Effects of cypermethrin and deltamethrin on the feeding behaviour of Aphis craccivora and transmission of cowpea aphid-borne mosaic virus

The effects of two synthetic pyrethroids, cypermethrin and deltamethrin, on the feeding behaviour of Aphis craccivora and its transmission of the nonpersistent cowpea aphid-borne mosaic virus (CAMV) were compared to those of an organophosphate (dimethoate) and carbamate (pirimicarb) in greenhouse and laboratory tests. Cypermethrin at 100, 150 and 200 mg a.i. litre^-1 and deltamethrin at 75, 100 and 150 mg a.i. litre^-1 restricted the acquisition and inoculation of CAMV, whereas dimethoate and pirimicarb had no significant effect. Cypermethrin protected against transmission of CAMV longer after application than deltamethrin and there was a strong interaction between The duration of the first probe was shorter on pyrethroid-treated plants than on dimethoate-or pirimicarb-treated plants, and on pyrethroid-treated plants aphids probably did not probe long enough to acquire or inoculate CAMV. It is concluded that the use of synthetic pyrethroids is potentially valuable in controlling CAMV in the field until resistance against the virus has been bred into cultivars.     

Side effects of insecticides on aphidius rhopalosiphi (Hym.: Aphidiidae) In laboratory

The toxicity of bifenthrin, cyfluthrin, λ-cyhalothrin, cypermethrin, deltamethrin, esfenvalerate, fluvalinate, phosalon and pirimicarb have been assessed in laboratory on the parasitic hymenoptera Aphidius rhopalosiphi. A strong toxic effect was found with every tested product when adult parasitoids were exposed to freshly applied residues on both glass plates and maize leaves for 24 hours. Only two products, fluvalinate and esfenvalerate, did not kill all the insects. No differences were observed between mortalities on glass plates and leaves. Applied on aphids mummies, cyfluthrin and deltamethrin slightly reduced the emergence of young parasitoids, but not their reproductive performance. The other tested products had no effects on adult emergence. On basis of these results, the insecticides are of comparable toxicity to A. rhopalosiphi in laboratory.     

Dosage reduction to improve the selectivity of deltamethrin between aphids and coccinellids in cereals

The toxicity of the pyrethroid insecticide deltamethrin to a cereal aphid and a coccinellid beetle predator was assessed. Deltamethrin gave effective aphid control in winter wheat at dose-rates of 6.25, 3.13 and 1.56g a.i./ha. The direct exposure of adultCoccinella septempunctata L. (Coleoptera: Coccinellidae) to spray drops was estimated at a range of positions in a cereal crop canopy from volumetric analysis of fluorescent tracer deposits. These measurements were used to calculate exposure to deltamethrin at the three experimental dose-rates. Observations of coccinellid beetle distribution through a cereal crop canopy permitted a realistic range of direct contact doses tobe calculated and the toxic effects of these levels of exposure to be predicted from laboratory dose-response data. Estimated beetle mortalities from direct exposure were 19, 8 and 3% at the three experimental dose-rates.In situbioassays with adultC. septempunctata which exposed beetles continuously to deltamethrin residues on flag leaves, resulted in 100, 94 and 39% mortality respectively at these dose-rates during the 10 days after spray application. Additionalin situ bioassays exposed beetles to deltamethrin residues on flag leaves for 24 h and then transferred surviving beetles to the soil under the cereal crop canopy for a further 9 days. This resulted in 89, 69 and 29% beetle mortality respectively at the three dose-rates. Mortality predictions combining both direct contact and residual exposure were made for the three dose-rates.to determine the maximum impact of summer sprays of deltamethrin on adult coccinellid populations in cereals. These worst case predictions suggested that a reduction in dose-rate by as much as three quarters of the recommended application rate in UK cereals may be necessary to preserve approximately 60% of adultC. septempunctata in the crop over the 10 days after a deltamethrin spray application. The methodology described may be appropriate for estimating selective dose-rates for key enemies in a range of crops.     

Potential for integrating eleven agricultural insecticides with the predatory bug Pristhesancus plagipennis (Hemiptera: Reduviidae)

A problem for growers attempting to implement integrated pest management programs is the lack of information regarding the compatibility of insecticides with natural enemies. To provide information about this problem, we evaluated the acute and residual effects of 11 commonly used insecticides on nymphs of Pristhesancus plagipennis (Walker) under both laboratory and field conditions. For each insecticide, the length of time that weathering residues caused > 50% mortality was evaluated and compared against the LC50 (acute-toxicity) divided by the recommended field rate. Plots thus combined the acute and residual toxicity of each insecticide. Results suggested that carbaryl, esfenvalerate, endosulfan, and deltamethrin had low residual and acute toxicity to P. plagipennis, whereas chlorpyrifos, methomyl, and monocrotophos were highly toxic at low concentrations and left persistent harmful residues. Cypermethrin, methidathion, malathion, and dimethoate were moderately toxic. The potential use of these insecticides to supplement the control activity of P. plagipennis is discussed.     

Pesticide Susceptibility of Two Coccinellids (Stethorus punctum picipes and Harmonia axyridis) Important in Biological Control of Mites and Aphids in Washington Hops

The susceptibility of Stethorus punctum picipes (Casey) and Harmonia axyridis Pallas larvae to pesticides used or with potential for use in Washington hops, was examined in laboratory bioassays. All pesticides tested except the miticide, hexythiazox, the insecticides, chlorpyrifos and pirimicarb, and the fungicide, mycobutanil, produced 100% mortality in S. punctum picipes at concentrations equivalent to field rates. The insecticides, pirimicarb, endosulfan, and thiamethoxam were least toxic to H. axyridis. Bifenthrin, diazinon, dimethoate, methomyl, carbaryl, malathion, phosmet, imidacloprid, and chlorpyrifos were highly toxic. The miticides, abamectin and fenpyroximate were highly toxic, milbemectin was moderately toxic but all other miticides tested were non-toxic. All fungicides had low toxicity. Selection and use of pesticides compatible with natural enemies and conservation biological control in Washington hop production is discussed.     

Studies on the toxicity of insecticidal drift to the first instar larvae of the Large White butterfly Pieris brassicae (Lepidoptera: Pieridae)

The toxicity (LD,) of eight insecticides to 2–day-old first instar larvae of Pieris brassicue was determined by topical application. On this basis, the insecticides could be ranked in ascending order viz. dimethoate > pirimicarb > phosalone > endosulfan > fenitrothion > pirimiphos-methyl > fenvalerate > diflubenzuron. Relative to endosulfan, dimethoate and pirimicarb were 30–25 times less toxic while at the other extreme, fenvalerate (x 12) and diflubenzuron (x 26) were much more toxic to the larvae of P. brassicae. A methodology was developed for examining the effects of spray drift through bioassay using these 2–day-old larvae. Six field trials with commercial formulations were carried out in which variables other than the insecticide and wind speed were held constant as far as possible. Phosalone (700 g active ingredient ha) produced no effect beyond 1 m downwind at low wind speed (2 m s); at high wind speed (4 m s-¹). larval mortality (5.3%) was recorded up to 2m. Fenitrothion (1050 g a.i. ha^-1) at moderate wind speed (3 m s-^l) caused mortality up to 4 m while fenvalerate (30 g a.i. ha-^l) at the same wind speed affected larvae up to a distance of 8 m. Diflubenzuron at a very low dosage (6.5 g a.i. ha-¹) also produced effects up to 8 m. At the maximum approved dosage (100 g a.i. ha^-1), and at high wind speed (4.25 m s-^l), diflubenzuron killed 8.4% of the larvae at 16 m distance. At wind speeds of 2 - 3.5 m s^-1, spray deposits on the upper surfaces of water sensitive papers were high at 0 m and declined exponentially with distance. At higher wind speeds (4 - 4.25 m s^-I) turbulence produced irregular deposits. Deposition on lower surfaces was much lower than on upper surfaces but the trends with distance and wind speed were the same. The exponential relationships between mortality and distance, and drift deposition and distance, were examined. The results are discussed with respect to laboratory toxicities, application rates, wind speeds and ecological factors.     

The toxicity of some soil-applied systemic insecticides to Aphis gossypii (Horn. Aphididae) and Phytoseiulus persimilis (Acarina: Phytoseiidae) on cucumbers

Tests with potted cucumber plants confirmed that granular or soil drench treatments applied against Aphis gossypii Glover may limit the performance of a predaceous species introduced to control another pest. Soil applications of thionazin, methomyl, demeton-S-methyl and aldicarb in equal amounts caused deaths, in descending order of toxicity, of the predatory mite Phytoseiulus persimilis Athias-Henriot. This effect was not demonstrated for pirimicarb, menazon or isolan on whole plants at rates up to 10 mg a.i. nor in laboratory tests on detached plant portions. Methomyl and thionazin, but not aldicarb, were relatively more toxic to P. persimilis than to its prey, Tetranychus urticae Koch. Some survival of P. persimilis occurred on plants treated with demeton-S-methyl, but this material was inferior to pirimicarb in both selectivity and persistence. Pirimicarb offers practical control of A. gossypii on cropping cucumbers, without phytoxicity or residues, when applied at 125 mg a.i./plant. It is therefore preferable to other aphicides for use on cucumbers during propagation or cropping, especially where the favoured means of control of T. urticae is by introductions of P. persimilis. Qualitative evidence of in vitro tests suggested that those systemic materials which affect P. persimilis do so by ‘food-chain’ toxicity, but that vaporization from the leaf may also be a factor.     

Side effects of flonicamide and pymetrozine on five aphid natural enemy species

The effects of flonicamide and pymetrozine, on inert and natural substrates, on the rove beetle Aleochara bilineata (Gyll.), the parasitic wasp Aphidius rhopalosiphi (DeStefani-Perez), the ladybird Adalia bipunctata (L.), the carabid beetle Bembidion lampros (Herbst), and the hoverfly Episyrphus balteatus (DeGeer) were assessed in the laboratory. Deltamethrin and pirimicarb were also tested as toxic reference compounds. The results indicated high selectivity of flonicamide and pymetrozine for all the species tested. No significant effects on B. lampros and A. bilineata were recorded for sand or on E. balteatus for plants. Pymetrozine on inert substrates had no effects on A. bipunctata larvae, whereas flonicamid was slightly toxic on glass plates but harmless on plants. Both compounds were toxic to adult A. rhopalosiphi on glass plates and on plants in the laboratory, but no effects were observed on plants treated in the field. In comparison, the toxic reference products were always more toxic. Compared with classical insecticides tested on the same species using similar methods, flonicamide and pymetrozine seem to be promising insecticides for aphid control in terms of selectivity for aphid antagonists.     

Toxicity of the new pyrethroid insecticide,deltamethrin, to Daphnia magna

The toxicity of deltamethrin, a synthetic pyrethroid insecticide, was determined under standardized conditions (ISO, 1982) in neonates and juveniles of Daphnia magna. Neonates (6 to 24 h old) were more sensitive than juveniles (48 to 72 h old). The 24- and 48-h EC₅₀s (immobilization) in neonates were 0.113 and 0.031 µg l^–1, respectively. The toxicity of deltamethrin was highly toxic. The 96-h EC₅₀ was in the ppt (µg l^–1) range. Toxicity tests with Daphnia may be used to detect toxic residues in water and sediment in areas treated with deltamethrin and other highly toxic pyrethroid pesticides.     

Lethal and sub‐lethal effects of faecal deltamethrin residues on dung‐feeding insects

Endectocides administered to livestock to facilitate pest and parasite control may be excreted in the faeces at concentrations that are toxic to coprophagous insects, including species of ecological importance. Although much research has focused on the effects of macrocyclic lactones, relatively less attention has been given to any similar impacts of the widely used pyrethroid insecticides. Here, the effects of faecal residues of the pyrethroid deltamethrin after application to Holstein–Friesian cattle in a proprietary pour‐on formulation are examined. Freshly dropped dung was collected 1, 3, 5 and 7 days after treatment and from an untreated control group. In laboratory bioasssays, female Lucilia sericata (Diptera: Calliphoridae) blow flies matured significantly smaller egg batches and had a lower percentage of eggs hatch after feeding on dung collected for up to 5 days after treatment, compared with flies feeding on dung from untreated cattle. In the field, artificial dung pats were constructed from the collected dung and left on pastureland for 7 days before being retrieved and searched for insects. Significantly more adult Diptera emerged from the faeces of untreated cattle than from the dung of treated cattle collected on days 1 and 3 after treatment. Adult Coleoptera were found in lower numbers in the dung of treated animals compared with control dung, suggesting a repellent effect. The results indicate that deltamethrin residues in cattle faeces have a range of lethal and sub‐lethal effects on dung‐feeding insects for up to a week after treatment, but that the precise duration and nature of toxicity varies depending on the sensitivity of the insect in question.     

The secretion of the systemic insecticides dimethoate and phorate into nectar

In pot experiments, root applications of dimethoate and phorate were made to plants of fuchsia, nasturtium and bean. Twenty-five mg dimethoate applied to a 5-in pot made nectar from fuchsia and nasturtium and nectaries of beans toxic to bees and Drosophila melanogaster. Similar amounts of phorate and disulfoton did not cause toxicity. Gas chromatography showed that 4 days after treatment there was at least 100 times more dimethoate than phorate in the nectar of fuchsia and nasturtium. The dimethoate in nectaries taken from bean plants treated at rates between 0·5 and 50 mg dimethoate per pot was assayed by gas chromatography. The concentration of dimethoate in the nectaries depended on the applied dose: it was greatest 4 days after treatment. Loss was more rapid with larger doses than with smaller doses.     

六种常用杀虫剂对八种蚜虫的选择毒性

作者自1982年开始研究了乐果、氧化乐果、抗蚜威、氰戊菊酯、溴氰菊酯和氯氰菊酯等6种杀虫剂对8种蚜虫的选择毒性.以桃粉大尾蚜Hyalopterus amygdali Blanchard为标准,氧化乐果对桃粉大尾蚜和瓜蚜Aphis gossypii Glover之间的选择毒性指数最高为163.77,乐果和抗蚜威分别是373.24和34.70,而氰戊菊酯仅为1.37.氰戊菊酯最高的选择毒性指数是在桃粉大尾蚜和麦长管蚜Sitobionavenae(F.)之间,也只有6.86,有机磷和氨基甲酸酯杀虫剂对不同蚜虫的选择毒性与乙酰胆碱酯酶(AChE)对巯基试剂(DTNB)的敏感度有明显的相关性,说明其选择毒性与AChE的巯基结合部位有关.同时还发现,抗蚜威对洋槐蚜Aphis robiniae Macchiati和瓜蚜AChE的1₅₀值与其LC₅₀值表现一致.这些都说明了这两类杀虫剂对不同种蚜虫的选择毒性与AChE有关.氰戊菊酯和溴氰菊酯对蚜虫的选择毒性与α-乙酸萘酯羧酸酯酶的活性具有明显的相关性,而与β-乙酸萘酯羧酸酯酶的活性则无任何关系.氯氰菊酯的选择毒性与上述两种酯酶的活性没有任何相关性.     

表面残留杀虫剂对蜘蛛的影响研究

以前的报道多集中于研究杀虫剂直接喷洒对蜘蛛的影响。本研究以三突花蛛和沟渠豹蛛为对象,测定了溴氰菊酯、毒死蜱和查虫清（植物源杀虫剂）共3种杀虫剂的表面残留对蜘蛛的驱避作用和急性毒性。结果表明：残留2h的毒死蜱和查虫清对三突花蛛无驱避作用,而残留2h的溴氰菊酯对三突花蛛有明显地驱避作用。3种杀虫剂的2h表面残留对沟渠豹蛛均有显著的驱避作用,其中溴氰菊酯的驱避作用最强。残留24h的3种杀虫剂对三突花蛛和沟渠豹蛛无明显的驱避作用。表面残留的毒死蜱和查虫清对蜘蛛的毒性小,溴氰菊酯的残留对三突花蛛和沟渠豹蛛毒性大。表面残留2h的溴氰菊酯对沟渠豹蛛的毒性显著高于残留24h的溴氰菊酯。     

Side-effects of pesticides on the predatory bug Orius laevigatus (Heteroptera: Anthocoridae) in the laboratory

Laboratory trials were carried out in order to test the effects of 29 pesticides on the predatory bug, Orius laevigatus. To evaluate residual contact activity, newly moulted fourth instar nymphs of O. laevigatus were placed on treated Petri dishes and their mortality was checked after 7 days. The fecundity of surviving females was tested for 14 days. Young O. laevigatus adults were fed with eggs of Ephestia kuehniella, treated with the (above-mentioned) pesticides, to assess the effect of pesticides by ingestion. Adult mortality, female fecundity and egg hatching were recorded. Azadirachtin, granulosis virus products, mineral oil, pirimicarb, tebufenozide, clofentezine, hexythiazox and copper oxychloride had no significant effect on the survival and fecundity of O. laevigatus when predators were exposed to pesticide residues by contact or by ingestion. Triflumuron and diflubenzuron appeared to be harmless by contact, but diflubenzuron was slightly toxic when ingested. Buprofezin and teflubenzuron were slightly to moderately toxic, while hexaflumuron, flufenoxuron, and lufenuron showed a marked toxicity by contact as well as by ingestion. A number of organophosphates, endosulfan and deltamethrin were detrimental especially by contact. Imidacloprid was very toxic by contact but only slightly toxic when ingested. Indoxacarb and methoxyfenozide were less toxic than imidacloprid. These findings should be considered when releases of O. laevigatus are used in greenhouses or on outdoor crops.     

Toxicity and residual effectiveness of insecticides on insecticide-treated spheres for controlling females of Rhagoletis pomonella (Diptera: Tephritidae)

This study evaluated the toxicity of five technical-grade insecticides of four different classes to apple maggot females, Rhagoletis pomonella (Walsh), following a 10-min exposure period in insecticide-coated glass jars, with or without a feeding stimulant (sucrose) present. According to LC90 values for toxicity by ingestion and tarsal contact, imidacloprid was 1.5 times more toxic than dimethoate or abamectin, diazinon was less toxic, and phloxine B (a phototoxic dye) least toxic. Based on LC90 values for tarsal contact alone, dimethoate was 2.3, 4.0, and 18.4 times more toxic than imidacloprid, abamectin, and diazinon, respectively. Contact alone with phloxine B caused no mortality. When exposure was assessed using spheres coated with a latex paint mixture containing sucrose and formulated dimethoate (Digon 400 EC) or imidacloprid (Provado 1.6 F) at concentrations ranging from 5 to 70 g (AI)/cm2, both insecticides showed reduced effectiveness compared with toxicities from glass jar tests, with Digon two times more toxic than Provado. After exposure to artificial rainfall and retreatment with sucrose, Digon- and Provado-treated spheres exhibited greatest residual effectiveness, with diazinon-treated spheres less effective. Spheres treated with formulated abamectin (Agri-Mek 0.15 EC) at 1.0% (AI) performed only slightly better than phloxine B-treated spheres, which completely lost effectiveness after exposure to rainfall. Spheres treated with formulated imidacloprid (Merit 75 WP) at 1.5% (AI) showed equal or better residual efficacy in killing apple maggot flies (> 80% mortality, shorter lethal duration of feeding) over a 12-wk exposure period to outdoor weather than spheres treated with Digon at 1.0% (AI) after both types were retreated with sucrose. Our results indicate that imidacloprid is a promising safe substitute for dimethoate as a fly killing agent on lure-kill spheres. Imidacloprid formulated as Merit 75 WP had greater residual efficacy than imidacloprid formulated as Provado 1.6 F.     

Fenitrothion: an alternative insecticide for the control of deltamethrin‐resistant populations of Triatoma infestans in northern Argentina

Deltamethrin‐based campaigns to control Triatoma infestans (Klug) (Hemiptera: Reduviidae) have decreased in success as a result of the development of insecticide resistance. We compared the in vitro effects of the pyrethroid deltamethrin and two doses of the organophosphate fenitrothion, presented on different materials, on T. infestans from La Esperanza, Argentina. Laboratory tests demonstrated a decrease in susceptibility to deltamethrin in the field population [LD₅₀: 30.32 nanograms per insect (ng/i)] compared with the reference population (LD₅₀: 0.13 ng/i), giving a high resistance ratio of 233.42. By contrast, similar susceptibility to fenitrothion was assessed in both the field and reference populations (LD₅₀: 21.65 ng/i and 21.38 ng/i, respectively). The effectiveness of the formulated insecticides varied according to the surfaces to which they were applied. The application of fenitrothion formulations to glass or brick resulted in mortality of 90–100%. The application of fenitrothion formulations to wood or mud caused mortality in the range of 6.7–56.7%. Resistant insects presented low mortality when exposed to the deltamethrin formulation and high mortality when exposed to fenitrothion formulations. Moreover, the insecticides demonstrated residual activity only when applied to glass. The present work demonstrates that fenitrothion is an alternative to pyrethroids for the management of deltamethrin‐resistant insects in La Esperanza. However, this effectiveness is not sustained over time.     

Comparative efficacy of different pesticides against mango bark beetle Hypocryphalus mangiferae Stebbing (Coleoptera: Scolytidae)

Hypocryphalus mangiferae Stebbing is one of the most destructive insect pests of mango trees and is found to be associated with the transmission of causal organisms of mango sudden death disease. The present study was carried out to evaluate the toxicity of deltamethrin, bifenthrin, chlorpyrifos, emamectin benzoate, imidacloprid and spinosad in laboratory and field trials. Bioassay results showed that the toxicity of chlorpyrifos was significantly higher than deltamethrin but similar to bifenthrin. Deltamethrin and bifenthrin toxicity, however, increased significantly (P < 0.01) from day 1 to day 3. Spinosad was the least toxic compound while emamectin was the most toxic among new chemical insecticides tested, but its toxicity increased significantly from day 1 to day 5. Comparison of the efficacies of the insecticides using lethal times to produce 50% mortality (LT₅₀) and 90% mortality (LT₉₀) showed that the relative potencies of chlorpyrifos, emamectin, imidacloprid and spinosad were greater than bifenthrin and deltamethrin. The results of field trials showed the highest number of beetles emerged from the control twigs while significantly fewer beetles emerged from the twigs treated with bifenthrin (P < 0.05), which accounted for 12% for bifenthrin compared to that of the control. The present study demonstrated increased toxicities of systemic insecticides and chlorpyrifos compared to toxicities of deltamethrin and bifenthrin, suggesting these insecticides could be an alternative tool in a comprehensive H. mangiferae management program to eradicate the beetles from mango orchards.     

禾谷缢管蚜和麦长管蚜玻璃管药膜法敏感毒力基线的建立

【目的】建立禾谷缢管蚜Rhopalosiphum padi（Linnaeus）和麦长管蚜Sitobion avenae（Fabricius）对常用杀虫剂的相对敏感基线。【方法】从田间采集麦蚜在实验室内饲养30代以上,利用玻璃管药膜法测定其对杀虫剂的敏感度,每条毒力基线为2次以上独立测定数据合并后的计算结果。【结果】用玻璃管药膜法建立了包括新烟碱类、吡啶类、氨基甲酸酯类、有机磷类和拟除虫菊酯类共22个药剂品种对禾谷缢管蚜和麦长管蚜3 h的敏感毒力基线。禾谷缢管蚜对新烟碱类药剂吡虫啉和啶虫脒的LC₅₀值分别为0.02和0.007 μg/cm²;对吡啶类药剂吡蚜酮的LC₅₀值为0.124 μg/cm²;对氨基甲酸酯类药剂丁硫克百威、硫双灭多威、灭多威、抗蚜威、西维因的LC₅₀值为0.0026~0.70 μg/cm²;对有机磷类药剂三唑磷、丙溴磷、氧乐果、乐果、马拉硫磷、辛硫磷、敌敌畏、毒死蜱的LC₅₀值为0.005~0.065 μg/cm²;对拟除虫菊酯类药剂三氟氯氰菊酯、高效氯氰菊酯、溴氰菊酯、联苯菊酯、氰戊菊酯、氯氰菊酯的LC₅₀值为0.033~0.240 μg/cm²。麦长管蚜对新烟碱类药剂吡虫啉和啶虫脒的LC₅₀值分别为0.15和0.12 μg/cm²;对吡啶类药剂吡蚜酮的LC₅₀值为0.41 μg/cm²;对氨基甲酸酯类药剂丁硫克百威、硫双灭多威、灭多威、抗蚜威、西维因的LC50值为0.005~0.76 μg/cm²;对有机磷类药剂三唑磷、丙溴磷、氧乐果、乐果、马拉硫磷、辛硫磷、敌敌畏、毒死蜱的LC₅₀值为0.018~0.36 μg/cm²;对拟除虫菊酯类药剂三氟氯氰菊酯、高效氯氰菊酯、溴氰菊酯、联苯菊酯、氰戊菊酯、氯氰菊酯的LC50值为0.20~2.94 μg/cm²。【结论】建立的两种麦蚜对22种杀虫药剂的相对敏感基线,包括当前所有可能用于防治麦蚜的药剂,可以用于以后麦蚜抗药性监测或其他相关研究的参照;禾谷缢管蚜对药剂的敏感度高于麦长管蚜。     

Soil contact toxicity of insecticides to the european earwigForficula auricularia [Dermaptera]

The soil contact effects of several commonly used agricultural insecticides on 2nd instar and adultForficula auricularia (L.) were studied in the laboratory. The earwigs were individually confined on soil surfaces sprayed under a track sprayer. Pirimicarb had no effect on either adult or 2nd instar earwigs. The LD_50,s of 2nd instar earwigs for γ HCH, fenitrothion, DDT and dimethoate were all lower than their normal field rates. Second instars were more susceptible to dimethoate and cypermethrin than adults. The pyrethroids cypermethrin and deltamethrin had LD_50,s above normal field rates. However, high levels of knockdown were induced by both insecticides at concentrations below normal application rates. The effects of this in the field remain unknown.     

Field bioassay to evaluate contact and residual toxicities of insecticides to carabid beetles (Coleoptera: Carabidae)

A 2-yr field study evaluated the effects of selected insecticides on Bembidion obscurellum Motschulsky and Bembidion quadrimaculatum L., carabid predators of the wheat midge, Sitodiplosis mosellana (Géhin). A bioassay method using caged beetles indicated that insecticides differed significantly in their contact and residual toxicities when applied at maximum recommended field rates. Deltamethrin, the least toxic insecticide, caused approximately 30% mortality in both beetle species, but its residual toxicity on the soil remained constant for 1 wk. Dimethoate was initially more toxic (73% mortality) than deltamethrin but less toxic after 1 wk (12% mortality). Carbofuran and chlorpyrifos, the most toxic contact sprays, caused 83 to 100% mortality. After 1 wk, the residual toxicity of carbofuran had declined markedly (5% mortality) whereas the toxicity of chlorpyrifos remained high (82% mortality). Pitfall trapping was an inconclusive method of evaluating the toxicity of insecticidal sprays to carabid adults. In plots treated with carbofuran, pitfall catches of Bembidion species were not significantly different from those in control plots during a 6-wk period after spraying. In plots treated with chlorpyrifos, catches of Bembidion species were significantly lower than those in control plots 3-16 d after spraying, but not thereafter. Results suggested that adult immigration and residual toxicity influence pitfall catches and recovery of carabid populations after spraying.