Effects of insecticides on behavior of adult Bactericera cockerelli (Hemiptera: Triozidae) and transmission of Candidatus Liberibacter psyllaurous

The potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), is a serious pest of potatoes (Solanum tuberosum L.) that can cause yield loss by direct feeding on crop plants and by vectoring a bacterial pathogen, Candidatus Liberibacer psyllaurous. Current pest management practices rely on the use of insecticides to control the potato psyllid to lower disease incidences and increase yields. Although many studies have focused on the mortality that insecticides can cause on potato psyllid populations, little is known regarding the behavioral responses of the potato psyllid to insecticides or whether insecticides can decrease pathogen transmission. Thus, the objectives of this study were to determine the effects of insecticides on adult potato psyllid behaviors, the residual effects of insecticides on potato psyllid behaviors over time, and effects of these insecticides on Ca. L. psyllaurous transmission. Insecticides tested included imidacloprid, kaolin particle film, horticultural spray oil, abamectin, and pymetrozine. All insecticides significantly reduced probing durations and increased the amount of time adult psyllids spent off the leaflets, suggesting that these chemicals may be deterrents to feeding as well as repellents. Nonfeeding behaviors such as tasting, resting, and cleaning showed variable relationships with the different insecticide treatments over time. The insecticides imidacloprid and abamectin significantly lowered transmission of Ca. L. psyllaurous compared with untreated controls. The implications of our results for the selection of insecticides useful for an integrated pest management program for potato psyllid control are discussed.     

6种杀虫剂对南美番茄潜叶蛾的毒力及田间防效

[目的]研究6种杀虫剂对南美番茄潜叶蛾卵、幼虫和成虫的毒力及其在温室番茄上的防治效果,为南美番茄潜叶蛾防治提供高效杀虫剂和施药技术。[方法]采用浸渍法和药膜法测定了6种杀虫剂对南美番茄潜叶蛾卵、幼虫和成虫的毒力,田间调查毒力较高杀虫剂对温室番茄上南美番茄潜叶蛾防效。[结果] 6种杀虫剂中的乙基多杀菌素、甲氨基阿维菌素苯甲酸盐和阿维菌素对南美番茄潜叶蛾卵有毒力作用,致死中浓度（LC₅₀）分别为1.415、13.588和23.194 mg·L^-1。6种杀虫剂对南美番茄潜叶蛾幼虫的LC₅₀分别为：阿维菌素0.026 mg·L^-1、四唑虫酰胺0.052 mg·L^-1、甲氨基阿维菌素苯甲酸盐0.057 mg·L^-1、乙基多杀菌素0.072 mg·L^-1、氯虫苯甲酰胺0.484 mg·L^-1和呋虫胺2.039 mg·L^-1。对于南美番茄潜叶蛾成虫,24 h时,仅甲氨基阿维菌素苯甲酸盐和四唑虫酰胺对成虫有较高毒力;72 h时,6种杀虫剂对成虫的LC₅₀分别为：甲氨基阿维菌素苯甲酸盐0.390 mg·L^-1、乙基多杀菌素1.646 mg·L^-1、四唑虫酰胺2.630 mg·L^-1、呋虫胺5.577 mg·L^-1、阿维菌素22.502 mg·L^-1和氯虫苯甲酰胺39.636 mg·L^-1。在成虫盛发期第4天施药,阿维菌素、四唑虫酰胺、甲氨基阿维菌素苯甲酸盐、乙基多杀菌素在南美番茄潜叶蛾危害严重的温室番茄上防效达80%以上。[结论]阿维菌素、四唑虫酰胺、甲氨基阿维菌素苯甲酸盐、乙基多杀菌素、氯虫苯甲酰胺和呋虫胺对南美番茄潜叶蛾卵、幼虫或成虫有较高毒力,其中阿维菌素、四唑虫酰胺、甲氨基阿维菌素苯甲酸盐和乙基多杀菌素田间防效较好。     

Effects of selected insecticides on adults of two parasitoid species of Liriomyza trifolii: Ganaspidium nigrimanus (Figitidae) and Neochrysocharis formosa (Eulophidae)

Abstract Liriomyza trifolii is an important pest of vegetables and ornamental crops around the world. This pest is attacked by many parasitoid species. The principal management tactic used against L. trifolii is insecticide application. Insecticides vary in their effects on parasitoid species and insecticides that have less harmful effects should be preferred for the control of this pest. In this study, novaluron, abamectin, λ‐cyhalothrin and spinetoram were investigated for their lethal effects on adults of Neochrysocharis formosa and Ganaspidium nigrimanus, two important parasitoids of L. trifolii. Three different bioassays were used on adult parasitoids: direct insecticide application, insecticide intake and insecticide residue. Adult parasitoid response to novaluron exhibited the least lethal effects among the bioassays and insecticides tested. Abamectin had significant mortality to both parasitoid species in the direct application and insecticide intake bioassays and mortality were high for G. nigrimanus in the residue bioassay. Spinetoram was the most harmful insecticide to the adult parasitoids in all three bioassays. λ‐cyhalothrin effects varied between the two parasitoids. In the direct application, it was harmful to G. nigrimanus and had no effect on N. formosa. In the insecticide intake bioassay λ‐cyhalothrin had no effect in survival of either species, and in the residue bioassay it reduced parasitoid survival of both species. Potential tolerance of N. formosa to λ‐cyhalothrin is discussed.     

Effect of insecticides on the mortalities of three whitefly parasitoid species, Eretmocerusmundus, Eretmoceruseremicus and Encarsiaformosa (Hymenoptera: Aphelinidae)

The toxicities of 24 insecticides for the biological control of whiteflies were evaluated for Eretmocerus mundus (Mercet), Eretmocerus eremicus Rose and Zolnerowich and Encarsia formosa Gahan using the residual film method (for adults) and the dipping method (for pupae). Mortalities from insect growth regulators (IGRs) (flufenoxuron and lufenuron), Bacillus thuringiensis (Bt), pymetrozine and sulfur were <30% for both pupae and adults of all three species, indicating that the parasitoids were not seriously affected by these insecticides. Neonicotinoids (acetamiprid, clothianidin, dinotefuran, imidacloprid and nitenpyram), synthetic pyrethroids (etofenprox and permethrin), organophosphates (acephate and fenitrothion), chlorphenapyr, emamectin benzoate, spinosad and tolfenpyrad were seriously harmful (100% mortality) and acaricides (chinomethionat, milbemectin and pyridaben) were moderately harmful or seriously harmful to adult parasitoids (leading to mortalities of >92%). For each insecticide, the mortality of pupae was generally lower than that of adults, even though the toxicity classification for the two groups was similar. The results indicate that IGRs, Bt, pymetrozine and sulfur are relatively harmless, and are compatible with the use of parasitoids to help control whiteflies for integrated pest management in greenhouses.     

Physiological susceptibility of the predator Macrolophus basicornis (Hemiptera: Miridae) to pesticides used to control of Tuta absoluta (Lepidoptera: Gelechiidae)

In order to aid the integration of biological and chemical controls for the tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), this study evaluated the relative toxicity of five insecticides to the leaf miner predator Macrolophus basicornis (Stal) (Hemiptera: Miridae). The insecticides evaluated were teflubenzuron, abamectin, chlorantraniliprole, chlorfenapyr, and cartap hydrochloride, all of which are recommended for control of T. absoluta in Brazil. Nymphs and adults of M. basicornis were exposed to tomato leaves treated with the insecticides, under laboratory and greenhouse conditions. The overall mortality caused by the products in both situations was recorded, and the survival of congeneric groups was analysed using the Weibull model. The persistence of the insecticides was also evaluated and they were categorised into toxicity classes proposed by the International Organisation for Biological Control (IOBC) based on predator mortality and persistence. Abamectin and chlorfenapyr were toxic to M. basicornis nymphs and adults in all bioassays. Cartap hydrochloride was slightly harmful to adults in laboratory assays, but harmful to nymphs, and moderately harmful under greenhouse conditions. Chlorantraniliprole and teflubenzuron were harmless in most assays, except when nymphs were exposed in the laboratory, where they were moderately and slightly harmful, respectively. Chlorantraniliprole and teflubenzuron should be preferred insecticides for use in tomato leaf miner IPM programmes that aim to conserve M. basicornis populations.     

Pymetrozine causes a nontarget pest, the Colorado potato beetle (Coleoptera: Chrysomelidae), to leave potato plants

Pymetrozine is a selective insecticide that targets aphids. Published assessments of the effects of pymetrozine on nontarget organisms focus mainly on predatory insects, and they rarely indicate toxicity. In a laboratory bioassay, survival of Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), larvae was not affected by pymetrozine exposure. We subsequently used pymetrozine to implement low-aphid-density treatments in a field experiment that involved separate manipulations of Colorado potato beetle density. Unexpectedly, the addition of Colorado potato beetle adults and eggs did not increase the densities of Colorado potato beetle larvae in plots that were sprayed with pymetrozine (applied with water and an adjuvant). In control plots sprayed with water and adjuvant (without pymetrozine), addition of Colorado potato beetles increased densities of their larvae. Data collected on a smaller scale suggest that a behavioral mechanism underlies the population-level pattern: Colorado potato beetle larvae become more active and are less likely to remain on a host plant after exposure to pymetrozine. Thus, potato, Solanum tuberosum L., growers who use pymetrozine against aphids also might benefit in terms of Colorado potato beetle control.     

Life history and life tables of Bactericera cockerelli (Hemiptera: Psyllidae) on potato under laboratory and field conditions in the lower Rio Grande Valley of Texas

Effective management of potato 'Zebra Chip' (ZC) disease caused by Cadidatus Liberibacter psyllaurous (syn. solanacearum) depends on the management of its insect vector insect, potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Psyllidae). To elucidate the age-specific population dynamics of B. cockerelli, the life-table parameters were determined on potato, Solanum tuberosum L., under both laboratory and field conditions in the Lower Rio Grande Valley (LRGV) of Texas. Generally, survival, fecundity, and longevity of B. cockerelli were significantly greater under laboratory than under field conditions. The mortality under laboratory conditions was mainly due to natural intrinsic mortality. However, under field conditions, most (83.2%) B. cockerelli were missing, and of those that were not, they developed slower, and had shorter preoviposition period, shorter oviposition period, shorter longevity, lower fecundity, and higher mortality than those under laboratory conditions. As a result, most of the life-table parameters of B. cockerelli, including the intrinsic rate of increase, finite rate of increase, and net reproductive rate, were significantly lower in the field under the environmental conditions of the LRGV of Texas than in the laboratory. The information could help increase our understanding of the epidemiology of the ZC diseases associated with the pathogens transmitted by this insect pest.     

复配杀虫剂BtA对棉铃虫的杀虫效果及对天敌中红侧沟茧蜂蛹和成虫的触杀毒性(英文)

为了科学施药, 合理保护和利用天敌对棉铃虫Helicoverpa armigera进行综合防治, 本研究在室内测定和比较了复配杀虫剂BtA和7种常用杀虫剂（阿维菌素、 Bt、 β-氯氰菊酯、辛硫磷、定虫隆、氰戊菊酯和丁硫克百威）对棉铃虫的杀虫效果及对其天敌中红侧沟茧蜂Microplitis mediator蛹和雌成虫的触杀毒性。采用浸叶法测定杀虫剂在室内72 h内对棉铃虫3龄幼虫的杀虫效果, 结果表明： 与其他杀虫剂相比, BtA对棉铃虫幼虫具有更高的毒性和致死效应 (LC₅₀=0.7364 mg/mL)。将棉铃虫3龄幼虫接到用浓度4 mg/mL上述杀虫剂分别处理过的大白菜上24, 48和72 h, 发现其死亡率之间存在显著差异（P≤0.05）。但在72 h后, BtA和其他杀虫剂对棉铃虫幼虫的杀虫效果之间并无显著差异(P>0.05)。BtA施药后, 随着时间的延长, 棉铃虫幼虫的死亡率也在增加。另外, 通过杀虫剂对寄生蜂中红侧沟茧蜂蛹和雌成虫的触杀毒性的生物测定发现： 与β-氯氰菊酯、 氰戊菊酯和丁硫克百威相比, BtA对中红侧沟茧蜂蛹和雌成虫的毒性较低, 对其蛹和雌成虫致死率分别仅为13.82%和7.33%。本研究证明BtA对鳞翅目害虫具有中等毒性, 而对寄生蜂中红侧沟茧蜂则具有较低毒性。     

Toxicity of pesticides to <Emphasis Type="Italic">Tamarixia radiata</Emphasis>, a parasitoid of the Asian citrus psyllid

Sixteen pesticides including two fungicides were evaluated for toxicity to adult Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae), a parasitoid of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). Percentage mortality data were evaluated to generally assess IPM-compatibility of the pesticides with adult parasitoids. The following were found to be least compatible with (most toxic to) adult T. radiata based on the toxicity of direct sprays and potential long residual life on leaves: carbaryl, chlorpyrifos, and fenpropathrin. Although highly toxic to the parasitoid as direct sprays or freshly dried residues, each of the following was more compatible with T. radiata because the toxicity of residues of these pesticides was either low at one to three days after application or relatively non-persistent: abamectin, chenopodium oil, fenpyroximate, and spirotetramat. Depending on environmental conditions, imidacloprid (foliar-applied), phosmet, pyridaben, sulfur and 435 spray oil might also be somewhat more compatible for the same reasons. The pesticides that consistently appeared to be most compatible with T. radiata were aluminum tris, copper hydroxide, diflubenzuron, and kaolin clay (Surround WP).     

Identification and location of symbionts associated with potato psyllid (Bactericera cockerelli) lifestages

The potato psyllid (Bactericera cockerelli, Sulc) is an invasive pest of solenaceous plants including potatoes (Solanum tuberosum L.)and tomatoes (Solanum lycopersicum L.). The insect transmits the phytopathogen Candidatus Liberibacter solanacearum, which has been identified as the causal agent of Zebra Chip in potatoes. The microbiome of the potato psyllid provides knowledge of the insect's bacterial makeup which enables researchers to develop targeted biological control strategies. In this study, the microbes associated with four B. cockerelli life stages were evaluated by 16S bTEFAP pyrosequencing. The sequences were compared with a 16S-rDNA database derived from NCBI's GenBank. Some bacteria identified are initial discoveries. Species of Wolbachia, Rhizobium, Gordonia, Mycobacterium, Xanthomonas and others were also detected and an assessment of the microbiome associated with B. cockerelli was established.     

Suitability of tomato leaves for larval development of Potato Tuber Moth,Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae)

The potato tuber moth (PTM) is an important pest of the potato plant and its tuber. With the expansion of its geographic range, the PTM could be potential threat to the tomato (Solanum lycopersicum L.), a congeneric species of the potato. To assess that risk, we tested larval feeding and development of PTM on leaves of five cultivated tomato varieties namely Moneymaker, Campari, Ailsa Craig, LA3475, E6203 and one wild tomato variety S. pimpinellifolium. PTM larvae accepted all tested plant leaves and developed into adults. Larval development was fastest on the Ailsa Craig variety. Pupae developed fastest on the Moneymaker variety and slowest on LA3475. Host acceptance and survival were highest on Ailsa Craig and lowest on LA3475. The significantly highest male proportion occurred on LA3475 variety. The study showed that PTM could be a potential threat to tomato cultivation which is rapidly increasing in temperate regions owing to climate change.     

Tomato psyllid behavioral responses to tomato plant lines and interactions of plant lines with insecticides

Adult tomato psyllid, Bactericerca (Paratrioza) cockerelli (Sulc) (Homoptera: Psyllidae), behavioral responses were evaluated for five tomato plant lines and for the interactions of insecticides with four commercial cultivars. Plant lines tested included the commercial 'Shady Lady', 'Yellow Pear', '7718 VFN', 'QualiT 21', and the plant introduction line PI 134417. Insecticides included a kaolin particle film, pymetrozine, pyriproxyfen, spinosad, and imidacloprid. Psyllids spent significantly more time feeding on 'Yellow Pear' than all other plant lines except '7718 VFN'. In comparisons among plant lines, psyllids exposed to the wild accession PI 1.34417 showed a 98% reduction in feeding, a significant increase in jumping behavior, and a significant tendency to abandon the leaves, thereby demonstrating repellency, not just an antixenosis response. Interactions between plant lines and insecticides influenced behavioral responses. All insecticides tested significantly reduced feeding durations on all cultivars except the preferred 'Yellow Pear'. However, nonfeeding activities such as walking, probing, resting, and jumping varied substantially with chemical and cultivar combination. The behavior assay results offered insight into host resistance mechanisms, provided a useful technique for measuring effects of interaction of plant lines with insecticides, and generated information for selecting insecticides for specific cultivars used in integrated pest management program for the tomato psyllid.     

Residual effects of four pesticides on the predatory bug,Orius albidipennis Reut. (Hem.: Anthocoridae)

Residual effects of abamectin (0.02%), propargite (0.1%), dichlorvos (DDVP) (0.15%) and pymetrozine (0.15%) were determined on Orius albidipennis at laboratory conditions. Planted cucumbers were sprayed with the highest recommended concentrations of all insecticides and experimental treatments were monitored during 20 days based on the period of pesticides residues. On the first day after spraying, the greatest of mortality belonged to dichlorvos and pymetrozine (97 ± 1.22, 57 ± 3.1, respectively, p < 0.01), while abamectin and propargite had the highest mortality after four (44 ± 1.87 and 24 ± 2.91, respectively, p < 0.01) and eight (51 ± 2.91 and 17 ± 2.23, respectively, p < 0.01) days after spraying. At day 16th, post treatment, abamectin had the highest residual mortalities on O. albidipennis (15 ± 1.58, p < 0.01) and finally mortality results at the 20th day showed there is no significant difference between insecticides (p < 0.01).     

Selectivity evaluation of insecticides used to control tomato pests to Trichogramma pretiosum

The effects of the insecticides abamectin, acetamiprid, cartap and chlorpyrifos on larvae, pupae (within the host egg) and adults of the egg parasitoid Trichogramma pretiosum Riley (Hym.: Trichogrammatidae) were evaluated under laboratory conditions, using three standard tests described by IOBC. When sprayed on the immature stages of this parasitoid, cartap and chlorpyrifos proved to be the most harmful insecticides, affecting both the emergence success and parasitism capacity of this parasitoid, whereas abamectin and acetamiprid were selective. Abamectin was harmful to adults (residue test on glass plates), slightly harmful to larvae, and moderately harmful to pupae (sprayed on the immature stages within host eggs Anagasta kuehniella (Zeller)); acetamiprid was moderately harmful to adults, harmless to larvae, and slightly harmful to pupae; cartap was harmful to adults, moderately harmful to larvae and harmful to pupae; chlorpyrifos to adults, harmless to larvae and harmful to pupae.     

Susceptibility of house flies (Diptera: Muscidae) and five pupal parasitoids (Hymenoptera: Pteromalidae) to abamectin and seven commercial insecticides.

Assays of five commercial insecticides applied as residual sprays at label rates to plywood indicated the most toxic insecticide overall for pteromalid parasitoids of house flies, Musca domestica L., was Atroban (permethrin), followed by Ciodrin (crotoxyphos), Rabon (tetrachlorvinphos), Ectrin (fenvalerate), and Cygon (dimethoate). Insecticide-susceptible house flies were susceptible to all five insecticides (mortality, 62-100%). Flies that were recently colonized from populations on dairy farms in New York were susceptible only to Rabon. Urolepis rufipes (Ashmead) was the most susceptible parasitoid species overall to these insecticides, followed by Muscidifurax raptor Girault & Sanders, Nasonia vitripennis Walker, Pachycrepoideus vindemmiae (Rondani), and Spalangia cameroni Perkins. Compared with susceptible flies, newly colonized flies showed moderate resistance to avermectin B1a (abamectin). Abamectin was more toxic to all of the parasitoids except N. vitripennis and S. cameroni than to newly colonized house flies when exposed for 90 min to plywood boards treated with 0.001-0.1% abamectin. Space sprays with Vapona (dichlorvos) killed all of the parasitoids and susceptible flies and 64% of the newly colonized flies when insects were placed directly in the path of the spray; mortality was substantially lower among flies and parasitoids protected under 5 cm of wheat straw. Space sprays with Pyrenone (pyrethrins) killed greater than 86% of all insects exposed to the spray path except for the newly colonized flies (1% mortality); mortality of insects protected under straw was low (less than 12%) except for S. cameroni (76%). Because responses of the five parasitoids to the different insecticides varied considerably, general conclusions about parasitoid susceptibility to active ingredients, insecticide class, or method of application were not possible.     

四种基质表面上常规杀虫剂对四纹豆象的药效评价（英文）

在害虫治理中, 在消费或贮藏粮食加工产品的建筑设施或场所进行害虫防治需要将杀虫剂施用在各种基质表面上。为了测定不同基质表面上杀虫剂的药效, 将四纹豆象Callosobruchus maculatus (F.)成虫接触田间推荐剂量的阿维菌素、 溴氰菊酯和毒死蜱。结果表明： 施用在玻璃、 瓷砖、 塑料和纸盘表面上, 阿维菌素对四纹豆象成虫的致死率分别为63.33%, 22.41%, 12.9%和11.9%, 而溴氰菊酯在这4种基质表面上对四纹豆象成虫的致死率分别为 55%, 44.2%, 41.3%和 37.4%。在所有基质表面上接触毒死蜱, 四纹豆象成虫的死亡率均为100%。对数据进行的Probit 分析表明, 毒死蜱制剂在玻璃、 瓷砖、 塑料和纸盘上对四纹豆象成虫 的LC₅₀ 值分别为 8.66, 13.6, 29.16和 56.5 μg/mL, 阿维菌素制剂的相应数值分别为119.4, 446.2, 774.2 和 836.4 μg/mL, 溴氰菊酯制剂的相应数值分别为 1 008, 1 131, 1 210和 1 336 μg/mL。据此推断, 毒死蜱对四纹豆象的毒性最强, 且在玻璃、 瓷砖、 塑料和纸盘表面上的毒性依次降低。     

Host plant choice experiments of Colorado potato beetle (Coleoptera: Chrysomelidae) in Virginia

Field and laboratory-choice experiments were conducted to understand aspects of host plant orientation by the Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), in Virginia. In laboratory bioassays, L. decemlineata oriented to volatiles emitted by potato, Solanum tuberosum L., foliage over both tomato, Lycopersicon esculentum L., and eggplant, Solanum melongena L., foliage, and eggplant over tomato foliage, all of which had been mechanically damaged. Field choice tests revealed more L. decemlineata adults, larvae, and egg masses on eggplant than on tomato. In other experiments, counts of live L. decemlineata on untreated paired plants and counts of dead beetles on imidacloprid-treated plants did not differ between potato and eggplant. L. decemlineata was significantly attracted to eggplant over both tomato and pepper. To determine whether feeding adults affected orientation to host plants, an imidacloprid-treated eggplant or potato plant was paired with an untreated eggplant or potato plant covered in a mesh bag containing two adult male beetles. Significantly more adults were attracted to eggplant with feeding male beetles paired with another eggplant than any other treatment combination. These results indicate that the presence of male L. decemlineata on plants affects host plant orientation and suggests that the male-produced aggregation pheromone may be involved.     

Effect of pesticides on Colpoclypeus florus (Hymenoptera: Eulophidae) and Trichogramma platneri (Hymenoptera: Trichogrammatidae), parasitoids of leafrollers in Washington.

Pesticides were evaluated for their effect on two parasitoid species, Colpoclypeus flouts and Trichogramma platneri, that are potential biological control agents of leafrollers in apple orchards. Organophosphate and carbamate insecticides were highly toxic to both parasitoids in topical applications, but foliar residues of some products were nontoxic after 7 d. At reduced rates, topically applied pyrethroids were low in toxicity to C. florus were highly toxic to T. platneri, and foliar residues were nontoxic after about 7 d. Imidacloprid and abamectin were highly toxic when applied topically to both parasitoids but were not toxic as 1-d-old residues. Insect growth regulators did not cause mortality either as topical applications or residues; however, diflubenzuron caused severe sublethal effects, completely blocking the production of C. florus offspring. Biorational pesticides, such as soap, oil, and B. thuringiensis products, caused no toxicity to C. florus but had a direct impact on T. platneri as topical applications through physical immobilization. The potential to integrate different pesticides with biological control of leafrollers and the need for a step-wise approach to evaluate the impact of pesticides against natural enemies is discussed.     

吡蚜酮对烟粉虱取食干扰效应的探讨

采用甘兰叶片浸液法测定了吡蚜酮对烟粉虱Bemisia tabaci(Gennadius)成虫、卵、1龄若虫和3龄若虫的致死作用。在所测试的浓度范围(9.38～300mg/L)内,烟粉虱若虫和成虫的校正死亡率均随吡蚜酮浓度的增大而顺次显著增大。取食75～150mg/L、9.38～37.5mg/L吡蚜酮处理叶片和清水处理叶片的存活成虫个体单头蜜露量(分别为0.37～0.42、0.59～0.72、1.48mm2)间存在显著差异(P<0.05)。用EPG技术研究了吡蚜酮对烟粉虱口针刺吸的不同阶段和取食活性的影响。接触低浓度吡蚜酮(75mg/L)时,最初粉虱能够正常开始取食,但不能从韧皮部正常吸取汁液。高浓度的吡蚜酮(300mg/L)抑制了口针向植物的插入。综合上述结果,说明吡蚜酮可望成为防治番茄黄曲叶病毒病载体-烟粉虱的重要药剂之一。