In vivo and in vitro metabolism of fipronil by larvae of the European corn borer Ostrinia nubilalis

In vivo and in vitro metabolism of [14C]fipronil was examined in a susceptible European corn borer (Ostrinia nubilalis, Hübner) laboratory strain. [14C]Fipronil penetrated the larval integument slowly, with 71.5% of the applied radioactivity recovered from surface rinses 24 h after topical application. Despite this slow penetration, radioactivity was detected in both the excrement and internal organo-soluble fractions. Radioactivity in the internal aqueous fraction and tissue pellet accounted for less than 0.8% of total radioactivity. The in vivo studies suggest that fipronil oxidation to its sulfone metabolite is the major route of metabolic conversion. In vitro studies were performed using subcellular microsomal fractions isolated from European corn borer larval midguts. Cytochrome P450-dependent monooxygenase activity (methoxyresorufin O-demethylase) was consistently observed in midgut preparations, and formation and detection of the sulfone metabolite in the same midgut preparations was also NADPH-dependent and inhibited by piperonyl butoxide. In vitro metabolism results indicate microsomal monooxygenases are responsible for the conversion of fipronil to its sulfone form in the European corn borer.     

An exposure study to assess the potential impact of fipronil in treated sunflower seeds on honey bee colony losses in Spain

BACKGROUND: There is great concern about the high losses and strong depopulation of honey bee colonies in some areas of Spain. Some beekeepers have suggested that sunflower seeds treated with the insecticide fipronil could be an important factor in causing those losses. Therefore, an in‐depth field study has been carried out in two regions of Spain where sunflower production is intense (Cuenca and Andalucía) and where, for some crops and varieties, fipronil has been used as seed insecticide. RESULTS: Samples of adult bees and pollen were analysed for bee pathogens and pesticide residues respectively. Neither fipronil residues nor its metabolites were detected in any of the samples analysed, indicating that short‐term or chronic exposure of bees to fipronil and/or its metabolites can be ruled out in the apiaries surveyed. Varroa destructor and Nosema ceranae were found to be very prevalent. CONCLUSION: The combination of the two pathogens could augment the risk of colony death in infected colonies, without fipronil residues exerting a significant effect in the given field conditions. Indeed, in this study the losses observed in apiaries located close to sunflower crops were similar to those in apiaries situated in forested areas with wild vegetation. Copyright © 2011 Society of Chemical Industry     

Effects of camptothecin and hydroxycamptothecin on insect cell lines Sf21 and IOZCAS-Spex-II

BACKGROUND: In recent years, concerns over the potential impact of synthetic pesticides on the environment have made the discovery and development of environmentally friendly pesticides a more pressing issue. Camptothecin (CPT) and its derivatives have attracted much attention owing to their unique mechanisms of action against insects. In this paper, two insect cell lines, Sf21 and IOZCAS‐Spex‐II, were used to conduct a preliminary investigation of the potential of CPT and hydroxycamptothecin (HCPT) as inducers of apoptosis in insect cell lines, and to illustrate the mechanism of action of CPT on insects at the cellular level. RESULTS: The results showed that both CPT and HCPT demonstrate potent cytotoxic effects to the tested insect cell lines in a time‐ and dose‐dependent manner. The DNA fragmentation, activation of caspases and cytochrome c release were observed in both IOZCAS‐Spex‐II and Sf21 treated with CPT and HCPT. There is no significant difference in cytotoxicity and caspase‐3 activation (P < 0.05, except when treated for 2 h) between CPT and HCPT, although the caspase‐3 activation was slightly stronger when treated with HCPT in both Sf21 and IOZCAS‐Spex‐II. CONCLUSION: The results confirm the existence of the mitochondrial‐dependent pathway of apoptosis induced by CPT and HCPT in Sf21 and IOZCAS‐Spex‐II cell lines. Further investigations are required to reveal the mitochondrial mechanisms and regulation of caspase activation during apoptosis. These studies will provide basic knowledge needed to understand the mechanisms of action of CPT and to develop CPT and its derivatives as insecticides. Copyright © 2011 Society of Chemical Industry     

Effect of fipronil seed treatments on the germination and early growth of rice

Fipronil seed treatments were evaluated to determine whether they directly influence germination and subsequent seedling growth in rice (Oryza sativa L). Continuous seed exposure to fipronil (four days) at 2 000 mg litre⁻¹ significantly impaired germination (P < 0.001). When exposure was restricted to a 1-h period 48 h after the initiation of germination, early post-germination growth was also impaired (assessment two days after exposure, P < 0.05). The proportion of seeds satisfying our criteria for normal germination fell by 2.3 and 2.6% respectively across 17 cultivars. Cultivar effects were highly significant (P < 0.001). When exposure to fipronil (2 000 mg litre⁻¹) was restricted to 2 h at initial seed wetting no significant growth impairment occurred. No significant differences (P > 0.05) were found between shoot lengths or root system dry weights of control plants and plants developing from seed exposed continuously (two days) to fipronil at rates of up to 2 000 mg litre⁻¹ during germination and harvested nine days after sowing. Treating germinated seed with fipronil for 1 h immediately prior to sowing at rates of up to 4 000 mg litre⁻¹ did not result in significant changes (P < 0.05) in plant growth parameters at either nine or 25 days after sowing. No evidence of fipronil having a direct phytostimulatory effect on rice was obtained. © 1999 Society of Chemical Industry     

The effect of insecticide on adipokinetic hormone titre in the insect body

The effect of an insecticide, permethrin (Ambush 25 EC), on the titre of two adipokinetic hormones in the central nervous system (CNS) and haemolymph of the firebug Pyrrhocoris apterus (L) was tested. Doses of 2.5, 12.5 and 25 ng of the insecticide elicited no significant effect on the titre of the adipokinetic peptides in CNS, but caused their dramatic elevation in the haemolymph of both macropterous and reproductive brachypterous bugs. Changes in diapausing brachypterous bugs were minimal and not significant. Using high-performance liquid chromatography (HPLC) and competitive ELISA, both adipokinetic peptides of P apterus (Pyrap-AKH and Peram-CAH-II) were identified and quantified in the CNS of all experimental groups. The ratios of the two peptides in the CNS of the bugs used were affected by insecticide treatment, but in all three groups of bugs the Pyrap-AKH level remained dominant. The insecticide-treated bugs were compared with those exposed to forced running (shaking) and dark shock. Both factors also acted as stressors and enhanced the titre of adipokinetic peptides in the haemolymph but had no effect on hormone titre in CNS. The results indicate an involvement of adipokinetic peptides in the response of insect to various stressors including insecticides.     

氟虫腈衍生物-糖基偶合物的合成及其在蓖麻韧皮部的输导性研究

为提高氟虫腈在植物体内的输导性,利用葡萄糖、半乳糖与木糖作为导向基团对其进行了糖基化修饰,设计合成了3个含乙酰保护基的糖基-氟虫腈偶合物(a,b,c)和3个脱保护基的偶合物(d,e,f)。采用液相色谱法测定了其在蓖麻幼苗韧皮部中的输导积累性。结果表明:化合物a、b、c无韧皮部输导性,而d、e、f 则具有良好的韧皮部输导性;培养2 h后,收集的第3 h内韧皮部液中 d、e、f 的浓度分别为21.45、14.14 和14.82 μ mol/L。饲料拌毒法测定结果表明,与母体化合物氟虫腈(LC50为4.49 μ mol/L)相比,6个偶合物对亚洲玉米螟Ostrinia furnacalis的杀虫活性均有所下降,LC50值在47.54~78.00 μ mol/L之间。     

苜蓿叶象啮小蜂寿命及产卵量的研究

在室内通过对苜蓿叶象啮小蜂Tetrastichus incertus(Ratzeburg)寿命、产卵量的研究发现,苜蓿叶象啮小蜂有较高的产卵量和寄生能力;在不喂食的条件下,苜蓿叶象啮小蜂产卵量最高,单头雌蜂的产卵范围为45粒~209粒,平均117粒,最高日产卵量为31粒;其寿命可达18d,最多可寄生37头寄主;苜蓿叶象啮小蜂与寄主在1:5的情况下寄生率达56.00%,并随着寄主密度的增大,苜蓿叶象啮小蜂的产卵量也有逐渐升高的趋势。     

Effect of vegetation on the longevity,mobility and activity of fipronil applied at the termiticidal rate in laboratory soil columns

BACKGROUND: Termiticides are applied at concentrations much higher than those used in agricultural settings. The longevity of fipronil has not yet been examined at the rates used for termite control, nor has the compound's movement in the soil been addressed. RESULTS: Fipronil was detected in the eluates of treated soil cones, increasing initially and then decreasing to a steady concentration of about 1 µg mL^?1. In larger PVC pipe plots, fipronil in the top treated soil depth (0–7.5 cm) dissipated more rapidly (half‐life of 11–13 months) than in treated soil at the next treated depth (7.5–15 cm; half‐life of 20–29 months). The presence of vegetation had no significant effect on the mobility, longevity or movement into untreated depths. Treated soil remained toxic to termites throughout the duration of the study. Fipronil moved into the 15–22.5 cm soil depth in sufficient concentration to cause 100% mortality to eastern subterranean termites in 3 day bioassays. CONCLUSION: Fipronil remains in treated soil at levels toxic to termites for at least 30 months. Movement of the active ingredient was observed in sufficient amounts to kill termites in non‐treated soil directly below the treated soil. Published 2010 by John Wiley & Sons, Ltd.     

新疆苹果蠹蛾幼虫期及蛹期的寄生蜂调查初报

经3年在新疆伊犁的调查，发现苹果蠹蛾幼虫和蛹的5种寄生蜂，包括1种重寄生蜂。它们是光点瘤姬蜂，蠹蛾玛姬蜂，红足微茧蜂，四齿革腹茧蜂和凹腹双短刺金小峰。     

Effects of azadirachtin on the regulation of midgut peristalsis by the stomatogastric nervous system inLocusta migratoria

A single injection of azadirachtin into nymphal and adult locusts results in a decrease of food intake but not in reduced food utilization. Feeding deterrency is correlated with a gradual inhibition of midgut peristalsis. Gut movement is under the control of the stomatogastric nervous system, especially the ingluvial ganglion, as demonstrated in anin vitro system. Serotonin is the most potent peristalsis-stimulating drugin vitro. Concurrent with the cessation of midgut peristalsis after azadirachtin injection, a depletion of the serotoninergic cell bodies in the frontal ganglion can be observed. Midgut preparations which show strongly inhibited contractions due to previous azadirachtin treatmentin vivo are minimally, or not at all, stimulatedin vitro by serotonin, depending on the amount of time that has elapsed since treatment. When midgut preparations of untreated locusts are challenged with azadirachtinin vitro, peristalsis is suppressed in a dose-dependent manner. Simultaneous application of azadirachtin and serotonin results in a slight stimulation of midgut peristalsis. We propose the hypothesis that azadirachtin interferes with the serotoninergic system of the stomatogastric ganglia and thus inhibits midgut peristalsis. The molecular mechanism of the action of azadirachtin remains to be determined.     

不同种类杀螨剂对壁蜂蜂螨的防治及安全性

为探讨不同杀螨剂对壁蜂Osmia cornifrons蜂螨的防控作用,筛选了适合壁蜂定巢繁殖的巢管管口内径范围,并采用药液浸渍法比较了螺螨酯、炔螨特、联苯肼酯、四螨嗪、三唑锡5种杀螨剂对壁蜂蜂螨的防治效果及安全性。结果表明,壁蜂芦苇巢管管口内径在8.00~8.49 mm范围时最适合壁蜂定巢繁殖,巢室数量最多,为8.5个,显著高于其它管口内径范围下的巢室数。与空白对照相比,5种杀螨剂各剂量处理对芦苇巢管中壁蜂的巢室数均无显著影响,不同剂量的三唑锡和四螨嗪浸渍芦苇巢管均可有效控制芦苇巢管内蜂螨的为害,2种药剂各剂量处理对巢管中蜂螨的防治效果为97.22%~100.00%,对巢室蜂螨的防治效果为98.75%~100.00%,防治效果显著;而不同剂量的螺螨酯、炔螨特和联苯肼酯对芦苇巢管中蜂螨的防治效果较低,各剂量处理对巢管蜂螨的防治效果为39.81%~80.56%,对巢室蜂螨的防治效果为46.01%~83.82%。表明四螨嗪和三唑锡浸渍处理芦苇巢管可作为有效防治壁蜂蜂螨为害的安全施药手段。     

The effects of phytochemical pesticides on the growth of cultured invertebrate and vertebrate cells

A range of cultured cells of invertebrate and vertebrate origin was grown in the presence of a number of phytochemical pesticides to test the effect of the latter on cell proliferation. The main observation was that azadirachtin was a potent inhibitor of insect cell replication, with an EC50 of 1.5 x 10(10) M against Spodoptera cells and of 6.3 x 10(9) M against Aedes albopictus cells, whilst affecting mammalian cells only at high concentrations (> 10(-4) M). As expected, the other phytochemical pesticides, except for rotenone, had little effect on the growth of the cultured cells. Rotenone was highly effective in inhibiting the growth of insect cells (EC50:10(-8) M) but slightly less toxic towards mammalian cells (EC50:2 x 10(-7) M). Neem terpenoids other than azadirachtin and those very similar in structure significantly inhibited growth of the cell cultures, but to a lesser degree. The major neem seed terpenoids, nimbin and salannin, for example, inhibited insect cell growth by 23% and 15%, respectively.     

A new derivative of fipronil: Effect of adding a glycinyl group to the 5-amine of pyrazole on phloem mobility and insecticidal activity

Glycinyl fipronil, a new fipronil derivative with 5-amine acylated by glycine, was synthesized. The phloem mobility of the synthesized derivative was higher that of the parent compound in intact soybean seedling and its insecticidal activity against the 3rd instar larvae of Plutella xylostella was comparable with that of fipronil.     

用Fuzzy综合评判分析小麦耕作制对昆虫群落的影响

本文以麦套油菜、麦套棉花和小麦单作等３种主要小麦栽培方式影响昆虫群落的调查资料为例，应用模糊综合评判分析了３种小麦栽培制对麦田益害昆虫群落的物种丰盛度，多样性指数和生境梯度指数等群落特征，影响优劣程度及其先后顺序，并讨论了运用此法分析昆虫群落时应注意的问题。     

Experimental study on the toxicity of imidacloprid given in syrup to honey bee (Apis mellifera) colonies

Two groups of eight honey bee colonies were fed with two different concentrations of imidacloprid in saccharose syrup during summer (each colony was given 1 litre of saccharose syrup containing 0.5 microg litre(-1) or 5 microg litre(-1) of imidacloprid on 13 occasions). Their development and survival were followed in parallel with control hives (unfed or fed with saccharose syrup) until the end of the following winter. The parameters followed were: adult bee activity (number of bee entering the hive and pollen carrying activity), adult bee population level, capped brood area, frequency of parasitic and other diseases, mortality, number of frames with brood after wintering and a global score of colonies after wintering. The only parameters linked to feeding with imidacloprid-supplemented saccharose syrup when compared with feeding with non-supplemented syrup were: a statistically non-significant higher activity index of adult bees, a significantly higher frequency of pollen carrying during the feeding period and a larger number of capped brood cells. When imidacloprid was no longer applied, activity and pollen carrying were re-established at a similar level for all groups. Repeated feeding with syrup supplemented with imidacloprid did not provoke any immediate or any delayed mortality before, during or following the next winter, whereas such severe effects are described by several French bee keepers as a consequence of imidacloprid use for seed dressing in neighbouring cultures. In any case, during the whole study, mortality was very low in all groups, with no difference between imidacloprid-fed and control colonies. Further research should now address several hypotheses: the troubles described by bee keepers have causes other than imidacloprid; if such troubles are really due to this insecticide, they may only be observed either when bees consume contaminated pollen, when no other sources of food are available, in the presence of synergic factors (that still need to be identified), with some particular races of bees or when colonies are not strong and healthy.     

人类活动对村级景观的影响

村落具有人类活动所造成的许多景观特征 ,是研究人为干扰对景观影响的良好场所。本文以研究点与村落中心间的距离作为人为干扰强度的划分指标 ,把村落按重度人为干扰、中度人为干扰和轻度人为干扰三个等级分为中心区、过渡区和基质区 ,分析人类活动与村级景观特征的相互关系。结果表明 :随着人为干扰强度的增加村级景观的斑块密度指数、破碎化指数、多样性指数、相对丰富度指数和均匀度指数均相应增大 ;中度人为干扰使得上述五种指数值最大 ;但中度干扰时景观优势度指数最小 ;随着干扰强度的增强 ,与人们生活密切相关的景观类型的分形维数减小 ,斑块的相似性增强     

啶氧菌酯对意大利蜜蜂幼虫生长发育及免疫应答的影响

为探究啶氧菌酯对意大利蜜蜂Apis mellifera ligustica幼虫生长发育和免疫应答的影响,使用田间推荐浓度（113、150、225和281 mg/L）的啶氧菌酯连续饲喂意大利蜜蜂工蜂幼虫,记录处理后工蜂幼虫的存活率、化蛹率、蛹重、羽化率和羽化初生重,并测量幼虫体内发育相关基因、营养相关基因及免疫相关基因表达情况。结果显示,不同浓度啶氧菌酯对意大利蜜蜂工蜂幼虫存活率、蛹重和羽化初生重均有显著影响,且具有显著的浓度效应;150、225和281 mg/L啶氧菌酯处理后意大利蜜蜂工蜂幼虫的化蛹率和蛹的羽化率均较对照显著下降。不同浓度啶氧菌酯均可诱导幼虫体内蜕皮激素受体（ecdysone receptor,Ecr）基因、卵黄原蛋白（vitellogenin,Vg）基因、蜜蜂防卫素（defensin 1,Def1）基因和膜翅抗菌肽（hymenoptaecin,Hym）基因的表达量上调,且大部分与对照差异显著;不同浓度啶氧菌酯均可显著抑制幼虫体内胰岛素样肽（insulin-like peptide 1,ILP1）基因的表达量;281 mg/L啶氧菌酯分别显著抑制和显著增加幼虫体内蜜蜂抗菌肽（apidaecin,Api）基因和蜂蛾抗菌肽（abaecin,Aba）基因的表达量,225 mg/L和281 mg/L啶氧菌酯可诱导幼虫体内ILP2的表达量显著上调,显著抑制幼虫体内储存蛋白（hexamerin,Hex）基因Hex70b的表达量,其他浓度处理对幼虫体内Api、Aba、ILP2和Hex70b无显著影响。表明啶氧菌酯对意大利蜜蜂工蜂幼虫有慢性毒性,长时间暴露会扰乱幼虫的生长发育和免疫应答。在生产实践中应当考虑啶氧菌酯对意大利蜜蜂的潜在风险。