联苯肼酯对智利小植绥螨的安全性及二者对二斑叶螨的联合控制作用

【目的】评价联苯肼酯对智利小植绥螨Phytoseiulus persimilis的安全性,以及该药剂与捕食性天敌智利小植绥螨联合使用的效果。【方法】采用室内生物测定与田间试验的方法测定了联苯肼酯对智利小植绥螨成螨和若螨致死率与繁殖能力的影响,以及二者联合使用对茄子上二斑叶螨的控制效果。【结果】结果表明143 mg/L联苯肼酯对智利小植绥螨成螨和若螨的存活和生殖能力均无显著影响,处理后96 h对若螨的最高致死率为2.30%,成螨为2.04%;处理组8 d的平均产卵量为15.08粒/雌,与对照平均产卵量15.45粒/雌无显著差异;处理组所产卵的平均孵化率为98.63%,与对照组平均孵化率98.13%无显著差异;联苯肼酯悬浮剂在143 mg/L浓度下对二斑叶螨的控制效果表现为速效性高于单独使用智利小植绥螨,但持效性低于智利小植绥螨,防效在第22天时开始下降。二者联合使用表现出较好的速效性与持效性,处理后第2天防效达97.35%,第18天时达100%。【结论】联苯肼酯对智利小植绥螨具有极高的安全性,该药剂与智利小植绥螨联合使用对二斑叶螨具有良好的控制效果。     

智利小植绥螨对茄子二斑叶螨控制效果研究

【目的】明确智利小植绥螨Phytoseiulus persimilis对茄子上二斑叶螨Tetranychus urticae的控制效果,探索智利小植绥螨控制茄子二斑叶螨的最优释放数量。【方法】在1︰10、1︰30和1︰50不同益害比及10、30和60头/叶二斑叶螨不同猎物密度下,研究了智利小植绥螨捕食二斑叶螨的效果以及智利小植绥螨的增殖率。【结果】随智利小植绥螨释放比例的提高,防治效率明显提高,益害比1︰10、1︰30和1︰50的防效分别在释放后第14、22和26天达100%;在不同猎物密度下,按益害比1︰30释放智利小植绥螨,防效均随时间延长而提高,且6 d后不同猎物密度下防效差异不明显,第20天时3种密度下的防效均达100%,表明其捕食作用受到益害比影响较大而受猎物密度影响不明显。随着捕食螨释放比例的降低和二斑叶螨密度的提高,智利小植绥螨的增殖率增加,在益害比为1︰50、二斑叶螨种群密为60头/叶时,智利小植绥螨的最高增殖率分别达643%和893%,表明智利小植绥螨具有较高的种群增殖力。【结论】智利小植绥螨对茄子二斑叶螨具有较好的防控效果,推荐在二斑叶螨发生早期时按益害比1︰10~1︰30释放智利小植绥螨,以保证较快的防控效果和较少的捕食螨释放量。     

朱砂叶螨密度效应研究

研究朱砂叶螨密度效应的结果表明,朱砂叶螨在卵期不存在密度作用,平均孵化率可达96.01％。但在幼若螨期,高密度则将导致较高的死亡率并调节种群的性比值。羽化成螨种群中雌性比例增加,但子代成螨则表现雄性比例的显著增大。雌成螨密度不同,产卵量和寿命均有显著差别。当雌成螨密度超过3头/cm~2时表现较强的扩散性。     

迷迭香油和花椒油对朱砂叶螨的生物活性

【目的】明确室内条件下迷迭香油和花椒油对朱砂叶螨Tetranychus cinnabarinus (Boisduval)的生物活性。【方法】采用熏蒸法和驱避法测定迷迭香油和花椒油对5日龄朱砂叶螨雌成螨的熏蒸活性、产卵抑制活性和驱避活性;并采用EthoVision XT6分析亚致死浓度下两种精油对雌成螨行为的影响。【结果】分别将5日龄雌成螨熏蒸处理12, 24和48 h后,迷迭香油对朱砂叶螨的致死率均显著高于花椒油处理组（P＜0.05）,且随着熏蒸时间的延长或精油浓度的升高,其熏蒸活性均增强;不同浓度的迷迭香油处理朱砂叶螨雌成螨24 h后的产卵抑制率均显著高于花椒油处理组（P＜0.05）。迷迭香油和花椒油处理朱砂叶螨雌成螨24 h的LC₃₀分别为6.731和120.142 μL/L;迷迭香油对朱砂叶螨雌成螨的驱避活性明显高于花椒油处理组。两种精油亚致死浓度处理朱砂叶螨雌成螨后,其自发运动方式发生了明显变化,移动频率在LC₁₀ 时呈现最高;且迷迭香油对朱砂叶螨雌成螨自发运动能力的影响比花椒油处理的影响更为明显。【结论】迷迭香油对朱砂叶螨的生物活性明显高于花椒油,因此,迷迭香油对朱砂叶螨的生物防治具有较高的应用价值。本研究为绿色蔬菜植物源杀螨剂的研究提供了科学依据。     

东莨菪内酯对朱砂叶螨的驱避和产卵抑制活性

本研究采用叶碟浸渍法测定了东莨菪内酯对朱砂叶螨Tetranychus cinnabarinus(Biosduvals)雌成螨的触杀活性,采用选择性的半叶法测定了驱避活性,同时采用非选择性的全叶法测定了产卵抑制活性。结果表明,东莨菪内酯对朱砂叶螨雌成螨具有较好的触杀活性,采用叶碟浸渍法处理48h后的LC50为0.297mg·mL-1,LC30为0.105mg·mL-1,LC10为0.023mg·mL-1。采用LC50、LC30和LC103个浓度的东莨菪内酯处理雌成螨后,发现东莨菪内酯对雌成螨没有表现出明显的驱避活性,处理区和对照区24h和48h的着螨率均为50%左右;采用LC50和LC102个浓度处理雌成螨后表现出了一定的产卵抑制活性,平均产卵抑制率分别为23.02%和13.23%,而LC30对雌成螨的产卵量表现出了促进作用,平均产卵抑制率为-8.25%,这可能是由于毒物兴奋效应所致。本研究旨在为东莨菪内酯的进一步开发和应用奠定理论基础。     

东莨菪内酯对朱砂叶螨实验种群的亚致死效应

为明确东莨菪内酯对朱砂叶螨Tetranychus cinnabarinus (Boisduval) 实验种群的亚致死效应, 为其作为植物源杀螨剂的进一步开发及应用提供理论依据, 在室内采用叶碟饲养的方法, 并利用生命表技术研究了东莨菪内酯亚致死剂量对朱砂叶螨F₀代和F₁代种群生长发育和繁殖的影响。结果表明： 东莨菪内酯LC₄₀, LC₃₀和LC₂₀剂量处理朱砂叶螨雌成螨后, 可刺激F₀代雌成螨产卵, 使产卵量分别增加了73.82%, 186.97%和70.18%, 而对成螨寿命、 产卵期和雌雄性比没有影响; F₁代的卵期、 幼螨期和若螨期与对照没有显著性差异 (P>0.05), 而成螨期和雌成螨寿命均低于对照; 对F₁代繁殖力的影响主要表现为产卵期缩短、 产卵量减少和雌性比下降; 子代种群的净生殖率(R₀)由50.5976最低降至33.9910, 世代平均历期(T)和种群倍增时间(Dt)均低于对照, 各处理后的朱砂叶螨种群均存在适合度缺陷。这些结果表明, 在亚致死剂量下, 东莨菪内酯能够降低朱砂叶螨种群的发育和繁殖速率, 这对东莨菪内酯在有害生物防治上的应用具有积极意义。     

亚致死浓度除虫脲对朱砂叶螨生长和繁殖的影响

【目的】除虫脲属于苯甲酰脲类杀虫剂,本研究旨在探讨亚致死浓度除虫脲对朱砂叶螨Tetranychus cinnabarinus生长发育和繁殖的影响,为除虫脲的合理使用提供一定的理论依据。【方法】本文采用叶碟浸渍法测定了除虫脲对朱砂叶螨的毒力,生命表技术探讨亚致死剂量除虫脲对朱砂叶螨实验种群生长发育和繁殖的影响。【结果】结果表明除虫脲对朱砂叶螨卵的LC50、LC30、LC10分别是15.825、6.089、1.534mg/L。和对照组相比,亚致死剂量(LC10和LC30)除虫脲处理朱砂叶螨卵后,幼螨期、前若期、后若期历期无显著差异,卵期、静息期却显著延长;卵的孵化率、幼螨存活率、若螨存活率、每雌日均产卵量、平均每雌产卵量、雌螨平均寿命均降低;各处理组产卵前期显著延长;产卵期缩短,其中LC30处理组产卵期显著缩短;各处理组的净生殖率(R0)显著降低,LC30组最低;内禀增长率(rm)、周限增长率(λ)均降低,而LC30组显著降低;种群倍增时间(Dt)延长,其中LC30组显著延长;平均世代历期(T)、性比例各处理组均无显著差异。【结论】亚致死剂量(LC10和LC30)除虫脲能够抑制朱砂叶螨的寿命和繁殖力。     

双去甲氧基姜黄素对朱砂叶螨的生物活性及作用方式

在室温26℃±1℃、湿度60%～80%、光照14 h条件下,测定了天然植物活性成分双去甲氧基姜黄素对重要植食性害螨朱砂叶螨各螨态的触杀和熏蒸活性,对幼螨、若螨、成螨的驱避活性,以及对雌成螨的产卵抑制活性.采用玻片浸渍法测得双去甲氧基姜黄素对朱砂叶螨雌成螨48 h的LCso为0.433 mg·mL-1.在0.883 mg·mL-1(LC70)的浓度下,双去甲氧基姜黄素对朱砂叶螨不同螨态触杀活性的大小依次为幼螨＞若螨＞成螨＞卵,其中对幼螨24h和48 h的校正死亡率分别为60.0%和83.3%;对朱砂叶螨各螨态的熏蒸作用不明显,024h和48 h的校正死亡率均小于3%;对幼螨、若螨以及成螨均表现出较强的驱避作用,其中对幼螨的效果最好,不同处理时间的驱避率均在85%以上,其次是若螨,对成螨的驱避性相对较差,72 h的驱避率仅为47.8%.同时对雌成螨有明显的产卵抑制作用,处理后120 h产卵抑制率达到89.3%.表明双去甲氧基姜黄素对朱砂叶螨的主要作用方式为触杀、驱避和产卵抑制作用.     

不同饥饿程度拟小食螨瓢虫对朱砂叶螨的捕食作用

为明确饥饿程度对拟小食螨瓢虫 Stethorus (Allosstethorus) parapauperculus 控害潜能的影响,本研究通过比较不同饥饿程度下拟小食螨瓢虫对朱砂叶螨 Tetranychus cinnabarinus 的功能反应和自身密度干扰效应,探讨不同饥饿程度拟小食螨瓢虫对朱砂叶螨的捕食作用。结果表明,饥饿程度对拟小食螨瓢虫朱砂叶螨的捕食量有明显的影响,瓢虫的取食量与朱砂叶螨的密度呈正相关,表现为饥饿48 h＞饥饿24 h＞未饥饿;拟小食螨瓢虫对各虫态朱砂叶螨的捕食作用均符合Holling Ⅱ模型。在一定空间范围内,拟小食螨瓢虫个体间存在竞争和相互干扰,Hassell Varley模型能较好地反映拟小食螨瓢虫在捕食各虫态朱砂叶螨时受自身密度的干扰情况。在同样饥饿状态下,随着瓢虫自身密度增加,捕食效率降低,干扰效应增大。     

4种蔬菜对朱砂叶螨的抗性研究

４种供试蔬菜品种以对朱砂叶螨Ｔｅｔｒａｎｙｃｈｕｓｃｉｎｎａｂａｒｉｎｕｓ（Ｂｏｉｓｄｕｖａｌ）种群生长发育,繁殖及种群密度有明显增加,品种间存在的抗螨性差异,其中苦瓜抗螨性能,丝瓜,茄子,豇豆则表现在不同程度度的感螨性,朱砂叶螨能够取食苦瓜叶片,但发育历期延长,雌成螨寿命缩短,死亡率较高,而且在高苦瓜上不产卵,朱砂叶螨在豇豆,茄子,丝瓜上,发育历期短,雌成螨寿命长,产卵量大,死亡率低,Ｒ０,γｍ     

Impact of nC24 agricultural mineral oil deposits on the searching efficiency and predation rate of the predatory mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae)

Walking activity, walking straightness, walking speed and searching efficiency of the predatory mite Phytoseiulus persimilis Athias-Henriot were measured on French bean leaf discs that were sprayed with either distilled water, or one of 0.25%, 0.50% and 1.00% w/w aqueous emulsions of an n C24 agricultural mineral oil (AMO). There was no significant difference in percentage of time that mites spent walking in the control (water-sprayed) conditions and in any of the oil treatments. Walking paths were significantly straighter in the oil treatments than in the control, but differences among the oil treatments did not differ significantly. Walking speeds in the oil treatments were significantly slower than in the control and decreased with increasing oil concentration. Deposits of oil at all concentrations significantly suppressed searching efficiency in comparison with control, and searching efficiency in the 1.00% oil treatment was significantly lower than in the 0.25% oil treatment. First predation of P. persimilis on AMO-contaminated eggs of two-spotted mite ( Tetranychus urticae Koch) on unsprayed leaf discs was significantly delayed in all oil treatments in comparison with the control. However there was no significant effect on the overall predation rate. In the tests of P. persimilis predation on AMO-contaminated T. urticae eggs on sprayed leaf discs, the number of first predation occurrences in the first hour was significantly lower in 0.50% and 1.00% oil treatments than in the control. Overall predation rates were significantly reduced by oil but they did not differ significantly among the oil treatments.     

Evaluation of predatory mites and Acramite for control of twospotted spider mites in strawberries in north central Florida

Greenhouse and field experiments were conducted from 2003 to 2005 to determine the effectiveness of two predatory mite species, Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus (McGregor), and a reduced-risk miticide, Acramite 50 WP (bifenazate), for control of twospotted spider mite, Tetranychus urticae Koch, in strawberries (Fragaria x ananassa Duchesne). In greenhouse tests, three treatments consisting of releases of P. persimilis, N. californicus, and an untreated control were evaluated. Both species of predatory mites significantly reduced twospotted spider mite numbers below those found in the control during the first 3 wk of evaluation. However, during week 4, twospotted spider mite numbers on the plants treated with P. persimilis increased and did not differ significantly from the control. Field studies used releases of P. persimilis and N. californicus, applications of Acramite, and untreated control plots. Both N. californicus and P. persimilis significantly reduced populations of twospotted spider mite below numbers recorded in the control plots. During the 2003-2004 field season P. persimilis took longer than N. californicus to bring the twospotted spider mite population under control (< 10 mites per leaflet). Acramite was effective in reducing twospotted spider mite populations below 10 mites per leaflet during the 2003-2004 field season but not during the 2004-2005 field season, possibly because of a late application. These findings indicate that N. californicus releases and properly timed Acramite applications are promising options for twospotted spider mite control in strawberries for growers in north Florida and other areas of the southeast.     

Differential Effects of Plant Species on a Mite Pest (Tetranychus Urticae) and its Predator (Phytoseiulus Persimilis): Implications for Biological Control

The influence of plant species on the population dynamics of the spider mite pest, Tetranychus urticae, and its predator, Phytoseiulus persimilis, was examined as a prerequisite to effective biological control on ornamental nursery stock. Experiments have been done to investigate how the development, fecundity and movement of T. urticae, and the movement of P. persimilis were affected by plant species. A novel experimental method, which incorporates plant structure, was used to investigate the functional response of P. persimilis. Development times for T. urticae were consistent with published data and did not differ with plant species in a biologically meaningful way. Plant species was shown to have a major influence on fecundity (P < 0.001) and movement of the pest mite (P < 0.01), but no influence on the movement of the predator. The movement of both pest and predator was shown to be related to the density of the adult pest mites on the plant (P < 0.001). Plant structure affected the functional response, particularly in relation to the ability of the predator to locate prey at low densities. The impact of these findings on the effective use of biological control on ornamental nursery stock is discussed.     

Biological, Chemical and Integrated Control of Two-spotted Spider Mite Tetranychus urticae on Dwarf Hops

Chemical, biological and integrated programmes for the control of two-spotted spider mite, Tetranychus urticae, were compared on dwarf hops in 1997 and 1998. In both years integrated control, which consisted of an application of the ovicidal acaricide clofentezine followed by a release of the predatory mite Phytoseiulus persimilis at 10 individuals per plant, was the most effective treatment. Similar numbers of spider mites were recorded on plots that were treated with P. persimilis only or with a single application of the acaricide tebufenpyrad, and plots with either of these treatments had higher levels of infestation than the plots under integrated control. The highest numbers of spider mites were found on the untreated plots. This study indicates that integrated control of T. urticae using clofentezine in conjunction with P. persimilis is likely to be more effective than an approach based on chemical or biological measures only. It is suggested that an integrated system would have the added benefit over a pesticide-only programme of reducing pressure on the pest for the selection of strains resistant to acaricides.     

The effect of chrysanthemum leaf trichome density and prey spatial distribution on predation of Tetranychus urticae (Acari: Tetranychidae) by Phytoseiulus persimilis (Acari: Phytoseiidae)

The effect of plant architecture, in terms of leaf hairiness, and prey spatial arrangement, on predation rate of eggs of the spider mite, Tetranychus urticae Koch, by the predatory mite Phytoseiulus persimilis Athias-Henriot was examined on cut stems of chrysanthemums. Three levels of leaf hairiness (trichome density) were obtained using two different chrysanthemum cultivars and two ages within one of the cultivars. The number of prey consumed by P. persimilis was inversely related to trichome density. At low prey densities (less than ten eggs per stem), prey consumption did not differ in a biologically meaningful way between treatments. The effect of prey spatial arrangement on the predation rate of P. persimilis was also examined. Predation rates were higher in prey patches on leaves adjacent to the release point of P. persimilis, but significantly greater numbers of prey were consumed in higher density prey patches compared to low density patches. The predators exhibited non-random searching behaviour, spending more time on leaves closest to the release point. The implications of these findings for biological control and predator-prey dynamics are discussed.     

Side-effects of three pesticides on the predatory mite, Phytoseiulus persimilis (Acari: Phytoseiidae)

Side-effects of three commonly used pesticides in Iran were evaluated on an introduced strain of the predatory mite. Phytoseiulus persimilis Athias-Henriot, reared for about 10 years without exposure to any pesticides. Application of pesticides was carried out either to detached bean leaves using a Potter tower at 1 mg wet deposit per cm2 or by a hand sprayer on bean plants until run off. According to an EPPO decision making scheme, pirimiphos-methyl was found to be harmful (E=90.8%) and heptenophos harmless (E=-3.7%) to the predatory mite in the residual initial toxicity tests. For determination of the hazard class of malathion a field test was found to be necessary (E=59.8%). Categories of 1, 2, 3 were determined for heptenophos, malathion and primiphos-methyl, respectively, using IOBC classification. Despite being harmful, it is possible to use pirimiphos-methyl 10 days before release of P. persimilis. Investigation of the contribution of both lethal and sub-lethal effects to total impact indicated the dominance of lethality in the case of pirimiphos-methyl, while malathion acted by both mechanisms. Heptenophos did not have negative effects on fecundity of P. persimilis but rather caused a higher rate of fecundity in comparison with the control. The mortality found in the heptenophos test was not significantly different from the control.     

The Effects of Timing and Rates of Release of Phytoseiulus persimilis against Two-spotted Spider Mite Tetranychus urticae on Dwarf Hops

Single inoculative releases of the phytoseiid mite Phytoseiulus persimilis were made against the two-spotted spider mite, Tetranychus urticae, on two varieties of dwarf hops in 1996 and 1997 at means of 20, 10, 5, 2.5 and nil per plant, and at up to three timings. The numbers of spider mites recorded on leaves after the predators were released were related inversely to the rates of release. The earliest releases of the predator maintained spider mites at lower population densities than did those made later in the year. In all treatments the numbers of spider mites decreased when the prey:predator ratio reached approximately 10:1.     

Comparison of single and combination treatments of Phytoseiulus persimilis, Neoseiulus californicus, and Acramite (bifenazate) for control of twospotted spider mites in strawberries

Greenhouse and field experiments were conducted from 2003 to 2005 to determine the effectiveness of combining releases of two predatory mite species, Phytoseiulus persimilis Athias-Henriot and Neoseiulus californicus (McGregor), and a reduced-risk miticide, Acramite (bifenazate), for control of twospotted spider mite (TSSM) (Tetranychus urticae Koch) in strawberries. In the greenhouse experiment, a combination treatment of P. persimilis and N. californicus was compared with single treatments of each species, Acramite application, and untreated control. All treatments significantly reduced TSSM numbers compared with the control. Field studies employed two approaches: one investigating the same five treatments as the greenhouse experiment and a second, comparing combination treatments of P. persimilis/N. californicus, Acramite/N. californicus, and Acramite/P. persimilis to single treatments of each and to control plots. Among the combination treatments, the P. persimilis/N. californicus treatment significantly reduced TSSM numbers compared with the control, but was not as effective as N. californicus alone during the 2003-2004 field season. Also, combination treatments of Acramite/N. californicus, and Acramite/P. persimilis significantly reduced TSSM populations compared with the control. These findings indicate that all three combination treatments are promising options for TSSM control in strawberries for growers in northern Florida and other strawberry producing areas of the world.     

Evaluation of dry-adapted strains of the predatory mite Neoseiulus californicus for spider mite control on cucumber, strawberry and pepper

The goal of this study was to evaluate spider mite control efficacy of two dry-adapted strains of Neoseiulus californicus. Performance of these strains were compared to a commercial strain of Phytoseiulus persimilis on whole cucumber, pepper and strawberry plants infested with Tetranychus urticae at 50 +/- 5% RH. Under these dry conditions predators' performance was very different on each host plant. On cucumber, spider mite suppression was not attained by any of the three predators, plants 'burnt out' within 4 weeks of spider mite infestation. On strawberry, all predators satisfactorily suppressed spider mites yet they differed in short term efficacy and persistence. Phytoseiulus persimilis suppressed the spider mites more rapidly than did the BOKU and SI N. californicus strains. Both N. californicus strains persisted longer than did P. persimilis. The BOKU strain was superior to SI in population density reached, efficacy in spider mite suppression and persistence. On pepper, in the first 2 weeks of the experiment the BOKU strain was similar to P. persimilis and more efficacious in spider mite suppression than strain SI. Four weeks into the experiment the efficacy of P. persimilis dropped dramatically and was inferior to the SI and BOKU strains. Overall, mean predator density was highest on plants harbouring the BOKU strain, lowest on plants with P. persimilis and intermediate on plants with the SI strain. Implications for biocontrol of spider mites using phytoseiid species under dry conditions are discussed.