新烟碱类和大环内酯类杀虫剂对四种赤眼蜂成蜂急性毒性和安全性评价

为了明确新烟碱类和大环内酯类杀虫剂对天敌赤眼蜂Trichogramma spp.的影响, 在室内采用药膜法测定了其对稻螟赤眼蜂Trichogramma japonicum Ashmead、 亚洲玉米螟赤眼蜂Trichogramma ostriniae Pang et Chen、 拟澳洲赤眼蜂Trichogramma confusum Viggiani和广赤眼蜂Trichogramma evanescens Westwood成蜂的急性毒性, 并进行了安全性评价。急性毒性测定结果表明： 在测定的新烟碱类药剂中, 噻虫嗪对拟澳洲赤眼蜂和稻螟赤眼蜂表现出最高的急性毒性, 其LC₅₀分别为0.24 (0.21~0.27) 和0.40 (0.37~0.44) mg a.i./L; 其次为烯啶虫胺, 该药剂对上述两种赤眼蜂的LC₅₀分别为0.83 (0.74~0.96) 和0.72 (0.65~0.80) mg a.i./L; 而吡虫啉对亚洲玉米螟赤眼蜂和拟澳洲赤眼蜂的毒性最低, 其LC₅₀分别为502.13 (459.80~549.62)和752.62 (687.51~828.63) mg a.i./L。在测定的大环内酯类药剂中, 阿维菌素对稻螟赤眼蜂的急性毒性最高, 其LC₅₀为0.49 (0.46~0.65) mg a.i./L, 而甲氨基阿维菌素苯甲酸盐对拟澳洲赤眼蜂表现出最低的急性毒性, 其LC₅₀为21.76 (19.59~24.40) mg a.i./L。安全性评价结果表明, 吡虫啉、 啶虫脒、 氯噻啉和甲氨基阿维菌素苯甲酸盐对4种赤眼蜂为低风险~中等风险性, 安全性系数为0.57~23.54; 噻虫啉和依维菌素对4种赤眼蜂却为中等风险~高风险性, 安全性系数为0.16~3.45; 而烯啶虫胺、 噻虫嗪和阿维菌素对4种赤眼蜂为高风险~极高风险性, 安全性系数为0.01~0.15。本研究测定的大部分杀虫剂对赤眼蜂都有一定的急性毒性风险。因此, 在害虫综合治理中应谨慎使用新烟碱类和大环内酯类杀虫剂尤其是烯啶虫胺、 噻虫嗪和阿维菌素, 以免造成对赤眼蜂的大量杀伤。     

两种室内生物测定方法评价杀虫剂对绿盲蝽的相对毒力

随着Bt棉在我国的广泛种植, 绿盲蝽Lygocoris lucorum Meyer-Dür的危害日益加重。化学防治作为棉田盲蝽综合治理的重要策略, 仍是其主要的防治手段。本研究主要用闪烁管药膜法和点滴法两种测定方法评价了传统杀虫剂、新型杀虫剂等30种杀虫剂对绿盲蝽成虫的急性触杀毒力, 其中多种杀虫剂是首次使用两种生测方法同时进行毒力测定。结果表明：有机氯类、有机磷类、氨基甲酸酯类和拟除虫菊酯类等传统杀虫剂对绿盲蝽成虫具有较高的触杀活性。8种对绿盲蝽成虫具有较高毒力的药剂, 其中5种为传统杀虫剂, 分别为马拉硫磷、毒死蜱、联苯菊酯、灭多威和硫丹。新型吡咯类杀虫剂对绿盲蝽表现出较高毒力, 以氟虫腈的毒力最高, 两种生测方法测定的LC₅₀分别为0.13 μg·mL^-1 和 0.15 μg·mL^-1。而昆虫生长调节剂、抗生素类及植物源杀虫剂对绿盲蝽成虫没有明显的触杀活性。     

三种杀虫剂对烟粉虱优势寄生蜂海氏桨角蚜小蜂的安全性评价

为评价噻虫嗪、阿维菌素和氟啶虫胺腈对烟粉虱优势寄生蜂海氏桨角蚜小蜂Eretmocerus hayati的安全性,采用琼脂保湿浸叶法分别测定了3种杀虫剂对烟粉虱成虫和海氏桨角蚜小蜂成蜂的室内毒力以及对海氏桨角蚜小蜂蛹羽化率的影响.结果表明,噻虫嗪、阿维菌素和氟啶虫胺腈对烟粉虱的LC50分别为453.76 mg/L、2.00 mg/L和29.47 mg/L,对海氏桨角蚜小蜂成蜂的LC50分别为0.23 mg/L、1.07 mg/L和0.64 mg/L.通过风险系数评估,表明阿维菌素对海氏桨角蚜小蜂成蜂安全,而噻虫嗪和氟啶虫胺腈对该蜂成蜂具有轻微到中度毒性.3种杀虫剂在烟粉虱和寄生蜂之间的选择性毒力指数表明噻虫嗪对海氏桨角蚜小蜂的负向选择性最强,其次是氟啶虫胺腈,阿维菌素最弱.3种杀虫剂均可显著降低海氏桨角蚜小蜂蛹的羽化率,对蛹的毒性为轻微有害,风险等级为2级.本研究结果将为烟粉虱综合治理中协调使用寄生蜂和化学药剂奠定理论基础.     

Toxicity of seventeen insecticides to Camponotus sericeus (Hymenoptera: Formicidae)

The success of chemical control depends on toxicity of insecticides against insect pests. Camponotus sericeus is an important urban pest with the ability to cause substantial damage to wooden structures, but there is a lack of information on toxicity of insecticides against C. sericeus. To determine the insecticide toxicity, workers of C. sericeus were exposed to 17 insecticides from different classes: carbamate (methomyl, bendiocarb), organophosphate (chlorpyrifos, profenofos, temephos), pyrethroid (bifenthrin, deltamethrin, permethrin), neonicotinoid (acetamiprid, imidacloprid, thiamethoxam), avermectin (abamectin, emamectin), pyrrole (chlorfenapyr), phenylpyrazole (fipronil), and spinosyn (spinosad and spinetoram), via residual bioassay method. The LC₅₀ ranged from: 0.15 to 0.20 µg/vial for carbamates, 0.09 to 0.27 µg/vial for organophosphates, 0.09 to 0.44 µg/vial for pyrethroids, 0.02 to 0.67 µg/vial for neonicotinoids, 0.54 to 0.82 µg/vial for avermectins, 0.78 µg/vial for pyrrole, 0.62 µg/vial for phenylpyrazole, and 1.96 to 2.05 µg/vial for spinosyns. Overall, acetamiprid was the most toxic one among the tested insecticides followed by permethrin, temephos, profenofos, bendiocarb and methomyl, while spinosad and spinetoram were the least toxic insecticides. Considering the potential toxicity of different insecticides against C. sericeus, future studies could investigate the practical application of these insecticides in order to design an effective management plan.     

Acute toxicity of neonicotinoids and some insecticides to first instar nymphs of a non-target damselfly, <Emphasis Type="Italic">Ischnura senegalensis</Emphasis> (Odonata: Coenagrionidae), in Japanese paddy fields

Systemic insecticides such as neonicotinoids and fipronil are widely applied in rice production. These insecticides have been suspected of reducing biodiversity in paddy ecosystems and reducing wild dragonfly populations in Japan. Conventional ecotoxicological risk assessment could not confirm this, as it has not considered interspecific variation in sensitivity to insecticides. We estimated the median effect concentration (EC50) of 15 systemic insecticides to first instar nymphs of a Japanese damselfly, Ischnura senegalensis (Rambur) (Odonata: Coenagrionidae), commonly found in rice paddy fields. Damselflies were found to be highly sensitive to pyrethroid pesticides, less so to phenylpyrazole, organophosphates, and carbamates, and least sensitive to neonicotinoids, nereistoxin, and diamide. Given the acute toxicity data, the sensitivity of the damselfly to neonicotinoids was considered to be lower than that of other aquatic insects, whereas the EC50 values of the damselfly were 2–3 orders lower than that of Daphnia magna Straus (Diplostraca: Daphniidae), which is a standard test species. These results indicate that the conventional ecological risk assessment based on acute toxicity data of D. magna would underestimate the impact of neonicotinoids on Odonata diversity in paddy ecosystems. We therefore recommend using the paddy-dwelling damselfly as a new test species for insecticide bioassay.     

Assessment of cross-resistance potential to neonicotinoid insecticides in Bemisia tabaci (Hemiptera: Aleyrodidae)

Laboratory bioassays were carried out with four neonicotinoid insecticides on multiple strains of Bemisia tabaci (Gennadius) to evaluate resistance and cross-resistance patterns. Three imidacloprid-resistant strains and field populations from three different locations in the southwestern USA were compared in systemic uptake bioassays with acetamiprid, dinotefuran, imidacloprid and thiamethoxam. An imidacloprid-resistant strain (IM-R) with 120-fold resistance originally collected from Imperial Valley, California, did not show cross-resistance to acetamiprid, dinotefuran or thiamethoxam. The Guatemala-resistant strain (GU-R) that was also highly resistant to imidacloprid (RR=109-fold) showed low levels of cross-resistance when bioassayed with acetamiprid and thiamethoxam. However, dinotefuran was more toxic than either imidacloprid or thiamethoxam to both IM-R and GU-R strains as indicated by low LC50s. By contrast, a Q-biotype Spanish-resistant strain (SQ-R) of B. tabaci highly resistant to imidacloprid demonstrated high cross-resistance to the two related neonicotinoids. Field populations from Imperial Valley (California), Maricopa and Yuma (Arizona), showed variable susceptibility to imidacloprid (LC50s ranging from 3.39 to 115 microg ml(-1)) but did not exhibit cross-resistance to the three neonicotinoids suggesting that all three compounds would be effective in managing whiteflies. Yuma populations were the most susceptible to imidacloprid. Dinotefuran was the most toxic of the four neonicotinoids against field populations. Although differences in binding at the target site and metabolic pathways may influence the variability in cross-resistance patterns among whitefly populations, comparison of whitefly responses from various geographic regions to the four neonicotinoids indicates the importance of ecological and operational factors on development of cross-resistance to the neonicotinoids.     

Activity of selected neonicotinoids and dicrotophos on nontarget arthropods in cotton: implications in insect management

Certain neonicotinoids are used in cotton, Gossypium hirsutum (L.), to control various piercing-sucking pests. We conducted field studies using three neonicotinoids (acetamiprid, thiamethoxam, and imidacloprid) and an organophosphate (dicrotophos) to assess the activity of these insecticides against nontarget arthropods, particularly predators, and to determine the potential economic consequences of such activity. Mortality among populations of the big-eyed bug, Geocoris punctipes (Say), and the red imported fire ant, Solenopsis invicta Buren, was highest after thiamethoxam and dicrotophos treatments. Numbers of arachnids were consistently lower after dicrotophos treatments, whereas none of the neonicotinoids caused appreciable mortality. Total predators in pooled data from five separate studies revealed that numbers, compared with untreated plots, were reduced by -75% in dicrotophos, 55-60% in thiamethoxam, and only 30% in both acetamiprid and imidacloprid plots. Acetamiprid and thiamethoxam exhibited significant mortality against field-deposited eggs of bollworm, Helicoverpa zea (Boddie). Both thiamethoxam and dicrotophos plots exhibited bollworm numbers that were approximately three times higher than treatment thresholds (three per 100 plants), whereas numbers in untreated plots were below threshold levels. In one study on Bt cotton, a significant negative correlation was observed between numbers of predators and bollworm larvae. Results demonstrated that neonicotinoids differ in activity against predaceous arthropods and bollworm eggs and that high predator mortality can result in resurgence of bollworm larvae and additional insecticide costs.     

Acetylcholinesterase target sites for developing environmentally friendly insecticides against Tetranychus urticae (Acari: Tetranychidae)

Experimental and Applied Acarology - The non-target toxicity and resistance problems of acetylcholinesterase (AChE) insecticides, such as organophosphates and carbamates, are of growing concern. To...     

Mortality of a wireworm, Agriotes obscurus (Coleoptera: Elateridae), after topical application of various insecticides

Ten insecticides representing seven chemical groups were applied at various concentrations topically by using a Potter Spray Tower to evaluate their relative toxicities on the European wireworm Agriotes obscurus L. (Coleoptera: Elateridae). Wireworms were stored at 15 degrees C after exposure to organophosphate (OP) (chlorpyrifos, diazinon), pyrethroid (tefluthrin), thianicotinoid (thiamethoxam, clothianidin), chloronicotinoid (imidacloprid, acetamiprid), phenyl pyrazole (fipronil), organochlorine (lindane), and spinosyn (spinosad) insecticides, and their postapplication health was evaluated weekly for up to 301 d. LC50, LC90, LT50, and LT90 values were calculated for each chemical except acetamiprid, and compared with those of lindane, clothianidin, and chlorpyrifos. Wireworms exposed to OPs died or recovered more quickly (LT50 < 20 d, LT90 < 50 d), than those exposed to all other insecticides tested except tefluthrin (LT50 = 25.5 d, LT90 = 66.5 d). Wireworms exposed to sublethal concentrations of all neonicotinoids quickly became moribund after application but made a full recovery. Wireworms exposed to fipronil at concentrations near the LC90 value showed no intoxication symptoms for up to 35 d, and they did not recover after symptoms developed. For each chemical, increasing the concentration increased the time required for wireworms to recover but decreased the time required to kill wireworms. Fipronil was highly toxic to wireworms (LC50 = 0.0001%), but acetamiprid (LC50 = 1.82%), imidacloprid (LC50 = 0.83%), tefluthrin (LC50 = 0.23%), diazinon (LC50 = 0.54%), and spinosad (LC50 = 0.51%) were not. The toxicity of both clothianidin (LC50 = 0.07%) and thiamethoxam (LC50 = 0.17%) were similar to those oflindane (LC50 = 0.06%) and chlorpyrifos (LC50 = 0.10%).     

Compatibility of two systemic neonicotinoids, imidacloprid and thiamethoxam, with various natural enemies of agricultural pests

Two systemic neonicotinoids, imidacloprid and thiamethoxam, are widely used for residual control of several insect pests in cotton (Gossypium spp.), vegetables, and citrus (Citrus spp.). We evaluated their impact on six species of beneficial arthropods, including four parasitoid species--Aphytis melinus Debach, Gonatocerus ashmeadi Girault, Eretmocerus eremicus Rose & Zolnerowich, and Encarsia formosa Gahan--and two generalist predators--Geocoris punctipes (Say) and Orius insidiosus (Say)--in the laboratory by using a systemic uptake bioassay. Exposure to systemically treated leaves of both neonicotinoids had negative effects on adult survival in all four parasitoids, with higher potency against A. melinus as indicated by a low LC50. Mortality was also high for G. ashmeadi, E. eremicus, and E. formosa after exposure to both compounds but only after 48 h posttreatment. The two predators G. punctipes and O. insidiosus were variably susceptible to imidacloprid and thiamethoxam after 96-h exposure. However, toxicity to these predators may be related to their feeding on foliage and not just contact with surface residues. Our laboratory results contradict suggestions of little impact of these systemic neonicotinoids on parasitoids or predators but field studies will be needed to better quantify the levels of such impacts under natural conditions.     

Insecticide resistance monitoring and correlation analysis to select appropriate insecticides against Nilaparvata lugens (Stål), a migratory pest in Korea

Nilaparvata lugens Stål is one of the important migratory pests of rice paddy fields in Korea. Resistance levels to nine insecticides were monitored in 12 local strains and correlation analysis was conducted to determine cross-resistance relationships among the tested insecticides. The local strains revealed 1.3- to 28.0-, 1.6- to 6.0-, 2.8- to 237.0-, 0.6- to 0.9-, and 0.7- to 1.3-fold resistance to carbamates, organophosphates, neonicotinoids, fipronil and etofenprox, respectively. Organophosphate insecticides revealed moderate correlations with benzofuranyl methylcarbamate (r = 0.566–0.614, p > 0.01). Three neonicotinoids were not correlated with each other, but imidacloprid and clothianidin were moderately correlated with several benzofuranyl methylcarbamate and organophosphate insecticides (r = 0.590–0.705, p > 0.05), indicating that unknown common factors (such as detoxification enzymes) might contribute to resistance to both insecticides. Fipronil and etofenprox exhibited low levels of resistance and cross-resistance with other insecticides, suggesting their potential as an effective insecticide for field application. Resistance level monitoring and correlation analysis would be valuable for the selection of appropriate insecticides to control insecticide-resistant N. lugens, a typical migratory pest in Korea.     

A Locomotor Deficit Induced by Sublethal Doses of Pyrethroid and Neonicotinoid Insecticides in the Honeybee Apis mellifera

The toxicity of pesticides used in agriculture towards non-targeted organisms and especially pollinators has recently drawn the attention from a broad scientific community. Increased honeybee mortality observed worldwide certainly contributes to this interest. The potential role of several neurotoxic insecticides in triggering or potentiating honeybee mortality was considered, in particular phenylpyrazoles and neonicotinoids, given that they are widely used and highly toxic for insects. Along with their ability to kill insects at lethal doses, they can compromise survival at sublethal doses by producing subtle deleterious effects. In this study, we compared the bee’s locomotor ability, which is crucial for many tasks within the hive (e.g. cleaning brood cells, feeding larvae…), before and after an acute sublethal exposure to one insecticide belonging to the two insecticide classes, fipronil and thiamethoxam. Additionally, we examined the locomotor ability after exposure to pyrethroids, an older chemical insecticide class still widely used and known to be highly toxic to bees as well. Our study focused on young bees (day 1 after emergence) since (i) few studies are available on locomotion at this stage and (ii) in recent years, pesticides have been reported to accumulate in different hive matrices, where young bees undergo their early development. At sublethal doses (SLD_48h, i.e. causing no mortality at 48h), three pyrethroids, namely cypermethrin (2.5 ng/bee), tetramethrin (70 ng/bee), tau-fluvalinate (33 ng/bee) and the neonicotinoid thiamethoxam (3.8 ng/bee) caused a locomotor deficit in honeybees. While the SLD_48h of fipronil (a phenylpyrazole, 0.5 ng/bee) had no measurable effect on locomotion, we observed high mortality several days after exposure, an effect that was not observed with the other insecticides. Although locomotor deficits observed in the sublethal range of pyrethroids and thiamethoxam would suggest deleterious effects in the field, the case of fipronil demonstrates that toxicity evaluation requires information on multiple endpoints (e.g. long term survival) to fully address pesticides risks for honeybees. Pyrethroid-induced locomotor deficits are discussed in light of recent advances regarding their mode of action on honeybee ion channels and current structure-function studies.     

几类杀虫剂对灰飞虱的相对毒力及田间种群的抗药性现状

采用浸苗法测定了6类11种杀虫剂对灰飞虱Laodelphax striatellus (Fallén)3龄若虫的毒力,并分析比较了江苏句容、通州、楚州、大丰、南京和苏州以及安徽庐江等7地灰飞虱种群对10种杀虫剂的抗药性水平。对云南种群而言,在所测杀虫剂中,以乙酰甲胺磷为标准药剂,氟虫腈的相对毒力最高;噻嗪酮、阿维菌素和噻虫嗪次之;高效氯氰菊酯、IPP（硝基亚甲基类化合物）、毒死蜱、敌敌畏和三唑磷间毒力处于同一数量级,低于阿维菌素等杀虫剂;吡虫啉的相对毒力最低。与云南种群相比,2007年采自苏、皖7个不同地区的灰飞虱种群对噻嗪酮产生了极高水平的抗性,其抗性倍数均超过200倍;对高效氯氰菊酯产生了中高水平的抗性,其抗性倍数为7.8～108.8;安徽庐江灰飞虱种群对三唑磷产生了7.7倍的抗性,对毒死蜱产生了12.0倍的抗性,江苏楚州、南京、大丰和句容灰飞虱种群对毒死蜱产生了5.7～12.6倍的抗性; 所有灰飞虱种群对敌敌畏仍然敏感,对氟虫腈、阿维菌素和新烟碱类杀虫剂吡虫啉、噻虫嗪和IPP等也比较敏感。     

Susceptibility of pest Nezara viridula (Heteroptera: Pentatomidae) and parasitoid Trichopoda pennipes (Diptera: Tachinidae) to selected insecticides

Susceptibility of the southern green stink bug, Nezara viridula (L.) (Heteroptera: Pentatomidae), and its endoparasitoid Trichopoda pennipes (F.) (Diptera: Tachinidae) to acetamiprid, cyfluthrin, dicrotophos, indoxacarb, oxamyl, and thiamethoxam was compared in residual and oral toxicity tests. In the residual toxicity test, cyfluthrin, dicrotophos, and oxamyl were highly toxic to N. viridula. Thiamethoxam was moderately toxic to these insects. Each of the four insecticides was highly toxic to T. pennipes after prolonged tarsal contact with dried residues of these chemicals. In the oral toxicity test, where N. viridula fed on food covered with insecticide residues, none of the insecticides were toxic to adults of this stink bug, but acetamiprid, dicrotophos, and thiamethoxam were moderately toxic to the nymphs. In the oral toxicity test, where N. viridula fed on a gel-food containing insecticides, cyfluthrin, dicrotophos, oxamyl, and thiamethoxam were highly toxic to this stink bug. In an oral toxicity test using contaminated sugar water, all of the insecticides were highly toxic to T. pennipes. Because insecticides were as toxic, or more toxic, to T. pennipes than to N. viridula, it is extremely important to conserve this parasitoid by applying these insecticides for control of southern green stink bugs only when the pest reaches economic threshold.     

Effect of insecticides on Tiphia vernalis (Hymenoptera: Tiphiidae) oviposition and survival of progeny to cocoon stage when parasitizing Popillia japonica (Coleoptera: Scarabaeidae) larvae

The effect of insecticides on oviposition of Tiphia vernalis Rohwer and subsequent survival of parasitoid progeny to the cocoon stage was determined in the laboratory by using larval Japanese beetle, Popillia japonica Newman, as the host. Insecticides tested were imidacloprid, thiamethoxam, halofenozide, chlorpyrifos, and carbaryl at labeled rates. Female T. vernalis were allowed 2 d to parasitize P. japonica larvae after the parasitoids had received a 4-d exposure to insecticide-treated soil. Another group of female T. vernalis were allowed 2 d to parasitize P. japonica larvae that had been exposed to insecticide-treated soil for 3-4 d. Percentage of parasitism of P. japonica larvae in these trials after exposure of adult parasitoids to carbaryl, chlorpyrifos, halofenozide, or imidacloprid-treated soil (23.3-50.0%) or adult parasitoids to chlorpyrifos, halofenozide, or imidacloprid-treated grubs (33.0-56.7%) was not negatively affected relative to the control treatment (21.7-54.2%). A third group of adult T. vernalis and P. japonica larvae were simultaneously exposed to chlorpyrifos or carbaryl treatments. Percentage parasitism in these trials was lower for T. vernalis adults exposed to the chlorpyrifos and carbaryl (15.0-25.0%) relative to the control (57.5-62.5%) with the exception of one trial with carbaryl (40.0%). However, exposure of the parasitoid and P. japonica to chlorpyrifos 0.5X, carbaryl 0.5X, imidacloprid, halofenozide, or thiamethoxam in several trials resulted in parasitism that was equivalent or greater than (45.0-80.0%) the untreated control (57.5-62.5%). Japanese beetle larval mortality in these trials was greater in the insecticide and parasitoid combination (97.5-100.0%) than with insecticides alone (45.0-100.0%). Percentage of survival of T. vernalis progeny to the cocoon stage was not negatively affected by a 4-d adult parasitoid exposure to carbaryl and chlorpyrifos treated soil (11.7-16.7% versus 18.3% control) or a 2-d exposure to P. japonica-treated larvae (16.7-18.3% versus 28.3% control). However, simultaneous exposure of T. vernalis progeny and P. japonica larvae to chlorpyrifos- and carbaryl-treated soil resulted in no parasitoids surviving to the cocoon stage. Between neonicotinoids, thiamethoxam had more adverse impact on percentage parasitism (52.5%) and survival to the cocoon stage (10.0%) than imidacloprid (80.0 and 32.5%, respectively). Results of this study indicate soil incorporation of imidacloprid and halofenozide had minimal effect on the number of P. japonica larvae parasitized by T. vernalis or survival of T. vernalis progeny to the cocoon stage; therefore, they are more suitable for use with T. vernalis. In contrast, chlorpyrifos, carbaryl, and thiamethoxam lowered the number of T. vernalis progeny surviving to the cocoon stage, and carbaryl and chlorpyrifos reduced the number of P. japonica larvae parasitized. The soil incorporation of insecticides is discussed as one explanation for the minimal effects of some insecticides on T. vernalis.     

Fumigant toxicity of plant essential oils to Thrips palmi (Thysanoptera: Thripidae) and Orius strigicollis (Heteroptera: Anthocoridae)

The fumigant toxicity of 92 plant essential oils to adult Thrips palmi Karny (Thysanoptera: Thripidae) and Orius strigicollis Poppius (Heteroptera: Anthocoridae) was examined by using a vapor phase toxicity bioassay and compared with those of dichlorvos, emamectin benzoate, spinosad, and thiamethoxam, four commonly used insecticides. Responses varied according to oil type and insect species. As judged by 24-h LC50 values, pennyroyal oil (2.63 mg/liter air) was the most toxic fumigant and was 23.6-fold more toxic than dichlorvos (62.09 mg/liter air) against adult T. palmi. Potent fumigant toxicity (LC50, 11.03-19.21 mg/liter air) was observed in armoise, basil, cedarleaf, coriander, cypress, howood, hyssop, marjoram, myrtle, niaouli, rosemary, and sage (Dalmatia) oils. Neither emamectin benzoate, spinosad, nor thiamethoxam exhibited fumigant action. Against adult O. strigicollis, dichlorvos (LC50, 6.3 x 10(-6) mg/liter air) was the most toxic fumigant, whereas the LC50 values of the 13 essential oils ranged from 17.29 to 158.22 mg/liter air. O. strigicollis was 1.4-22.1 times less susceptible than T. palmi to the essential oils. The essential oils described merit further study as potential fumigants for the control of T. palmi in greenhouses.     

韭菜迟眼蕈蚊对新烟碱类杀虫剂的抗药性及抗性机制初探

【目的】为明确韭菜迟眼蕈蚊Bradysia odoriphaga对新烟碱类杀虫剂的抗性水平及其抗性机制。【方法】通过测定不同地区韭菜迟眼蕈蚊对3种新烟碱类杀虫剂吡虫啉、噻虫嗪和噻虫胺的敏感度,及通过增效剂实验和酶活性测定,初步探索抗性产生机制,为韭菜迟眼蕈蚊抗性治理提供依据。【结果与结论】4个不同的韭菜迟眼蕈蚊田间种群对3种新烟碱类杀虫剂均产生了不同水平的抗性。其中,唐山种群对3种新烟碱杀虫剂均产生了较高的抗性。研究发现,唐山种群的7-乙氧基香豆素-O-脱乙基酶(ECOD)比活力为(3.89±0.31)pmol/(mg·pro·min),显著高于敏感品系。增效剂PBO对唐山种群的吡虫啉毒力的增效比为2.64,高于对敏感品系的增效比1.08。因此,P450s酶活性的升高与韭菜迟眼蕈蚊对吡虫啉的抗性有关。     

Toxicity of several insecticide formulations against adult German cockroaches (Dictyoptera: Blattellidae)

Toxicity of bendiocarb, chlorpyrifos, cyfluthrin, cypermethrin, fenvalerate, hydramethylnon, malathion, propetamphos, propoxur, and pyrethrins against the adult German cockroaches, Blattella germanica (L.), was investigated. At LD50, cyfluthrin was the most toxic insecticide to adult males (0.53 microgram/g), adult females (1.2 micrograms/g), and gravid females (0.85 microgram/g). Malathion was the least toxic insecticide to adult males (464.83 micrograms/g), adult females (335.83 micrograms/g), and gravid females (275.90 micrograms/g). Males and gravid females were generally more sensitive than nongravid females to the insecticides that we tested. In tests with malathion, however, males were more tolerant. The order of toxicity of the insecticide classes varied among the stages of adult German cockroaches. The order of toxicity for males and nongravid females was pyrethroids greater than pyrethrins = organophosphates (except malathion) greater than carbamates = amidinohydrazone. The order of toxicity for gravid females was pyrethroids greater than pyrethrins = organophosphates (except malathion) greater than carbamates greater than amidinohydrazone. These differences in toxicity suggest that sex differences should be considered when determining insecticide toxicity for German cockroaches.     

Biorational insecticides: mechanism and cross-resistance

Potency and cross-resistance of various biorational insecticides, exemplified by the whitefly Bemisia tabaci, have been studied. Bemisia tabaci were exposed to the juvenile hormone mimic pyriproxyfen for the past 12 years resulting in an over 2,000-fold resistance, but there was no appreciable cross-resistance with the benzoylphenyl urea novaluron. Similarly, no cross-resistance was found between pyriproxyfen and the two neonicotinoids, acetamiprid and imidacloprid. On the other hand, a slight cross-resistance of 5-13-fold was observed with another neonicotinoid thiamethoxam. Among the neonicotinoids, a resistant strain of B. tabaci to thiamethoxam (approximately 100-fold) showed no appreciable cross-resistance to either acetamiprid or imidacloprid, while another strain 500-fold resistant to thiamethoxam resulted in a mild of 4-6-fold resistance to acetamiprid and imidacloprid. In other assays, B. tabaci strain resistant to thiamethoxam (approximately 100-fold) had no cross-resistance to pyriproxyfen. Our findings indicate that no appreciable cross-resistance was observed between the benzoylphenyl urea novaluron, the juvenile hormone mimic pyriproxyfen, and the neonicotinoids acetamiprid and imidacloprid. Hence, these compounds could be used as components in insecticide resistance management programs.     

不同类型杀虫剂对烟粉虱捕食性天敌日本刀角瓢虫的毒力

采用试管药膜法,测定了不同类型杀虫剂对日本刀角瓢虫Serangium japonicum Chapin的毒力。结果表明,灭多威和敌敌畏对日本刀角瓢虫具有极强的毒力,其25%推荐剂量即可导致日本刀角瓢虫全部死亡;氯虫苯甲酰胺、吡虫啉和噻虫嗪对日本刀角瓢虫也具有很强的毒力,其田间推荐剂量可导致日本刀角瓢虫全部死亡,其50%推荐剂量对日本刀角瓢虫的致死率也高达73.33%～100.00%;乐果、烯啶虫胺、丁醚脲田间推荐剂量对日本刀角瓢虫的致死率分别为40.00%、56.67%、50.00%,预示着上述这些杀虫剂的田间应用对刀角瓢虫具有很高的直接杀伤风险。高效氯氰菊酯、联苯菊酯、毒死蜱、甲氰菊酯、高效氯氟氰菊酯、虫螨腈、阿维菌素、吡蚜酮、噻嗪酮、定虫隆和氟虫脲对日本刀角瓢虫的毒力较低甚至没有直接致死作用。研究结果将为合理使用杀虫剂,协调利用化学防治与生物防治对烟粉虱进行综合防治提供依据。