Neonicotinoid insecticides imidacloprid and clothianidin affect differently neural Kenyon cell death in the cockroach Periplaneta americana

The intracellular toxicity of the neonicotinoid insecticides imidacloprid and clothianidin was studied on cockroach Periplaneta americana Kenyon cells using the trypan blue exclusion test and the adenylate kinase (AK) detection reagent. To evaluate cytotoxicity, Kenyon cells were exposed to different concentrations (1, 5, 10, 50 and 100 μM) of both imidacloprid and clothianidin at different delays (1, 3, 5, 8 and 24 h). Our data show that both imidacloprid and clothianidin decreased cell viability, with a more pronounced effect following imidacloprid exposure. Indeed, a significant decrease of cell viability was observed for 50 and 100 μM imidacloprid at 8 and 24 h, with trypan blue exclusion test. Study of the AK activity revealed that 50 and 100 μM imidacloprid induced an increase of AK activity, except for 50 μM at 24 h whereas at the same concentrations, clothianidin induced a transient effect at 5 and 8 h. According to previous studies showing that imidacloprid was a partial agonist and clothianidin a full agonist of insect nicotinic acetylcholine receptors, we demonstrated that both imidacloprid and clothianidin were also able to induce distinct intracellular toxic effects.     

新农药防治抗性棉蚜试验

１９９３～１９９５年在太原、临猗等地进行了咪蚜胺、硫丹和丁硫克百威防治棉蚜田间药效试验。结果表明，这３种新农药对棉花苗期蚜虫均有良好的防治效果，尤以咪蚜胺和丁硫克百威的防效最为突出。在棉蚜发生盛期，２５％咪蚜胺可湿性粉剂以２０００倍液喷雾防治，２～１４天的防效可达９５％～１００％，持效期在１４大以上；２０％丁硫克百威乳油以１０００～２０００倍液喷雾，１～５天的防效可达９２％～１００％。试验充分说明咪蚜胺的防效和持效，明显好于对照农药４０％久效磷水剂，是理想的防治抗性棉蚜的替代药剂。     

阿克泰对烟粉虱的防治效果研究

研究了阿克泰的不同施用方法对烟粉虱的防治效果.结果表明:用3 000倍阿克泰药液灌根可以获得最佳防治效果,药后9天,防治效果为94.51%.     

Lethal and sublethal effects of imidacloprid on two earthworm species (Aporrectodea nocturna and Allolobophora icterica)

The chemical imidacloprid is the major component of many widely used insecticides and is relatively persistent in soils. A set of experiments was carried out to estimate the lethal (mortality) and sublethal (weight loss) effects of one of these insecticides, Confidor, on two earthworm species commonly found in agricultural soils. A preliminary experiment in the absence of earthworms showed that imidacloprid was not rapidly degraded, with a decrease of less than 10% after 2 weeks, and that it was distributed in a reasonably homogeneous manner throughout the soil (less than 10% of variation between samples). The LC₅₀ of imidacloprid for the anecic species Aporrectodea nocturna and the endogeic species Allolobophora icterica was between 2 and 4 mg kg^–1 dry soil. This result is consistent with previous findings obtained with other earthworm species and natural soils. When sublethal effects were examined, significant decreases in weight were observed at concentrations of 0.5 and 1 mg kg^–1 dry soil for the two earthworm species whereas no effect was observed at a concentration of 0.1 mg kg^–1 dry soil (NOEC value). These concentrations are close to 0.33 mg kg^–1 which is the Predictive Environmental Concentration. Weight loss appears to be a valuable endpoint that can be used with worms freshly collected in the field as long as variability in the response of a control is taken into account.     

溴氰菊酯·吡虫啉对假眼小绿叶蝉的联合作用

[目的]研究溴氰菊酯与吡虫啉对假眼小绿叶蝉的联合作用。[方法]采用浸渍法测定溴氰菊酯与吡虫啉单剂及混剂对假眼小绿叶蝉的毒力。[结果]结果表明,溴氰菊酯、吡虫啉及5个不同配比（体积比）混剂对假眼小绿叶蝉均有一定的毒杀活性,其中以25．0％（溴氰菊酯）＋50．0％（吡虫啉）比例混配为最佳配比,共毒系数为203．47。[结论]该试验可为现有防治药剂利用、延缓害虫抗药性相关研究提供参考。     

Effect of cyantraniliprole on feeding behavior and virus transmission of Frankliniella fusca and Frankliniella occidentalis (Thysanoptera: Thripidae) on Capsicum annuum

The anthranilic diamide insecticide cyantraniliprole was previously shown to reduce transmission of Tomato spotted wilt virus (TSWV) to pepper, Capsicum annuum, by Frankliniella fusca but not Frankliniella occidentalis. This study examines the effects of cyantraniliprole and imidacloprid on thrips feeding using electrical penetration graphing (EPG), and on TSWV transmission in field cage studies. Some antifeedant responses were observed in the EPG studies when thrips fed on cyantraniliprole- and imidacloprid-treated plants; however, these responses were variable between species and among the 2, 6, and 10 day post-treatment time intervals during which feeding behavior was observed. Cyantraniliprole significantly reduced the probability of TSWV infection when spread by F. fusca in field-grown pepper when viruliferous thrips were released 7 days but not when released at 14 days after the insecticide treatment in one of 2 field trials. In the second trial cyantraniliprole significantly reduced the probability of infection when F. fusca were released 14 days but not 7 days after treatment. In both years, imidacloprid prevented or significantly reduced transmission of TSWV by F. fusca in field-grown pepper when viruliferous thrips were released 7 days and 14 after treatment. In one of two years, cyantraniliprole significantly reduced the incidence of TSWV in field-grown pepper that was spread by F. occidentalis when viruliferous thrips were released 7 days after the insecticide treatment, but not 14 days after the treatment. Imidacloprid did not reduce the incidence of TSWV in field-grown pepper when viruliferous F. occidentalis were released. Although these studies demonstrate that probing behavior of these thrips species is altered on cyantraniliprole-treated pepper plants, results of field cage studies did not consistently show a reduction in incidence of TSWV-infected plants.     

70%吡虫啉湿拌种剂在玉米上的残留分析方法

采用高效液相色谱法测定吡虫啉在玉米和土壤中的残留量。结果表明,70%吡虫啉湿拌种剂在土壤、玉米植株和子粒中的添加回收率分别是89.9%～97.9%、93.5%～100.9%和90.3%～94.9%。此法操作简便、快速,结果重现性好,定量准确。     

吡虫啉对高粱蚜虫的防治效果及对高粱产量的影响

研究了5种不同浓度的吡虫啉溶液对高粱蚜虫的防治效果及对高粱产量的影响。结果表明在一定浓度范围内,随着溶液浓度的增加,吡虫啉对高粱蚜虫的防治效果增强,同时对高粱的增产效果也越明显。综合考虑经济实惠、有利于环境保护等因素,建议防治高粱蚜虫的最佳吡虫啉溶液浓度为0.100 0μg/ml。     

Imidacloprid impairs memory and brain metabolism in the honeybee (Apis mellifera L.)

Imidacloprid is a chloronicotinyl insecticide which interacts with insect nicotinic acetylcholine receptors. Thirty minutes after oral treatment of honeybees with imidacloprid, the olfactory learning performances in a proboscis extension reflex (PER) procedure were impaired. In parallel, an increase of the cytochrome oxidase labelling was found into the calyces of the mushroom bodies. Imidacloprid administered 15 min or 1 h after a one-trial conditioning of PER impaired the medium-term olfactory memory. By contrast, the short-term (30 s or 3 min conditioning-treatment time interval) and long-term (24 h conditioning-treatment time interval) memories were unaffected. The impairment of medium-term olfactory memory by imidacloprid is discussed in the context of neural circuits suspected to mediate memory formation in the honeybee brain.     

Effectiveness of imidacloprid in combination with a root nitrogen fertilizer applied to tomato seedlings against Bemisia tabaci (Hemiptera: Aleyrodidae)

The whitefly Bemisia tabaci (biotype B) is a worldwide pest of vegetables and field crops. We tested the efficacy of imidacloprid (IM) with a root fertilizer ‘Root Feed (RF)’ (9% N, 7% Ca, 1.5% Mg and 0.1% B) sub-irrigated in the growing medium against the whitefly on tomato. Tomato seedlings (3–4 true leaves) were treated with 0, 3, 6 or 12 mg active ingredient (a.i.) seedling⁻¹ of IM and with RF (0, 0.02, 0.04 or 0.08 ml seedling⁻¹). The efficacy of 12 mg IM seedling⁻¹ was further evaluated in the greenhouse for 60 days. The survival of B. tabaci adults, nymphs, and egg production were negatively affected by the treatments in a dosage-dependent manner. Treatment of 12 mg IM seedling⁻¹ caused >60% adult and nymph mortality 50 days after treatment (DAT). The active ingredient of IM in tomato leaves also increased with the increase of IM dosage. The RF exhibited a limited effect on B. tabaci. However, the mortality of whitefly adults and nymphs treated with RF (0.02 or 0.04 ml seedling⁻¹) positively interacted with IM, and was greater than IM alone. In the greenhouse, 12 mg IM seedling⁻¹ greatly reduced the number of whitefly adults and increased the dry weight of the tomato plants at 30 DAT. In conclusion, application of 12 mg IM seedling⁻¹ on tomato seedlings before transplanting effectively controled B. tabaci for up to 50 days, and the efficacy of IM combined with 0.02 ml RF seedling⁻¹ performed even better. This could be a cost-effective method for managing B. tabaci on tomato and other vegetables.