毒死蜱亚致死剂量对二斑叶螨实验种群动态的影响

【目的】为探讨毒死蜱(Chlorpyrifos)对二斑叶螨Tetranychus urticae Koch种群动态的影响,室内研究了毒死蜱亚致死剂量对二斑叶螨实验种群成螨和若螨的生长发育、存活和繁殖情况的影响。【方法】用浸虫法进行测定,生命表方法分析亚致死效应。【结果】结果表明毒死蜱亚致死剂量LC25处理成螨后,雌成螨寿命、总产卵量、子代孵化率、性比与对照组无显著差异,其净增值率、内禀增长率、周限增长率以及种群加倍时间显著低于对照组。毒死蜱亚致死剂量LC25处理若螨后,总产卵量、净增值率、世代平均周期显著低于对照组,内禀增长率、周限增长率以及种群加倍时间与对照组无显著差异。扩散试验证明毒死蜱对二斑叶螨有较强的刺激扩散作用。【结论】以上结果说明毒死蜱亚致死剂量对不同发育阶段的二斑叶螨发育和繁殖的影响不同,毒死蜱对二斑叶螨的刺激扩散作用可能是引起二斑叶螨再猖獗的原因之一。     

不同葫芦科作物对二斑叶螨的抗性评价

【目的】二斑叶螨Tetranychus urticae Koch是世界性重大农业害螨,葫芦科作物是其重要寄主植物。为明确不同葫芦科作物对二斑叶螨生长发育的抗性/适合性,开展了二斑叶螨在葫芦科作物上的产卵和取食选择性研究。【方法】选择苦瓜、葫芦、南瓜、丝瓜、西瓜、甜瓜和黄瓜作为供试寄主植物,室内采用离体叶片和室外采用活体植株比较了二斑叶螨对7种作物的取食选择性及其种群生存与繁殖动态。【结果】供试7种葫芦科作物中,二斑叶螨对黄瓜的选择率最高,为35.49%,其次为甜瓜和西瓜;二斑叶螨在南瓜和黄瓜叶碟上的生存率和繁殖率高,12 h单雌产卵数分别为9.72粒和7.83粒;在葫芦和苦瓜叶碟上,二斑叶螨48 h螨口减退率达47.5%和32.5%,表现为较低的取食和生存适合度,同时葫芦和苦瓜活体植株上二斑叶螨繁殖率显著低于其他5种葫芦科作物。【结论】二斑叶螨在黄瓜、西瓜和甜瓜上的种群发育适合度高,在葫芦和苦瓜上适合度低。这一结果可为田间防控二斑叶螨生态措施的制定及开展葫芦科作物抗螨性机理和抗螨育种提供科学依据。     

叶螨及两种替代食物对尼氏真绥螨发育和繁殖的影响

在温度25 ℃、相对湿度80％条件下,以油茶花粉、二斑叶螨和腐食酪螨3种食物饲喂尼氏真绥螨,研究不同食物对尼氏真绥螨生长发育和繁殖的影响.结果表明：尼氏真绥螨虽能取食腐食酪螨的卵,但因摄食量不足导致不能完成正常发育;而取食油茶花粉和二斑叶螨能正常完成发育,并进行繁殖.取食油茶花粉的尼氏真绥螨全世代发育历期、雌螨寿命、产卵历期、平均每雌总产卵量分别为6.18 d、24.97 d、16.72 d和23.03粒,取食二斑叶螨的尼氏真绥螨分别为5.67 d、25.72 d、18.17 d和25.38粒;以二斑叶螨为食的尼氏真绥螨发育快,寿命和产卵历期长,平均每雌产卵量高.以油茶花粉和二斑叶螨为食的尼氏真绥螨实验种群数量动态均呈上升趋势,其中以油茶花粉饲养的种群趋势指数最高（I=14.28）,以二斑叶螨饲养的种群加倍时间最短（t=3.5201 d）.     

二斑叶螨对不同品种茄子的选择性与适合度

【目的】为明确二斑叶螨Tetranychus urticae Koch对不同品种茄子的选择性与适合度。【方法】通过二斑叶螨对不同品种茄子的田间选择性试验以及在室内不同品种茄子对二斑叶螨种群数量、个体生长发育和繁殖的影响试验,分析了二斑叶螨对9个茄子栽培品种和1个野生茄子品种的寄主选择性,以及在不同品种上的种群动态、发育历期和繁殖力。【结果】二斑叶螨对野生品种蒜芥茄Solanum sisymbriifolium的选择性最差,在该品种上除卵可以正常孵化外其他时期均不能存活。在茄子S.melongena品种间,二斑叶螨对京茄6号和日友长直壮青长茄的选择性最强,分别达到195和183头/株,对布利塔和长竹丝茄的选择性最差,分别为63.5和59.75头/株。接入20对成螨后第28天,紫龙王4号上的数量最多(1 009头/株),京茄6号和嫁接的京茄6号上的数量次之(分别为981和909头/株)。二斑叶螨在京茄6号上的发育历期最短,为9.31 d;在长丰2号上发育历期最长,为11.08 d。京茄6号、京茄黑霸和嫁接的京茄6号上二斑叶螨开始产卵的前5 d内单雌产卵量分别为35.92,33.20和31.34粒/头,是产卵量较多的3个品种,且3个品种之间差异不显著;紫龙王4号、茄砧1号、布利塔和长丰2号上的产卵量较少,分别为18.56,19.24,22.26和23.36粒/头,且4个品种之间差异不显著。【结论】二斑叶螨对紫黑圆茄类的京茄6号的选择性较强、适合度较高,对紫黑长茄布利塔的选择性和适合度为中等,对野生品种蒜芥茄的选择性和适合度表现为最差。     

不同载体植物对二斑叶螨-深点食螨瓢虫生长发育和繁殖的影响

【目的】筛选出适宜二斑叶螨Tetranychus urticae Koch、深点食螨瓢虫Stethorus punctillum Weise生长发育和繁殖的载体植物,为深点食螨瓢虫的人工生产繁育提供技术支持。【方法】在(25±1)℃,光周期14L︰10D的条件下,测定二斑叶螨在花生Arachis hypogaea L.、豇豆Vigna unguiculata (L.) Walp、玉米Zea mays L.、辣椒Capsicum annuum L.、茄子Solanum melongena L.上的发育历期、产卵量;深点食螨瓢虫在这5种载体植物上的发育历期、产卵量、成虫获得率等。【结果】二斑叶螨和深点食螨瓢虫在不同植物上的生长发育和繁殖均存在显著差异,二斑叶螨在花生上的发育历期最短,为9.8d;在花生和豇豆上的平均产卵量最大,分别是117.2粒和116.0粒。深点食满瓢虫在5种植物上的发育历期由短到长依次为花生和豇豆(差异不显著)、玉米、辣椒、茄子;深点食螨瓢虫在花生、豇豆、玉米、辣椒、茄子上的产卵量依次为112.6粒、103.8粒、85.2粒、68.2粒、53.4粒。成虫获得率在花生、豇豆、玉米、辣椒、茄子上低依次是80.1%、70.3%、66.7%、9.7%、29.8%。【结论】在花生、豇豆、玉米、辣椒、茄子这5种供试植物中,花生是最适宜二斑叶螨和深点食螨瓢虫繁殖的植物。     

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。     

不同营养源添加的人工饲料对加州新小绥螨的生物学影响

【目的】加州新小绥螨Neoseiulus californicus是世界范围内广泛分布的天敌捕食螨,对二斑叶螨Tetranychus urticae防效显著。2010年我国发现其本土品系,并已实现规模化饲养。但传统饲养方法成本较高,为降低生产成本,本研究开展了人工饲料的相关试验。【方法】本文对比了两种饲喂装置的饲养效果,采用3种营养源,以不同添加量配制8种人工饲料,饲喂加州新小绥螨,研究人工饲料对加州新小绥螨的生物学影响。【结果】采用渗透装置,饲喂添加20%柞蚕蛹血淋巴的人工饲料饲养效果较好,加州新小绥螨可以完成生长发育,并产卵,产卵量为7.0粒/雌。用人工饲料饲养雌成螨,其产卵量为27.1粒/雌。【结论】此研究结果对实现人工饲料规模化生产加州新小绥螨提供了重要信息。     

猫眼尺蠖在三种女贞属植物上的实验种群两性生命表

【目的】猫眼尺蠖Problepsis superans是一种鳞翅目尺蛾科食叶害虫, 有报道称它只危害园林植物小叶女贞Ligustrum quihoui Carr., 关于其他寄主及其寄主对其生命特征的影响很少研究。开展本研究有助于了解小叶女贞及其可能寄主金叶女贞Ligustrum×vicaryi Hort.和女贞Ligustrum lucidum Ait.对猫眼尺蠖生长发育和繁殖的影响。【方法】在室内25±1℃, 相对湿度为75%±5%, 光周期为16L∶8D条件下, 组建了猫眼尺蠖在这3种植物上的实验种群年龄-龄期两性生命表。【结果】金叶女贞、小叶女贞和女贞对猫眼尺蠖幼虫历期、产卵量有明显影响, 对卵期、蛹期、产卵前期（指雌虫羽化至开始产卵）、雄虫存活时间等无显著影响。猫眼尺蠖取食金叶女贞幼虫历期（21.33 d）显著短于取食小叶女贞（23.46 d）和女贞(27.28 d), 产卵量（529.1粒/雌）显著高于在小叶女贞（442.5粒/雌）和女贞（339.7粒/雌）上。猫眼尺蠖在金叶女贞和小叶女贞上的内禀增长率(r)、周限增长率(λ)、净增殖率(R₀)无显著差异, 但两者都显著大于在女贞上。猫眼尺蠖在3种植物上的平均世代周期(T)差异显著, 它们从小到大为: 金叶女贞、小叶女贞、女贞, 在3种植物上总繁殖率(GRR)没有显著差异。【结论】金叶女贞和小叶女贞相比女贞提供了猫眼尺蠖较好质量的食物, 金叶女贞和女贞具备作为猫眼尺蠖的寄主或临时寄主的可能。     

迎春花花粉对伪钝绥螨生长发育和繁殖的影响

伪钝绥螨Amblyseius fallacis Garman是控制害螨的有效天敌,研究迎春花花粉和二斑叶螨Tetranychus urticaeKoch对伪钝绥螨生长发育和繁殖的影响,比较伪钝绥螨取食2种食料时各种参数的异同。结果表明,迎春花花粉可使伪钝绥螨正常生长发育并产卵,但发育时间较取食二斑叶螨的长,产卵量与取食二斑叶螨的相当。取食迎春花花粉时伪钝绥螨的内禀增长率、净增殖率和周限增长率均低于取食二斑叶螨时的值,世代平均周期较取食二斑叶螨略短,而种群倍增所需时间更长。由以上结果可知迎春花花粉可作为伪钝绥螨的替代或补充食料。     

Wolbachia在山楂双叶螨中的感染及对寄主生殖的影响

【目的】共生菌Wolbachia在多种叶螨寄主中引起细胞质不亲和及适合度改变,影响寄主的生物学特性。山楂双叶螨Amphitetranychus viennensis是重要的果树害螨,常暴发成灾。本研究旨在明确Wolbachia在山楂双叶螨中的感染情况及对寄主生殖的影响。【方法】采集自然种群的山楂双叶螨,运用多位点序列分型技术（multilocus sequence typing, MLST）对其体内Wolbachia感染率及株系进行分析;通过杂交试验及生物学观察,分析感染Wolbachia对山楂双叶螨单雌产卵量、后代孵化率、性比及死亡率的影响。【结果】山楂双叶螨自然种群感染一种株系的Wolbachia （wVie）,该Wolbachia株系与小黑花椿象Orius strigicollis和丽蝇蛹集金小蜂Nasonia vitripennis中的Wolbachia株系亲缘关系较近,而与叶螨属Tetranychus叶螨感染的Wolbachia株系亲缘关系较远。Wolbachia与4种分化较小的线粒体单倍型相关联。Wolbachia感染雌虫与不感染雌虫产卵量没有显著差异（P>0.05）。不感染雌虫与感染雄虫交配,卵孵化率显著低于其他杂交组合 (P<0.05),但孵化率仍达近75%。各交配组合的后代性比及死亡率变化不明显（P>0.05）。【结论】Wolbachia在山楂双叶螨种群中的侵染历史较短,对山楂双叶螨的产卵力、后代性比、死亡率没有影响。Wolbachia在山楂双叶螨中诱导产生弱的CI表型。     

Reproduction and survival of the predatory bugOrius albidipennis on various arthropod prey

The daily rate of oviposition, fecundity, survival and adult longevity ofOrius albidipennis (Reuter) (Hemiptera: Anthocoridae) were studied in the laboratory in Israel. These parameters were compared on three arthropod prey species: the two-spotted spider mite,Tetranychus urticae Koch; the onion thrips,Thrips tabaci Lindeman; and eggs of the almond moth,Ephestia cautella Walker. The fecundity and survival on the thrips diet (217.2 eggs/female and 98.7%, respectively) and on moth eggs (184.1 eggs/female and 84.6%, respectively) were significantly higher than on the spider mite diet (110.9 eggs/female and 40.4%, respectively). Female longevity was significantly higher onEphestia eggs (63.0 days) than on thrips (45.1 days) and mites (35.1 days). There were no significant differences in male longevity among the three diets (57.5, 64.1 and 54.5 days, respectively).     

Euseiusfinlandicus (Acari: Phytoseiidae) as a potential biocontrol agent against Tetranychus urticae (Acari: Tetranychidae): life history and feeding habits on three different types of food

Life history and reproductive parameters of the generalist predatory mite Euseius (Amblyseius) finlandicus (Oudemans) were studied in the laboratory at 25 +/- 1 degrees C, with a 16L:8D photoperiod and 60 +/- 15% RH, to investigate its response to different food sources: an eriophyid mite Aceria sp., tulip pollen Tulipa gesnerana L., and two-spotted spider mite Tetranychus urticae Koch. Total developmental time of the immature stages was the shortest on eriophyid mites, followed by pollen, and then spider mites. Fecundity was highest on pollen (43.69 eggs; 1.63 eggs/female/day), then eriophyid mites (39.73 eggs; 1.37 eggs/female/day) and lowest on spider mites (18.16 eggs; 0.80 eggs/female/day). Intrinsic rate of increase (Rm), net reproductive rate (Ro) and finite rate of increase (lambda) followed the same pattern [pollen (0.168, 27.96 and 1.183, respectively), eriophyid mites (0.153, 20.81 and 1.167), spider mites (0.110, 9.44 and 1.119)]. Mean generation time (days) was the shortest on pollen (19.90), followed by eriophyid mites (20.02), and then spider mites (20.59). Average spider mite larvae consumed by E. finlandicus during immature stages were 9.18 for males and 11.85 for females. Adult E. finlandicus females consumed an average of 166.38 spider mite protonymphs during adult stage compared to an average of 66.55 by males. The number of prey protonymphs consumed per day by females was highest in the oviposition period, lower in the pre-oviposition period and the lowest in the post-oviposition period. The eriophyid mite as a prey recorded the shortest developmental time, while pollen as food recorded the highest oviposition rate in E. finlandicus. The potential of this predator as a biocontrol agent against T. urticae is discussed.     

Direct and indirect effects of imidacloprid on fecundity and abundance of Eurytetranychus buxi (Acari: Tetranychidae) on boxwoods

Populations of spider mites often reach high levels on urban plants. In many cases, insecticide applications targeting other herbivores trigger outbreaks of spider mites. Recently, elevated populations of spider mites on a diversity of plants in urban landscapes have been associated with applications of imidacloprid, a neonicotinoid insecticide. Imidacloprid has also been linked to increased fecundity in two species of spider mites. In this study, we evaluated the indirect (plant-mediated) and direct impact of imidacloprid on fecundity and longevity of Eurytetranychus buxi Garman (Acari: Tetranychidae), feeding on boxwoods, Buxus sempervirens L. Moreover, we compared the abundance of E. buxi on imidacloprid-treated and untreated boxwoods in the landscape and a greenhouse to determine if changes in the fecundity of mites exposed to imidacloprid were linked to outbreaks of E. buxi. We found that females consuming imidacloprid-treated plants laid more eggs than females feeding on untreated boxwoods, while their longevity remained unchanged. Fecundity was not affected, however, when spider mites were directly sprayed with imidacloprid and consumed foliage of untreated boxwoods. Furthermore, populations of E. buxi were greater on boxwoods treated with imidacloprid in the landscape and greenhouse. On landscape boxwoods, elevated populations of E. buxi persisted into a second year. We also observed general lack of predators of spider mites on treated and untreated boxwoods in the field suggesting that imidacloprid’s eruptive effect on E. buxi stems more from indirect changes in plant quality than from a loss of top-down regulation from E. buxi’s natural enemies.     

Relationship between dispersal and fecundity ofTetranychus urticae Koch (Acari: Tetranychidae) exposed to flucythrinate

The effects of the synthetic pyrethroid flucythrinate on dispersal and fecundity of the two-spotted spider mite,Tetranychus urticae Koch, was investigated using a vial exposure technique that allowed treatment of mites without incidental treatment of host plant and allowed determination of the actual dose received by the mites. Flycythrinate elicited both immediate and delayed dispersal. Immediate dispersal within 120 min posttreatment was more sensitive than delayed dispersal and fecundity at 24, 48, and 72 h posttreatment. The lowest flucythrinate concentrations elicited immediate dispersal without subsequent inhibition of fecundity, providing support for the hypothesis that pyrethroid-induced mite population outbreaks can result from dispersal of healthy mites to areas of low competition. Delayed dispersal, however, was observed only in mites that had reduced fecundity. No significant increases in egg production were observed; however, mites exposed to the lowest concentrations of flucythrinate showed a trend toward increased fecundity at 48 and 72 h posttreatment. Since the mites were treated rather than the host plant, it appeared that the dispersal associated with flucythrinate was manifested primarily through a general stimulation of locomotor activity rather than directional locomotor response.Contribution from the Missouri Agricultural Experiment Station, Columbia, MO, Journal Series No. 10037.     

Secretion of phytase from the roots of several plant species under phosphorus-deficient conditions

Phosphorus (P) deficiency increased the secretion of phytases from roots of various plant species. The secretory phytases were collected with a dialysis membrane tube for 24 hours from roots of sixteen plant species grown with low or adequate supply of P in nutrient solutions. The activity of not only secretory phytase, but also acid phosphatase, increased with the low P treatment in all of the plant species examined. Secretion of phytase by the roots under P-deficient conditions was highest in Brachiaria decumbens CIAT 606, Stylosanthes guianensis CIAT 184 and tomato, moderate in Brachiaria brizantha CIAT6780, Stylosanthes guianensis CIAT 2950, alfalfa, white clover and orchard grass, and lowest in Andropgon gayanus CIAT 621, Stylosanthes capitata CIAT 10280, upland rice, timothy, redtop, alsike clover, red clover and white lupin plants. An immunoreactive protein band that reacted with a polyclonal antibody raised against wheat bran phytase, corresponding to molecular weight 35–40 kD, could be detected in seven of the species tested. These results indicate that the secretory phytase may provide an efficient mechanism for certain plants to utilize inositol hexaphosphate in soil.     

Feed intake and milk production in dairy cows fed different grass and legume species: a meta-analysis

The aim of this meta-analysis was to compare feed intake, milk production, milk composition and organic matter (OM) digestibility in dairy cows fed different grass and legume species. Data from the literature was collected and different data sets were made to compare families (grasses v. legumes, Data set 1), different legume species and grass family (Data set 2), and different grass and legume species (Data set 3+4). The first three data sets included diets where single species or family were fed as the sole forage, whereas the approach in the last data set differed by taking the proportion of single species in the forage part into account allowing diets consisting of both grasses and legumes to be included. The grass species included were perennial ryegrass, annual ryegrass, orchardgrass, timothy, meadow fescue, tall fescue and festulolium, and the legume species included were white clover, red clover, lucerne and birdsfoot trefoil. Overall, dry matter intake (DMI) and milk production were 1.3 and 1.6 kg/day higher, respectively, whereas milk protein and milk fat concentration were 0.5 and 1.4 g/kg lower, respectively, for legume-based diets compared with grass-based diets. When comparing individual legume species with grasses, only red clover resulted in a lower milk protein concentration than grasses. Cows fed white clover and birdsfoot trefoil yielded more milk than cows fed red clover and lucerne, probably caused by a higher OM digestibility of white clover and activity of condensed tannins in birdsfoot trefoil. None of the included grass species differed in DMI, milk production, milk composition or OM digestibility, indicating that different grass species have the same value for milk production, if OM digestibility is comparable. However, the comparison of different grass species relied on few observations, indicating that knowledge regarding feed intake and milk production potential of different grass species is scarce in the literature. In conclusion, different species within family similar in OM digestibility resulted in comparable DMI and milk production, but legumes increased both DMI and milk yield compared with grasses.     

The influence of methyl jasmonate (JA-Me) and B-glucosidase on induction of resistance mechanisms of strawberry against two-spotted spider mite (Tetranychus urticae Koch.)

The goal of the research was to study the influence of methyl jasmonate (JA-Me) and beta-glucosidase treatments on fecundity and preference to infestation and oviposition of two-spotted spider mite feeding on strawberry. The experiments were conducted in laboratory conditions on leaves of Aga and Kent cultivars. Leaves were treated with: a. solution of 0.1% JA-Me in 0.05% Triton X-100 (by spraying); b. beta-glucosidase dissolved in 0.1 M citrate buffer at pH 6 (by petiole); c. 0.05% solution of the Triton X-100 (by spraying); d. 0.1 M citrate buffer at pH 6 (by petiole). In the no-choice test, application of JA-Me on leaves of strawberry caused reducing of number of eggs laid during three days of the experiment. In the choice test, which was carried out for determination of non-preference mechanism of resistance, there was a statistically significant lower number of mites on leaves treated with JA-Me compared to leaves treated with other compounds as well as to non-treated leaves after 24 hours from solutions application. Moreover, at the same experiment, females of two-spotted spider mite laid the least number of eggs on leaves treated with JA-Me. Analysis conducted using liquid chromatography method, revealed increase of the level of phenolic compounds like chlorogenic acid and rutin on leaves treated with JA-Me. Thus, it appears that JA-Me may be involved in antybiosis or non-preference mechanisms of resistance of strawberry to two-spotted spider mite.     

Biocontrol of Two-spotted Spider Mite Tetranychus urticae on Dwarf Hops by the Phytoseiid Mites Phytoseiulus persimilis and Neoseiulus californicus

Two female Phytoseiulus persimilis and their offspring eliminated two-spotted spider mite Tetranychus urticae from hop leaf discs faster than two female Neoseiulus californicus and their offspring at 25°C. A combination of one female of each species and their offspring eliminated spider mites faster than the N. californicus alone, but slower than P. persimilis alone. Air relative humidities of 55% and 93% had no effect on predation. Both predator species cannibalised eggs and juveniles when spider mite numbers were low. In field experiments in 1996, fewer spider mites were recorded where P. persimilis was released, irrespective of the presence of N. californicus. Pest numbers on cv. 'First Gold' were lower than on cv. 'Herald'. No differences were recorded between the numbers of spider mite eggs in predator release treatments on 'First Gold', but fewer active stages of spider mites were recorded on plots with P. persimilis than controls soon after the time of peak pest population densities. On 'Herald', fewer spider mite active stages and eggs were recorded where predators were released than on untreated controls.     

Lima bean�Clady beetle interactions: spider mite mediates sublethal effects of its host plant on growth and development of its predator

Cultivated plants can have negative effects on natural enemies that attack spider mites. In this study, we tested the hypothesis that spider mites mediate effects of a lima bean, Phaseolus lunatus L., cultivar on the life history of a lady beetle Stethorus punctillum Weise. We provisioned laboratory arenas with two-spotted spider mites, Tetranychus urticae Koch, from planters containing Henderson Bush Bean or Fordhook 242 lima bean plants and monitored the growth, development, larval survival, fecundity, and adult life span of predators. We determined the protein content and the linamarin (a cyanogenic glycoside) content in foliage, spider mites, and predators. Predators took longer to develop and were smaller sized when consuming mites from the Henderson foliage. There was no significant mite-mediated effect of cultivar on predator fecundity or life span. Although soluble protein was greater in foliage of the Henderson than the Fordhook cultivar, mites contained less protein when reared on the Henderson, and predators contained less protein when fed with mites from the Henderson. Linamarin content was greater in Henderson than Fordhook foliage, and greater in spider mites and predators in the Henderson treatment. Linamarin in Henderson foliage may reduce the ability of spider mites to utilize plant protein. As a result, prey quality is reduced and predators that feed on these prey (from the Henderson treatment) grow at a slower rate and are smaller sized than their cohorts (from the Fordhook treatment). In conclusion, T. urticae mediates the effects of the Henderson cultivar on S. punctillum development but not fecundity or life span.