Integration of soil applied neonicotinoid insecticides and acibenzolar-S-methyl for systemic acquired resistance (SAR) control of citrus canker on young citrus trees

Soil application of systemic neonicotinoid insecticides for control of psyllid vectors of Huanglongbing disease on young citrus trees also produces season-long SAR control of citrus canker caused by Xanthomonas citri subsp. citri Schaad et al. The neonicotinoids imidacloprid (IMID) and thiamethoxam (THIA) were compared with soil or sprinkler applications of the commercial SAR inducer acibenzolar-S-methyl (ASM) and foliar sprays of copper hydroxide (CH) and/or streptomycin (STREP) to evaluate their effects on the percentage of canker-infected leaves on 2-yr-old ‘Vernia’ orange and 3-yr-old ‘Ray Ruby’ grapefruit trees in Southeast Florida. All treatments significantly reduced the incidence of foliar canker compared to the untreated check. Soil drenches of ASM and season long rotations with IMID and THIA were highly effective for suppressing foliar canker on young grapefruit and orange trees under weather conditions absent of high intensity rains or tropical storms. Sprinkler application of ASM was less effective than soil drench. The level of control for SAR treatments was comparable to eleven 21-day interval sprays of CH and/or STREP. SAR induced by soil-applied insecticides provides substantial benefits for canker disease management on young citrus trees that may be augmented with ASM.     

Comparing the Impact of a Neonicotinoid and Biorational Agroneem on Herbivorous and Beneficial Arthropods on Cowpea and Tomato

Cowpea （Vigna unguiculata L. Walp.） and tomato （Lycopersicum esculentum L. Karst） are attacked by a wide range of insect pests worldwide. In many cases, pesticides are used to control the pests. In 2010 and 2011, we conducted field experiments to evaluate and compare the effectiveness of a biorational （Agroneem~） and conventional pesticide （imidacloprid or thiamethoxam） on insect pests of these crops. In the first year, two varieties of cowpea （Mississippi Silver and Pinkeye Purple Hull） and two of tomato （Mariana and German Johnson） were used; in the second year, the better performing of each group （Mississippi Silver and Mariana） were used for the study. A split-plot design with four replications in Year 1, and a randomized complete block design with six treatment combinations in Year 2. In the first year, both pesticide groups were applied following manufacturer＇s recommendation （10-14 d cycles）; and in the second year, the application of the pesticides was driven by economic thresholds level （ETL） of insect pests. The most prevalent species of insects recorded in both crops were in the families： Chrysomelidae, Pentatomidae, Cicadellidae, Vespidae, Sarcophagidae, Thripidae and Sphingidae. In both years, the diversity of insects on cowpea was greater than on tomato and more insects were observed in the second year compared to the first, despite the absence of significant difference （P 〉 0.05） between varieties in the treated plots. The yield of cowpea and tomato was comparable in all sprayed plots.     

新农药哌虫啶在三种典型土壤中的吸附与淋溶研究

应用振荡平衡法和柱淋洗法研究了哌虫啶在红壤、棕壤和黑土3种典型土壤中的吸附和淋溶特性,并探讨了3种土壤改良剂对其淋溶的影响。结果表明:哌虫啶在黑土、红壤和棕壤中的吸附平衡时间分别为12、12和9 h,分配系数Kd分别为23.16、11.24和4.68,吸附常数Kf分别为22.03、11.69和5.05,KOC值分别为1 619、2 094和495,吸附自由能值分别为-16.96、-17.59和-14.02 k J mol-1,Freundlich和线性等温吸附模型均能较好地描述哌虫啶在土壤中的吸附过程,其吸附能力顺序分别为黑龙江黑土福建红壤山东棕壤。哌虫啶在3种供试土壤中淋溶性存在差异,在棕壤中迁移性最强,随着施药量的增加,其淋出率也略有提高,但3个不同水平施药量差异不显著。在黑土中迁移性最弱,红壤和黑土中的哌虫啶残留量随着土壤深度的增加逐渐降低。土壤中添加0.5%的活性炭、腐殖酸和草炭能显著地降低农药哌虫啶在土壤中的淋溶性,减少对地下水的污染风险。     

Insecticides applied to soil of transplant plugs for Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae) management in broccoli

Chemical control with insecticides, typically applied as foliar sprays or chemigation, is the primary tactic used to manage Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae). We evaluated the efficacy of 14 insecticides, including both systemic and non-systemic insecticides, against B. hilaris applied as a seedling tray drench. Experiments were conducted in both greenhouse and field settings. In all experiments, we used the maximum label rate of insecticides and calculated dose per seedling based on this rate and standard plant density per hectare. Each seedling in the tray received 2-mL insecticide solution, and the seedlings were then exposed to B. hilaris adults after transplanting in cages for greenhouse experiments or natural B. hilaris populations in the field experiments. A scale system (0–4) was used to evaluate the severity of B. hilaris feeding injury on leaves where 0 = no injury and 4 = >75% of the leaf margins with B. hilaris feeding injury. We evaluated damage using the rating system, percentage of damaged leaves, number of feeding injury sites, as well as plant height, leaf width, and fresh and dry weight. In the greenhouse experiment, percentage of injured leaves, number of injury sites, and damage rating were significantly lower for transplants treated with acetamiprid, clothianidin, dinotefuran, imidacloprid, and thiamethoxam, and cyclaniliprole compared with the untreated. There was a relationship between feeding injury sites and plant height, leaf width, fresh and dry weight (R² > 0.5) in both 2015 field experiments. Similarly, the transplants treated with acetamiprid, clothianidin, dinotefuran, imidacloprid, thiamethoxam, thiamethoxam + chlorantraniliprole, imidacloprid + β-cyfluthrin and cyclaniliprole had significantly lower damage ratings than those treated with chlorpyrifos, bifenthrin, tolfenpyrad, flonicamid, cyantraniliprole, spinetoram and the untreated control. For transplanted broccoli, treatment of transplant plugs with neonicotinoid insecticides prior to planting can be an effective method for controlling B. hilaris.     

新烟碱类杀虫剂对家蚕的急性毒性评价与中毒症状观察

为明确新烟碱类杀虫剂对非靶标生物家蚕的毒性以及对生态环境的安全性影响,采用浸叶法测定6种新烟碱类杀虫剂及其它3类对照杀虫剂对家蚕的急性毒性,并观察不同种类杀虫剂引起家蚕的急性中毒症状差异。6种新烟碱类杀虫剂中噻虫胺、吡虫啉、噻虫啉和烯啶虫胺对家蚕2龄幼虫96 h的LC50分别为0.065 1、0.174、0.258、0.445 mg/L,属剧毒级农药,噻虫嗪和啶虫脒对家蚕2龄幼虫96 h的LC50分别为1.31、2.73 mg/L,属高毒级农药,6种药剂均对家蚕存在极大的安全风险性。新烟碱类杀虫剂引起家蚕中毒的症状主要表现为拒食,身体扭曲呈"C"或"S"形,头部肿大等。其它3类杀虫剂中,抗生素类杀虫剂阿维菌素的毒性属剧毒级,并在测定药剂中的毒性最高,家蚕中毒症状主要表现为吐液、头部或尾部翘起、拒食等;有机磷类杀虫剂毒死蜱的毒性属高毒级,家蚕中毒症状与新烟碱类杀虫剂相似;吡咯类杀虫剂虫螨腈的毒性属中毒级。因新烟碱类杀虫剂对家蚕的毒性强,建议远离桑园使用,以避免对养蚕生产造成危害。     

Insecticide resistance in house flies from the United States: Resistance levels and frequency of pyrethroid resistance alleles

Although insecticide resistance is a widespread problem for most insect pests, frequently the assessment of resistance occurs over a limited geographic range. Herein, we report the first widespread survey of insecticide resistance in the USA ever undertaken for the house fly, Musca domestica, a major pest in animal production facilities. The levels of resistance to six different insecticides were determined (using discriminating concentration bioassays) in 10 collections of house flies from dairies in nine different states. In addition, the frequencies of Vssc and CYP6D1 alleles that confer resistance to pyrethroid insecticides were determined for each fly population. Levels of resistance to the six insecticides varied among states and insecticides. Resistance to permethrin was highest overall and most consistent across the states. Resistance to methomyl was relatively consistent, with 65–91% survival in nine of the ten collections. In contrast, resistance to cyfluthrin and pyrethrins + piperonyl butoxide varied considerably (2.9–76% survival). Resistance to imidacloprid was overall modest and showed no signs of increasing relative to collections made in 2004, despite increasing use of this insecticide. The frequency of Vssc alleles that confer pyrethroid resistance was variable between locations. The highest frequencies of kdr, kdr-his and super-kdr were found in Minnesota, North Carolina and Kansas, respectively. In contrast, the New Mexico population had the highest frequency (0.67) of the susceptible allele. The implications of these results to resistance management and to the understanding of the evolution of insecticide resistance are discussed.     

Insecticide resistance in Bemisia tabaci biotype Q (Hemiptera: Aleyrodidae) from China

Dispersion of invasive biotypes of the tobacco whitefly, Bemisia tabaci, has led to protracted crop protection constraints in numerous countries over recent decades. These polyphagous, highly efficient vectors of plant viruses present an intractable problem as they frequently carry a diverse suite of insecticide resistance mechanisms. In many areas of China, native biotypes have been supplanted by the invasive and globally widespread biotype B since the 1990s. More recently, biotype Q has established, posing a new and more potent threat to agricultural production systems throughout the country. Insecticide resistance profiles for a range of Chinese B. tabaci strains covering biotypes B and Q were examined, to establish the potential for insecticides to play a pivotal role in biotype competition and ultimate displacement. Commonly used compounds including pyrethroids, neonicotinoids, abamectin and pyriproxyfen were targeted as widespread use is pre-requisite to drivers of population dynamics on a national scale.     

Field efficacy of wintertime insecticide applications against greenbugs, Schizaphis graminum (Rondani) (Hemiptera: Aphididae) on winter wheat (Triticumaestivum L.)

Winter wheat producers in Oklahoma often combine an insecticide with a top-dress application of nitrogen during late fall and winter to control existing greenbug populations. We evaluated the efficacy of three classes of insecticides applied in cold weather field conditions ranging from −13.3 to 28.9 °C from 2002 to 2004 for greenbug control in winter wheat in replicated small plots. Insecticides provided control ranging from 0% to 98%, but generally responded similarly to temperature. Percent control of greenbugs resulting from applications of dimethoate, chlorpyrifos and λ-cyhalothrin was correlated with maximum, minimum and average daily temperatures that occurred two days post-treatment. While percent control was unique for each insecticide, a combined regression of percent control against average daily temperature predicted that a 95% level of control would be achieved when post-treatment temperatures exceeded 13.6 °C. Rainfall that occurred post-treatment affected the efficacy of dimethoate but did not affect the other insecticides. Insecticide persistence was extended under cooler temperatures, allowing acceptable control 14 days post-treatment if temperatures warmed. The decision to apply insecticides should be made based on existing treatment thresholds for greenbug, but if treatment with an insecticide is warranted, winter wheat producers can expect reasonable control of greenbugs from insecticides applied during the winter, as long as post-treatment temperatures exceed 13 °C within the following 14 days.     

常用低毒杀虫剂对韭菜迟眼蕈蚊防治效果评价

[目的]筛选对韭菜迟眼蕈蚊安全高效的防治药剂.[方法]采用胃毒触杀法测定吡虫啉、噻虫胺、噻虫嗪、辛硫磷、甲维盐、阿维菌素、虱螨脲、氟铃脲、氟啶脲、蚊蝇醚、灭蝇胺11种常用低毒药剂对韭菜迟眼蕈蚊幼虫的毒力.[结果]噻虫胺、噻虫嗪、吡虫啉、辛硫磷4种药剂对韭菜迟眼蕈蚊幼虫表现出较高的杀虫活力,对韭菜迟眼蕈蚊2龄幼虫的半数致死浓度(LC50)分别为0.312、0.965、1.269和2.517 mg/L,对韭菜迟眼蕈蚊4龄幼虫的LC50分别为1.354、3.268、2.916和7.725 mg/L;昆虫生长调节剂虱螨脲、氟啶脲和氟铃脲对韭菜迟眼蕈蚊4龄幼虫也表现出较高杀虫活性,LC50分别为0.309、0.408和0.475 mg/L;盆栽试验和田间小区试验验证了噻虫胺、吡虫啉、辛硫磷、噻虫嗪、噻虫嗪+虱螨脲、噻虫胺+虱螨脲均对韭菜迟眼蕈蚊幼虫表现出良好的防治效果,田间防效均在93％以上.[结论]虱螨脲、氟啶脲和氟铃脲等昆虫生长调节剂和噻虫胺、噻虫嗪等新烟碱类药剂能有效防治韭菜迟眼蕈蚊,具有良好的应用前景.