Assessment of cross-resistance potential to neonicotinoid insecticides in Bemisia tabaci (Hemiptera: Aleyrodidae)

Laboratory bioassays were carried out with four neonicotinoid insecticides on multiple strains of Bemisia tabaci (Gennadius) to evaluate resistance and cross-resistance patterns. Three imidacloprid-resistant strains and field populations from three different locations in the southwestern USA were compared in systemic uptake bioassays with acetamiprid, dinotefuran, imidacloprid and thiamethoxam. An imidacloprid-resistant strain (IM-R) with 120-fold resistance originally collected from Imperial Valley, California, did not show cross-resistance to acetamiprid, dinotefuran or thiamethoxam. The Guatemala-resistant strain (GU-R) that was also highly resistant to imidacloprid (RR=109-fold) showed low levels of cross-resistance when bioassayed with acetamiprid and thiamethoxam. However, dinotefuran was more toxic than either imidacloprid or thiamethoxam to both IM-R and GU-R strains as indicated by low LC50s. By contrast, a Q-biotype Spanish-resistant strain (SQ-R) of B. tabaci highly resistant to imidacloprid demonstrated high cross-resistance to the two related neonicotinoids. Field populations from Imperial Valley (California), Maricopa and Yuma (Arizona), showed variable susceptibility to imidacloprid (LC50s ranging from 3.39 to 115 microg ml(-1)) but did not exhibit cross-resistance to the three neonicotinoids suggesting that all three compounds would be effective in managing whiteflies. Yuma populations were the most susceptible to imidacloprid. Dinotefuran was the most toxic of the four neonicotinoids against field populations. Although differences in binding at the target site and metabolic pathways may influence the variability in cross-resistance patterns among whitefly populations, comparison of whitefly responses from various geographic regions to the four neonicotinoids indicates the importance of ecological and operational factors on development of cross-resistance to the neonicotinoids.     

Compatibility of two systemic neonicotinoids, imidacloprid and thiamethoxam, with various natural enemies of agricultural pests

Two systemic neonicotinoids, imidacloprid and thiamethoxam, are widely used for residual control of several insect pests in cotton (Gossypium spp.), vegetables, and citrus (Citrus spp.). We evaluated their impact on six species of beneficial arthropods, including four parasitoid species--Aphytis melinus Debach, Gonatocerus ashmeadi Girault, Eretmocerus eremicus Rose & Zolnerowich, and Encarsia formosa Gahan--and two generalist predators--Geocoris punctipes (Say) and Orius insidiosus (Say)--in the laboratory by using a systemic uptake bioassay. Exposure to systemically treated leaves of both neonicotinoids had negative effects on adult survival in all four parasitoids, with higher potency against A. melinus as indicated by a low LC50. Mortality was also high for G. ashmeadi, E. eremicus, and E. formosa after exposure to both compounds but only after 48 h posttreatment. The two predators G. punctipes and O. insidiosus were variably susceptible to imidacloprid and thiamethoxam after 96-h exposure. However, toxicity to these predators may be related to their feeding on foliage and not just contact with surface residues. Our laboratory results contradict suggestions of little impact of these systemic neonicotinoids on parasitoids or predators but field studies will be needed to better quantify the levels of such impacts under natural conditions.     

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.     

Dynamics of resistance to the neonicotinoids acetamiprid and thiamethoxam in Bemisia tabaci (Homoptera: Aleyrodidae)

The dynamics of resistance in the sweetpotato whitefly, Bemisia tabaci (Gennadius), to the neonicotinoids acetamiprid and thiamethoxam was studied extensively in cotton fields in Israel during the cotton-growing seasons 1999-2003. Whitefly strains were collected in early and late seasons mainly in three locations in northern, central, and southern Israel. The whiteflies were assayed under laboratory conditions for susceptibility to neonicotinoids, as part of the Israeli cotton insecticide resistance management strategy. Selections to both acetamiprid and thiamethoxam and cross-resistance between them also were conducted in the laboratory. Although no appreciable resistance to acetamiprid was observed up to 2001, a slight increase of approximately five-fold resistance was detected during 2002 and 2003. However, from 2001 to 2003 thiamethoxam resistance increased >100-fold in the Ayalon Valley and Carmel Coast cotton fields. In cross-resistance assays with both neonicotinoids, the strain that had been selected with thiamethoxam for 12 generations demonstrated almost no cross-resistance to acetamiprid, whereas the acetamiprid-selected strain exhibited high cross-resistance of >500-fold to thiamethoxam.     

Effect of neonicotinoid synergists on entomopathogenic nematode fitness

In previous greenhouse and field studies, the neonicotinoid insecticide imidacloprid interacted synergistically with five entomopathogenic nematode species against five scarab species. Two other neonicotinoids, thiamethoxam and acetamiprid, showed a weaker interaction with nematodes in scarab larvae. Entomopathogenic nematodes have the potential to recycle in hosts after inundative applications, thereby increasing the persistence of nematodes and insect control. Thus we investigated the effect of neonicotinoids on nematode fitness after tank mixing and after combined applications. Tank mixing only had a negative effect on nematode survival and infectivity in a few nematode–insecticide combinations and only if both insecticide concentration and exposure time were several times higher than typical for field applications. Combined application of nematodes with imidacloprid generally had no negative effect on the percentage of scarab cadavers producing progeny or the number of nematode progeny emerging per cadaver. In experiments with a synergistic increase in scarab mortality, the total number of progeny in combination treatments was up to four times higher than in nematodes only treatments. Similarly, nematode populations in soil from combination treatments were 13.2 times greater than for nematodes only treatments at 28 days after treatment. Combined imidacloprid–nematode applications did not affect the pathogenicity or infectivity of the nematode progeny. Combining thiamethoxam with nematodes had no negative effects on nematode reproduction in the majority of treatments. However, due to the weaker interaction of thiamethoxam and nematodes on scarab mortality, the total number of nematode progeny per treatment generally did not increase compared with nematodes only treatments. The demonstrated tank mix compatibility of imidacloprid and nematodes improves the feasibility of combining these agents for curative white grub control. The positive effect of imidacloprid on nematode reproduction after combined application may increase the likelihood of infection of white grubs by subsequent generations of nematodes, thereby improving their field persistence and biological control potential.     

Systemic control efficacy of neonicotinoids seeds dressing on English grain aphid (Hemiptera: Aphididae)

English grain aphid, Sitobion avenae (Fabricius) (Hemiptera: Aphididae), is an important pest of wheat (Triticum aestivum L.), and is usually controlled by intensive foliar sprays of pesticides under field conditions. In order to reduce labour costs and increase the utilization of pesticides, neonicotinoids seed treatment was studied as a simple and accurate control technology for S. avenae. We evaluated the mortality of imidacloprid, acetamiprid, thiamethoxam, clothianidin, nitenpyram and dinotefuran to the English grain aphid by seed dressing methods in the laboratory, and found that the toxicity with that LC₅₀ of clothianidin (20.97?a.i.?g/100?kg seeds) and thiamethoxam (28.84?a.i.?g/100?kg seeds) to S. avenae are higher than other neonicotinoids. LC₅₀ values of nitenpyram, imidacloprid and acetamiprid ranged between 120?a.i.?g/100?kg seeds and 210?a.i.?g/100?kg seeds. Dinotefuran showed the lowest toxicity with LC₅₀ value 565.76?a.i.?g/100?kg seeds to English grain aphid. Field plot experiments were conducted to investigate the control efficacy of neonicotinoids seed treatment for the aphid, and the effects on growth of wheat. Field observations indicated that clothianidin and thiamethoxam provided the better control efficacy on the English grain aphid than imidacloprid, and had no influence on wheat seedling emergence. These results showed that seed treatment by neonicotinoids was effective against S. avenae throughout the growth period, furthermore, thiamethoxam and clothianidin were the effective and safe alternative options for S. avenae management in the crop.     

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.     

Mortality and oviposition of western cherry fruit fly (Diptera: Tephritidae) exposed to different insecticide baits for varying periods in the presence and absence of food

Spinosad bait is used to control western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), by killing flies before they oviposit. However, effects of different insecticide baits on management of reproductively mature flies are largely unknown. Objectives here were to determine mortality and oviposition of reproductively mature R. indifferens exposed to different insecticide baits for varying periods in the presence and absence of dried yeast extract and sucrose food. Spinosad bait (spinosad in a mix of protein, sugar, and other ingredients) was compared with acetamiprid, thiamethoxam, and imidacloprid in sucrose or Nu-Lure + sucrose bait. When flies were exposed to treatments and then offered cherries, Prunus avium (L.) L., for oviposition or when they were exposed to treatments and cherries simultaneously, both thiamethoxam bait and imidacloprid bait resulted in higher mortality and lower oviposition than spinosad bait and acetamiprid bait. Exposures to thiamethoxam bait and imidacloprid bait for six and 24 h were similarly effective, but 6-h exposures to spinosad bait and acetamiprid bait were less effective than 24-h exposures. There was little difference between sucrose and Nu-Lure + sucrose baits. When food was present, thiamethoxam bait and imidacloprid bait caused greater mortality and lower oviposition than spinosad bait and acetamiprid bait, but when food was absent, patterns were less consistent. Because of its ability to kill flies sooner after it is exposed to flies when food is present or absent, thiamethoxam or imidacloprid in sucrose or Nu-Lure bait may reduce infestations in cherries more than spinosad bait when mature R. indifferens are present in orchards.     

韭菜迟眼蕈蚊对新烟碱类杀虫剂的抗药性及抗性机制初探

【目的】为明确韭菜迟眼蕈蚊Bradysia odoriphaga对新烟碱类杀虫剂的抗性水平及其抗性机制。【方法】通过测定不同地区韭菜迟眼蕈蚊对3种新烟碱类杀虫剂吡虫啉、噻虫嗪和噻虫胺的敏感度,及通过增效剂实验和酶活性测定,初步探索抗性产生机制,为韭菜迟眼蕈蚊抗性治理提供依据。【结果与结论】4个不同的韭菜迟眼蕈蚊田间种群对3种新烟碱类杀虫剂均产生了不同水平的抗性。其中,唐山种群对3种新烟碱杀虫剂均产生了较高的抗性。研究发现,唐山种群的7-乙氧基香豆素-O-脱乙基酶(ECOD)比活力为(3.89±0.31)pmol/(mg·pro·min),显著高于敏感品系。增效剂PBO对唐山种群的吡虫啉毒力的增效比为2.64,高于对敏感品系的增效比1.08。因此,P450s酶活性的升高与韭菜迟眼蕈蚊对吡虫啉的抗性有关。     

Insecticide resistance in Bemisia tabaci from Cyprus

Abstract A comprehensive study on the Bemisia tabaci (biotype B) resistance to neonicotinoid insecticides imidacloprid, acetamiprid and thiamethoxam, and pyrethroid bifenthrin was conducted in Cyprus. The resistance level to eight field‐collected B. tabaci populations was investigated. The activities of enzymes involved in metabolic detoxification and the frequencies of pyrethroid and organophosphates target site resistance mutations were determined. Moderate to high levels of resistance were detected for imidacloprid (resistance factor [RF] 77–392) and thiamethoxam (RF 50–164) while low resistance levels were observed for acetamiprid (RF 7–12). Uniform responses by the Cypriot whiteflies could be observed against all neonicotinoid insecticides. No cross‐resistance between the neonicotinoids was detected as well as no association with the activity of the P450 microsomal oxidases. Only imidacloprid resistance correlated with carboxylesterase activity. Low to extremely high resistance was observed for insecticide bifenthrin (RF 49–1 243) which was associated with the frequency of the resistant allele in the sodium channel gene but not with the activity of the detoxification enzymes. Finally, the F331W mutation in the acetylcholinesterase enzyme ace1 gene was fixed in all B. tabaci populations from Cyprus.     

Insecticide,sugar, and diet effects on feeding and mortality in Rhagoletis indifferens (Dipt., Tephritidae)

The effects of spinosad bait and various insecticides, the presence of sugar in insecticides, and diet on feeding responses and mortality in western cherry fruit fly, Rhagoletis indifferens Curran (Dipt., Tephritidae), were determined. Numbers of feeding events on insecticides with sugar were greater than on insecticides alone, but there was only a small effect of diet on feeding responses to insecticides with sugar. Feeding durations on imidacloprid, thiamethoxam and acetamiprid with sugar were shorter than on sugar water and spinosad bait, as the neonicotinoids paralysed flies quickly. Flies that fed on sugar only (nitrogen‐starved) suffered higher mortalities when exposed to spinosad, thiamethoxam and azinphos‐methyl than to imidacloprid, acetamiprid and indoxacarb, and mortality in between these two groups of treatments when exposed to spinosad bait. Mortalities were greater when sugar was added to insecticides, and were higher in nitrogen‐starved than fully‐fed (yeast extract + sugar fed) flies. Flies that fed once on thiamethoxam were killed more quickly than those that fed once on spinosad bait and spinosad. Results suggest that thiamethoxam is comparable to spinosad in its effects on mortality, and that using it with sugar in bait may also have similar results as using spinosad bait or spinosad. One benefit of using thiamethoxam with sugar may be that it kills flies more quickly, before they can oviposit, than spinosad bait, although whether a fly will feed on it may depend on how much sugar or nitrogenous food it has eaten.     

Establishment of baseline susceptibility data to various insecticides for Homalodisca coagulata (Homoptera: Cicadellidae) by comparative bioassay techniques

Homalodisca coagulata Say, adults from three locations in California were subjected to insecticide bioassays to establish baseline toxicity. Initially, two bioassay techniques, petri dish and leaf dip, were compared to determine the most useful method to establish baseline susceptibility data under laboratory and greenhouse conditions. Comparative dose-response data were determined by both techniques to endosulfan, dimethoate, cyfluthrin, and acetamiprid. Toxic values were similar to some insecticides with both techniques but not for all insecticides, revealing susceptibility differences among the three populations of H. coagulata. In subsequent tests, the petri dish technique was selected to establish baseline susceptibility data to various contact insecticides. A systemic uptake bioassay was adapted to estimate dose-mortality responses to a systemic insecticide, imidacloprid. A 2-yr comparison of toxicological responses showed all three populations of H. coagulata to be highly susceptible to 10 insecticides, including chlorpyrifos, dimethoate, endosulfan, bifenthrin, cyfluthrin, esfenvalerate, fenpropathrin, acetamiprid, imidacloprid, and thiamethoxam. In general, two pyrethroids, bifenthrin and esfenvalerate, were the most toxic compounds, followed by two neonicotinoids, acetamiprid and imidacloprid. The LC50 values for all insecticides tested were lower than concentrations used as recommended field rates. Baseline data varied for the three geographically distinct H. coagulata populations with the petri dish technique. Adult H. coagulata collected from San Bernardino County were significantly more susceptible to select pyrethroids compared with adults from Riverside or Kern counties. Adults from San Bernardino County also were more sensitive to two neonicotinoids, acetamiprid and imidacloprid. The highest LC50 values were to endosulfan, which nonetheless proved highly toxic to H. coagulata from all three regions. In the majority of the tests, mortality increased over time resulting in increased susceptibility at 48 h compared with 24 h. These results indicate a wide selection of highly effective insecticides that could aid in managing H. coagulata populations in California.     

几种几丁质合成抑制剂对棉铃虫生物活性的研究

几种几丁质合成抑制剂对棉铃虫Heliothis armigera(Hǖbner)生物活性的室内研究结果表明:以IKI-7899和昆调1055饲喂棉铃虫成虫能降低其产卵的孵化率,但对其寿命和产卵量均无影响.以IKI-7899浸卵,125ppm的浓度即可致使处理卵孵化出的幼虫在二、三龄前死亡50%以上.IKI-7899和昆调1055对棉铃虫幼虫的触杀毒力均高于其胃毒毒力,并表现较高的生物活性,而灭幼脲Ⅰ号和苏脲Ⅰ号的活性极低.以含毒人工饲料饲喂幼虫两天,IKI-7899、昆调1055和灭幼脲Ⅰ号的毒力值均比饲喂一天的高5倍以上;而连续饲喂至化蛹期的毒力值比饲喂一天的高50倍以上.     

A field study investigating the insecticidal efficacy against Diaphorina citri Kuwayama on Kinnow mandarin,Citrus reticulata Blanco trees

Asian citrus psyllid is a most damaging insect pest of citrus. In this field study, the efficacy of seven insecticides (emamectin benzoate, bifenthrin, chlorfenapyr, fipronil, imidacloprid, pyriproxyfen and thiamethoxam) was evaluated against Diaphorina citri Kuwayama in the citrus orchard of Kinnow mandarin, Citrus reticulata Blanco. The insecticides revealed a differential and substantial relative efficacy against D. citri compared to the untreated plants. The insecticidal effect attributed as percent reduction in insect population was more prominent after three days of spray: highest reduction values were recorded with thiamethoxam (50.89%), imidacloprid (44.27%) and bifenthrin (42.94%) after first spray, and thiamethoxam (83.36%), imidacloprid (73.20%) and bifenthrin (72.66%) after second spray. Thus, neonicotinoids (thiamethoxam and imidacloprid) and pyrethroid (bifenthrin) resulted as highly effective against D. citri at three days after both sprays. At seven days, imidacloprid (63.53%) and fipronil (62.47%) presented relatively higher population reduction after first spray, and thiamethoxam (92.66%) and chlorfenapyr (89.59%) after second spray. At 12 days, the insecticidal effect on insect population became significantly at par after each spray except chlorfenapyr that reflected high population reduction (93.17%) only after second spray. It is also obvious from the data that there is need of regular monitoring to suppress the psyllids population below threshold level by timely application of the second insecticidal spray.     

Effects of kaolin particle film on oviposition,larval mining,and infestation of cotton by pink bollworm (Lepidoptera: Gelechiidae)

We tested effects of kaolin particle film on oviposition, larval mining, and infestation of cotton by pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), in the laboratory, greenhouse, and field. In laboratory choice tests, females laid seven times more eggs on untreated bolls than on bolls treated with kaolin. When neonates were put on bolls in the laboratory, each boll with a treated and untreated half, larvae and mines were found 24 h later on the untreated half but not on the treated half. In oviposition choice tests with whole plants in the greenhouse, females laid four times more eggs on untreated plants than on treated plants and the number of eggs on bolls was five times higher for untreated plants than for treated plants. Kaolin treatments altered the distribution of eggs among plant parts, with untreated bolls receiving a higher percentage than treated bolls, whereas the opposite occurred for petioles. In field tests, treatment with kaolin alone reduced the proportion of bolls infested with pink bollworm, but a mixture of kaolin and the pyrethroid lambda-cyhalothrin was most effective. The results suggest that kaolin particle film may be useful against pink bollworm, particularly in conjunction with other control tactics.     

Systemic insecticides reduce feeding, survival, and fecundity of adult black vine weevils (Coleoptera: Curculionidae) on a variety of ornamental nursery crops

Systemic activity of the neonicotinoids clothianidin, dinotefuran, and thiamethoxam and the anthranilic diamide chlorantraniliprole was tested against adult black vine weevils, Otiorhynchus sulcatus (F.) (Coleoptera: Curculionidae), on Astilbe, Euonymus, Heuchera, Rhododendron, Sedum, and Taxus. Insecticide treatments were applied to the soilless substrate of containerized plants. Bioassays were conducted 12 or 13, 26, and 42 d after treatment (DAT) and ran for 7 d; and feeding, mortality, and weight gain or loss by weevils were evaluated. Foliage was removed from test plants and then placed in arenas with adult black vine weevils. The neonicotinoids reduced feeding and weight gain by adult black vine weevils on most plant species with residual activity 42 DAT on some plant species. At 12 DAT, mortality was caused by the three neonicotinoids on Astilbe and by thiamethoxam on Sedum; and at 26 DAT dinotefuran caused mortality on Astilbe. Chlorantraniliprole reduced feeding on Taxus at 12 DAT, with no activity detected in other bioassays. Another set of bioassays was conducted to examine survival and fecundity of adult black vine weevils during prolonged feeding on Heuchera and Taxus systemically treated with dinotefuran or thiamethoxam. Bioassay procedures were similar to those described above, except they ran continuously for 56 d. Prolonged feeding on dinotefuran and thiamethoxam treated Heuchera and Taxus resulted in high mortality of adult black vine weevils and reduced fecundity. These studies show that the systemic activity of neonicotinoids is influenced by plant species and that systemic neonicotinoids have the potential to suppress black vine weevil populations in containerized nursery crops.     

Biological and chemical control of the Asiatic garden beetle, Maladera castanea (Coleoptera: Scarabaeidae)

The efficacy of chemical and biological control agents against larvae of the Asiatic garden beetle, Maladera castanea (Arrow), in turfgrass under laboratory, greenhouse, and field conditions were determined. In field trials where insecticides were applied preventively against eggs and young larvae, the molt-accelerating compound halofenozide and the neonicotinoids imidacloprid and thiamethoxam were ineffective, whereas another neonicotinoid, clothianidin, provided 62-93% control. In greenhouse experiments against third instars in pots, the carbamate insecticide carbaryl was ineffective, whereas the organophosphate trichlorfon provided 71-83% control. In laboratory, greenhouse, and field experiments, the entomopathogenic nematode Heterorhabditis bacteriophora Poinar and Steinernema glaseri Steiner (not tested in the field) were ineffective against third instars, whereas S. scarabaei Stock & Koppenh?fer provided excellent control. In microplot field experiments at a rate of 2.5 x 10(9) infective juveniles per ha, H. bacteriophora provided 12-33% control and S. scarabaei 71-86% control. Combinations of S. scarabaei and imidacloprid did not provide more control of third instars compared with S. scarabaei alone.     

Toxic effects of 12 pesticides on green lacewing,Chrysoperla nipponensis (Okamoto) (Neuroptera: Chrysopidae)

In this study, we formulated pesticides from 12 products, namely machine oil EC, imidacloprid WP, thiamethoxam WP, acetamiprid WP, methidathion EC, acequinocyl WP, clothianidin WP, deltamethrin EC, mancozeb WP, benomyl WP, difenoconazole WP, and bitertanol WP. These 12 pesticides were selected to determine their toxicity to green lacewing, Chrysoperla nipponensis, at the maximum field recommended dosage under laboratory conditions. Machine oil EC had extremely detrimental effects on eggs of C. nipponensis, resulting in 99% mortality (categorized as Class IV) when eggs were treated with machine oil EC by dipping. Mean larval corrected mortalities (%) for methidathion EC and deltamethrin EC were 62.5% (categorized as Class II) and 87.5% (categorized as Class III) respectively, when larvae were topically treated. As a result of dipping treatments of pupae with pesticides, machine oil EC and thiamethoxam WP were classified as slightly harmful (categorized as Class II). Methidathion EC showed high toxicity, resulting in a total effect index rate 100% (categorized as Class IV). Taxonomical notes of the genus Chrysoperla and C. nipponensis are reviewed here.     

Lethal and sublethal effects of insecticide residues on Orius insidiosus (Hemiptera: Anthocoridae) and Geocoris punctipes (Hemiptera: Lygaeidae)

Laboratory-reared predators, the insidious flower bug, Orius insidiosus (Say), and big-eyed bug Geocoris punctipes (Say), were exposed to 10 insecticides, including three newer insecticides with novel modes of action, using a residual insecticide bioassay. These species are important predators of several economic pests of cotton. Insecticides tested were: azinphos-methyl, imidacloprid, spinosad, tebufenozide, fipronil, endosulfan, chlorfenapyr, cyfluthrin, profenofos, and malathion. There was considerable variation in response between both species tested to the insecticides. Tebufenozide and cyfluthrin were significantly less toxic to male O. insidiosus than malathion. Tebufenozide was also significantly less toxic to female O. insidiosus than malathion. Imidacloprid, tebufenozide, and spinosad were significantly less toxic to male G. punctipes than chlorfenapyr, endosulfan, and fipronil. Spinosad, tebufenozide, and azinphos-methyl were significantly less toxic to female G. punctipes than fipronil and endosulfan. Fecundity of O. insidiosus was significantly greater in the spinosad treatment compared with other treatments including the control. Consumption of bollworm, Helicoverpa zea (Boddie), eggs by O. insidiosus was significantly lower in the fipronil, profenofos, and cyfluthrin treatments compared with other treatments including the control. Consumption of H. zea eggs by G. punctipes was significantly lower in the malathion, profenofos, endosulfan, fipronil, azinphos-methyl, and imidacloprid treatments compared with the control. Egg consumption by G. punctipes was not significantly different in the tebufenozide treatment compared with the control. The lower toxicity of spinosad to G. punctipes is consistent with other reports. Based on these results, the following insecticides are not compatible with integrated pest management of cotton pests: malathion, endosulfan, profenofos, fipronil, and cyfluthrin; while imidacloprid, tebufenozide, azinphos-methyl, and spinosad should provide pest control while sparing beneficial species.     

Comparison of susceptibility of pest Euschistus servus and predator Podisus maculiventris (Heteroptera: Pentatomidae) to selected insecticides

Susceptibility of the brown stink bug, Euschistus serous (Say), and the spined soldier bug, Podisus maculiventris (Say), to acetamiprid, cyfluthrin, dicrotophos, indoxacarb, oxamyl, and thiamethoxam, was compared in residual and oral toxicity tests. Generally, susceptibility of P. maculiventris to insecticides was significantly greater than or not significantly different from that of E. servus. Cyfluthrin and oxamyl were more toxic to the predator than to E. servus in residual and feeding tests, respectively. Dicrotophos is the only compound that exhibited both good residual and oral activity against E. servus, but even this toxicant was more toxic to the predator than to the pest in oral toxicity tests. Feeding on indoxacarb-treated food caused high mortality for both nymphs and adults of P. maculiventris. In contrast, E. servus was unaffected by feeding on food treated with this compound. Insecticide selectivity to P. maculiventris was detected only with acetamiprid for adults in residual toxicity tests and for nymphs in oral toxicity tests. Because insecticide selectivity to P. maculiventris was limited, it is extremely important to conserve P. maculiventris in cotton fields by applying these insecticides for control of brown stink bugs only when the pest reaches economic threshold.