Susceptibilities of northern fowl mite,Ornithonyssus sylviarum (Acarina: Macronyssidae), and chicken mite,Dermanyssus gallinae (Acarina: Dermanyssidae), to selected acaricides

The relative toxicities of ten acaricides to northern fowl mite,Ornithonyssus sylviarum (Canestrini and Fanzago), and the chicken mite,Dermanyssus gallinae (De Geer), were determined simultaneously by holding the mites inside disposable glass Pasteur pipettes previously immersed in acetone solutions of various concentrations (w/v) of technical grade acaricides. The LC₉₀s (parts per million) of the acaricides after 24 h exposure for the northern fowl mite and the chicken mite, respectively, were: bendiocarb (13.1, 0.18), tetrachlorvinphos (14.5, 4.07), carbaryl (15.0, 0.83), pirimiphos methyl (18.3, 2.03), permethrin (23.1, 8.46), lambda cyhalothrin (80.7, 11.4), dichlorvos (252.8, 3.75), malathion (238.4, 6.59), amitraz (6741, 9430) and fenvalerate (>10000, 60.2). After 48 h exposure there were only slight increases in mortalities of both species except for increased mortalities for the northern fowl mite with lambda cyhalothrin, amitraz and fenvalerate, and for the chicken mite with amitraz.     

禾谷缢管蚜和麦长管蚜玻璃管药膜法敏感毒力基线的建立

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

Susceptibility of the bedbug,Cimex lectularius,to selected insecticides and various treated surfaces

Abstract. Adult bedbugs, Cimex lectularius, were exposed for 24 h (25^oC) to filter paper treated with various dilutions of the technical grade of nine insecticides dissolved in acetone to determine the concentration-response relationships. The order of toxicity, from most to least based on the LC₅₀'s was: dichlorvos, pirimiphos methyl, lambda-cyhalothrin, bendiocarb, permethrin, malathion, carbaryl, tetrachlorvinphos, and fenvalerate. The residual toxicities of commercial formulations of six of the chemicals diluted with water and applied to wood, cardboard, cloth and galvanized metal, were determined by exposing adult bedbugs at 3,7 and 12 weeks after treatment. The formulation of bendiocarb (FICAM® 76% W) had little residual activity on all surfaces at 12 weeks after treatment. The formulation of carbaryl (SEVIN® 21.5% L) was toxic to bedbugs on all surfaces at 12 weeks after treatment, but required high concentrations on wood, cardboard, and cloth. The formulation of pirimiphos methyl (ACTELLIC® 57% EC) had no residual activity on any of the surfaces at 12 weeks after treatment. The formulation of tetrachlorovinphos (RABON® 50% W) had residual activity for 12 weeks on all surfaces except metal. The formulation of permethrin (ATROBAN® 11% EC) had residual activity on only metal and wood while the formulation of lambda-cyhalothrin (KARATE® 13.1% EC) had residual activity 12 weeks on all surfaces.     

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

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

Use of meta‐analysis to predict degradation of carbaryl and malathion in freshwater for exposure assessment

Carbaryl (1‐naphthyl methylcarbamate) and malathion (diethyl mercaptosuccinate, S‐ester with O, O‐dimethyl phosphorodithioate) are insecticides used to control grasshopper infestations on rangeland. Insecticides used to control grasshopper infestations pose a hazard to aquatic organisms because although no‐spray buffer zones are observed around aquatic habitats, pesticide may be deposited by drift or mobilized from upland areas by runoff. A number of processes may affect the fate of carbaryl and malathion in the aquatic environment, but no method is available for estimating degradation over the range of conditions that occur in the field. We used results of published studies in meta‐analyses to estimate degradation models that predict half‐life of carbaryl and malathion in freshwater over temperature and pH ranges relevant to western grasshopper‐management programs. Estimated degradation models were:

In (half‐life carbaryl) = 24.3 ‐ 2.36(pH) ‐ 0.0788(t)

and In (half‐life malathion) = 5.98 + 2.84(pH) ‐ 0.326(pH ²) ‐ 0.202(t) + 0.00135(t ²)

where half‐life has units of hours, and temperature (t) has units °C. Both models accounted for a significant amount of total variation (P<0.0001) and had r²>0.97. Accuracy of these degradation models was evaluated by comparing predicted degradation of carbaryl and malathion to field and laboratory data. We suggest that use of these degradation models be restricted to conditions where water has 7 ≤. pH ≤. 10 for carbaryl, and 7 ≤ pH ≤ 8.2 for malathion.     

Field tests with insecticides and insect growth regulators to control insect pests of cowpea and its effects on certain beneficial insects

A small‐plot tests were conducted on cowpea, Vigna ungiculata (L.) Walp, to determine the effectiveness of 14 selected insecticides representing four insecticide classes (organophosphates, carbamates, pyrethroids, and insect growth regulators, IGRs), and four insecticide/IGR mixtures on cowpea insect pests and its effects on certain beneficial insects. By day 3 after treatement, the insecticides phenthoate, isoxathion, cyanophos, carbaryl, and cypermethrin used at sub‐recommended rates reduced the leafhopper, Empoasca spp., populations by >83% than those in the control. On that day, all insecticide treatments significantly reduced the cowpea aphid, Aphis craccivora, numbers below that of the control. The prothiofos, isoxathion, pirimicarb, and fenpropathrin treatments provided continuing control to both leafhoppers and aphids through day 21 after spraying. It seems that most insecticide treatments were not effective in whitefly, Bemisia tabaci, control. The best control of the whitefly immatures was obtained by day 3 after spraying in plots received thiodicarb (76%) and fenpropathrin (60%). All selected insecticides and rates used had very low residual effect against B. tabaci immatures. By day 3 posttreatment, the carbaryl (2.02 kg/ha) caused completely protection for cowpea pods frMw blue pea butterfly, Lampides boeticus, larvae. The IGRs, flufenoxuron and Dowco‐439, applied alone and those applied in mixtures with insecticides, carbaryl/teflubenzuron, chlorpyrifos/XRD‐473, and methomyl/ flufenoxuron, exhibited satisfactory control (>81%) to butterfly larvae on day 7 posttreatment. All treatments did not exhibit a considerable residual activity against L. boeticus larvae through 2–3 weeks followed spray. Most insecticides applied at the higher rates used significantly reduced the numbers of limabean pod borer, Etiella zinckenella, larvae found in cowpea pods collected on day 7 after application. The IGRs, flufenoxuron and Dowco‐439, applied alone, at 0.119 kg/ha, or in mixtures, methomyl/flufenoxuron (0.167 kg/ha) and chlorpyrifos/Dowco‐439 (0.911 kg/ha) caused >73% control of E. zinckenella larvae through day 21 posttreatment. The best control of cowpea weevil, Callosobru‐chus spp., adults (>83%), on day 3 after spraying, was obtained in treatments of cyanophos (1.19 kg/ha), prothiofos (1.43 kg/ha), flufenoxuron (0.119 kg/ha), and chlorpyrifos/Dowco‐439 (0.911 kg/ha). The IGR flufenoxuron applied alone or in mixture, methomyl/flufenoxuron (0.164 kg/ ha) exhibited satisfactory residual activity against Callosobruchus adults through day 21 posttreatment. Percentage seed damage by the larvae of cowpea weevils was significantly lower in most treatments than that of control. Populations of insect predators found in all treated plots were extremely reduced than those found in untreated plots. By day 21 after spraying, the IGRs flufenoxuron, XRD‐473, and Dowco‐439, applied at the low rate of 0.071 kg/ha, seemed to be less effect against insect predators than other insecticides used.     

Forest bolsters bird abundance,pest control and coffee yield

Efforts to maximise crop yields are fuelling agricultural intensification, exacerbating the biodiversity crisis. Low‐intensity agricultural practices, however, may not sacrifice yields if they support biodiversity‐driven ecosystem services. We quantified the value native predators provide to farmers by consuming coffee's most damaging insect pest, the coffee berry borer beetle (Hypothenemus hampei). Our experiments in Costa Rica showed birds reduced infestation by ~ 50%, bats played a marginal role, and farmland forest cover increased pest removal. We identified borer‐consuming bird species by assaying faeces for borer DNA and found higher borer‐predator abundances on more forested plantations. Our coarse estimate is that forest patches doubled pest control over 230 km² by providing habitat for ~ 55 000 borer‐consuming birds. These pest‐control services prevented US$75–US$310 ha‐year⁻¹ in damage, a benefit per plantation on par with the average annual income of a Costa Rican citizen. Retaining forest and accounting for pest control demonstrates a win–win for biodiversity and coffee farmers.     

硅藻土及其混配剂对书虱的防治效果

采用拌粮法 ,用硅藻土单剂、配方 1 (硅藻土 +95 %马拉硫磷EC)、配方 2 (硅藻土 +2 . 5 %溴氰菊酯EC)、配方 3 (硅藻土 +80 %敌敌畏EC)、配方 4(硅藻土 +0 . 4%天惠虫清EC)、配方 5 (硅藻土 +5 %双氧威WP)、配方 6(硅藻土 +5 %抑太保EC)对嗜卷书虱Liposcelisbostrychophila进行防治研究 ,结果表明 :配方 4为优选配方 ,处理 2 4h后 ,3种浓度的致死率均达到 1 0 0 % ;配方 1、配方 2、配方 3、配方 5、配方 6对嗜卷书虱的致死率处理 48h后达到 1 0 0 % ;单用硅藻土处理 96h后达到 1 0 0 % ,各配方处理间差异极显著。     

Pyrethroid-degrading Sphingobium sp. JZ-2 and the purification and characterization of a novel pyrethroid hydrolase

A pyrethroid-degrading bacterium strain JZ-2 was isolated from activated sludge treating pyrethroid-manufacturing wastewater. Based on the morphological, physiological and biochemical characterization, and phylogenetic analysis of the 16S rRNA gene sequence, the strain was identified as Sphingobium sp. Strain JZ-2 was capable of degrading fenpropathrin, cypermethrin, permethrin, cyhalothrin, deltamethrin, fenvalerate and bifenthrin. This strain degraded fenpropathrin by hydrolysis of the carboxylester linkage to yield 3-phenoxybenzaldehyde and 2,2,3,3-tetramethylcyclopropanecarboxylic acid. 3-Phenoxybenzaldehyde, 3-phenoxybenzoate, protocatechuate and catechol are the intermediates of fenpropathrin degradation. Protocatechuate and catechol were further oxidized by ortho-cleavage pathway. A novel pyrethroid hydrolase from cell-free extract was purified 108.5-fold to apparent homogeneity with a 10.2% overall recovery. It was a monomer with a molecular mass of 31 ± 1 kDa, a pI of 4.85. The optimal pH and temperature were 7.5 and 40 °C, respectively. No cofactors or coenzymes were required for the pyrethroid-hydrolysis activity. The enzyme was strongly inhibited by many irons (Ag⁺, Cu²⁺, Hg²⁺ and Zn²⁺), SDS, p-chloromercuribenzoic acid, phenylmethylsulfonyl fluoride and malathion.     

棉铃虫对氰戊菊酯-辛硫磷混剂的抗性演化及解毒酶活性变化

用氰戊菊酯-辛硫磷混剂（有效成分1∶10,简称氰-辛混剂）对棉铃虫Helicoverpa armigera室内品系(YS)进行16代的抗性选育,获得棉铃虫对氰-辛混剂的抗性品系（YS-FP）。YS-FP品系与YS品系相比,对氰-辛混剂的抗性为14.7倍,对其中的单剂氰戊菊酯和辛硫磷的抗性分别为2 170倍和3.1倍。随着筛选的进行,氰戊菊酯和辛硫磷之间的共毒系数在F₂代出现短暂的增加,然后逐渐降低,它们之间的互作由增效变为拮抗。交互抗性测定结果表明,YS-FP品系对氯氰菊酯、溴氰菊酯、三氟氯氰菊酯、三唑磷和灭多威产生了明显的交互抗性,对硫丹、多杀菌素和爱玛菌素没有产生交互抗性。YS-FP品系6龄幼虫中肠细胞色素P450氧化酶甲氧基香豆素O-脱甲基活性为YS品系的10倍,3龄幼虫谷胱甘肽S-转移酶和酯酶活性分别是YS品系的1.7倍（CDNB结合作用）和2.4倍（α-NA 酯酶水解作用）。氰-辛混剂的筛选导致了棉铃虫多种解毒酶活性的增加,特别是细胞色素P450氧化酶活性增强最为明显。本研究结果表明氰-辛混剂对棉铃虫的筛选导致了广谱的交互抗性和多种代谢抗性机理,并且两个单剂之间的互作由增效变为拮抗,因此氰 辛混剂在棉铃虫抗性治理中的作用是有限的和暂时的。     

Comparison of biological and conventional insecticide treatments for the management of the pineapple fruit borer, Strymon megarus (Lepidoptera: Lycaenidae) in Costa Rica

Carbaryl is currently one of the most commonly used insecticides for the control of the pineapple fruit borer, Strymon megarus (Godart), in commercial pineapple production. To evaluate more sustainable biological alternatives to conventional insecticides, three microbial and one botanical insecticide were studied. Beauveria bassiana, Metarhizium anisopliae, Bacillus thuringiensis (Bt) and a plant extract from Quassia amara were compared with carbaryl in replicated field trials in Costa Rica during 2005 and 2006. In both years of testing, the untreated control received over 50% fruit damage from S. megarus. Bt and carbaryl provided the highest level of control and the lowest level of fruit damage compared to all other treatments. Based on the results of this study, Bt appears to be an acceptable biological alternative to the conventional insecticide (carbaryl) for control of S. megarus on pineapple. In addition, Bt was the least expensive treatment used in this study.     

Fruit Yield,not DBH or Fruit Crown Volume,Correlates with Time Spent Feeding on Fruits by Wild Leontopithecus rosalia

Assessing fruit availability is a critical element in testing hypotheses concerning resource use by frugivores. One method to estimate fruit availability is to measure tree diameter at breast height (DBH) and assume a positive correlation with fruit tree productivity. Our first objective was to test the relationship between DBH and tree productivity. We used as our measures of tree productivity: volume of the fruit bearing region of the tree crown (FBRv) and fruit yield measured as grams of dry fruit matter per fruit bearing region (FBR). Our second objective was to determine if time spent feeding on fruits by golden lion tamarins was correlated with 3 measures of tree productivity within their territories. We define tree productivity within a territory as tree productivity × tree density (fruit tree productivity/ha). We used as our measures of tree productivity/ha: (1) DBH × tree density, (2) fruit yield × tree density, and (3) FBRv × tree density. We measured DBH and FBRv for 17 fruit species commonly eaten by golden lion tamarins in Poço das Antas Reserve, Brazil. We counted fruits in trees and collected fruits to calculate fruit yield. We used measures of tree densities to calculate tree productivity/ha. We found that DBH correlated with fruit yield. The time tamarins spent feeding did not correlate with DBH ( × tree density) or FBRv ( × tree density), but it correlated with fruit yield ( × tree density). Our results emphasize the importance of recording temporal and spatial measures of fruit productivity that are meaningful to the frugivore studied.     

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

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

The Antioxidant Activity of Regularly Consumed Fruit and Vegetables Reflects their Phenolic and Vitamin C Composition

Recent studies are emphasising the importance and putative modes of action of specific flavonoids as bioactive components of the diet in in vivo and in vitro models. Thus, it is important to have a clear idea of the major phenolic families of which fruit and vegetables are comprised and the levels contained therein. Regularly consumed fruit and vegetables of mixed varieties available on the UK market were analysed for the composition of the major individual phenolic components. The total phenolic content (applying the Folin assay) and the vitamin C levels were also determined. The antioxidant capacities of aqueous/methanolic extracts were comparatively assessed using the TEAC (Trolox Equivalent Antioxidant Capacity), the FRAP (Ferric Reducing Ability of Plasma) and ORAC (Oxygen Radical Absorbance Capacity) assays, which comprise contributions from polyphenols, simple phenols and the ascorbate component. The results were calculated in terms of 100 &#117 g fresh weight (FW) uncooked portion sizes. Fruit and vegetables rich in anthocyanins (e.g. strawberry, raspberry and red plum) demonstrated the highest antioxidant activities, followed by those rich in flavanones (e.g. orange and grapefruit) and flavonols (e.g. onion, leek, spinach and green cabbage), while the hydroxycinnamate-rich fruit (e.g. apple, tomato, pear and peach) consistently elicited the lower antioxidant activities. The TEAC, FRAP and ORAC values for each extract were relatively similar and well-correlated with the total phenolic and vitamin C contents. The antioxidant activities (TEAC) in terms of 100 &#117 g FW uncooked portion size were in the order: strawberry &#100 raspberry=red plum &#100 red cabbage>>>grapefruit= orange>spinach>broccoli>green grape &#59 onion> green cabbage>pea>apple> cauliflower &#59 pear> tomato &#59 peach=leek>banana &#59 lettuce.     

Insecticide effects onEntomophthora muscae [Zygomycetes: Entomophthorales]

Studies were conducted to determine the effect of insecticide residues on germination of primary conidia ofentomophthora muscae (Cohn) Fresenius and to determine the relative susceptibility of healthy and infectedMusca domestica L. to insecticides. Primary conidia were discharged fromM. domestica cadavers onto glass microscope slides treated with insecticides. All insecticides significantly inhibited germination relative to control slides. Permethrin and naled had the least inhibition (36–40 %), while malathion and dimethoate almost completely inhibited germination (87–94 %). Tetrachlorvinphos/dichlorvos and carbaryl were intermediate (57–59 %). Healthy flies were not significantly different from infected flies in terms of susceptibility to naled, dimethoate, or permethrin. Infected flies exposed on the last day of pathogen incubation died on the bottom of the Petri dishes, rather than climbing and attaching as did untreated, infected flies. Both control and treated groups produced large numbers of primary conidia.     

Integrated agroforestry systems improve soil carbon storage,water productivity,and economic returns in the marginal land of the semi-arid region

Environmental crises, land degradation, and frequent crop failure threaten the livelihoods of millions of the populace in the semi-arid agroecosystems. Therefore, different combinations of annual crops with perennial fruit trees were assessed to restore the soil carbon, and enhance farm productivity and profitability in a semi-arid climate. The study hypothesized that the integration of perennial fruit trees with seasonal crops may enhance farm productivity, economic returns, and environmental sustainability. Integration of phalsa (Grewia asiatica) with mung bean (Vigna radiata) - potato (Solanum tuberosum) system recorded the highest system productivity (25.9 Mg/ha) followed by phalsa with cowpea (Vigna unguiculata) -mustard (Brassica juncea) systems (21.2 Mg/ha). However, Karonda (Carissa sp.) with mung bean - potato system recorded maximum net return (3529.1 US$/ha), and water use efficiency (33.0 kg/ha-mm). Concerning the benefit-cost (B:C) ratio, among the agroforestry systems, the karonda + cowpea - mustard system registered a maximum BC ratio (3.85). However, SOC density remained higher (9.10 Mg/ha) under the phalsa + cowpea - mustard and Moringa + mung bean - potato system (9.16 Mg/ha) over other systems. Similarly, phalsa + mung bean - potato system had the highest C sustainability index (27.6), carbon sequestration potential (0.6–0.67 Mg/ha/year), and water use efficiency (33.0 kg/ha-mm). Hence, the study suggested that the integration of short-duration leguminous and oilseeds with fruit trees offer a myriad of benefits and an efficient system for restoring the soil C without compromising the food and livelihood security of the rural populace in semiarid regions.     

Effects of pesticides on division of two lepidopteran cell lines and onAutographa Californica MNPV development in TN368 cells

Summary The concentration of each of 10 pesticides (azinphosmethyl, captan, carbaryl, chlordimedorm, dichlorvos, dimenthoate, fenvalerate, methomyl, methyl parathion, trichlorfon) causing a 50% inhibition (ID₅₀) in cell number relative to an untreated culture for a time period equal to four cell doublings was determined for the TN368 and IPLB-HZ1075 cell lines. The range of ID₅₀ values with either of the cell lines was similar, with captan being most toxic within an ID₅₀ range of 5 to 6 μM/2×10⁵ cells/ml, and methomyl least toxic within a range of 2900 to 3200 μM/2×10⁵ cells/ml. Yet there were significant differences between cell lines in pesticide susceptibility. Fenvalerate, dichlorvos, and chlordimeform were 16, 3, and 1.5 times more toxic, respectively, for TN368 cells than HZ1075 cells, whereas dimethoate and carbaryl were each 2 times more toxic for HZ1075 cells. In general, increasing toxicity paralleled decreasing water solubility, although the order of the pesticides varied somewhat according to the particular cell line and medium. Moreover, there was little aberrant cell morphology in either of the cell cultures during incubation with most of the pesticides at their ID₅₀ levels. Preincubation of TN368 cells with any one of seven different pesticideis before inoculation withAutographa californica MNPV, and subsequent incubation of infected cells in medium plus pesticide, did not significantly suppress polyhedra development except for trichlorfon-incubated cells. In addition, there was a small but consistent variation from control cells in extracellular virus titers assayed from two of five of the pesticide incubations. The titer was consistently depressed with trichlorfon and elevated with fenvalerate, however, further work is required to determine the biological significance of these differences. Primary funding for this research was provided by the Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC, under grant no. R-809453. Additional funding was provided by the Pennsylvania State University College of Agriculture Experiment Station—Project no. 2758. The contents of this publication do not necessarily reflect the views, policies, or recommendations of the Environmental Protection Agency, and the Agency does not necessarily endorse any of the commercial products used in this study. The Pennsylvania State Agricultural Experiment Station. Authorized for publication as Journal Series Paper No. 7432.     

Resistance and synergistic effects of insecticides in Bactrocera dorsalis (Diptera: Tephritidae) in Taiwan

Oriental fruit flies, Bactrocera dorsalis (Hendel), were treated with 10 insecticides, including six organophosphates (naled, trichlorfon, fenitrothion, fenthion, formothion, and malathion), one carbamate (methomyl), and three pyrethroids (cyfluthrin, cypermethrin, and fenvalerate), by a topical application assay under laboratory conditions. Subparental lines of each generation treated with the same insecticide were selected for 30 generations and were designated as x-r lines (x, insecticide; r, resistant). The parent colony was maintained as the susceptible colony. The line treated with naled exhibited the lowest increase in resistance (4.7-fold), whereas the line treated with formothion exhibited the highest increase in resistance (up to 594-fold) compared with the susceptible colony. Synergism bioassays also were carried out. Based on this, S,S,S-tributyl phosphorotrithioate displayed a synergistic effect for naled, trichlorfon, and malathion resistance, whereas piperonyl butoxide displayed a synergistic effect for pyrethroid resistance. All 10 resistant lines also exhibited some cross-resistance to other insecticides, not only to the same chemical class of insecticides but also to other classes. However, none of the organophosphate-resistant or the methomyl-resistant lines exhibited cross-resistance to two of the pyrethroids (cypermethrin and fenvalerate). Overall, the laboratory resistance and cross-resistance data developed here should provide useful tools and information for designing an insecticide management strategy for controlling this fruit fly in the field.     

Contact toxicity of some chemical and biological pesticides to several insect parasitoids and predators

Eight pesticides; methyl parathion, malathion (organo-phosphates), toxaphene (chlorinated hydrocarbon), carbaryl (carbamate), pyrethrin (plant derivative),Bacillus thuringiensis, nuclear polyhedrosis virus (Heliothis) (microbial insecticides), and 2,4-DB (postemergence herbicide) were evaluated at the minimum recommended field dose and reduced dosages for contact toxicity toBrachymeria intermedia (Hymenoptera: Chalcididae), Campoletis sonorensis (Hymenoptera: Ichneumonidae), Chelonus blackburni (Hymenoptera: Braconidae), Meteorus leviventris (Braconidae), Voria ruralis (Diptera: tachninidae), Chrysopa carnea (Neuroptera: Chrysopidae), andHippodamia convergens (Coleoptera: Coccinellidae). At minimum field dosages, percent mortality of parasitoids and predators was>27%, for the chemical insecticides. Mortality from pyrethrin was <31%, in all cases and 0% for 5 of the 8 species tested. Mortality of parasitoids and predators exposed toB. thuringiens is and NPV was<4% while mortality from 2,4-DB was<7%. The toxicity of chemical insecticides to parasitoids and predators at reduced dosages in increasing order of toxicity was malathion > carbaryl > toxaphene > methyl parathion.