Evaluation of different formulations of deltamethrin in comparison with permethrin for impregnation of netting

Five formulations of deltamethrin and one of permethrin were impregnated into cotton and nylon netting and tested for their efficacy and persistence in killing Anopheles gambiae Giles which were attempting to penetrate the netting in search of blood meals. Emulsifiable concentrates persisted better than wettable powders of deltamethrin, and all the deltamethrin formulations performed better than permethrin, even though the latter was applied at an eight times higher dose. The insecticidal effect of both compounds persisted better on nylon than on cotton; it was adversely affected by repeated washing.     

Purification and characterisation of proteins secreted by the entomopathogenic fungus Metarhizium anisopliae with insecticidal activity against adults of the Mediterranean fruit fly,Ceratitis capitata (Diptera: Tephritidae)

BACKGROUND: The control of the Mediterranean fruit fly (medfly) Ceratitis capitata (Wied) is usually performed with protein bait sprays incorporating chemical insecticides that may have adverse effects on humans, non‐target organisms and the environment. In recent years, scientists have sought more environmentally friendly insecticides for medfly control, such as plant‐ and microorganism‐derived compounds. Among these compounds, entomopathogenic fungi are an unexplored source of natural insecticides. RESULTS: The crude soluble protein extract (CSPE) of the entomopathogenic fungus Metarhizium anisopliae (Mestch.) (strain EAMa 01/58‐Su) shows chronic insecticidal activity when administered per os. Mortality in flies exhibits a dose response. The CSPE produces an antifeedant effect in adult flies, a result probably due to a progressive deterioration of the fly midgut after ingestion of the extract. Protease and temperature treatments show that insecticidal activity against C. capitata is due to proteinaceous compounds that are highly thermostable. Four monomeric proteins from this crude extract have been purified by liquid chromatography and gel electroelution. Although all four monomers seem to be involved in the insecticidal activity of the CSPE, the 15 kDa and the 11 kDa proteins appear to be mainly responsible for the observed insecticidal effect. CONCLUSIONS: Four new fungal proteins with insecticidal activity have been purified and identified. These proteins might be combined with insect baits for C. capitata biocontrol. Copyright © 2009 Society of Chemical Industry     

Evaluation of toxicity and genotoxic effects of spinosad and deltamethrin in Drosophila melanogaster and Bactrocera oleae

BACKGROUND: The insecticides spinosad and deltamethrin are being increasingly used in pest management programmes. In order to assess further their toxic effects to target and non‐target insect species, an evaluation was made of their insecticidal profile on Bactrocera oleae (Rossi) and Drosophila melanogaster (Meig.). Moreover, possible genotoxic effects of the two pesticides were investigated using the somatic mutation and recombination test (SMART) in D. melanogaster. RESULTS: Both insecticides were highly effective against B. oleae, exhibiting similar LC₅₀ values. Moreover, they were found to be more effective against Bactrocera than against Drosophila adults. However, spinosad was significantly more toxic than deltamethrin to D. melanogaster. The results showed a lack of genotoxic activity of both insecticides under the in vivo experimental procedure employed, at least at applied doses. CONCLUSION: The present study provides information for lethal and sublethal effects of spinosad and deltamethrin against a target and a non‐target species. Both insecticides can exert high toxicity to B. oleae when adults are exposed even to very low doses for long periods of time. The results contribute to the database on the genotoxic potential of spinosad and deltamethrin, suggesting a safety profile for both insecticides. Copyright © 2011 Society of Chemical Industry     

Impact of some alternative methods to chemical control in controlling aphids (Hemiptera: Sternorrhyncha) and their side effects on natural enemies on young Moroccan citrus groves

Aphid control in Moroccan citrus orchards is based mainly on carbamate and neonicotinoid sprays, especially methomyl and imidacloprid. The extensive use of these insecticides may have side effects on natural enemies and environment quality and raises human health concerns. This research aimed to assess the control of aphids with insecticidal soap, kaolin and augmentative biological control using the indigenous predator Adalia decempunctata L. (Coleoptera: Coccinellidae). The insecticides were applied and the predators were released in April 2009 and 2010. Under field experimentation, the methomyl and imidacloprid foliar pulverization were very effective against aphids. In contrast, the insecticidal soap and kaolin application were less efficient while A. decempunctata adults were effective only in the first week after release. The side effects on beneficial insects were also assessed and discussed. The possibility of employing A. decempunctata in an integrated pest management package in citrus groves is discussed in relation to effectiveness and side effects on beneficial arthropods.     

Effects of two different neem products on different stages of Nezara viridula (L.) (Heteroptera, Pentatomidae)

In this study, the effects of two different commercial neem insecticides (NeemAzal T/S and Neem Oil) were determined on different stages of Nezara viridula (L.) (Heteroptera: Pentatomidae) under laboratory conditions. Neem Azal and Neem Oil were applied at concentrations of 0.5 % and 2 %, respectively. Mortality was recorded after 3, 7 and 14 days for nymphs and adults; 7 and 14 days for old (4-day-old) eggs; and 14 days for newly laid (one-day-old) eggs. Both products have no significant effect on adults and newly laid eggs. However Neem Oil was found to be more effective than NeemAzal T/S on nymphs and on old laid eggs after 7 and 14 days. It can be concluded that both neem products have potential for insecticidal efficacy (approximately 60 %) against nymphs of N. viridula. at concentrations recommended by manufacturers for registered pests.     

Persistence on cotton foliage of insecticide residues toxic to Heliothis larvae

Control measures for Heliothis spp. on cotton are usually applied against eggs and newly hatched larvae that infest plant terminal growth. In order to investigate the rate of degradation of a range of insecticides, leaf disc samples were collected, at intervals after application, from both fully expanded cotton leaves and unfolding terminal leaves. The samples were subjected separately to bioassay with newly hatched larvae, and to chemical analysis of the surface deposits. On old leaves, larval mortality caused by two biological insecticides declined by half after field exposure for 36 h, but for the synthetic insecticides, the interval ranged from 4.5 days with endosulfan to 18 days with fenvalerate. On new leaves, the longest interval was 7 days with fenvalerate. Chemical half-life on old leaves ranged from 1 day with endosulfan to 12 days with DDT, and was also shorter on young leaves than the equivalent biological half-life. Bioassay appears to be the most reliable method of assessing insecticidal activity over time. Dosage/mortality data were integrated to give LC₅₀ and LC₉₀ values. Leaf expansion may have the greatest effect on insecticide persistence during the 6 week period of rapid growth commencing 2 months after sowing. Expansion was slower when plants were water stressed, and accelerated following irrigation. The implications of the above findings for cotton pest management are discussed.     

Effects of two different neem products on different stages of Nezara viridula (L.) (Heteroptera, Pentatomidae)

In this study, the effects of two different commercial neem insecticides (NeemAzal T/S and Neem Oil) were determined on different stages of Nezara viridula (L.) (Heteroptera: Pentatomidae) under laboratory conditions. Neem Azal and Neem Oil were applied at concentrations of 0.5 % and 2 %, respectively. Mortality was recorded after 3, 7 and 14 days for nymphs and adults; 7 and 14 days for old (4-day-old) eggs; and 14 days for newly laid (one-day-old) eggs. Both products have no significant effect on adults and newly laid eggs. However Neem Oil was found to be more effective than NeemAzal T/S on nymphs and on old laid eggs after 7 and 14 days. It can be concluded that both neem products have potential for insecticidal efficacy (approximately 60 %) against nymphs of N. viridula. at concentrations recommended by manufacturers for registered pests.     

稻谷加工过程中4种常用杀虫剂残留的消解规律

为控制水稻籽粒中农药的残留量,提高稻米食用的安全性,研究了稻谷中三唑磷、毒死蜱、丁硫克百威和氯虫苯甲酰胺4种杀虫剂从农田到餐桌的残留消解规律,阐明了水稻生长后期4种农药的施药期、用药量、采收间隔期与籽粒中农药残留分布的关系,并结合食用加工过程,分析了稻米入口前农药的残留消解情况,评估了稻米食用的安全性。田间试验参照农药登记残留试验准则进行,采用液相色谱-串联质谱法测定4种农药在稻谷不同加工过种中的残留量。结果表明:脱壳和碾米2种稻谷加工过程对4种农药的去除具有促进作用,其加工因子 (P_F) 均小于0.5;稻米食用加工过程中淘洗2次结合高压蒸煮可有效降低4种农药在稻米中的残留量,P_F<0.2,可进一步提高农药摄入的安全性。农药种类、施药剂量与采收间隔期和稻米的安全性密切相关。氯虫苯甲酰胺和丁硫克百威主要分布在稻壳和谷糠中,两者占总含量的85%以上,因此即使蜡熟期施药1次,采收间隔期21 d,2种农药也均未检出;而毒死蜱和三唑磷在收获后的籽粒中仍有检出,残留量范围分别为0.032~0.043 mg/kg和0.053~0.073 mg/kg。精米中三唑磷含量分配比随采收间隔期延长先降低后增加,其累积具有显著的滞后性,使得三唑磷残留量高于中国国家标准中规定的最大残留限量 (MRL) 0.05 mg/kg,应适当延长采收间隔期以降低其最终残留量。即使在乳熟期施药,所有剂量处理收获后的大米经淘洗2次结合高压蒸煮后,4种农药的残留水平均低于MRL值。因此,适当的食用加工方式能够有效降低稻米中农药的残留量,提高稻米食用的安全性。     

菊酯类药剂对草地贪夜蛾的毒力及对钠离子通道的诱导特性

为明确菊酯类药剂对草地贪夜蛾Spodoptera frugiperda的防治效果,采用点滴法在室内测定高效氯氟氰菊酯、高效氯氰菊酯、联苯菊酯、溴氰菊酯和茚虫威原药对草地贪夜蛾3龄幼虫的毒力,利用实时荧光定量PCR技术测定3龄幼虫在这5种药剂诱导不同时间下其体内钠离子通道基因片段的表达量变化。结果显示,高效氯氟氰菊酯、溴氰菊酯、联苯菊酯、茚虫威和高效氯氰菊酯这5种药剂处理草地贪夜蛾3龄幼虫24 h后的LD50值分别为74.911、83.280、152.662、179.372、567.250 mg/L;处理48 h后的LD50值分别为18.946、67.874、120.888、132.790、461.635 mg/L;同时发现草地贪夜蛾3龄幼虫钠离子通道基因的表达均呈现不被诱导或诱导下调现象,表明草地贪夜蛾幼虫可通过降低靶标基因的表达量进而减少药剂对其的毒性。表明供试4种拟除虫菊酯类药剂和1种氯虫苯甲酰胺类药剂可作为草地贪夜蛾田间应急防控药剂施用。     

Neem and other Botanical insecticides: Barriers to commercialization

In spite of the wide recognition that many plants possess insecticidal properties, only a handful of pest control products directly obtained from plants,i. e., botanical insecticides, are in use in developed countries. The demonstrated efficacy of the botanical neem (based on seed kernel extracts ofAzadirachta indica), and its recent approval for use in the United States, has stimulated research and development of other botanical insecticides. However, the commercialization of new botanical insecticides can be hindered by a number of issues. The principal barriers to commercialization of new botanicals are (i) scarcity of the natural resource; (ii) standardization and quality control; and (iii) registration. These issues are no problem (i) or considerably less of a problem (ii, iii) with conventional insecticides. In this review I discuss these issues and suggest how the problems may be overcome in the future. Based on a paper presented at the symposiumBiopesticides for Crop Protection, Seoul National University Suwon, South Korea, 22 August 1996.     

防治金银花尺蠖幼虫高效药剂的筛选及应用评价

为筛选防治金银花尺蠖Heterolocha jinyinhuaphaga Chu幼虫的高效、低残留杀虫剂，采用浸虫法和浸叶法分别测定了13种杀虫剂对金银花尺蠖幼虫的触杀毒力和胃毒毒力，筛选出高活性药剂，并对筛选的药剂进行田间防效试验及检测其在金银花中的农药残留量。毒力测定结果表明，甲维盐对金银花尺蠖2龄和4龄幼虫的毒力最高，触杀毒力LC_ct50分别为0.291、0.391 mg/L，胃毒毒力LCst50分别为0.081、0.275 mg/L；多杀菌素、氟铃脲、氯虫苯甲酰胺药剂对金银花尺蠖幼虫也表现出较高的致毒作用。田间药效试验表明，有效成分用量2.25 g （a.i.）/hm²的甲维盐、有效成分用量11.25 g （a.i.）/hm²的多杀菌素对金银花尺蠖幼虫均有极好的防治效果，药后7 d防治效果分别为96.39%和93.13%，表明甲维盐和多杀菌素是防治金银花尺蠖幼虫的特效药剂。残留检测分析结果表明，有效成分用量6、12 g （a.i.）/hm²的甲维盐喷雾处理3 d后，金银花中农药残留量分别为0.0219、0.0725 mg/kg，7 d后分别为0.0070、0.0168 mg/kg。     

Susceptibility of cocooned pupae and adults of the parasitoid <Emphasis Type="Italic">Microplitis mediator</Emphasis> to selected insecticides

The braconid parasitoid Microplitis mediator (Haliday) is a key natural enemy of the cabbage moth, Mamestra brassicae (L.), in Europe. In the context of an Integrated Pest Management approach, the use of selective insecticides is essential for the conservation of naturally occurring beneficial arthropods. The present laboratory study investigated the side effects of six insecticides applied at recommended field rates on adults and cocooned pupae of M. mediator. Male and female parasitoids were paired in drum cells contaminated with dry residues of insecticides. Besides lethal effects after 24 h, parasitization capacity and longevity of the surviving parasitoids was evaluated. Lethal effects on cocooned pupae were also investigated by assessing adult emergence from treated cocoons. Pirimicarb caused 100% adult mortality after 24 h, whereas the other tested insecticides caused no direct toxic effects. However, sub-lethal effects in terms of reduced parasitization activity, percentage of parasitism or female longevity were found for flonicamid, pymetrozine, spinosad and thiacloprid. Spirotetramat shortened only male longevity. Adult emergence from treated cocoons was reduced only by flonicamid and pymetrozine.     

Metabolic detoxication and synergistic ratio of lindane analogs in house flies

Biodegradability of lindane analogs using house fly whole body, microsomes, and microsome supernatant fraction was examined. It decreased in the order of alkoxy ～ methylthio > methyl analogs > lindane in the whole body experiments, as well as with microsomes in the presence of NADPH. With the supernatant in the presence of glutathione, a different trend was observed. The synergistic effects of piperonyl butoxide when used together with lindane analogs were mostly explained in terms of the inhibition of the microsomal metabolism. Piperonyl butoxide was also shown to inhibit the penetration of compounds into the fly body and to make the central nervous system of the American cockroach less sensitive to the action of insecticides causing after and repetitive discharges. It was observed that the value of the percentage of metabolic disappearance of insecticides after a certain period decreases as the dose level initially applied in the whole body experiments increases. The synergistic ratio parallels the percentage of disappearance value after the insecticidal activity test period when a dose corresponding to the unsynergized LD₅₀ is initially applied. When quantitative comparisons are required for biodegradability of insecticides using house flies as the test insects, it should be on the basis of direct metabolism experiments using a fixed dose throughout the series of insecticides, but not on the basis of the synergistic ratio.     

Binding activity of substituted benzyl derivatives of chloronicotinyl insecticides to housefly‐head membranes,and its relationship to insecticidal activity against the housefly Musca domestica

Variously substituted benzyl derivatives of chloronicotinyl insecticides were synthesized with a wide range of substituents including halogens, NO₂, CN, CF₃ and small alkyl and alkoxy groups at the ortho, meta and para positions, as well as multiple‐substituted benzyl analogues. Their binding activity to the α‐bungarotoxin binding site in housefly (Musca domestica) head membrane preparations was measured. Among the compounds tested, the activity of the meta‐CN derivative was the highest, being 20–100 times higher than those of imidacloprid, acetamiprid and nitenpyram. The synergized insecticidal activity against houseflies was also measured for selected compounds with the metabolic inhibitor, NIA16388 (propargyl propyl phenylphosphonate). For the nitromethylene analogues, including both benzyl and pyridylmethyl analogues, higher binding activity usually resulted in higher insecticidal activity. © 2000 Society of Chemical Industry     

Laboratory evaluation of fipronil,a phenylpyrazole insecticide,against adult Anopheles (Diptera: Culicidae) and investigation of its possible cross‐resistance with dieldrin in Anopheles stephensi

Adult mosquitoes from two strains of Anopheles gambiae and from three strains of Anopheles stephensi were exposed to 0.25% fipronil‐treated papers in WHO test kits or to 500 mg fipronil m⁻² impregnated mosquito netting in bioassay spheres. For comparison, tests were also carried out with the pyrethroid permethrin, using the same methods and doses, and on papers treated with 0.4 and 4% of the cyclodiene insecticide dieldrin. Compared with the same doses of permethrin, fipronil showed less and delayed activity. Two of the An stephensi strains were resistant to fipronil and dieldrin. To investigate whether this was due to a resistance mechanism in the An stephensi strains acting against both insecticides, the most fipronil‐ and dieldrin‐tolerant strain was further selected in two separate lines with one of the insecticides, followed by tests with the insecticide that the line had not been selected with. This indicated a concomitant rise of resistance to dieldrin in the fipronil‐selected line and vice versa. Repeated back‐crossing of the two lines with a susceptible strain and re‐selection with either dieldrin or fipronil gave evidence for the involvement of a single resistance mechanism to both insecticides. Permethrin resistance in both lines declined with selection for dieldrin or fipronil and confirms the absence of cross‐resistance between fipronil and pyrethroids. © 2001 Society of Chemical Industry     

Insecticidal and repellent activities of insecticide-sucrose solutions to Culex pipiens molestus (Diptera: Culicidae) under laboratory and field conditions

BACKGROUND: Culex pipiens molestus Forskal has been reported as a dominant species in underground structures of urban areas in the Republic of Korea (ROK) during all seasons and becomes bothersome to humans in late autumn and winter. Most Cx. pipiens molestus in septic tanks are controlled in the ROK using larvicides such as Bt and IGR. However, there are a number of problems associated with larvicides, such as high cost and requirement for frequent use. In the present work, a new control method for Cx. pipiens molestus in septic tanks by using mixtures of sucrose solution with insecticides was investigated. RESULTS: The insecticidal and repellent activities of ten insecticides were evaluated for best control of Cx. pipiens molestus in septic tanks. Firstly, differences in susceptibilities to insecticides were evaluated in topical assays by forced direct contact bioassay and in a screened wire cage by free direct contact bioassay. The difference in insecticide susceptibility in the mosquitoes was the result of repellency by the insecticides. In three septic tanks, the density of Culex mosquitoes was sharply reduced by a deltamethrin–sucrose solution kit. CONCLUSIONS: The results demonstrated the potential for mosquito control by deltamethrin–sucrose solution, and the study offers basic information related to mosquito control in septic tanks. Copyright © 2011 Society of Chemical Industry     

Susceptibility to insecticides in the Q biotype of Bemisia tabaci is correlated with bacterial symbiont densities

BACKGROUND: The presence of symbiotic microorganisms may influence an insect's ability to tolerate natural and artificial stress agents such as insecticides. The authors have previously shown that Rickettsia in the B biotype of the whitefly Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) increases this insect's susceptibility to several insecticidal compounds. This communication reports a comparison of the susceptibilities of three isofemale strains of the Q biotype of B. tabaci harbouring different bacterial complements to major insecticides from different chemical groups: one strain harboured only Arsenophonus, one harboured Rickettsia and Arsenophonus and one harboured Arsenophonus and Wolbachia. RESULTS: The presence of different symbiont combinations in the three strains had a significant influence on their susceptibility to most of the insecticides tested. Thiamethoxam, imidacloprid, pyriproxyfen and spiromesifen had a significant influence on strains that had the double infections Rickettsia–Arsenophonus and Wolbachia–Arsenophonus, which also carried higher amounts of symbionts as assessed by quantitative real‐time PCR. No significant differences in mortality rates were observed when the tested strains were treated with diafenthiuron. CONCLUSION: The results suggest a correlation between the presence of high bacterial densities in B. tabaci and the insect's ability to detoxify toxic compounds such as insecticides. Copyright © 2009 Society of Chemical Industry     

印楝杀虫剂防治蝗虫的应用前景

印楝杀虫剂是公认的最优秀的生物农药之一，在环境中无残留，对非靶标生物安全，对中华稻蝗(Oxyachinensis)、东亚飞蝗(Locusta migratoria manilensis)、黄脊竹蝗(Ceraoris kiangsu)、青脊竹蝗(Ceraoris nigricornis)、沙漠蝗(Schistocerca gregaria)、血黑蝗(Melanoplus sanguinipes)和泣黑背蝗(Eyprepocnermis plorclnS)等多种蝗虫具有优异的杀虫活性，并具有独特的杀虫作用机理，是防治蝗虫的理想药剂。     

Effects of sublethal concentration of diazinon,fenitrothion and chlorpyrifos on demographic and some biochemical parameters of predatory bug,Andrallus spinidens Fabricius (Hemiptera: Pentatomidae) in laboratory conditions

Effects of three insecticides, diazinon, fenitrothion and chlorpyrifos on Andrallus spinidens Fabricius (Hemiptera: Pentatomidae), a predator of lepidopterous larvae in rice fields were investigated. The insecticides were applied topically at lethal dose (LD₃₀) on the fifth instar nymphs of A. spinidens and evaluated on life table and some biochemical parameters of the predatory bugs. The results showed that pre-oviposition period, fecundity and longevity of treated bugs were significantly affected compared with the control. Analysis of life table parameters of A. spinidens revealed adverse effects of insecticides on net reproductive rate (R₀), intrinsic rate of increase (r), finite rate of increase (λ), doubling time (DT) and mean generation time (T). Among the tested insecticides, fenitrothion was the most toxic insecticide. The lowest value of r was 0.060 day^?1 in fenitrothion. Effects of insecticides on the detoxification enzymes showed that all compounds had inhibitory effect on esterases, acetylcholinesterases and glutathione S-transferases. According to this study, the insecticides cause harmful effects on demographic and biochemical parameters of A. spinidens and are not compatible with the predatory bug even at sublethal concentration.     

Toxicity of indoxacarb and spinosad to the multicolored Asian lady beetle, Harmonia axyridis (Coleoptera: Coccinellidae), via three routes of exposure

The use of selective insecticides may improve conservation of natural enemies and therefore contribute to the success of integrated pest management (IPM) programs. In this study, the toxicity of two commonly used selective insecticides, indoxacarb and spinosad, to the multicolored Asian lady beetle, Harmonia axyridis (Pallas), was evaluated. Third instars and adults of H. axyridis were exposed to indoxacarb at 50 and 100% of the field rate (FR), to spinosad at 100% FR and to water (untreated check) under laboratory conditions via three routes of exposure. Treatments were applied directly on insects (i.e., topical application), on Petri dishes (i.e., residues), or on soybean aphids, Aphis glycines Matsumara (i.e., treated prey). Mortality of exposed individuals in each life stage was recorded 2 and 7 days after treatment. Logistic regression indicated that indoxacarb at 100% FR, followed by indoxacarb at 50% FR, was more insecticidal than spinosad to third instars. Mortality was higher when H. axyridis were exposed to both insecticides via residues followed by treated prey. Indoxacarb at 100 or 50% FR was insecticidal to adults. Adults were tolerant to spinosad via all routes of exposure. The present results suggest that indoxacarb may decrease H. axyridis field populations by causing mortality to larvae and adults via all routes of exposure. Implications of the toxicity of indoxacarb to H. axyridis within an IPM context and possible reasons for the differences in susceptibility of H. axyridis for each route of exposure are discussed.