Development, oviposition, and mortality of Neoseiulus fallacis (Acari: Phytoseiidae) in response to reduced-risk insecticides

Eight reduced-risk insecticides (acetamiprid, thiamethoxam, imidacloprid, thiacloprid, methoxyfenozide, pyriproxyfen, indoxacarb, and spinosad) and three conventional insecticides (azinphosmethyl, fenpropathrin, and esfenvalerate) were tested against Neoseiulus fallacis (Garman) (Acari: Phytoseiidae), the most abundant predacious mite in North Carolina apple (Malus spp.) orchards. To assess the effect of insecticides on development and mortality of N. fallacis immatures, 12-h-old eggs were individually placed on bean leaf disks previously dipped in insecticide solutions. Tetranychus urticae Koch (Acari: Tetranychidae) females were added as a food source. None of the reduced-risk insecticides significantly affected immature N. fallacis compared with the control; however, the pyrethroids esfenvalerate and fenpropathrin were highly toxic to immatures. To evaluate the effect of insecticides on mortality and oviposition of adult N. fallacis, 7- to 8-d-old females were confined on insecticide-treated bean leaves with Malephora crocea (Aizoaceae) pollen added as a food source. Spinosad resulted in the highest mortality, whereas azinphosmethyl, acetamiprid, fenpropathrin, and imidacloprid were moderately toxic, and mortality from esfenvalerate, indoxacarb, thiacloprid, methoxyfenozide, pyriproxyfen, and thiamethoxam did not differ significantly from the control. Oviposition was affected in a similar manner, with the exception of acetamiprid that did not affect oviposition, and thiamethoxam that reduced oviposition.     

Life stage toxicity and residual activity of insecticides to codling moth and oriental fruit moth (Lepidoptera: Tortricidae)

The codling moth, Cydia pomonella (L.), and oriental fruit moth, Grapholita molesta (Busck), are two key pests of apple (Malus domestica Borkh.) in North Carolina. Growers extensively relied on organophosphate insecticides, primarily azinphosmethyl, for > 40 yr to manage these pests. Because of organophosphate resistance development and regulatory actions, growers are transitioning to management programs that use new, reduced-risk, and OP-replacement insecticides. This study evaluated the toxicity of a diversity of replacement insecticides to eggs, larvae, and adults, as well as an assessment of their residual activity, to codling moth and oriental fruit moth. Laboratory-susceptible strains of both species were used for all bioassays. Fresh field-harvested apples were used as a media for assessing the ovicidal activity of insecticides. For larval studies, insecticides were topically applied to the surface of lima bean-based diet, onto which neonates were placed. Toxicity was based on two measures of mortality; 5-d mortality and development to adult stage. Ovicidal bioassays showed that oriental fruit moth eggs were generally more tolerant than codling moth eggs to insecticides, with novaluron, acetamiprid, and azinphoshmethyl having the highest levels of toxicity to eggs of both species. In contrast, codling moth larvae generally were more tolerant than oriental fruit moth to most insecticides. Methoxyfenozide and pyriproxyfen were the only insecticides with lower LC50 values against codling moth than oriental fruit moth neonates. Moreover, a number of insecticides, particularly the IGRs methoxyfenozide and novaluron, the anthranilic diamide chlorantriliprole, and the spinosyn spinetoram, provided equal or longer residual activity against codling moth compared with azinphosmethyl in field studies. Results are discussed in relation to their use in devising field use patterns of insecticides and for insecticide resistance monitoring programs.     

Toxicity,persistence, and efficacy of indoxacarb on cabbage looper (Lepidoptera: Noctuidae) on cabbage

Toxicity of indoxacarb was bioassayed against eggs and young (first and second instars) and older larvae (third and fourth instars) of cabbage looper, Trichoplusia ni (Hübner), on cabbage (Brassicae oleracea variety capitata L.), and persistence of field-aged leaf residues of indoxacarb was bioassayed with second and third instars of T. ni on cabbage. Efficacies of indoxacarb and several other newer insecticides to T. ni were tested under field conditions for two seasons in south Texas. LC50 and LC90 values for T. ni eggs were relatively high, indicating that indoxacarb has little ovicidal effects on T. ni eggs. Indoxacarb was highly toxic to T. ni larvae, having low LC50 and LC90 values. Bioassays of field-aged leaf residues of indoxacarb tested in the spring of 1998 (0-, 3-, 5-, and 12-d-old residues) and the fall of 2000 (0-, 3-, 5-, 7-, 9-, and 13-d-old residues) indicated that ingesting indoxacarb was highly toxic to the second and third instars of T. ni, giving 100% mortality for the second instars at 2 d after exposure, and 100% mortality for third instars at 5 d after exposure. Two trials conducted under field conditions show that indoxacarb at 0.072 g (AI) /ha rate was effective against T. ni in cabbage, providing marketable cabbage with three applications per season. In addition, indoxacarb was as effective as spinosad and chlorfenapyr and significantly more effective than tebufenozide and emamectin benzoate.     

Evaluating new insecticides for the control of Helicoverpa spp. (Lepidoptera: Noctuidae) on capsicum and zucchini

Abstract  The efficacy of insecticides in controlling Helicoverpa spp., predominantly H. armigera (Hübner), on capsicum and zucchini was tested in small plot trials. Indoxacarb, methoxyfenozide, spinosad, emamectin benzoate and novaluron provided control, as measured by the percentage of damaged fruit, equal to or better than standard treatments of methomyl or methomyl alternated with methamidophos on capsicum. The Helicoverpa nucleopolyhedrovirus gave control equivalent to the standard treatment, as did Bacillus thuringiensis aizawai , but B. thuringiensis kurstaki was ineffective. Helicoverpa armigera larvae were present in zucchini flowers but did little damage to the fruit. None of the insecticides significantly reduced the percentage of damaged zucchini fruit compared with the untreated control. Bifenthrin, spinosad, emamectin benzoate and methoxyfenozide were effective in controlling larvae in flowers, while methomyl, B. thuringiensis aizawai , B. thuringiensis kurstaki and novaluron were not effective. Data indicated that all the insecticides effectively controlled larvae of Diaphania indica (Saunders), cucumber moth, in the zucchini flowers. There has been a limited range of insecticides available to manage Helicoverpa spp. in these vegetable crops, but these trials demonstrate the effectiveness of a number of newer insecticides that could be used and that would be compatible with integrated pest management programs in the crops.     

Field and laboratory tests of new insecticides against the apple maggot, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae)

Laboratory bioassays and field tests were conducted to compare the effectiveness of the new insecticides, imidacloprid, indoxacarb, pyriproxyfen, spinosad, thiacloprid, and thiamethoxam, against apple maggot. The activity ranking of the compounds in reducing oviposition in laboratory bioassays was: imidacloprid, 95% reduction at 11 ppm > thiamethoxam, 91% and thiacloprid, 89% reduction at 100 ppm > spinosad, 98% reduction at 316 ppm > indoxacarb, 80% reduction at 1000 ppm > pyriproxyfen, 0% reduction at 38 ppm. In laboratory bioassays, the only insecticides that were toxic to flies at concentrations equal to or below the recommended field rates were imidacloprid, (50% of flies at 11 ppm), spinosad (90% of flies at rates > 10 ppm), and thiamethoxam (approximately 50% of flies at 32 ppm). In field trials, thiacloprid was the only material that consistently controlled apple maggot fruit infestation that was comparable to standard treatments of organophosphate insecticides. Spinosad applied at weekly intervals, and indoxacarb applied as biweekly sprays provided adequate control of apple maggot damage when infestation levels in the field were low, but were not effective in preventing damage in small plots when apple maggot pressure was high.     

西花蓟马田间种群对常用杀虫剂的抗性现状及防治对策

【目的】西花蓟马Frankliniella occidentalis在中国是一种严重危害温室蔬菜的入侵害虫。本研究旨在了解该害虫在中国的抗药性现状,为防治该害虫提供理论支持。【方法】采用Munger cell法测定了北京,山东寿光和青岛以及云南晋宁和呈贡等5个地区西花蓟马田间种群对多杀菌素、毒死蜱、阿维菌素、甲维盐、氟氯氰菊酯、溴虫腈、灭多威、吡虫啉和啶虫脒9种杀虫剂的抗药性水平,同时利用这些田间种群测定了多功能氧化酶抑制剂胡椒基丁醚（PBO）、谷胱甘肽S 转移酶抑制剂顺丁烯二酸二乙酯（DEM）和羧酸酯酶抑制剂三丁基三硫磷酸酯（DEF）对多杀菌素、吡虫啉和甲维盐的增效作用。【结果】生物测定结果表明,北京、晋宁及呈贡种群分别对多杀菌素产生了34.45, 47.45和64.45倍的高水平抗性;晋宁种群对灭多威和甲维盐分别产生了16.58和11.03倍的中等水平抗性;呈贡种群对甲维盐、啶虫脒、吡虫啉、阿维菌素、溴虫腈分别产生了24.17, 21.69, 20.05, 16.45和10.31的中等水平抗性;青岛种群对啶虫脒和吡虫啉产生了17.70和12.49倍的中等水平抗性;寿光种群没有对任何杀虫剂产生高等或中等水平抗性。增效剂生物测定结果表明,对于吡虫啉和甲维盐,多功能氧化酶抑制剂PBO在所有田间种群上均有显著的增效作用。谷胱甘肽S-转移酶抑制剂DEM在呈贡、寿光和青岛种群中对吡虫啉存在显著增效作用;在北京、呈贡和寿光种群中,DEM对甲维盐存在显著增效作用。羧酸酯酶抑制剂DEF在呈贡、晋宁和青岛种群中对吡虫啉存在显著增效作用;在北京、呈贡和晋宁种群中,DEF对吡虫啉存在显著增效作用。但所有增效剂在各田间种群中对多杀菌素均无显著增效作用。【结论】结果提示：在使用多杀菌素防治西花蓟马时,应与其他杀虫剂轮换使用;此外,可通过添加酶抑制剂来增强甲维盐和吡虫啉对西花蓟马的防效。     

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.     

Effects of Some Pesticides on Development of Ascaris suum Eggs

To evaluate the effects of pesticides to parasite eggs, Ascaris suum eggs were incubated with 5 different pesticides (1:1,500-1:2,000 dilutions of 2% emamectin benzoate, 5% spinetoram, 5% indoxacarb, 1% deltamethrin, and 5% flufenoxuron; all v/v) at 20℃ for 6 weeks, and microscopically evaluated the egg survival and development on a weekly basis. The survival rate of A. suum eggs incubated in normal saline (control eggs) was 90±3% at 6 weeks. However, the survival rates of eggs treated with pesticides were 75-85% at this time, thus significantly lower than the control value. Larval development in control eggs commenced at 3 weeks, and 73±3% of eggs had internal larvae at 6 weeks. Larvae were evident in pesticide-treated eggs at 3-4 weeks, and the proportions of eggs carrying larvae at 6 weeks (36±3%-54±3%) were significantly lower than that of the control group. Thus, pesticides tested at levels similar to those used in agricultural practices exhibited low-level ovicidal activity and delayed embryogenesis of A. suum eggs, although some differences were evident among the tested pesticides.     

Effects of insecticides on the foraging behaviour and survival of Cotesia vestalis,a larval parasitoid of the diamondback moth,Plutella xylostella

The effects of the insecticides etofenprox, malathion, diazinon, methomyl, alanycarb, clothianidin and emamectin benzoate on the foraging behaviour and survival of Cotesia vestalis (Hymenoptera: Braconidae), a larval parasitoid of the diamondback moth Plutella xylostella (Lepidoptera: Plutellidae) were investigated in the laboratory. The period required for C. vestalis females to reach P. xylostella‐infested Komatsuna (Brassica rapa) plants treated with etofenprox, methomyl or malathion was significantly longer than that to infested plants treated with emamectin benzoate or clothianidin; and the period to reach alanycarb or diazinon‐treated plants was intermediate between them. The period to reach emamectin benzoate‐ or clothianidin‐treated plants was not significantly different from that to distilled water‐sprayed plants, suggesting that etofenprox, methomyl and malathion have strong inhibitory effects on the flight response, whereas the inhibitory effects of alanycarb and diazinon are relatively weak. By contrast, emamectin benzoate and clothianidin showed no inhibitory effect. The time of residency on the clothianidin‐treated plants was significantly longer than that on other insecticide‐treated plants (etofenprox, methomyl, alanycarb, malathion or diazinon), with the time of residency on emamectin benzoate‐treated plants being intermediate between them. These results suggest that etofenprox, methomyl, alanycarb, malathion, and diazinon have a strong inhibitory effect on host‐searching behaviour, while emamectin benzoate and clothianidin have a relatively weak effect. Furthermore, the mortality of wasps after foraging on the clothianidin‐treated plants was significantly higher than after foraging on other insecticide‐treated plants (etofenprox, methomyl or malathion), with subsequent mortality on alanycarb‐, diazinon‐ and emamectin benzoate‐treated plants being intermediate between them. Our results suggest that subsequent mortality increases with decreased inhibitory effect on the foraging behaviour of C. vestalis.     

Evaluating the efficacy of insecticides to control Sceliodes cordalis (Doubleday) (Lepidoptera: Crambidae) in eggplant

The efficacy of insecticides in controlling Sceliodes cordalis , eggfruit caterpillar, in eggplant was tested in four small plot trials because there has been a very limited range of insecticides available to manage this pest. Weekly applications of bifenthrin, flubendiamide, methoxyfenozide, chlorantraniliprole and spinosad and twice weekly applications of methomyl provided control as measured by a percentage of damaged fruit significantly lower than that in an untreated control. Twice weekly applications of methoxyfenozide, chlorantraniliprole or spinosad were not significantly more effective than weekly applications. Bacillus thuringiensis kurstaki , emamectin benzoate, indoxacarb, methomyl and pyridalyl applied weekly were ineffective, with percentages of damaged fruit not significantly different from the untreated control. These trials have identified a number of insecticides that could be used to manage S. cordalis , including several that would be compatible with integrated pest management programs in eggplant.     

瓜实蝇不同寄主种群对4种杀虫剂的敏感性

为探索瓜实蝇Zeugodacus cucurbitae不同寄主种群对杀虫剂的敏感性,本研究在室内通过药膜法测定了瓜实蝇节瓜、黄瓜、丝瓜和苦瓜种群4日龄成虫对4种杀虫剂的敏感性,随后将瓜实蝇不同寄主种群致死中浓度LC50进行比较,计算抗性倍数。结果表明,4个寄主种群对甲维盐的敏感性为节瓜 > 苦瓜 > 丝瓜 > 黄瓜,其中节瓜、苦瓜种群对甲维盐最敏感,其次是丝瓜、黄瓜,LC50值分别为0.250、0.391、0.809和1.035 mg/L。4个寄主种群对灭多威的敏感性表现为节瓜 > 黄瓜 > 苦瓜 > 丝瓜,LC50值分别为0.302、0.318、0.652和0.804 mg/L。对多杀菌素的敏感性大小依次为黄瓜、节瓜、丝瓜、苦瓜,LC50值分别为1.157、1.198、1.232和2.029 mg/L。对啶虫脒的敏感性为苦瓜 > 节瓜 > 黄瓜 > 丝瓜,LC50值分别为17.946、20.166、20.190和21.986 mg/L,其中对甲维盐的敏感性差异幅度最大,为4.140倍,其次是灭多威,为2.654倍,对啶虫脒的敏感性差异幅度最小,为1.225倍。表明寄主植物可引起瓜实蝇对杀虫剂的敏感性变化。     

Efficacy of several insecticides alone and with horticultural mineral oils on light brown apple moth (Lepidoptera: Tortricidae) eggs

The aim of the research was to identify efficacious and less environmentally harmful treatments than the standard chlorpyrifos sprays used for the control light brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), eggs on nursery stock. A series of dip experiments showed a range of responses when comparing the efficacy of insecticides on egg hatch of E. postvittana. The insecticides that compared most favorably with chlorpyrifos were lamda-cyhalothrin and gamma-cyhalothrin, and thiacloprid. Indoxacarb, novaluron, and spinosad caused significant mortality only when combined with All Seasons mineral oil. All Seasons, showed ovicidal properties when evaluated alone and demonstrated adjuvant properties when combined with the above-mentioned insecticides, except gamma-cyhalothrin and thiacloprid. Several other horticultural mineral oils performed similarly, except the efficacy of spinosad varied with the oil product used, suggesting that the oil type selected is important for some insecticide and oil combinations. Several insecticides evaluated in this study are likely candidates for further work to develop treatments against E. postvittana eggs on nursery plants. Mineral oils are ovicidal and combinations with insecticides are likely to be advantageous.     

Insecticide toxicity to the borer <Emphasis Type="Italic">Neoleucinodes elegantalis</Emphasis> (Guenée) (Lepidoptera: Crambidae): developmental and egg-laying effects

Neoleucinodes elegantalis (Guenée) (Lepidoptera: Crambidae) is one of the major pests of solanaceous plants in South America. It is considered a great threat by the European and Mediterranean Plant Protection Organization due to the serious economic damage that it causes on tomato farms; therefore, controlling this pest is a challenging task in South America. Controlling N. elegantalis at the egg stage is the best way to prevent it from damaging crops; however, thorough studies about the effectiveness of chemicals on the different life stages of this insect pest are lacking. In this study, the effects of different chemical classes were evaluated on N. elegantalis adults, female oviposition behavior, larvae, eggs, and embryonic development. None of the tested insecticides demonstrated toxicity to the adults; however, the results showed that cartap hydrochloride affects oviposition behavior. Moreover, methomyl and cartap hydrochloride exhibited high toxicity against the eggs and larvae, with higher than 80% of mortality. These insecticides interrupted larval hatching and caused alterations in the chorion layer. Flubendiamide and deltamethrin demonstrated toxicity on N. elegantalis larvae; however, lufenuron, indoxacarb, methoxyfenozide, and chlorantraniliprole demonstrated low toxicity on both eggs and larvae, with lower than 70% of mortality. Fruit treated with cartap hydrochloride had a deterrent effect. The ovicidal activity revealed by methomyl and cartap hydrochloride might provide new approaches regarding insecticide effects on eggs. Methomyl, cartap hydrochloride, flubendiamide, and deltamethrin demonstrated toxicity on larvae. The evaluation of the chorion of the eggshell in this study has clarified the toxic effect of methomyl and cartap hydrochloride on eggs.     

The Insect Growth Regulator Pyriproxyfen Terminates Egg Diapause in the Asian Tiger Mosquito,Aedes albopictus

The Asian tiger mosquito, Aedes albopictus, is a highly invasive mosquito species that transmits chikungunya and dengue. This species overwinters as diapausing eggs in temperate climates. Early diapause termination may be a beneficial strategy for winter mosquito control; however, a mechanism to terminate the diapause process using chemicals is not known. We tested the hypothesis that a hormonal imbalance caused by the administration of juvenile hormone analog would terminate egg diapause in A. albopictus. We tested the insect growth regulator pyriproxyfen on all developmental stages to identify a susceptible stage for diapause termination. We found that pyriproxyfen treatment of mosquito eggs terminated embryonic diapause. The highest rates of diapause termination were recorded in newly deposited (78.9%) and fully embryonated (74.7%) eggs at 0.1 and 1 ppm, respectively. Hatching was completed earlier in newly deposited eggs (25–30 days) compared to fully embryonated eggs (71–80 days). The combined mortality from premature diapause termination and ovicidal activity was 98.2% in newly deposited and >98.9% in fully embryonated eggs at 1 ppm. The control diapause eggs did not hatch under diapausing conditions. Pyriproxyfen exposure to larvae, pupae and adults did not prevent the females from ovipositing diapausing eggs. There was no effect of pyriproxyfen on diapausing egg embryonic developmental time. We also observed mortality in diapausing eggs laid by females exposed to pyriproxyfen immediately after blood feeding. There was no mortality in eggs laid by females that survived larval and pupal exposures. In conclusion, diapausing eggs were the more susceptible to pyriproxyfen diapause termination compared to other life stages. This is the first report of diapause termination in A. albopictus with a juvenile hormone analog. We believe our findings will be useful in developing a new control strategy against overwintering mosquito populations.     

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。     

不同茶园灰茶尺蠖和茶尺蠖对5种杀虫剂的抗药性监测

为了明确茶园暴食性害虫灰茶尺蠖Ectropis grisescens和茶尺蠖E. obliqua抗药性现状,制定有效的防治措施,本研究采用浸叶法分别测定了5种茶园常用杀虫剂对5个地理种群灰茶尺蠖和2个地理种群茶尺蠖的抗药性。结果表明,不同茶园灰茶尺蠖和茶尺蠖对供试药剂的抗性水平存在差异：浙江兰溪、浙江金华、河南南阳地区的灰茶尺蠖种群和浙江杭州、浙江安吉的茶尺蠖种群对联苯菊酯产生了中高等抗性;浙江杭州的茶尺蠖种群对苦参碱的抗性达到中等水平,其余供试种群对苦参碱抗性处于敏感水平;所有供试种群对虫螨腈、甲氨基阿维菌素苯甲酸盐和茚虫威这3种药剂的抗性均处于敏感水平。从化学防治的角度来看,目前茶园灰茶尺蠖和茶尺蠖对虫螨腈、甲氨基阿维菌素苯甲酸盐和茚虫威敏感性高,抗性低,推荐合理科学使用,并避免长期使用单一农药。     

Bruchid (Coleoptera: Bruchidae) ovicidal phenylbutanoid from Zingiber purpureum

The larvicidal activity of the dichloromethane extract of Zingiber purpureum Roscoe (Zingiberaceae) rhizome against the second instar of Aedes aegypti (L.) (Diptera: Culicidae) is shown to be due to 4-(3',4'-dimethoxyphenyl)buta-1,3-diene. The diene also showed ovicidal activity against the bruchid Callosobruchus maculatus (F.) (Coleoptera: Bruchidae). Most of the eggs laid by bruchids on treated cowpea seeds were transparent, and very few of them contained developing embryos. The few larvae produced from these embryos were unable to penetrate the seed coat and enter the seed. Similar effects were seen when adults were exposed to the compound and then placed on untreated cowpea seeds, suggesting that a new type of maternally mediated ovicidal effect was involved. Coated and impregnated granular formulations of the extract were evaluated for use in the control of bruchid infestation of stored cowpea seeds. Coated granules showed activity similar to that of the crude extract but were found to lose activity rapidly. Impregnated granules were found to be less active than the crude extract.     

Monitoring of diamondback moth (Lepidoptera: Plutellidae) resistance to spinosad, indoxacarb, and emamectin benzoate

Six to nine populations of the diamondback moth, Plutella xylostella (L.), were collected annually from fields of crucifer vegetables in the United States and Mexico from 2001 to 2004 for baseline susceptibility tests and resistance monitoring to spinosad, indoxacarb, and emamectin benzoate. A discriminating concentration for resistance monitoring to indoxacarb and emamectin benzoate was determined based on baseline data in 2001 and was used in the diagnostic assay for each population in 2002-2004 together with a discriminating concentration for spinosad determined previously. Most populations were susceptible to all three insecticides, but a population from Hawaii in 2003 showed high levels of resistance to indoxacarb. Instances of resistance to spinosad occurred in Hawaii (2000), Georgia (2001), and California (2002) as a consequence of a few years of extensive applications in each region. The collaborative monitoring program between university and industry scientists we discuss in this article has provided useful information to both parties as well as growers who use the products. These studies provide a baseline for developing a more effective resistance management program for diamondback moth.     

Prevalence and stability of insecticide resistances in field population of Spodoptera litura (Lepidoptera: Noctuidae) from Huizhou,Guangdong Province,China

The field population of Spodoptera litura from Huizhou, Guangdong Province, China was evaluated for resistance to 21 insecticides, including conventional and new chemistry insecticides. Extreme levels of resistance were observed to metaflumizone and emamectin benzoate with resistance factors of 234.1 and 183.3, respectively. Resistance to abamectin was also high (perhaps extremely high) and over 71.9-fold. The Huizhou population of S. litura possessed high resistance to deltamethrin (96.5-fold) and moderate resistance to beta cyfluthrin and lambda cyhalothrin but remained susceptible to bifenthrin. Moderate resistance to chlorantraniliprole (22.3-fold), endosulfan (22.2-fold), tebufenozide (10.7-fold) and thiodicarb (14.3-fold), and low-level resistance to fipronil, indoxacarb and spinosad were also reported in this population. This field population remained susceptible to acetamiprid, chlorfenapyr, chlorfluazuron, hexaflumuron, chlorpyrifos, pyridalyl and spinetoram. The stabilities of resistance to metaflumizone, emamectin benzoate, deltamethrin, chlorantraniliprole and endosulfan were evaluated, the resistance level decreased when the insecticide stress was removed, suggesting stop of the application of insecticides with high level resistance could be implemented into the resistance management. Because S. litura from Huizhou developed resistance to multiple insecticides, integration of different control practices, especially the rotation of insecticides with biocontrol agents, should be performed in the management of this pest. The results suggested the suspension of the application of insecticide to which S. litura had developed high level of resistance in order to mitigate the resistance status, and the use of the insecticides to which this pest remained sensitive, including spinetoram, pyridalyl, indoxacarb, hexaflumuron, chlorfluazuron, chlorfenapyr and bifenthrin, could be incorporated into the alternating application for resistance management.     

Ovicidal and larvicidal effectiveness of several insect growth inhibitors and regulators on the codling moth Cydia pomonella L. (Lep., Tortricidae)

Several insect growth inhibitors (IGIs) and regulators (IGRs) were tested in the laboratory for their ovicidal and larvicidal properties on the codling moth C. pomonella , by dipping apples in solutions of them. The IGIs which block chitin synthesis – diflubenzuron, hexaflumuron and teflubenzuron – were noticeably more effective against eggs than on newborn larvae with preventive ovicidal 50% lethality concentrations (LC₅₀) values of approximately 0.6, 1.3 and 15 p.p.m., respectively, and larvicidal LC₅₀ values of 104, 1208 and 204 p.p.m. Flufenoxuron, on the other hand, is almost as effective on larvae (LC₅₀ : 9.9 p.p.m.) as on eggs (LC₅₀ : 5.4 p.p.m.). Fenoxycarb, an IGR juvenile hormone analogue, acts as an excellent ovicidal product with an LC₅₀ value of 0.05 p.p.m. Tebufenozide, an IGR ecdyson (moulting hormone) agonist, is exclusively larvicidal with an LC₅₀ at 0.4 p.p.m. Methoxyfenozide, an IGR of the same family and currently being developed, acts as effectively on eggs as on larvae with ovicidal and larvicidal LC₅₀ values of about 0.6 and 0.8 p.p.m., respectively. When ovicidal products are applied as a curative treatment on eggs less than 24 h old, their effectiveness is much lower than that obtained from preventive application.