526;长柄俑小蜂自身密度对寄生产生干扰效应,用Hassell-Varley模型可表示为:α=0.1085P-0.1929。     

Attraction and mortality of oriental fruit flies to SPLAT‐MAT‐methyl eugenol with spinosad†

Studies were conducted in 2007 and 2008 in Hawaii, USA to quantify attraction and feeding responses resulting in mortality of the male oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), to a novel male annihilation treatment (MAT) formulation consisting of specialized pheromone and lure application technology (SPLAT) in combination with methyl eugenol (ME) and spinosad (=SPLAT‐MAT‐ME with spinosad) in comparison with Min‐U‐Gel‐ME with naled (Dibrom). Our approach involved a novel behavioral methodology for evaluation of slow‐acting reduced‐risk insecticides. Methyl eugenol treatments were weathered for 1, 2, 4, and 8 weeks in California, USA, and shipped to Hawaii for bioassays. In field tests involving bucket traps to attract and capture wild males, and in toxicity studies conducted in 1 m³ cages using released males of controlled ages, SPLAT‐MAT‐ME with spinosad performed similar to or outperformed the standard formulation of Min‐U‐Gel‐ME with naled for material aged for up to 8 weeks in the 2008 tests. In laboratory feeding tests in which individual males were exposed for 5 min to the different ME treatments, mortality induced by SPLAT‐MAT‐ME with spinosad recorded at 24 h did not differ from that caused by Min‐U‐Gel ME with naled at 1, 2, and 4 weeks. Spinosad has low contact toxicity, and when mixed with SPLAT offers a reduced‐risk alternative for control of B. dorsalis, without many of the negative effects to humans and non‐targets of broad‐spectrum contact poisons such as naled. Our results indicate that SPLAT‐MAT‐ME with spinosad offers potential for control of males in an area‐wide integrated pest management (IPM) system without the need for conventional organophosphates.     

桔小实蝇对五种芒果气味挥发性物质的行为反应

为了探究寄主气味挥发物对桔小实蝇行为的影响,本研究应用Y型嗅觉仪测定了桔小实蝇Bactrocera dorsalis(Hendel)成虫对5种芒果气味挥发性物质(乙酸乙酯,α-蒎稀,异松油烯,3-蒈烯和石竹烯)及5种物质混合物的行为反应。结果表明,桔小实蝇雌、雄虫对5种物质及5种物质混合物的行为反应无显著性差异。结果还揭示,桔小实蝇成虫对乙酸乙酯有明显的趋性反应,对异松油烯有明显的忌避反应,而对α-蒎烯、3-蒈烯、石竹烯和5种物质的混合物均没有明显的行为定向反应。说明桔小实蝇成虫对芒果不同气味挥发物的行为反应存在差别,这可为研发桔小实蝇成虫防治新方法提供基础信息。     

Over-wintering stage polymorphism of a bruchine beetle: geographical variation in optimal diapause strategy

Abstract.  1. Most temperate insects undergo diapause at a specific developmental stage to overcome severe winters. The bruchine beetle Bruchidius dorsalis in a warmer region in Japan, however, has diverse over-wintering stages – non-diapausing larvae, diapausing larvae, and diapausing adults, whereas in a cooler region, it over-winters only as the final instar larva or adult in diapause.
2. The geographical pattern of over-wintering stages in 12 populations was investigated over a wide range along the mainland of Japan. It revealed that a distinct geographical pattern of over-wintering stages exists in relation to temperature conditions. In regions with warmer climates, the proportion of non-diapausing larvae increased and B. dorsalis had a more complex over-wintering stage structure.
3. Life cycles were also compared between two areas of Japan by field experiments. In the cooler area, the first generation over-wintered in the diapausing larval or adult stage. Conversely, in the warmer area, diapause was induced later and some of the first-generation adults produced second-generation offspring before over-wintering.
4. Based on the geographical cline of climates and the differences in cold hardiness among stages, we can demonstrate that the over-wintering stage variation among and within populations results from an adaptive timing of diapause induction in each region, because the late larval or adult diapauses protect pupae or eggs – which unlike other stages are not cold hardy – from being produced late in the season.     

应用寄生蜂和不育雄虫防控田间橘小实蝇

食品安全已成为当今社会广受关注的问题。尽管国内的一些学者就阿里山潜蝇茧蜂[Fopius arisanus(Sonan)]和橘小实蝇SIT技术分别开展了不同程度的研究,然而关于应用该蜂和不育雄虫对橘小实蝇[Bactrocera dorsalis(Hendel)]进行田间联合防治的研究还未见相关报道。为此,为探讨天敌昆虫和雄性不育技术对橘小实蝇的田间综合治理(IPM)技术,开展了阿里山潜蝇茧蜂和橘小实蝇不育雄虫的田间释放试验:首先应用性引诱剂降低田间野生雄虫数量;而后,释放橘小实蝇不育雄虫,进一步降低田间橘小实蝇种群数量;最后,释放阿里山潜蝇茧蜂对田间残余的橘小实蝇卵进行追踪寄生,以达到持续控制的目的。通过监测整个防控期田间橘小实蝇的种群数量以及果实受害率和防治效果作为评价指标评价该防治方法的综合防治效果。结果表明:应用阿里山潜蝇茧蜂、橘小实蝇不育雄虫并配合引诱剂的综合措施对橘小实蝇的种群数量有明显控制作用,田间总体防治效果可达90%左右。此外,提出完善橘小实蝇田间防控措施的建议,并提出该研究的不足以及有待进一步开展研究的方向。     

Purification and biochemical characterization of glutathione S-transferases from four field populations of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

Glutathione S-transferases (GSTs) are a group of detoxification enzymes that catalyze the nucleophilic addition of glutathione to a wide variety of endogenous and xenobiotic compounds. In this study, GSTs were purified from four field populations of Bactrocera dorsalis with different insecticide susceptibilities by glutathione-agarose affinity chromatography. The populations were collected from Dongguan (DG) and Guangzhou (GZ) of the Guangdong Province, Haikou of the Hainan province (HN), and Kunming of the Yunnan province (YN), China. Differences in GST characteristics among the four populations were studied using purified enzyme samples through comparative SDS-PAGE, kinetic, and inhibition experiments. The specific activities of the purified enzymes were similar, but the purification yield of the GZ population (31.54%) was the lowest. SDS-PAGE analysis showed only one band at approximately 23 kDa for these four populations. Kinetic analyses showed that the affinities of the purified GSTs from the GZ and YN populations for 1-chloro-2.4-dinitrobenzene (CDNB) were much higher than those of GSTs from the other two populations, whereas the HN population had the highest catalytic capability in terms of V(max) value. The optimum temperature for CDNB conjugation was 37 °C and the optimum pH was 7.5 in all four populations. Inhibition kinetics showed that ethacrynic acid, diethyl maleate, tetraethylthiuram disulfide, curcumin, bromosulfalein, and β-cypermethrin had excellent inhibitory effects on GSTs in the four populations of B. dorsalis, but the low inhibitory effects of malathion and avermectin did not differ between populations. These results suggest that GSTs may have a role in detoxification of β-cypermethrin in B. dorsalis.     

Dietary wheat germ oil influences gene expression in larvae and eggs of the oriental fruit fly

Changes in animal nutrition, particularly essential dietary components, alter global gene expression patterns. Our goal is to identify molecular markers that serve as early indicators of the quality of insect culture media. Markers of deficient culture media will increase the efficiency of developing optimal systems for mass rearing beneficial insects and some pest species because decisions on culture media quality can be made without waiting through one or several life cycles. The objective of our current study is to discover molecular markers of essential dietary lipid deficiency in the oriental fruit fly, Bactrocera dorsalis. We reared groups of fruit flies separately on media either devoid of or supplemented with wheat germ oil (WGO) and analyzed gene expression in third instar larvae and F(1) eggs using 2D electrophoresis. Gel densitometry revealed significant changes in expression levels of genes encoding eight proteins in larvae and 22 proteins in eggs. We identified these proteins by using mass spectrometry (MALDI TOF/TOF) and bioinformatic analyses of the protein sequences. Among these, we identified one gene encoding the receptor of activated C Kinase 1 (RACK1) that increased in expression by 6.8-fold in eggs from adults that were reared as larvae on media supplemented with WGO. RACK1 is an essential component of at least three intracellular signal transduction pathways, making it a good molecular marker candidate of lipid deficiency in fruit flies and possibly many other insect species.     

CDNA cloning and characterization of S6 kinase and its effect on yolk protein gene expression in the oriental fruit fly Bactrocera dorsalis (Hendel)

p70 S6 kinase (S6K), a serine/threonine protein kinase, is a downstream target of target of rapamycin (TOR) gene and an important regulator of protein synthesis responsible for cell growth and reproduction. In this study, a S6K gene, named BdS6K (GenBank Accession No. GQ203802), was isolated from the oriental fruit fly Bactrocera dorsalis (Hendel). Quantitative RT-PCR showed that BdS6K mRNA is expressed at a higher level in egg than in other developmental stages, as well as in ovary than in fat body. Downregulation of BdS6K activity by rapamycin treatment in larval stage resulted in the developmental defects of larvae, pupae, and adults, with a reduced yolk protein (YP) expression in the fat body throughout the first reproductive cycle with a substantial reduction in ovary size, and also repressed the egg development in female fruit fly. Knockdown of BdS6K gene by RNA interference in the adult significantly decreased the YP expression. These observations support the involvement of BdS6K signaling in the regulation of the YP synthesis and egg development in B. dorsalis.