Surface‐applied insecticide treatments for quarantine control of Japanese beetle,Popillia japonica Newman (Coleoptera: Scarabaeidae), larvae in field‐grown nursery plants

BACKGROUND: Japanese beetles, Popillia japonica Newman, are a quarantine challenge for nursery shipments from infested to non‐infested states. Marathon (imidacloprid) and Discus (imidacloprid + cyfluthrin) are approved preharvest nursery treatments (US Domestic Japanese Beetle Harmonization Plan; DJHP). This study evaluated approved and non‐approved (acephate, carbaryl, clothianidin, dinotefuran, halofenozide, thiamethoxam, trichlorfon) preharvest treatments, optimal rates (labeled 1×, 0.3–0.75× or 2–3×) and optimal timings (June, July, August and September) to control early‐instar (grubs) P. japonica in field nurseries. RESULTS: Most insecticides effectively reduced grub densities, except for acephate, carbaryl and trichlorfon. Clothianidin, thiamethoxam and halofenozide provided grub control equivalent to DJHP standards during most years. Across all test years and timings, percentage grub reductions were: Marathon (1×: 59.2–100; 3×: 78.9–100), Discus (1×: 60.7–100), clothianidin (1×: 96.1–100; 3×: 97.4–100), thiamethoxam (1×: 75.0–100; 3×: 80.0–100), halofenozide (1×: 70.0–100; 3×: 90.0–100) and dinotefuran (1×: 13.2–88.2; 3×: 71.1–93.4). CONCLUSIONS: July application was more consistent and effective than other timings, and higher rates (2× and 3×) did not generally improve grub control. Overall, clothianidin, thiamethoxam and halofenozide (and dinotefuran applied in August) were equivalent to current DJHP standards. These insecticides may be suitable for DJHP Category 2 states, potentially lowering grower costs. Copyright © 2009 Society of Chemical Industry     

Variation in the laboratory susceptibility of turf‐infesting white grubs (Coleoptera: Scarabaeidae) to biological,biorational and chemical control products

BACKGROUND: White grubs are the most widespread and damaging pests in turfgrass habitats of the northeast USA, and their management is highly dependent on chemical pesticides. Because this complex includes at least eight species, opportunities for pest management would be enhanced by understanding how susceptibility to control products varies across taxa. The objective of this laboratory study was to measure variation in the susceptibility of four species to 18 biological, biorational and chemical insecticides used as curative controls. RESULTS: Across species, the most efficacious biological and chemical insecticide alternatives were Steinernema scarabaei and chlorpyrifos respectively. For biorational and chemical insecticides, the European chafer [Amphimallon majale (Razoumowsky)] was the least susceptible species. For biologicals, the Japanese beetle (Popillia japonica Newman) was the least susceptible. Considering all control products, the oriental beetle [Anomala orientalis (Waterhouse)] was the most susceptible. CONCLUSION: The magnitude of variation in susceptibility supports the idea that a single product will not reliably suppress populations of all taxa, and highlights the need for pest management practitioners to identify white grub species before intervention. This differential susceptibility could have broader consequences for grub management if a numerically dominant target species is more completely suppressed than a co‐occurring species. Copyright © 2009 Society of Chemical Industry     

淮北地区农田金龟子三种优势种在土壤中垂直活动规律观察

在安徽省淮北地区,暗黑金龟子Holotrichia parallela Motsehulsky和铜绿金龟子Anomala corpulenta MotschuIsky 1年发生1代,一般以三龄幼虫越冬;大黑金龟子Holotrichia oblita Faldermann两年发生1代,以成虫和三龄幼虫交替越冬。三种金龟子相同虫态(龄、期)在地下的垂直分布基本一致。3月下旬至4月上旬,铜绿、大黑金龟子越冬幼虫上升为害,而暗黑金龟子越冬幼虫则停留在越冬土室内直至化蛹。大黑金龟子成虫羽化后蛰伏至翌年4月,然后出土;另两种成虫羽化后于当年5月下旬开始出土。从成虫出土后至三龄幼虫下蛰前,群体分布在浅土层。幼虫为害夏季作物,并在下蛰前为害秋播小麦。土温决定了幼、成虫春季的上升和秋季的下蛰。群体在浅土层活动期,土壤湿度是群体升降的主要因素。土壤结构、寄主植物成熟期和幼虫龄期均能影响群体的垂直分布。暗黑金龟子从三龄幼虫下蛰至羽化成虫上升,这期间群体垂直分布不变,呈正态分布。     

Comparison of foliar and soil formulations of neonicotinoid insecticides for control of potato leafhopper, Empoasca fabae (Homoptera: Cicadellidae), in wine grapes

BACKGROUND: The potential of systemic neonicotinoid insecticides to control potato leafhopper, Empoasca fabae (Harris), a damaging pest of wine grapes in the eastern United States, was investigated. Soil or foliar applications were made to potted or field‐grown vines, and the response of leafhoppers was determined in clip cages over the following month on young or mature leaves. RESULTS: Foliar application of imidacloprid caused immediate and long‐lasting reductions in E. fabae survival on both leaf ages, whereas the activity of soil‐applied imidacloprid was delayed. Clothianidin, imidacloprid and thiamethoxam all provided long‐lasting reduction in leafhopper survival on young and mature foliage when applied through either delivery route. However, the percentage of moribund nymphs was significantly greater on foliar‐treated vines and increased over time in mature and immature leaves compared with soil‐treated vines. Residue analysis of foliar‐applied imidacloprid showed an 89% decline in mature leaves from day 1 to day 27, and a 98% decline in immature leaves over the same time period. Comparison of soil‐applied clothianidin, imidacloprid and thiamethoxam in field‐grown vines showed significant reduction in E. fabae only on mature leaves of vines treated with thiamethoxam. CONCLUSIONS: Neonicotinoids can control E. fabae in small vines, even in rapidly expanding foliage where this pest causes greatest injury. Soil application provides superior long‐term vine protection because declining residues on foliar‐treated vines lead to suboptimal activity within 2–3 weeks. Vineyard managers of susceptible cultivars may take advantage of this approach to E. fabae management by using foliar applications of the three neonicotinoids tested here, or by using soil‐applied thiamethoxam. Copyright © 2011 Society of Chemical Industry     

Effects of cycloxaprid,a novel cis‐nitromethylene neonicotinoid insecticide,on the feeding behaviour of Sitobion avenae

BACKGROUND: Cycloxaprid with cis‐configuration is a novel neonicotinoid insecticide, developed in China, that has good industrialisation prospects for its high activity against imidacloprid‐resistant pests. Studies were carried out to investigate the biological activity of cycloxaprid and its effect on the feeding behaviour of Sitobion avenae. RESULTS: The results demonstrated that cycloxaprid had good contact and root‐systemic activity. The electrical penetration graph (EPG) revealed that cycloxaprid significantly increased the total time of non‐probing periods and greatly inhibited phloem ingestion of treated aphids because it significantly reduced the total time and the frequency of phloem ingestion. Furthermore, cycloxaprid can increase the phloem salivation of treated aphids by comparison with aphids treated with imdacloprid and distilled water. Consequently, a sublethal dose of cycloxaprid impaired aphid ingestion of phloem sap and thereby reduced the weight of aphids. On the other hand, EPG data showed that a sublethal dose of cycloxaprid had no significant effect on xylem sap ingestion, in contrast to imidacloprid. CONCLUSION: All these tests indicated that cycloxaprid had both contact and root‐systemic activity, with sublethal effects resulting in reduction in Sitobion avenae phloem‐feeding behaviour and growth rate. Copyright © 2012 Society of Chemical Industry     

Surface contact toxicity and synergism of several insecticides against different stages of the tropical bed bug, Cimex hemipterus (Hemiptera: Cimicidae)

BACKGROUND: Five formulated insecticides (lambda‐cyhalothrin at 10 mg m^?2, bifenthrin at 50 mg m^?2, fipronil at 10 mg m^?2, fenitrothion at 50 mg m^?2, imidacloprid at 5 mg m^?2) and one active ingredient (DDT at 500 mg m^?2) were evaluated using a surface contact method against early and late instars and adults of two strains of the tropical bed bug, Cimex hemipterus (F.). Synergism of lambda‐cyhalothrin and fipronil using piperonyl butoxide (PBO) was also assessed. RESULTS: The order of susceptibility of different stages of bed bugs was as follows: early stage ? lambda‐cyhalothrin > bifenthrin = imidacloprid > fipronil > fenitrothion > DDT; late stage—lambda‐cyhalothrin > bifenthrin > fenitrothion > imidacloprid > fipronil > DDT; adult—lambda‐cyhalothrin > imidacloprid > bifenthrin > fenitrothion > fipronil > DDT. The late instars exhibited significantly higher LT₅₀ among the life stages. The addition of PBO to fipronil increased the susceptibility of the insects. CONCLUSIONS: Lambda‐cyhalothrin, bifenthrin, fenitrothion and fipronil at the recommended application rates were effective against C. hemipterus. Although imidacloprid demonstrated good initial response against C. hemipterus, the insects showed substantial recovery 72 h post‐treatment. The late instars (fourth and fifth instars) should be used as the model for toxicological evaluation. Copyright © 2011 Society of Chemical Industry     

Mobility of imidacloprid from alginate-bentonite controlled-release formulations in greenhouse soils

The mobility of imidacloprid [1-(6-chloro-3-pyridinyl)methyl]-N-nitro-2-imidazolidinimine] from alginate-based controlled-release (CR) formulations was investigated in two different soil profiles. In one, a layered bed system simulating the typical arrangement under a plastic greenhouse, which is composed of sand, peat, amended soil and native soil, was used. In the other, the layer containing amended soil was used in order to determine the mobility of the insecticide in a soil system with a low content of organic matter and a high content of clay. Two CR formulations based on sodium alginate (1.87% wt/wt), imidacloprid (1.21%), natural or acid-treated bentonite (3.28%), and water (93.64%) were compared to technical grade imidacloprid. The use of alginate CR formulations produced less vertical mobility of the active ingredient as compared to the technical product. With the technical grade product treatment, the total amount of imidacloprid leached from columns packed with amended soil was 82.3% of that applied, whereas for the alginate-based CR formulations containing natural or acid-treated bentonite, the leached percentages were 44.7% and 37.1%, respectively. In the column experiments simulating the layered bed system, no insecticide was found in the leachate when the alginate-based CR formulations containing natural bentonite were used. However, 3% of the applied imidacloprid appeared when the treatment was carried out with technical grade material. Sorption-desorption capacities of the various soil layers for imidacloprid molecules were also calculated using batch experiments. © 1999 Society of Chemical Industry     

Toxicities and sublethal effects of seven neonicotinoid insecticides on survival, growth and reproduction of imidacloprid-resistant cotton aphid, Aphis gossypii

BACKGROUND: Imidacloprid has been a major neonicotinoid insecticide for controlling Aphis gossypii (Glover) (Homoptera: Aphididae) and other piercing–sucking pests. However, the resistance to imidacloprid has been recorded in many target insects. At the same time, cross‐resistance of imidacloprid and other insecticides, especially neonicotinoid insecticides, has been detected. RESULTS: Results showed that the level of cross‐resistance was different between imidacloprid and tested neonicotinoid insecticides (no cross‐resistance: dinotefuran, thiamethoxam and clothianidin; a 3.68–5.79‐fold cross‐resistance: acetamiprid, nitenpyram and thiacloprid). In the study of sublethal effects, imidacloprid at LC₂₀ doses could suppress weight gain and honeydew excretion, but showed no significant effects on longevity and fecundity of the imidacloprid‐resistant cotton aphid, A. gossypii. However, other neonicotinoid insecticides showed significant adverse effects on biological characteristics (body weight, honeydew excretion, longevity and fecundity) in the order of dinotefuran > thiamethoxam and clothianidin > nitenpyram > thiacloprid and acetamiprid. CONCLUSION: The results indicated that dinotefuran is the most effective insecticide for use against imidacloprid‐resistant A. gossypii. To avoid further resistance development, the use of nitenpyram, acetamiprid and thiacloprid should be avoided on imidacloprid‐resistant populations of A. gossypii. Copyright © 2011 Society of Chemical Industry     

Fitness costs of laboratory-selected imidacloprid resistance in the brown planthopper, Nilaparvata lugens Stål

Imidacloprid has been used as a key insecticide to control the brown planthopper, Nilaparvata lugens Stål, for several years, but no obvious resistance has been identified in field populations as yet. To evaluate the risk, a field population was collected and selected with imidacloprid in the laboratory. After 37‐generation selection a strain with 250‐fold resistance had been successfully achieved. Fitness analysis by constructing life tables demonstrated that resistant hoppers had obvious disadvantages in their reproduction. The fitness of highly resistant hoppers had decreased dramatically (0.169 and 0.104) to only one‐fifth to one‐tenth of that of the susceptible strain. Hence it was concluded that the brown planthopper had the potential to develop high resistance to imidacloprid but that the lower fitness of resistant hoppers could result in a quick recovery of sensitivity when the population did not come into contact with imidacloprid. This means that a reasonable resistance management programme with less imidacloprid use may efficiently delay or even stop resistance development. Copyright © 2006 Society of Chemical Industry     

Neonicotinoid insecticides alter diapause behavior and survival of overwintering white grubs (Coleoptera: Scarabaeidae)

The chloronicotinyl, imidacloprid, and the thianicotinyl, thiamethoxam, are effective insecticides against white grubs when applied as preventative treatments during or immediately after egg laying. Their efficacy sharply declines when the grubs reach late-instar stage. As both imidacloprid and thiamethoxam act on post-synaptic nicotinic acetylcholine receptors and modify insect behavior, we hypothesized that the two compounds will interfere with overwintering behavior of scarabs, thus reducing their ecological fitness and exposing them to increased winter mortality. We tested this hypothesis by applying the two compounds curatively against late second-instar and early third-instar Popillia japonica and Cyclocephala borealis grubs in turfgrass. Imidacloprid provided control of P japonica equivalent to the most widely used curative organophosphate, trichlorfon, by 14 days after treatment, but thiamethoxam had no affect. In contrast, both imidacloprid and thiamethoxam caused significant reductions in C borealis populations. Both insecticides altered the overwintering behavior of P japonica by significantly reducing the normal downward movement of grubs in October. Halofenozide, an ecdysone agonist, also caused rapid mortality of the late second-instar C borealis equivalent to trichlorfon, but had no affect on P japonica. In another experiment on a site naturally infested with entomopathogenic nematodes, the exclusive treatment of third-instar P japonica with imidacloprid resulted in no significant mortality in the autumn (up to 15 days after treatment), but caused a significant reduction in the survival of overwintered grubs. There was an increase in the numbers of grubs infected with nematodes in the imidacloprid and trichlorfon treatments compared with control, but these differences were significant only for trichlorfon. These results indicate that imidacloprid can effectively control late second-instars of both P japonca and C borealis and can significantly reduce survival of overwintered third-instar P japonica by altering their normal overwintering behavior.     

吡虫啉和毒死蜱对尿素氮在土壤中转化的影响

为了考察杀虫剂施用对尿素态氮在土壤中转化过程的影响,采用室内培养法,通过测定土壤铵态氮和硝态氮质量分数以及反硝化损失的动态变化,研究了在施用尿素的土壤（有效氮含量为200 mg/kg）中分别添加不同剂量的吡虫啉和毒死蜱2种杀虫剂时,杀虫剂对尿素的水解、土壤氮的硝化及反硝化过程的影响。结果表明:吡虫啉和毒死蜱各剂量处理在第3天时对尿素水解具有显著的促进作用（PPPPP<0.01）,减少反硝化损失量39.69%。     

Synergistic effect of imidacloprid combined with synergistic agents (Beichuang,Jiexiaoli) on Myzus persicae (Hemiptera: Aphididae)

Myzus persicae is a well known aphid pest, which can transport plant viruses to plants of the nightshade/potato family, namely the Solanaceae, and other food crops. Our aim was to explore the effects of imidacloprid combined with synergistic agents (Beichuang and Jiexiaoli) on Myzus persicae. Different concentrations of imidacloprid combined with synergistic agents were used to treat M. persicae. Biological activity of M. persicae was analyzed under indoor conditions, and the control efficiency of the admixture was determined through field experiments. The penetration rate of the admixture on tobacco leaf and M. persicae was analyzed, and the liquid surface tension and contact angle was measured. Imidacloprid combined with Beichuang and Jiexiaoli showed significant synergistic effects with high control efficacy. Beichuang and Jiexiaoli significantly improved the penetration of imidacloprid into the cuticle of tobacco leaves and the insect body wall. The surface tension and contact angles were abated by synergists. The combination of imidacloprid with Beichuang and Jiexiaoli showed a significant synergistic effect, which can be used for decreasing the dosage of imidacloprid and improving its long-term control efficacy.     

Toxicity and dissipation of soil insecticides applied in the management of arecanut white grub, <Emphasis Type="Italic">Leucopholis burmeisteri</Emphasis> Brenk. (Coleoptera: Scarabaeidae)

White grubs, Leucopholis spp. are subterranean pests of arecanut grown in South India. Grub infestation leads to yellowing, stem tapering, and crown size and yield reduction. Use of chemical insecticide to mage the white grubs gives varying degree of success. Hence an attempt was made to screen newer and safer insecticides. Imidacloprid (LC₅₀ at 120 h = 16.849 ppm on III instar larvae), chlorpyriphos (LC₅₀ = 14.242) and bifenthrin (LC₅₀ = 12.797 ppm) were identified as effective insecticides. Evaluation of these insecticide in the field over two year period indicated the following efficacy in reducing larval population: chlorpyriphos @ 4 kg a.i/ha (83.31%) > bifenthrin @ 4 kg a.i./ha (82.83%) > imidacloprid @ 0.24 kg a.i./ha (75.84%) > bifenthrin @ 2 kg a.i./ ha (74.26%) > chlorpyriphos @ 2 kg a.i./ha (69.15%) > chlorpyriphos @ 1 kg a.i./ha (61.79%) > imidacloprid @ 0.12 kg a.i./ha (56.54%) > bifenthrin @ 1 kg a.i./ha (54.34%) > imidacloprid @ 0.06 kg a.i./ha (41.47%). Bifenthrin in soil persisted for a longer period than chlorpyriphos. On the day of application, 59.46 ppm bifenthrin residue was recovered from soil. On 10th day, it was 7.29 ppm which decreased to 2.59 ppm on 30th day and was beyond detection limit on 65th day. Chlorpyriphos exhibited a rapid degradation in the initial stage; 27.46 ppm residue on the day of application, which further reduced to 0.964 ppm on 10th day, and was below the detection limit on the 30th day. Growth of Trichoderma harzianum was not affected by bifenthrin even up to 40 ppm concentration. However, chlorpyriphos affected the growth of Trichoderma at higher than 5 ppm dose. Similarly, imidacloprid inhibited the colony growth from 2 ppm onwards. Having high lipophylic property and contact toxicity, bifenthrin would be an ideal alternative insecticide to chlorpyriphos for the management of white grubs in palm garden, which is safe and long persisting.     

Response of a red clone of Myzus persicae (Hemiptera: Aphididae) to sublethal concentrations of imidacloprid in the laboratory and greenhouse

BACKGROUND: Pest resurgence following a pesticide application may occur owing to a stimulatory (hormetic) response to sublethal insecticide concentrations. The objective of the present study was to examine the potential for a greenhouse‐derived red clone of Myzus persicae to exhibit resurgence owing to a hormetic response following a systemic imidacloprid treatment in a bell pepper greenhouse. RESULTS: No differences in mortality and fecundity were observed among apterous adults exposed to sublethal imidacloprid concentrations on excised pepper leaves fed aqueous solutions of imidacloprid. Survival of first‐generation progeny was negatively affected by imidacloprid exposure, yet surviving progeny exhibited no differences in development rates or fecundity from progeny of adults unexposed to imidacloprid. Aphid mortality declined most rapidly in clip cages on pepper leaves at the top of the pepper canopy as compared with leaves present at the middle or bottom of the pepper canopy. CONCLUSION: Imidacloprid decays rapidly in mature pepper plants, resulting in sublethal concentrations in the upper canopy in as little as 4 weeks. Sublethal insecticide concentrations have been implicated in the resurgence of pest populations; however, exposure to sublethal doses of imidacloprid are unlikely to result in pesticide‐induced resurgence of the M. persicae aphid clone examined in this study. Copyright © 2011 Society of Chemical Industry     

Cross‐resistance,inheritance and biochemical mechanisms of imidacloprid resistance in B‐biotype Bemisia tabaci

BACKGROUND: The B‐type Bemisia tabaci (Gennadius) has become established in many regions in China, and neonicotinoids are extensively used to control this pest. Imidacloprid resistance in a laboratory‐selected strain of B‐type B. tabaci was characterised in order to provide the basis for recommending resistance management tactics. RESULTS: The NJ‐Imi strain of B‐type B. tabaci was selected from the NJ strain with imidacloprid for 30 generations. The NJ‐Imi strain exhibited 490‐fold resistance to imidacloprid, high levels of cross‐resistance to three other neonicotinoids, low levels of cross‐resistance to monosultap, cartap and spinosad, but no cross‐resistance to abamectin and cypermethrin. Imidacloprid resistance in the NJ‐Imi strain was autosomal and semi‐dominant. It is shown that enhanced detoxification mediated by cytochrome‐P450‐dependent monooxygenases contributes to imidacloprid resistance to some extent in the NJ‐Imi strain. Results from synergist bioassays and cross‐resistance patterns indicated that target‐site insensitivity may be involved in imidacloprid resistance in the NJ‐Imi strain of B. tabaci. CONCLUSION: Although oxidative detoxification mediated by P450 monooxygenases is involved in imidacloprid resistance in the NJ‐Imi strain of B‐type B. tabaci, target‐site modification as an additional resistance mechanism cannot be ruled out. Considering the high risk of cross‐resistance, neonicotinoids should be regarded as a single group when implementing an insecticide rotation scheme in B. tabaci control. Copyright © 2009 Society of Chemical Industry     

Susceptibility to neonicotinoids and risk of resistance development in the brown planthopper, Nilaparvata lugens (Stål) (Homoptera: Delphacidae)

BACKGROUND: In recent years, outbreaks of the brown planthopper, Nilaparvata lugens (Stål), have occurred more frequently in China. The objective of this study was to determine the susceptibility of N. lugens to neonicotinoids and other insecticides in major rice production areas in China. RESULTS: Results indicated that substantial variations in the susceptibility to different insecticides existed in N. lugens. Field populations had developed variable resistance levels to neonicotinoids, with a high resistance level to imidacloprid (RR: 135.3–301.3‐fold), a medium resistance level to imidaclothiz (RR: 35–41.2‐fold), a low resistance level to thiamethoxam (up to 9.9‐fold) and no resistance to dinotefuran, nitenpyram and thiacloprid (RR < 3‐fold). Further examinations indicated that a field population had developed medium resistance level to fipronil (up to 10.5‐fold), and some field populations had evolved a low resistance level to buprofezin. In addition, N. lugens had been able to develop 1424‐fold resistance to imidacloprid in the laboratory after the insect was selected with imidacloprid for 26 generations. CONCLUSION: Long‐term use of imidacloprid in a wide range of rice‐growing areas might be associated with high levels of resistance in N. lugens. Therefore, insecticide resistance management strategies must be developed to prevent further increase in resistance. Copyright © 2008 Society of Chemical Industry     

Responses of the cabbage seedpod weevil,Ceutorhynchus obstrictus (Marsham) (Coleoptera: Curculionidae), to seed treatments of canola (Brassica napus L.) with the neonicotinoid compounds clothianidin and imidacloprid

BACKGROUND: The cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham), is a major pest in the production of canola (Brassica napus L.) in North America and Europe, and effective population control is often essential for economical crop production. In North America, neonicotinoid insecticides have been used for several years in canola as seed treatments for reducing herbivory by flea beetles. The neonicotinoids clothianidin and imidacloprid were investigated to determine their effects on preimaginal development and on emergence of new‐generation adults of C. obstrictus in comparison with effects of lindane, a chlorinated hydrocarbon seed treatment. RESULTS: Mean numbers of second‐ and third‐instar larvae were significantly higher in plants seed‐treated with lindane than in plants treated with the neonicotinoid compounds, even though weevil oviposition was similar for all treatments. Emergence of new‐generation adults was reduced by 52 and 39% for plants seed‐treated with clothianidin and imidacloprid, respectively, compared with emergence from plants treated with lindane. CONCLUSION: Seed treatment with both clothianidin and imidacloprid produced systemic insecticidal effects on larvae of C. obstrictus, with clothianidin slightly more effective than imidacloprid. Use of clothianidin or imidacloprid as seed treatments can comprise an important component in the integrated management of cabbage seedpod weevil in canola. Copyright © 2009 Society of Chemical Industry     

Effect of reduced risk pesticides for use in greenhouse vegetable production on Bombus impatiens (Hymenoptera: Apidae)

BACKGROUND: Bumble bees [Bombus impatiens (Cresson)] are widely used for supplemental pollination of greenhouse vegetables and are at risk of pesticide exposure while foraging. The objective of this study was to determine the lethal and sub‐lethal effects of four insecticides (imidacloprid, abamectin, metaflumizone and chlorantraniliprole) and three fungicides (myclobutanil, potassium bicarbonate and cyprodinil + fludioxonil) used or with potential for use in Ontario greenhouse vegetable production to B. impatiens. RESULTS: Imidacloprid, abamectin, and metaflumizone were harmful to worker bees following direct contact, while chlorantraniliprole and all fungicides tested were harmless. Worker bees fed imidacloprid‐contaminated pollen had shortened life spans and were unable to produce brood. Worker bees consumed less pollen contaminated with abamectin. Metaflumizone, chlorantraniliprole and all fungicides tested caused no sub‐lethal effects in bumble bee micro‐colonies. CONCLUSION: We conclude that the new reduced risk insecticides metaflumizone and chlorantraniliprole and the fungicides myclobutanil, potassium bicarbonate and cyprodinil + fludioxonil are safe for greenhouse use in the presence of bumble bees. This information can be used preserve greenhouse pollination programs while maintaining acceptable pest management. Copyright © 2009 Society of Chemical Industry     

Soil microbial degradation of neonicotinoid insecticides imidacloprid, acetamiprid, thiacloprid and imidaclothiz and its effect on the persistence of bioefficacy against horsebean aphid Aphis craccivora Koch after soil application

BACKGROUND: The neonicotinoids imidacloprid, imidaclothiz, acetamiprid and thiacloprid consist of similar structural substituents but differ considerably with respect to soil use. Therefore, the effects of soil microbial activity on the degradation and bioefficacy persistence of the four neonicotinoids were evaluated. RESULTS: In unsterilised soils, 94.0% of acetamiprid and 98.8% of thiacloprid were degraded within 15 days, while only 22.5% of imidacloprid and 25.1% of imidaclothiz were degraded over a longer period of 25 days. In contrast, in sterilised soils, the degradation rates of acetamiprid and thiacloprid were respectively only 21.4% and 27.6%, whereas the degradation rates of imidaclothiz and imidacloprid were respectively 9.0% and almost 0% within 25 days. The degradation products of imidacloprid and imidaclothiz were identified as olefin, nitroso or guanidine metabolites, the degradation product of thiacloprid was identified as an amide metabolite and no degradation product of acetamiprid was detected. A bioefficacy assay revealed that the bioefficacy and persistence of imidacloprid, imidaclothiz, acetamiprid and thiacloprid against horsebean aphid A. craccivora were related to their degradation rate and the bioefficacy of their degradation products in soil. CONCLUSION: Soil microbial activity played a key role in the bioefficacy persistence of neonicotinoid insecticides and therefore significantly affected their technical profile after soil application. Copyright © 2011 Society of Chemical Industry     

Inheritance mode and realized heritability of resistance to imidacloprid in the brown planthopper,Nilaparvata lugens (Stål) (Homoptera: Delphacidae)

BACKGROUND: The brown planthopper, Nilaparvata lugens (Stål), is a serious pest that causes enormous losses to the rice crop in Asia. The genetic basis of imidacloprid resistance was investigated in N. lugens. RESULTS: The resistant strain, selected for imidacloprid resistance from a field population of N. lugens collected from Nanjing, Jiangsu Province, China, showed a 964‐fold resistance compared with the laboratory strain. Progenies of reciprocal crosses (F₁ and F₁′) showed similar dose–mortality responses (LC₅₀) to imidacloprid, and also exhibited a similar degree of dominance (D), 0.58 for F₁ and 0.63 for F₁′. Chi‐square analyses of self‐bred and backcross progenies (F₂, F₂′ and BC respectively) rejected the hypothesis for a single gene control of the resistance. The estimated realized heritability (h²) of imidacloprid resistance was 0.1141 in the resistant strain of N. lugens. CONCLUSION: The results showed that imidacloprid resistance in N. lugens was autosomal and was expressed as an incompletely dominant trait, probably controlled by multiple genes. Copyright © 2009 Society of Chemical Industry