多杀霉素亚致死浓度对棉铃虫幼虫生理及代谢的影响

为明确田间使用多杀霉素亚致死浓度对棉铃虫Helicoverpa armigera幼虫的影响,用含多杀霉素亚致死浓度LC₂₅的人工饲料持续饲喂棉铃虫3龄幼虫,并对饲喂后其体重、取食量、累计蛹化率、蛹发育历期和蛹重等生长发育及脂肪体内甘油三脂（triglyceride,TG）含量和相关基因SREBP、FAS和HSL表达情况进行测定。结果表明,多杀霉素对棉铃虫的亚致死浓度LC₂₅为0.21 mg/kg;多杀霉素亚致死浓度处理4~6 d后,棉铃虫3龄幼虫体重分别为0.065、0.263和0.329 g,较对照显著降低;处理6 d后,其取食量为0.082 g,较对照显著降低;处理4~7 d后,其累计化蛹率分别为60.90%、63.20%、65.50%和65.50%,较对照显著降低。多杀霉素亚致死浓度处理后,棉铃虫蛹发育历期由对照9.89 d显著延长至10.74 d,单头蛹重为0.274 g,显著低于对照的0.324 g;其脂肪体TG含量较对照显著降低。多杀霉素亚致死浓度处理24~72 h后,参与脂肪酸合成信号通路中重要基因SREBP和FAS的相对表达量较对照均显著下调,而参与脂肪代谢的重要基因HSL则较对照显著上调。     

Systemic effects of a neem insecticide onLiriomyza huidobrensis larvae

In an effort to expand the spectrum of larvicides effective against the pea leafminer,Liriomyza huidobrensis (Blanchard), we studied the effects of a neem-based insecticide (Neemix-45) on the development of the leafminer under laboratory conditions. Bean plants were treated with a soil drench of 1, 5, 10 or 25 ppm azadirachtin or by dipping leaves in 1 or 15 ppm azadirachtin at various times before or during the development of the leafminer. Treating the plants with the neem insecticide before exposure to egg-laying adults had a greater effect on inhibiting the development of pupae and adult eclosion than treatment at the 1st-instar larval stage. The systemic effects from a soil drench had a greater adverse effect on pupation and adult eclosion than leaf dipping. Drenching plants with 1 ppm azadirachtin 24 h before exposure to adults had a greater effect (0% adult eclosion) than leaf dipping at the same time period and concentration (15. 6% adult eclosion). Similar results were obtained when drenching plants infested with lst-instar larvae with 1 ppm azadirachtin (11. 7% eclosion)vs dipping leaves at the same time period and concentration (44. 7% eclosion).     

多杀菌素亚致死浓度对小菜蛾解毒酶系活力的影响

采用多杀菌素亚致死浓度,以浸叶法分别处理小菜蛾Plutella xylostella (L.)敏感种群(SS)和亚致死选育种群 的3龄幼虫,分别测定饲喂处理6、12、24、48和72 h后小菜蛾体内羧酸酯酶(CarE)、谷胱甘肽S-转移酶(GST) 和多功能氧化酶(MFOs)的活性,分析了酶活性的变化动态。结果表明,SS种群小菜蛾CarE的活性在不同时间段波动较大,经多杀菌素处理后,开始时段比活力增加,随着处理时间的延长,比活力逐渐被抑制,Sub-SS种群的GarE活力高于SS种群;多杀菌素对GST具有明显的诱导作用,亚致死浓度处理后GSTs比活力呈上升趋势,且具有一定的时间效应;对细胞色素P450酶系的O-脱甲基酶活性具有明显的抑制作用,多杀菌素亚致死浓度连续处理5代后,该酶活性更低。     

Note: Systemic effects of a spinosad insecticide onLiriomyza huidobrensis Larvae

In an effort to expand the spectrum of larvicides effective againstLiriomyza huidobrensis (Blanchard), the effect of spinosad was studied on the mortality of the leafminer under laboratory conditions. Bean plants infested with various leafminer stages (egg through third instar) were treated by dipping leaves in a liter of water containing 24, 48 or 96 mg a.i. spinosad or by drenching the soil of plants with 200 ml of water containing 12 mg, 24 mg or 48 mg a.i. spinosad. In general, leaf dipping was more efficacious and adverse effects were observed sooner than with soil drench. All concentrations of spinosad significantly reduced the number of adults that emerged except leaf dip of third instar; only the highest concentration caused significant reduction of pupae and adults. Spinosad would likely be a valuable insecticide for control of the pea leafminer,L. huidobrensis. http://www.phytoparasitica.org posting Nov. 4, 2005.     

Note: Toxicity of some insecticides onBracon hebetor under laboratory conditions

Insecticides which were environmentally friendly and the least toxic, were screened against a laboratory strain ofBracon hebetor (Say) (Hymenoptera: Braconidae) for their suitability for release in IPM of cotton. Concentrations ranging from 1 to 1000 ppm of the formulated insecticides in acetone were applied in glass vials and also by a leaf method, whereby cotton leaves were dipped in aqueous solutions of the same concentrations of insecticides. Adult parasitoids were exposed in both methods. According to the LC₅₀ at 24 h exposure, Λ-cyhalothrin and spinosad were the most (7 and 5 ppm) and least (263 and 225 ppm) toxic in the vial and the leaf method, respectively, toB. hebetor. The possible use of the parasitoid for IPM of cotton is discussed. http://www.phytoparasitica.org posting July 20, 2006.     

亚致死浓度多杀菌素对西花蓟马解毒酶系活力的影响

采用亚致死浓度(LC25)多杀菌素对西花蓟马Frankliniella occidentalis相对敏感(SS)种群进行连续选育,获得亚致死(Sub)种群。处理36代后,Sub种群对多杀菌素的敏感性下降到SS种群的5.2倍。用SS和Sub种群各自的LC10和LC25浓度多杀菌素分别处理两种群的2龄若虫,1、6 、12、24和48 h后测定羧酸酯酶(CarE)、谷胱甘肽S-转移酶(GSTs) 和多功能氧化酶(MFOs)的比活力。结果表明,Sub种群对照组CarE和GSTs比活力在除第48 h外的其他时间段都高于SS种群对照组,且6 h时两者CarE比活力差异显著,Sub种群是SS种群的1.37倍;Sub种群对照组MFOs比活力在各时间段都高于SS种群对照组,在1 和6 h时差异显著,前者分别是后者的1.62和1.36倍。再经各自的LC10和LC25浓度多杀菌素处理后,在各时间段Sub种群的CarE比活力均高于SS种群;LC25浓度处理后,Sub种群的GSTs和MFOs比活力虽在短时间内低于SS种群,但随处理时间的延长其比活力均高于SS种群。说明SS种群经亚致死浓度多杀菌素选育36代后,其体内CarE、GSTs和MFOs比活力有上升趋势;继续用亚致死浓度多杀菌素处理,则Sub种群体内解毒酶活力的动态调节能力要强于SS种群。     

Toxicity,persistence and efficacy of indoxacarb and two other insecticides on Plutella xylostella (Lepidoptera: Plutellidae) immatures in cabbage

Toxicities of indoxacarb on eggs and 5-day-old larvae of diamondback moth, Plutella xylostella L., on cabbage and those of field-aged leaf residues on 5-day-old larvae were determined in the laboratory. The persistence and efficacies of indoxacarb and two other newer insecticides (spinosad and emamectin benzoate) to P. xylostella were tested under field conditions. Results from laboratory bioassays indicate that indoxacarb was highly toxic to P. xylostella larvae through food ingestion, with LC₅₀ and LC₉₀ values of 24.1 and 90.1 mg AI l ^{- 1}, respectively. However, indoxacarb had no significant effects on eggs and larvae through direct contact compared with water control. The toxicity of field-aged leaf residues of indoxacarb (0-, 3-, 5-, 7-, 10-, 14-, 17- and 21-day-old residues) declined slowly and gradually under the field conditions in South Texas. Almost all larvae died on day 5 after feeding on the leaves with 0 - 14-day residue, and the mortalities were as high as 94 and 78% for the 14- and 17-day-old leaf residues. With one application, indoxacarb suppressed P. xylostella larvae below the economic threshold for 14 - 21 days. Two field trials showed that indoxacarb at 0.05 - 0.07 kg AI ha ^{- 1} was effective against P. xylostella, providing marketable cabbage with three applications per season. In addition, indoxacarb was as effective as spinosad, and significantly more effective than emamectin benzoate.     

Laboratory and field evaluation of spinosad against the gypsy moth,Lymantria dispar

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     

Sub-lethal influences of different insecticides on oviposition preference of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) on cotton in relation to altered plant morphology

We investigated the sub-lethal influences of spinosad, chlorpyriphos, endosulfan, acephate and cypermethrin on the oviposition responses of Helicoverpa armigera (Hübner) to cotton plants, under cage and laboratory conditions. The rank order of toxicity (LC₅₀ values as a per cent) of test insecticides against third instar larvae using the leaf disc method was: spinosad > chlorpyriphos > endosulfan > acephate > cypermethrin. On whole plants, females laid more eggs on acephate LC₅₀-, acephate LC₃₀- and cypermethrin LC₅₀-treated cotton plants than on the control. The chlorpyriphos-treated plants were least preferred for oviposition. When excised cotton leaves from different treatments were used in a multiple-choice test, cypermethrin LC₅₀- and endosulfan LC₃₀-treated leaves received more eggs than the control. The repeated application of sub-lethal concentrations of different insecticides reduced plant height in the case of acephate LC₃₀ and cypermethrin LC₅₀, while plant spread and upper canopy leaf area were reduced in both treatments of acephate and cypermethrin. Reduced plant spread, upper canopy leaf area followed by plant height were found associated with oviposition preference by H. armigera females.     

Sublethal effects of nine insecticides on Drosophila suzukii and its major pupal parasitoid Trichopria drosophilae

Background

Although the pupal parasitoid Trichopria drosophilae is used in conservative and augmentative biocontrol of Drosophila suzukii infestations, current pest management strategies mostly rely on multiple insecticide applications. In this context, the aim of the study was to investigate the baseline toxicity of nine insecticides on D. suzukii larvae and their multiple sublethal effects (LC₁₀) on immature stages of the pest feeding on contaminated diet and T. drosophilae developing within the intoxicated host.

Results

Chlorpyriphos and azadirachtin showed the lowest and the highest LC₁₀, the values of which were 9.78 × 10¹³ and 1.46 × 10³ times lower than their recommended label field rate, respectively. Among tested insecticides, imidacloprid, malathion and dimethoate were the only treatments that did not affect the juvenile development time of D. suzukii, while spinosad and the organophosphates chlorpyriphos and dimethoate did not influence fly pupal size. No sublethal effects were recorded on T. drosophilae degree of infestation (DI) and juvenile development time. On the contrary, cyazypyr and dimethoate negatively affected the success of parasitism (SP) and the number of progeny of the pupal parasitoid, in association with malathion for the first parameter and spinosad for the fertility. Compared to the untreated control, more female progeny emerged following azadirachtin exposure, while dimethoate caused the opposite effect. Imidacloprid, lambda-cyhalothrin and spinetoram decreased hind tibia length of emerged parasitoids.

Conclusion

This study provides new insights on the (eco)toxicological profile of nine insecticides and new information needed to support the deployment of T. drosophilae in the field within the sustainable management techniques against D. suzukii. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Beet armyworm (Spodoptera exigua) resistance to spinosad

Susceptibility to spinosad (Success®/Tracer®) of beet armyworm (Spodoptera exigua) from the southern USA and Southeast Asia was determined through exposure of second‐ and third‐instar larvae to dipped cotton leaves. LC₅₀ estimates of susceptibility of second‐ and third‐instar larvae of field populations ranged from 0.279 to 6.14 and 0.589 to 14.0 mg spinosad litre⁻¹, respectively. A Thailand population was 22‐ and 24‐fold less susceptible than the six other US field populations evaluated, and 85‐ and 58‐fold less susceptible than a reference laboratory population, respectively. From these results, we initiated experiments to test the hypothesis that the Thailand population was resistant to spinosad. F₁ crosses between the resistant Thailand population and a susceptible reference strain yielded individuals that were 22‐fold less sensitive to spinosad than the susceptible parent. This same resistant strain exhibited significantly greater survivorship on plants treated with spinosad in the field. Lastly, selection of an Arizona population resulted in a significant reduction in susceptibility to spinosad, further substantiating the hypothesis of a genetic basis for resistance to spinosad. These findings indicate a vulnerability of this new insecticide to resistance development in beet armyworm and should serve as a warning against excessive use of it. © 2000 Society of Chemical Industry     

Life-table analyses for the tomato leaf miner,Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae): effects of plant genotype

BACKGROUND

Host plant resistance plays an important role in integrated pest management programs. Crop resistance assessments commonly focus on only a single dependent variable, such as larval survival/plant damage, which limits the ability to appreciate the impact of host plants on pest populations in the full sense. Therefore, we performed life-table analyses for tomato leaf miner Tuta absoluta, on 19 Solanum lycopersicum genotypes and a wild Solanum habrochaites accession. These analyses assess the ability of the pest to attain a high population density on different tomato genotypes. Based on the resulting ranking of tomato resistance at the vegetative stage (45-day-old plants), we tested the resistance of six selected genotypes at the reproductive stage (4-month-old plants).

RESULTS

T. absoluta performance was significantly inferior on vegetative-stage S. habrochaites plants (LA 1777); time taken for the first instars to mine the leaves (5 ± 0.14 days), development time of early- and late-stage larvae (8.8 ± 0.2 and 4.2 ± 0.2 days, respectively), pupal period (11.2 ± 0.58 days), and total developmental time (29.4 ± 0.83 days) were significantly longer, fecundity was significantly lower (18.66 ± 7.24 days), and the highest total mortality (63.33%) also recorded compared with other genotypes, resulting in the lowest net reproductive rate (R₀) (11.20 ± 2.51). For the six selected genotypes, the ranking of plant resistance did not change between plants at the vegetative and reproductive stages.

CONCLUSION

This study suggested that of 20 screened tomato genotypes, LA 1777 and EC-620343 are the least suitable hosts for T. absoluta to establish fast-growing populations, and thus can be employed in integrated T. absoluta management. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

The effects of foliar spray application of silicon on plant damage levels and components of larval biology of the pest butterfly Chlosyne lacinia saundersii (Nymphalidae)

We investigated sunflower leaf palatability to Chlosyne lacinia saundersii Doubleday & Hewitson (Lepidoptera: Nymphalidae) in plants treated with silicon (Si) and subjected to mechanical injury. We also examined the effects of those treatments on plant development. The experimental study was carried out as a completely randomized design, consisting of the six treatments (10 replicates each): (1) control, (2) plants mechanically injured, (3) Si applied around the plant stem (Si drench), (4) Si drench + injured, (5) Si drench + foliar spray, and (6) Si drench + foliar spray + injured. Si drench + injured significantly reduced the percentage of caterpillar-injured leaves (CIL), leaf area consumed (LAC), and caterpillar weight (CW), leading to increased caterpillar mortality. The only intrinsic plant characteristic affected by the treatments was Si content (SiC), which was higher in plants treated with either Si drench + foliar spray or Si drench + foliar spray + injured. Negative correlations were observed between SiC and the variables CIL, LAC and CW, whereas positive correlations were observed between CIL and LAC, CIL and CW, and LAC and CW. The treatment strategy of Si combined with artificial mechanical injury affects leaf palatability and development of C. lacinia saundersii, conferring resistance to sunflower plants as a function of Si accumulation, although it did not increase crop vegetative variables.     

Paradoxical effects of sublethal exposure to the naturally derived insecticide spinosad in the dengue vector mosquito,Aedes aegypti

BACKGROUND: Recent studies have indicated that spinosad, a mixture of two tetracyclic macrolide compounds produced during the fermentation of a soil actinomycete, may be suitable for controlling a number of medically important mosquito species, including the dengue vector, Aedes aegypti L. The authors determined the effects of a 1 h exposure to a 50% lethal concentration (LC₅₀) of spinosad in the larval stage on the wing length, longevity and reproductive capacity of the adult survivors. RESULTS: The LC₅₀ of spinosad for a wild‐caught population of Ae. aegypti from Chiapas, southern Mexico, was estimated to be 0.06 mg AI L^?1 in late third instars. Paradoxically, the female survivors of exposure to this concentration were significantly larger (as determined by wing length) laid more eggs, but were slightly less fertile than control females. This was probably due to elimination of the smaller and more susceptible fraction of mosquito larvae from the experimental population following spinosad treatment. Male survivors, in contrast, were significantly smaller than controls. No significant differences were detected in the adult longevity of treated and control insects of either sex. CONCLUSIONS: The increase in reproductive capacity of spinosad‐treated females did not compensate for mortality in the larval stage and would be unlikely to result in population increase in this mosquito under the conditions that were employed. Sustained‐release formulations would likely assist in minimizing the occurrence of sublethal concentrations of this naturally derived product in mosquito breeding sites. Copyright © 2008 Society of Chemical Industry     

Comparative studies on acylurea insect growth regulators and neuroactive insecticides for the control of the armyworm Spodoptera exempta walk

Leaf-dip bioassays with commercial pesticide formulations were used throughout this study. Third-instar larvae of Spodoptera littoralis were bioassayed for comparative purposes. The end-point mortality against the third-instar larvae (L3) of two Spodoptera exempta populations (Bangor and Gent) and a S. littoralis population (NRI) was found to occur at 72 h and 120 h for neuroactive compounds (carbamate, organophosphate and pyrethroid insecticides) and acylureas respectively. Overall, the acylureas were found to be more toxic (up to 240-fold at the LC₅₀ level) than the most active of the neuroactive compounds tested, the pyrethroids. This difference was greatest against S. littoralis, which was markedly less sensitive to the latter compounds. The Gent population of S. exempta was also found to be significantly less sensitive (7-folt at LC₅₀) to the pyrethroid, lambda-cyhalothrin, than the Bangor strain. Two of the most toxic neuroactive and non-neuroactive compounds, the pyrethroid, cypermethrin and the acylurea, teflubenzuron were chosen for further studies with S. exempta (Gent) and S. littoralis. Relatively little difference in the toxicity of teflubenzuron was observed against different larval instars (L2, L3 and L4) of S. exempta when compared with cypermethrin. Choice-chamber-experiments on feeding behaviour showed that when L3 larvae of either species were exposed to both treated and untreated leaves. teflubenzuron had no significant effect on larval distribution, the percentage of each leaf disc consumed or larval weight gain when compared with untreated controls. In contrast, a marked dose-dependent repellent response to cypermethrin-treated leaves was shown by S. littralis after 6 h. together with corresponding reductions in the percentage of the treated leaf consumed and in larval weight gain. Similarly, when L3 S. exempta were exposed only to pesticidetreated leaves, cypermethrin significantly reduced premoult larval weight gain, whereas tefiubenzuron had no premoult effect. However, following exposure of L3 S. exempta and S. littoralis to teflubenzuron for 48 h prior to moulting, L4 which survived the moult showed reduced weight gain compared with controls, the reduction being more pronounced on maize than on artificial diet. This antifeedant effect increased in proportion to the concentration of teflubenzuron originally administered. The effect of exposure time to teflubenzuron was examined by placing L3 S. exempta and S. littoralis on leaves treated with the approximate LC₅₀ or LC₉₅ dose for 6–48 h. The exposure time required to produce appreciable mortality (relative to LC values) within the treated population was found to be 24 h.     

亚致死浓度氯虫苯甲酰胺对小菜蛾药剂敏感度和解毒酶活性的影响

采用叶片药膜法,使用亚致死浓度(LC10、LC25)的氯虫苯甲酰胺对小菜蛾Plutella xylostella(L.)3龄幼虫连续处理5代后,试虫对氯虫苯甲酰胺的敏感度分别比敏感品系下降了57.3% 和67.7%,同时对多杀菌素的敏感度也分别下降了60.2% 和51.5%,但对毒死蜱和高效氯氰菊酯的敏感度变化不明显。采用该浓度的氯虫苯甲酰胺分别处理小菜蛾3龄幼虫24、48和72 h,可诱导其羧酸酯酶(CarE)比活力上升,但对细胞色素P450 O-脱乙基酶(ECOD)、谷胱甘肽S-转移酶(GSTs)和芳基酰胺酶(AA)有明显的抑制作用;连续处理5代后,小菜蛾CarE和ECOD的比活力显著高于对照组,分别为对照组的1.16、1.40倍和1.65、1.56倍,但GSTs和AA的比活力则分别比对照下降了11.0%、27.5%和43.6%、52.5%。结果表明,小菜蛾对氯虫苯甲酰胺产生抗性的风险较高;羧酸酯酶和多功能氧化酶可能与小菜蛾对氯虫苯甲酰胺的敏感度下降有关。     

蓖麻不同部位蓖麻碱的含量及其杀虫活性

采用高效液相色谱(HPLC)外标法测定并比较了蓖麻Ricinus communis不同部位和不同生长期蓖麻叶中蓖麻碱的含量,并研究了其对甜菜夜蛾Spodoptera exigua的毒杀效果。结果表明,蓖麻不同部位中蓖麻碱的含量差异较大,由高到低依次为叶(1.005%)>籽壳(0.568%)>饼粕(0.451%)>茎(0.429%)>籽仁(0.235%);不同生长期蓖麻叶中蓖麻碱的含量也存在很大差别,其中鲜绿叶中的含量最高。提取的蓖麻碱对甜菜夜蛾具有良好的毒杀效果,施药72 h后对2龄幼虫的LC50值为0.35 mg/mL。     

Compatibility of spinosad with predaceous mites (Acari) used to control Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)

BACKGROUND: Spinosad is a biopesticide widely used for control of Frankliniella occidentalis (Pergande). It is reported to be non‐toxic to several predatory mite species used for the biological control of thrips. Predatory mites Typhlodromips montdorensis (Schicha), Neoseiulus cucumeris (Oudemans) and Hypoaspis miles (Berlese) have been used for control of F. occidentalis. This study investigated the impact of direct and residual toxicity of spinosad on F. occidentalis and predatory mites. The repellency of spinosad residues to these predatory mites was also investigated. RESULTS: Direct contact to spinosad effectively reduced the number of F. occidentalis adults and larvae, causing > 96% mortality. Spinosad residues aged 2–96 h were also toxic to F. occidentalis. Direct exposure to spinosad resulted in > 90% mortality of all three mite species. Thresholds for the residual toxicity (contact) of spinosad (LT₂₅) were estimated as 4.2, 3.2 and 5.8 days for T. montdorensis, N. cucumeris and H. miles respectively. When mites were simultaneously exposed to spinosad residues and fed spinosad‐intoxicated thrips larvae, toxicity increased. Residual thresholds were re‐estimated as 5.4, 3.9 and 6.1 days for T. montdorensis, N. cucumeris and H. miles respectively. Residues aged 2–48 h repelled T. montdorensis and H. miles, and residues aged 2–24 h repelled N. cucumeris. CONCLUSION: Predatory mites can be safely released 6 days after spinosad is applied for the management of F. occidentalis. Copyright © 2011 Society of Chemical Industry     

低剂量乙基多杀菌素对小菜蛾解毒酶的影响

为探讨低剂量乙基多杀菌素对小菜蛾Plutella xylostella（L.）解毒酶的影响,采用叶片浸渍法,测定了乙基多杀菌素和多杀菌素对小菜蛾敏感种群的毒力,并比较了低剂量（LC25和LC50）处理6、12、24、48和72 h时小菜蛾体内羧酸酯酶（CarE）、谷胱甘肽S-转移酶（GST）和多功能氧化酶系（MFOs）活性的变化动态。结果表明:乙基多杀菌素对小菜蛾的杀虫活性优于多杀菌素,处理48 h后其LC25和LC50浓度分别为0.018和0.048 mg/L,经此低剂量浓度处理后,小菜蛾CarE活性波动较大,6~24 h,处理组CarE活性高于对照组,且均呈先升后降趋势,24~72 h,处理组CarE活性均低于对照组,并且具有一定的时间效应;对GST具有明显的诱导作用,GST活性均高于对照组;对MFOs具有明显的抑制作用,除在48 h时相差不大外,其他时间MFOs活性均显著低于对照组。结果表明,GST可能参与了乙基多杀菌素在小菜蛾体内的代谢。     

Effects of Plant Defence Activators on Anthracnose Disease of Cashew

The plant defence activators acibenzolar-S-methyl (Benzo[1,2,3]thiadiazole-7-carbothioic acid-S-methyl ester, ASM), 2,6-dichloro-isonicotinic acid (DCINA), salicylic acid (SA), and dibasic potassium phosphate (K₂HPO₄) were tested for their ability to protect cashew (Anacardium occidentale) seeds and leaves from anthracnose disease caused by Colletotrichum gloeosporioides. No inhibition of the early stages of pathogen development was caused by concentrations equal to or lower than 1.1mM a.i. ASM, 1.2mM a.i. DCINA, 5mM SA and 50mM K₂HPO₄. Maximum reduction of the disease in detached leaves, without phytotoxic effects, was obtained with 0.07mM a.i. ASM and DCINA, 5mM SA, and 50mM K₂HPO₄, with a time interval of at least 72h between application of the activator and inoculation with the pathogen. On attached leaves, foliar sprays were slightly more efficient than soil drench treatments, with 5mM SA being the most effective treatment, while 50mM SA as well as 0.3mM a.i. ASM and DCINA caused phytotoxic effects. In field-grown plants, protection was conferred by a soil drench of concentrations as low as 12.6M a.i. ASM and DCINA and 2.6mM SA. These concentrations were not phytotoxic suggesting that plant defence activators have potential for control of anthracnose disease in the field.