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1.
The tomato borer, Tuta absoluta (Meyrick), was first recorded in Turkey in August 2009 and rapidly became a serious pest in the Mediterranean and Aegean coastal regions in field and greenhouse grown tomatoes. Currently, insecticides are considered one of the major tools for the management of T. absoluta in Turkey. This study, investigated the efficacy of 7 different insecticides, against T. absoluta in laboratory bioassays. To determine the lethal concentration (LC) values and feeding activity of the larvae, tomato leaf parts mined by 1–3 day old L1 larvae were dipped into different insecticide concentrations. Mortality was recorded 5 days after insecticide treatments. Spinosad, chlorantraniliprole + abamectin or indoxacarb treatment resulted in 100% mortality with minimal or no feeding in all populations at their recommended doses of 120, 50.4 and 60 mg a.s. L?1, respectively. In general, the LC99 values of populations for these insecticides were similar and also lower than that of the recommended field doses. The effect of pyridalyl was low, resulting in low mortality with serious feeding damage at the dose of 125 mg a.s. L?1. The efficacies of abamectin, metaflumizone and azadirachtin were found to be moderate to low at the recommended doses (4.5, 240 and 50 mg a.s. L?1, respectively). However, these insecticides may affect pupation and adult emergence rates hence further studies are recommended to investigate these insecticides.  相似文献   

2.
Toxicity assays with tebufenozide, the first commercial non-steroidal ecdysteroid agonist, against a laboratory strain of the beet armyworm, Spodoptera exigua (Hübner), demonstrated the promise of this new compound for the control of this important pest. Experiments to select insects artificially from the laboratory strain by continuous exposure of larval instars to corresponding LC25 doses of tebufenozide for over 12 generations (G0→G12: 14–15 months), revealed no loss in susceptibility to the insecticide for up to five generations. Moreover, retention and fate of 14C-labelled tebufenozide were investigated using G6 larvae from the selection experiments and the results compared with those for the susceptible (G0) larvae. In addition, piperonyl butoxide, an inhibitor of monooxygenases, when ingested by larvae along with tebufenozide, increased the susceptibility of intoxicated larvae to this ecdysteroid agonist, indicating its oxidative metabolism in Spodoptera larvae. © 1998 Society of Chemical Industry.  相似文献   

3.
BACKGROUND: Azinphos‐methyl is the main insecticide used to control codling moth on apple and pears in Northern Patagonia. The aim of this study was to evaluate the toxicological and biochemical response of diapausing larvae of codling moth in orchards subjected to different insecticide selection pressure. RESULTS: Dose–mortality assays with azinphos‐methyl in diapausing larvae of Cydia pomonella L. showed significant differences between the LD95 from a population collected in one untreated orchard (2.52 µg moth?1) compared with that in a laboratory‐susceptible population (0.33 µg moth?1). Toxicity to azinphos‐methyl in field populations of diapausing larvae collected during 2003–2005 was evaluated by topical application of a discriminating dose (2.5 µg moth?1) that was obtained from larvae collected in the untreated orchard (field reference strain). Significantly lower mortality (37.71–84.21%) was observed in three out of eight field populations compared with that in the field reference strain. Most of the field populations showed higher esterase activity than that determined in both the laboratory susceptible and the field reference strains. Moreover, there was a high association between esterase activity and mortality (R2 = 0.64) among the field populations. On the other hand, a poor correlation was observed between glutathione S‐transferase activity and mortality (R2 = 0.33) among larvae collected from different orchards. CONCLUSIONS: All the field populations evaluated exhibited some degree of azinphos‐methyl tolerance in relation to the laboratory susceptible strain. Biochemical results demonstrated that esterases are at least one of the principal mechanisms involved in tolerance to this insecticide. Copyright © 2008 Society of Chemical Industry  相似文献   

4.
The toxicity of the naturally derived insecticide spinosad was tested against the gypsy moth, Lymantria dispar. Bioassays using red oak leaf disks, treated with spinosad in a Potter spray tower, yielded an LC50 value of 0.0015 µg AI cm−2 (3‐day exposure; 13‐day evaluation; 2nd instar larvae). Applied to foliage to run‐off in the laboratory (potted red oak seedlings) and the field (4 m‐tall birch trees), spinosad effectively controlled 2nd instar larvae at concentrations ranging from 3 to 50 mg litre−1. Toxicity in the laboratory, and efficacy and persistence in the field, were comparable to those achieved with the insecticide permethrin. Laboratory studies supported field observations that control was achieved in part by knockdown due to paralysis. In addition, laboratory results demonstrated that crawling contact activity may play an important role in field efficacy; 50% of treated larvae were paralyzed 16 h after a 2‐min crawling exposure to glass coated with a 4 mg litre−1 spinosad solution. © 2000 Society of Chemical Industry  相似文献   

5.
Wang Z  Kim JR  Wang M  Shu S  Ahn YJ 《Pest management science》2012,68(7):1041-1047
BACKGROUND: An assessment was made of the toxicity of imperatorin and osthole identified in Cnidium monnieri fruit, 11 related compounds and five insecticides to larvae from insecticide‐susceptible Culex pipiens pallens (KS‐CP strain) and Aedes aegypti and wild C.p. pallens (YS‐CP colony) using a direct‐contact mortality bioassay. Results were compared with those of the conventional larvicide temephos. RESULTS: Imperatorin (LC50 = 3.14 and 2.88 mg L?1) was 1.9‐, 3.7‐ and 4.2‐fold and 2.4‐, 4.5‐ and 4.6‐fold more toxic than isopimpinellin, isoimperatorin and osthole against susceptible C. p. pallens and A. aegypti larvae respectively. Overall, all of the compounds were less toxic than temephos (0.011 and 0.019 mg L?1). The toxicity of these compounds was virtually identical against larvae from the two Culex strains, even though YS‐CP larvae were resistant to fenthion (resistance ratio RR = 390), deltamethrin (RR = 164), cyfluthrin (RR = 14) and temephos (RR = 14). This finding indicates that the coumarins and the insecticides do not share a common mode of action. The structure–activity relationship indicates that the chemical structure and alkoxy substitution and length of the alkoxyl side chain at the C8 position are essential for imparting toxicity. CONCLUSION: The C. monnieri fruit‐derived coumarins and the related coumarins described merit further study as potential insecticides or lead molecules for the control of insecticide‐resistant mosquito populations. Copyright © 2012 Society of Chemical Industry  相似文献   

6.
Eleven sesquiterpene lactone derivatives of parthenin ( 1 ), obtained from wild feverfew, Parthenium hysterophorus, were prepared by chemical and photochemical transformations. The compounds tested were a pyrazoline adduct ( 2 ) of parthenin, its cyclopropyl ( 3 ) and propenyl ( 4 ) derivatives, anhydroparthenin ( 5 ), a dihydro‐deoxygenated product ( 6 ), a formate ( 7 ) and its corresponding alcohol ( 8 ) and acetate ( 9 ), a rearranged product ( 10 ), lactone ( 11 ) and hemiacetal ( 12 ). All these derivatives, along with parthenin, were tried for their antifeedant action against sixth‐instar larvae of Spodoptera litura, for insecticidal activity against the adults of store grain pest Callosobruchus maculatus, for phytotoxic activity against Cassia tora, and for nematicidal activity against the juvenile stage‐II (J2) of the root knot nematode Meloidogyne incognita. Antifeedent bioassay revealed that parthenin is moderately antifeedant. Among the derivatives, the saturated lactone ( 11 ) was found to be about 2.25 times more active than parthenin. The pyrazoline adduct ( 2 ) was found to be the most effective as an insecticide, with LC50 values after 24, 48 and 72 h of 96, 43 and 32 mg litre−1, respectively, which are comparable with neem extract. Compound 4 was found to be the most effective inhibitor of germination and seedling growth of C tora, with ID50 values for germination, plumule length and radicle length of 136, 326 and 172 compared with 364, 738 and 427 mg litre−1, respectively, for parthenin. Compound 10 was found to be the most effective in terms of nematicidal activity. The LC50 values for this compound were 273 and 104 mg litre−1, respectively, after 48 and 72 h compared with 862 and 512 mg litre−1 observed for parthenin after 48 and 72 h. © 2001 Society of Chemical Industry  相似文献   

7.

BACKGROUND

Tuta absoluta (Lepidoptera: Gelechiidae) is difficult to control by means of foliar insecticides, partly because of the endophytic feeding behavior of its larvae. The biopesticide spinosad is applied as a foliar spray for control of T. absoluta and has systemic properties when applied as a soil drench to the growing medium of tomato plants. The aims of this study were to determine the: (i) instar-dependent tolerance of larvae to spinosad; (ii) efficacy of spinosad drench application for the control of larvae; (iii) residual period of systemic activity of spinosad in leaves and fruit after drenching; and (iv) effect of spinosad drenching on tomato plant growth parameters.

RESULTS

The estimated LC50 value (Lethal Concentration at which 50% of the larvae died) differed between instars. The LC50 for second-instar larvae (0.41 ppm) to spinosad was significantly lower than that for third- (0.64 ppm) and fourth-instar (0.63 ppm) larvae. The LC80 value (Concentration at which 80% of the larvae died) for fourth-instar larvae (2.48 ppm) was 2.6- and 1.7-fold higher than that for the second- and third-instar larvae, respectively. The spinosad concentration recorded in leaves at 25 days after treatment (DAT; 0.26 μg g−1) was significantly lower than that in leaves sampled at 3, 10 and 15 DAT. High larval mortalities were, however, recorded for the duration of the experiment, which lasted 25 days (equivalent to one T. absoluta generation).

CONCLUSION

Systemic spinosad effectively controlled T. absoluta larvae over a prolonged period. However, drenching this insecticide violates the recommendation of the Insecticide Resistance Action Committee to avoid treating consecutive insect generations with the same mode of action and can therefore result in the evolution of insecticide resistance. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.  相似文献   

8.
BACKGROUND: Uraba lugens Walker (Lepidoptera: Nolidae) has the potential to become a serious pest of susceptible forestry and urban trees in New Zealand. Stem injection of insecticides provides a method for the control of U. lugens in public locations where foliar applications are not suitable. Field and laboratory studies were conducted in 2009 and 2010 to determine a dose response profile of U. lugens larvae to acephate injected at 0.0, 0.25, 0.50 and 1.00 g cm?1 tree diameter measured at breast height (dbh). The concentration of the injected solution varied across years. RESULTS: The highest mortality (85–100%) of U. lugens larvae occurred at 1.00 g acephate injected cm?1 dbh. The lower rates (0.25 and 0.50 g acephate cm?1) were more effective in 2010 than in 2009, a factor attributed to the change in volume of injected solution. CONCLUSION: Systemic injections of acephate at rates above 0.50 g cm?1 dbh provide a tool for the management of U. lugens in public places. It is recommended that stem injection operations for control of U. lugens larvae be timed to coincide with the emergence of first instars so that larvae are exposed to lethal insecticide doses. Copyright © 2011 Society of Chemical Industry  相似文献   

9.
The toxic effects of six acylurea insecticides on larvae of the tobacco hornworm were investigated at each of four environmental temperatures (20, 25, 30 and 35°C). This spans the range of temperatures which the insects can tolerate. For all the acylureas tested, mortality increased with temperature when either newly hatched or fourth-instar larvae were given insecticide in their food. Sub-lethal growth inhibition also became more pronounced at progressively higher environmental temperatures. This temperature dependence of acylurea action was not due to altered uptake of the insecticide, since there was no significant variation with temperature in the amount of [14C]flufenoxuron taken up by fifth-instar larvae when given a single meal containing labelled insecticide. Additionally, mortality of fourth-instar larvae given a single intra-haemocoelic injection of flufenoxuron was significantly greater at higher temperatures, implying that temperature affects a process that occurs after insecticide uptake. The intrinsic ability of acylureas to inhibit chitin synthesis is temperaturesensitive, since flufenoxuron inhibited the incorporation of [14C]N-acetylalucosamine into chitin by proleg epidermis in vitro significantly less well at 20°C than at the higher temperatures tested. However, there was no significant variation between the effectiveness of in-vitro chitin synthesis inhibition at 25, 30 and 35°C. These data show that the effectiveness of acylurea insecticides is subject to strong temperature effects in the range of temperatures likely to be experienced in the field.  相似文献   

10.
棉铃虫核多角体病毒的生产方法及其在生物防治中的应用   总被引：4，自引：0，他引：4  
本文是报道棉铃虫Heliothis armigera核多角体病毒(NPV)的生产方法及其在棉田应用的试验研究结果。NPV用棉铃虫幼虫生产。从虫卵接种开始,用人工饲料饲养棉铃虫幼虫,到四龄用病毒感染,六天后收集病死虫,病毒致死率80～85%,单虫含量4～6×10~9PIB。由棉饼粉、粗棉油等配制成诱饵加低剂量西维因作病毒增效剂与NPV混用,显著提高病毒的防治效果。四年田间试验表明,NPV杀虫剂防治棉铃虫的效果相当于或优于常用高效化学农药。1979年开展了大面积飞机微量喷雾PVN杀虫剂的试验,也取得了比较好的防治效果。  相似文献   

11.
Factors involved in insecticide resistance were evaluated by using 14C-labeled methyl parathion and aldrin to compare rates of absorption and metabolism by Heliothis virescens (F.) larvae that were resistant (R) and susceptible (S) to methyl parathion. Tests with third-stage R and S larvae suggested that the rate of insecticide absorption from the cuticular surface was not a major resistance factor. Further evidence for this assumption was demonstrated by the resistance of R larvae to injected and orally administered doses of methyl parathion. Smaller amounts of unmetabolized methyl parathion and aldrin were recovered from S larvae, an indication that differences in metabolism were probably related to the resistance.  相似文献   

12.
BACKGROUND: Feeding assays using adult rice water weevils and foliage of plants treated as seeds with chlorantraniliprole and thiamethoxam at different rates were conducted to evaluate the systemic adulticidal and feeding effects. Dose–mortality relationships were determined for thiamethoxam seed treatments by combining leaf area lost due to feeding and insecticide residues analyzed by LC/MS/MS. Changes in adulticidal activity of thiamethoxam were also investigated by contrasting adult mortalities at the 5–6‐leaf and tillering stages of rice. RESULTS: Adult weevil mortalities and leaf consumption rates on foliage were affected in thiamethoxam but not in chlorantraniliprole treatments when rice was at the 6–7‐leaf stage. The LD50 for weevils feeding on thiamethoxam‐treated rice at the 2–3‐leaf stage was 447 pg insecticide weevil?1 (95% CL: 25–830 pg weevil?1) but was lower (142 pg weevil?1; 95% CL: 102–180 pg weevil?1) in experiments with 3–4‐leaf‐stage plants. Mortalities on leaves from 5–6‐leaf‐stage plants were consistently higher than on leaves from tillering plants. Thiamethoxam residues measured by ELISA increased with seed treatment rate and differed between plant stages. CONCLUSION: The LD50 values developed in this study are the first values for leaf‐feeding insects on foliage of plants treated as seeds with thiamethoxam. The attrition of adulticidal activity of thiamethoxam in foliage of older plants may help to explain the reduced effectiveness of seed treatments against rice water larvae that is seen at later stages of rice growth in field studies. The differential activity of these two seed treatments on adults suggests that adult mortality contributes to the field efficacy of thiamethoxam but not to that of chlorantraniliprole. Copyright © 2012 Society of Chemical Industry  相似文献   

13.
Spanish Cydia pomonella (L.) field populations have developed resistance to several insecticide groups. Diagnostic concentrations were established as the LC90 calculated on a susceptible strain (S_Spain) for five and seven insecticides and tested on eggs and neonate larvae field populations, respectively. The three most relevant enzymatic detoxification systems (mixed-function oxidases (MFO), glutathione S-tranferases (GST) and esterases (EST)) were studied for neonate larvae.In eggs, 96% of the field populations showed a significantly lower efficacy when compared with the susceptible strain (S_Spain) and the most effective insecticides were fenoxycarb and thiacloprid. In neonate larvae, a significant loss of susceptibility to the insecticides was detected. Flufenoxuron, azinphos-methyl and phosmet showed the lowest efficacy, while lambda-cyhalothrin, alpha-cypermethrin and chlorpyrifos-ethyl showed the highest. Biochemical assays showed that the most important enzymatic system involved in insecticide detoxification was MFO, with highest enzymatic activity ratios (5.1-16.6 for neonates from nine field populations). An enhanced GST and EST activities was detected in one field population, with enzymatic activity ratios of threefold and fivefold for GST and EST, respectively, when compared with the susceptible strain. The insecticide bioassays showed that the LC90 used were effective as diagnostic concentrations. Measures of MFO activity alongside bioassays with insecticide diagnostic concentrations could be used as tools for monitoring insecticide resistance in neonate larvae of C. pomonella.  相似文献   

14.
为阐明虱螨脲对小菜蛾亚致死效应的生化机制,采用室内生物测定法测定了LC_(10)和LC_(25)亚致死浓度处理小菜蛾3龄幼虫1、6、12、24、48和72 h后其体内保护酶系和解毒酶系的活力变化。结果表明:虱螨脲LC_(10)处理对小菜蛾幼虫体内超氧化物歧化酶(SOD)活力表现为早期诱导、后期抑制的作用,而对过氧化物酶(POD)则表现为先抑制后诱导的作用,对过氧化氢酶(CAT)仅在72h时具有诱导作用;LC_(25)处理对SOD表现为诱导-抑制-诱导-抑制的作用,对POD具有抑制作用,而对CAT具有诱导作用。经虱螨脲亚致死浓度处理后,小菜蛾幼虫体内酯酶和多功能氧化酶活力被明显抑制,且基本表现为浓度越高抑制作用越强;而谷胱甘肽S-转移酶(GST)活力仅在处理后1 h被诱导,之后被显著抑制。表明虱螨脲进入小菜蛾幼虫体内后,初期可诱导SOD、CAT和GST活力升高,以适应外界毒害的影响;但随着时间的延长,3种解毒酶活力被抑制,使其难以代谢,从而增强了对小菜蛾的毒性。  相似文献   

15.
为评价从朱红毛斑蛾Phauda flammans幼虫僵虫中分离的虫生真菌在害虫生物防治中的应用潜力,通过形态学鉴定及ITS基因序列分析对分离菌株进行鉴定,并运用时间-剂量-死亡率模型分析该分离菌株对朱红毛斑蛾1~6龄幼虫的毒力。结果显示,结合形态学特征和ITS基因序列分析将该虫生真菌鉴定为球孢白僵菌Beauveria bassiana,并将该菌株命名为PfBb。球孢白僵菌PfBb菌株可侵染朱红毛斑蛾1~6龄幼虫,随着该菌株孢子液浓度的增加,其对朱红毛斑蛾幼虫的毒力逐渐增强。PfBb菌株孢子液处理朱红毛斑蛾1~5龄幼虫6 d时的LC50分别为2.61×104、1.04×105、1.11×106、1.54×106和1.44×107 个/mL,处理6龄幼虫8 d时的LC50为1.02×107 个/mL。随着处理时间的增加,PfBb菌株对朱红毛斑蛾1~6龄幼虫的LC50和LC90随之降低,表明存在剂量效应。当处理浓度相同时,朱红毛斑蛾1~6龄幼虫的僵虫率随着虫龄的增加而降低,但在较高浓度1.0×107~1.0×109 个/mL处理时,1~5龄幼虫的僵虫率无显著差异,说明1.0×107个/mL球孢白僵菌PfBb菌株孢子液防治朱红毛斑蛾幼虫即可达到理想的防治效果。表明球孢白僵菌PfBb菌株对朱红毛斑蛾有较大的生防应用潜力。  相似文献   

16.
为筛选防治农业新发害虫双委夜蛾Athetis dissimilis（Hampson）的有效药剂,采用浸叶法测定了其不同龄期幼虫对8类18种常用杀虫剂的敏感性,并观察了幼虫对不同药剂的中毒症状。结果表明:3~6龄双委夜蛾幼虫对辛硫磷、联苯菊酯、高效氯氟氰菊酯、溴氰菊酯、甲氨基阿维菌素苯甲酸盐、氯虫苯甲酰胺和溴氰虫酰胺的敏感性较高,LC50值为0.138 1~27.40 mg/L;3龄及4龄幼虫对毒死蜱、高效氯氰菊酯、氟啶脲、茚虫威和虫螨腈敏感性较高,LC50值小于22.63 mg/L,而5龄和6龄幼虫对上述药剂的敏感性均有所降低,LC50值大于38.13 mg/L;各龄期幼虫对甲基嘧啶磷、灭幼脲及新烟碱类杀虫剂的敏感性均较低,LC50值大于40.83 mg/L。双委夜蛾幼虫对不同类别杀虫剂的中毒症状存在差异,其中,经有机磷类、新烟碱类、吡咯类及齅二嗪类杀虫剂处理后,幼虫表现为体表干燥、体壁皱缩;而经拟除虫菊酯类杀虫剂处理后幼虫表现为体壁柔软、充满体液。就生物活性测定结果而言,推荐溴氰虫酰胺、氯虫苯甲酰胺、辛硫磷、联苯菊酯、高效氯氟氰菊酯、溴氰菊酯及甲氨基阿维菌素苯甲酸盐等药剂可用于双委夜蛾的应急防治。  相似文献   

17.
Permethrin at concentrations as high as 10?6 had no detectable effect upon neuromuscular transmission at 20-21°C in the body-wall muscles of susceptible larvae of Lucilia sericata and susceptible and resistant (kdr) strains of larvae of Musca domestica. At the higher concentrations of 5 × 10?6M, muscle cells in all strains and species of larva were slowly depolarised, resulting in failure of neuromuscular transmission when the level of depolarisation corresponded with the peak height of the postsynaptic potentials. Multiple postsynaptic potentials were sometimes obtained in response to a single electrical stimulus to the motor axon. Neither of these effects is considered to result from interference with release of the neurotransmitter or its binding to the postsynaptic receptors. Spontaneous activity in sensory nerve fibres from susceptible larvae was increased followed by intermittent bursting and block at concentrations of permethrin as low as 10?9M at 20-21°C and 10?10 at 26°C. Resistant larvae of M. domestica were 1000 times less sensitive, needing concentrations of permethrin as high as 10?6M at 20-21°C and 10?7M at 26°C to affect sensory discharge. The results are discussed in relationship to the cause of knockdown by pyrethroid insecticides and to possible changes in the nervous system which may be brought about by the kdr resistance factor.  相似文献   

18.
BACKGROUND: The housefly, Musca domestica L., and stable fly, Stomoxys calcitrans (L.) are cosmopolitan pests of both farm and home environments. Houseflies have been shown to be resistant to a variety of insecticides, and new chemistries are slow to emerge on the market. Toxicities of selected semiochemicals with molecular structures indicative of insecticidal activity were determined against adults from an insecticide‐susceptible laboratory strain of houseflies. The three most active semiochemicals were also evaluated against recently colonized housefly and stable fly strains. RESULTS: Nineteen semiochemicals classified as aliphatic alcohols, terpenoids, ketones and carboxylic esters showed toxicity to houseflies and stable flies. Rosalva (LC50 = 25.98 µg cm?2) followed by geranyl acetone and citronellol (LC50 = 49.97 and 50.02 µg cm?2) were identified as the most toxic compounds to houseflies. Permethrin was up to 144‐fold more toxic than rosalva on the susceptible strain. However, it was only 35‐fold more toxic to the insecticide‐tolerant field strain. The compounds generated high toxicity to stable flies, with LC50 values ranging from 16.30 to 40.41 µg cm?2. CONCLUSION: Quantification of LC50 values of rosalva, citronellol and geranyl acetone against susceptible housefly and field‐collected housefly and stable fly strains showed that semiochemicals could serve as potent insecticides for fly control programs. Copyright © 2010 Society of Chemical Industry  相似文献   

19.
A muscarinic acetylcholine receptor (mAChR) has been demonstrated and partially characterized in larvae of the cattle tick Boophilus microplus. Its properties are compared with mAChR from an epithelial cell line from the dipteran insect Chironomus tentans. Competition studies with cholinergic ligands of different specificity revealed the muscarinic nature of the cholinergic receptors investigated in both species. In homogenates from tick larvae, specific binding sites for [3H]quinuclidinyl benzilate (QNB) with high affinity (1·2±(0·13) nM ; Bmax 22·5 pmol mg protein−1) were detected that do not bind nicotinic compounds specifically. The estimated IC50 values for nicotine, imidacloprid and α-bungarotoxin were all in the mM range. Additionally, with tick larvae, high-affinity nicotinic binding sites were detected with [3H]nicotine which could be displaced by high concentrations of imidacloprid or QNB. The estimated IC50 values for nicotine, α-bungarotoxin, imidacloprid and QNB were 43(±8) nM , 0·8(±0·2) μM , 2·8(±0·6) μM and 78(±1·9) μM , respectively. With homogenates of the non-neuronal insect cell line from C. tentans, only high-affinity binding sites for [3H]QNB were found. Muscarinic antagonists selectively displaced [3H]quinuclidinyl benzilate (QNB) binding to tick larvae homogenates. The mAChR of B. microplus preferred pirenzepine (IC50 2·13(±1·02) μM ) among different subtype-specific mAChR antagonists (4-DAMP had IC50 49·9(±9·13) μM and methoctramine had IC50 121(±14·2) μM ) indicating a type of binding site similar to the vertebrate M1 mAChR subtype. The tick muscarinic receptor seems to be a G-protein-coupled receptor, as concluded from the 4·8-fold reduction in receptor affinity for binding of the muscarinic agonist oxotremorine M upon treatment with the non-hydrolysable GTP-analogue γ-S-GTP. Binding data for the agonists oxotremorine M (IC50 71·3(±19·6) μM ) and carbachol (IC50 253(±87·1) μM ) parallel the biological efficacy of these compounds, in that, while oxotremorine M showed some activity against ticks, carbachol was ineffective.  相似文献   

20.
The F1 sterility technique (inherited sterility using substerile insects) has been proposed for reproductive suppression of lepidopteran pests. Management of lepidopteran pests using F1 sterility may be greatly influenced by other possible strategies, including chemical control measures. Within this context, a laboratory investigation was undertaken of the tobacco caterpillarSpodoptera litura (Fabricius) (Lepidoptera: Noctuidae) to assess the bioefficacy of a substerilizing dose (70 Gy) of gamma radiation on bio-characteristics(viz., adult survival, fecundity, egg hatch, F1 larval weight, F1 pupation, F1 sex ratio); to establish the median lethal dose (LD50) of an oxime carbamate insecticide, thiodicarb (Larvin®75 WP), toS. litura; and determine the interaction of thiodicarb with the F1 insects derived from a substerilizing gamma dose. A dose of 70 Gy administered to 7-day-old male pupae reduced the the eclosion by ~ 10%. When the eclosed males (derived from treated pupae) were mated with normal females, the fecundity and fertility were decreased as compared with control (0 Gy). Analysis of body weight of the F1 larvae showed no significant influence of radiation,i.e., growth was comparable to that of normal progeny, which is a positive factor in the sterile-insect technique. Bioassay on newly molted 6th instar larvae with thiodicarb (Larvin®75 WP) showed that the LD50 of the insecticide was 6.76µg g-1 in the combined treatment (radiation to P1 male pupae + thiodicarb to F1 larvae), as compared with 28.67 µg g-1 in the chemical treatment (thiodicarb), indicating that the toxicity of the insecticide to the F1 progeny was increased 4.24 times by the radiation treatment, which is a markedly pronounced effect. Further studies of the combined effect of radiation and insecticide on pupation and sex ratio of F1 progeny showed that pupation was affected more by the combined treatment than by the insecticide alone, whereas the sex ratio was skewed in favor of males in both the combined treatment and the chemical treatment, indicating that thiodicarb was selectively more toxic to females. The possible interaction and potential and the feasible approaches of integrating F1 sterility and thiodicarb treatment are discussed for management of the lepidopteran pestS. litura.  相似文献   

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