Effect of temperature on life history of the predatory mite Amblyseius (Neoseiulus) californicus (Acari: Phytoseiidae)

Amblyseius (Neoseiulus) californicus is an indigenous mite in Japan that feeds on many spider mite species. We evaluated the development, survivorship and life-history parameters of A. californicus on a diet of eggs of Tetranychus urticae (red form). More than 97.3% of A. californicus eggs hatched and more than 81.6% of newly hatched larvae attained maturity at temperatures between 15 and 35 degrees C. Females oviposited at 37.5 degrees C, but no eggs hatched. At 40 degrees C, no females laid eggs. The lower threshold temperature from egg to oviposition was 10.3 degrees C and the thermal constant was 86.2 degree-days. Based on these data, the maximum number of generations that could complete development in a year under field conditions in Ibaraki, central Japan, would be between 21 and 28. At 25 degrees C, females laid a mean of 41.6 eggs during a mean oviposition period of 19.4 days. The intrinsic rates of natural increase (rm) were 0.173 at 20 degrees C, 0.274 at 25 degrees C and 0.340 at 30 degrees C.     

新型球孢白僵菌孢子悬乳剂的高效杀蚜活性及其评价方法

用球孢白僵菌（Beauveria bassiana）SG8702的孢子悬乳剂与未剂型化孢子粉对桃蚜进行了杀蚜活性对比测定。孢子悬乳剂与孢子粉分别用水稀释成5个序列浓度,对甘蓝叶片上蚜虫进行相同时间的弥雾接种,前者孢子附着量分别为1.5～701.1个孢子/mm2 ,后者附着量分别为2.8～1005.9个孢子/mm2。蚜虫接种后置于23℃和12L：12D条件下饲养,定时观察8d。经时间—剂量—死亡率模拟分析,悬乳剂的剂量效应参数明显高于孢子粉,且杀蚜时间效应提前。用模型参数估计悬乳剂和孢子粉的LC50,接种后第4天分别为9.0和634个孢子/mm2,第7天为3.3和5.3个孢子/mm2。悬乳剂和孢子粉的LT50随叶面孢子附着量增大而下降,在100个孢子/mm2下为3.2d和4.5d。这表明孢子悬乳剂的杀蚜活性比未剂型化的孢子粉显著增强。作者讨论了杀虫微生物制剂评价的技术规范问题。     

飞虱虫疠霉继发性感染对桃蚜数量增长的控制作用

用飞虱虫疠霉（Pandora delphaics)“孢子浴”接种的桃蚜(Myzus persicae)无翅成蚜在离体甘蓝菜叶片（65cm^2)上建立蚜群,在不同温度（10－30℃）和湿度（74％－100％RH）的组合条件下任其繁衍,发病和交互感染,以评价该菌的控蚜效果。在25个温,湿度组合处理（8次重复,每重复含3头接种成蚜)中,蚜群均不同程度的发病死亡,在历时30d的观察中,以高温（20－30℃）,高湿（95％RH）组合条件下的蚜群发病快且死亡率高,蚜尸上产生的孢子有效地引起若蚜继发性感染。与相同温度下不带菌的对照蚜群相比,次于30℃下,各湿度除个别例外,第8d的控蚜率达30％以上,第20d达80％以上。在10℃和15℃下,控蚜效果一般不如上述较高温度下,且与湿度的关联程度相对较低,但最大控蚜效果均发生在100％RH处理中。结果表明,飞虱虫疠霉用于蚜虫防治的潜力很大,值得深入研究和开发利用。     

Temperature-dependent fumigant activity of essential oils against twospotted spider mite (Acari: Tetranychidae)

Fumigant activity of 34 commercial essential oils was assessed on female adults and eggs of twospotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) at three temperatures (5, 15, and 25 degrees C). Common thyme, cinnamon, and lemongrass oils were equally effective on twospotted spider mite adults showing 85.8-100% mortality at 5 and 10 microl/liter air at 25 degrees C. At a lower temperature of 15 degrees C, lemongrass and peppermint resulted in > or =90% mortality of adults at 10 microl/liter air. Only lemongrass was relatively active at 5 microl/liter air, at 15 degrees C. At 5 degrees C, lemongrass and peppermint caused significantly higher adult mortality than controls but only at 10 microl/liter air. Common thyme oil showed the highest ovicidal activity at 5 microl/liter air at 25 degrees C. Among the main components of common thyme and lemongrass oils, citral was lethal to twospotted spider mite adults at all tested temperatures. Carvacrol, thymol, and citral caused the same inhibitory effects on the hatch of twospotted spider mite eggs at 25 degrees C. However, citral was more active than other compounds to twospotted spider mite eggs at 15 degrees C. Therefore, we conclude that citral has the best potential for development as a fumigant against twospotted spider mite on agricultural products harvested late in the growing season.     

温湿度对安徽虫瘟霉在桃蚜居群中流行的影响

用安徽虫瘟霉(Zoopphthoraanhuiensis)接种桃蚜(Myzuspersicae)无翅成蚜3头和健蚜3头组成新的蚜群若干,在不同温湿组合条件下任其繁殖、发病和传染,以评价温湿度对该菌在蚜群中流行的影响.持续26d观察,在偏低温与各湿度(90～100%RH)的组合中均成功诱发了蚜病流行,其程度受湿度影响较小.在10℃与各湿度组合中,最终感病死亡率为72.9%～98.2%,15℃下为78.7%～94.4%,流行强度极大.而20℃下仅100%RH诱发了高强度流行病,其余湿度下感病死亡率仅为5.1%～12.8%.在25℃,100%RH下死亡率仅27.2%.与所有湿度组合中的对照蚜群相比,10℃下流行病控蚜效果为89.5%～96.9%,15℃下为96.1%～98.2%,20℃下为45.9%～85.7%,25℃下为56.4%～69.7%.逐步回归分析表明,安徽虫瘟霉引发的蚜病流行与温度及其相对湿度和蚜群带菌后天数的互作项密切相关(r2=0.82,a＜0.01),这些变量在很大程度上决定了安徽虫瘟霉是否在蚜群中流行.     

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.     

飞虱虫疠霉分生孢子在不同温湿度组合条件下的存活率*

用荧光染色法研究了不同温度（１０～３０℃）和湿度（５１～１００％ＲＨ）组合条件下飞虱虫疠 霉 Ｐａｎｄｏｒａ ｄｅｌｐｈａｃｉｓ分生孢子的存活率。在无放回抽样观察中,孢子弹射后第２４ ｈ的存活 率在５１％、７４％、８５％、９０％、９５％和１００％ＲＨ与不同温度的组合中分别为４２～８１％、６９～８９％、７０～ ９５％、 ６７～１００％、 ７６～１００％和 ５６～１００％。存放４个月后,不同温度下的孢子存活率在 ５１％、 ７４％、 ８５％和 ９０％ＲＨ下分别为 ５５～７４％、 ５２～８７％、 ３８～７３％和 １～６５％。而在≥９５％ ＲＨ下孢子存活率 ２４ｈ 后锐减,至第７ ｄ几乎全部失活。以上结果表明,弹射后的飞虱虫疠霉孢子在头２４ ｈ的存活 易受低湿影响,但存活下来的孢子能继续在低湿下存活较久;饱和或接近饱和的高湿度最不 利孢子长久存活。     

Influence of temperature, photoperiod and humidity on oviposition and egg hatch of the root-feeding flea beetle Longitarsus bethae (Chrysomelidae: Alticinae), a natural enemy of the weed Lantana camara (Verbenaceae)

The root-feeding flea beetle Longitarsus bethae Savini & Escalona, was introduced into South Africa as a candidate biological control agent for the noxious and invasive weed, Lantana camara L. As part of the study to predict the beetles' survival in its new range, the influence of climatic conditions on its egg development and reproductive performance were investigated in the laboratory. The threshold temperature (T degrees) and degree-days (DD) required for egg hatch were determined after exposing the eggs to various constant temperatures (12, 17, 22, 27 and 32 degrees C) in separate growth chambers. The DD required for egg hatch was 178.6, and the temperature threshold required for egg hatch was 11.3 degrees C. Survival of eggs varied from 27 to 56% at 32 and 17 degrees C, respectively, and was optimum between 17 and 25 degrees C. Oviposition was examined under high and low relative humidity (RH) regimes while egg hatch was determined at six RH levels, each maintained in a separate controlled growth chamber set at a constant temperature (25 degrees C). Whilst RH had no influence on oviposition, eggs were highly susceptible to aridity, and continuous exposure to relative humidity below 63% for more than three days was wholly lethal at 25 degrees C. Optimum egg hatch occurred at RH between 85 and 95% for up to 12 days. The effect of day length on oviposition and subsequent egg hatch was investigated under two photoperiod regimes. Neither oviposition nor subsequent egg hatch was influenced by photoperiod. The knowledge obtained will be useful for mass rearing as well as field release programmes for L. bethae.     

Induction of egg hatching by high humidity in the cicada Cryptotympana facialis

The timing of egg hatching in Cryptotympana facialis was examined in relation to short-term weather conditions. The brief underwater submergence, once a week, of dead twigs bearing cicada egg nests resulted in high hatching rates both at 25 degrees C and under outdoor conditions protected from rainfall. Under outdoor conditions with natural rainfall, most eggs hatched on rainy days. There was a significant positive correlation between the number of hatching eggs and daily relative humidity (RH). When eggs picked from twigs were exposed to various humidity levels, many eggs hatched quickly at higher humidity without direct contact with liquid water. Newly hatched nymphs showed a low tolerance to desiccation; at 81% RH at 25 degrees C, most of them died within 6 h. Under outdoor conditions, most nymphs died within 2 h on sunny days, whereas nymphs survived longer on rainy days. When newly hatched nymphs were released on dry ground, only 24% of them succeeded in burrowing into the soil, and many were killed by ants or desiccation. However, 92% of nymphs released onto wet ground successfully burrowed into it. The direct induction of hatching by high humidity ensures the survival and establishment in the soil of newly hatched nymphs in this species.     

Development of Iphiseiodes quadripilis (Banks) (Acari: Phytoseiidae) on pollen or mite diets and predation on Aculops pelekassi (Keifer) (Acari: Eriophyidae) in the laboratory

Development and reproduction of Iphiseiodes quadripilis (Banks) were evaluated on single food diets of pollen (Malephora crocea Jacquin [ice plant] or Quercus sp. [oak]), spider mites, [Eutetranychus banksi (McGregor) or Panonychus citri (McGregor) (Acari: Tetranychidae)], or the citrus rust mite Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae). Experiments were conducted in an environmental chamber at 28 degrees +/- 1 degrees C, 14:10 (L:D) daylength, and 45% RH. I. quadripilis completed development and laid viable eggs that subsequently hatched on diets of either ice plant or oak pollen or eggs and motile stages of E. banksi. P. citri was acceptable as prey, but survival of larvae to adults was only 36%, whereas survival on E. banksi, ice plant pollen, and oak pollen was 48, 60, and 68%, respectively. The webbing produced by P. citri seemed to inhibit foraging behavior of I. quadripilis larvae and nymphs. Larvae of I. quadripilis developed only to the second nymphal instar on a diet of P. oleivora alone or water alone. Starved I. quadripilis females and deutonymphs were observed preying on the pink citrus rust mite, Aculops pelekassi (Keifer) (Eriophyidae). During 4-min observation trials, two series of I. quadripilis fed on 1.8 +/- 0.47 and 3.5 +/- 0.45 A. pelekassi motile stages after being starved for 6 and 24 h, respectively. I. quadripilis females did not prey on P. oleivora in arenas containing both rust mite species.     

Life history of hawthorn spider mite Amphitetranychus viennensis (Acarina: Tetranychidae) on various apple cultivars and at different temperatures

Development duration and reproduction rate of hawthorn spider mite Amphitetranychus viennensis (Zacher) were carried out on five different apple cultivars (Amasya (local cultivar), Golden Delicious, Granny Smith, Starking Delicious and Starkrimson Delicious) at 25 degrees C, 65 +/- 10% RH and 16:8 L:D. In addition, the same parameters were determined on Golden Delicious leaves at three constant temperatures (20, 30 and 35 degrees C, 65 +/- 10% RH and 16:8 L:D) in the laboratory. A. viennensis showed a better performance on Golden Delicious than on the other apple cultivars. This was mainly due to a short development time (10.7 days), high daily egg production (5.2 eggs/female/day) and early reproduction peak. The highest intrinsic rate of natural increase (rm) was determined on the variety Golden Delicious (rm = 0.247/day), while the lowest one was observed on the variety Starking Delicious (rm = 0.215/day). The developmental periods of A. viennensis varied from 7.4 to 18.8 days at 35 and 20 degrees C for females, while it varied from 7.9 to 17.2 days at 30 and 20 degrees C for males. The development threshold of the eggs and pre-adult stages were 9.72 and 9.07 degrees C, total effective temperature was 72.99 and 185.18 degree-days, respectively. The mean generation time (To) of the population ranged from 16.13 days at 30 degrees C to 29.15 days at 20 degrees C. The net reproductive rate (R0) increased from 54.33 female/female at 20 degrees C to 78.34 female/female at 25 degrees C, and decreased to 75.71 female/female at 30 degrees C. The highest intrinsic rate of increase (rm) was reached at 30 C (rm = 0.268/day), the lowest one at 20 degrees C (rm = 0.136/day).     

常用化学杀螨剂对两种生防真菌孢子的相容性测定

用营养液萌发法和平板萌发法测定了10种常用化学杀螨剂与球孢白僵菌（Beauveria bassiana）和玫烟色拟青霉（Paecilomyces fumosoroseus）分生孢子的生物相容性.结果表明,营养液萌发法比平板法灵敏.以24 h内的孢子萌发率作为指标,供试杀螨剂的常用浓度及其5和10倍稀释液对活孢率的影响在不同杀螨剂间差异极显著,并在两种真菌间也存在差异.三唑锡、浏阳霉素、三氯杀螨醇和阿维菌素对生防真菌孢子的抑制力很强,不宜混用.速螨酮、克螨特、乐斯本、尼索朗及双甲脒等杀螨剂与真菌孢子的相容性优良,可与菌剂田间混用.将速螨酮、克螨特和乐斯本分别按3种浓度与白僵菌的孢子悬乳剂混配后在4 ℃恒温和室内变温下长期共贮,结果显示,3种杀螨剂对孢子活力的影响迥异,混配制剂在室内变温下的贮存期均未达到12个月,离商品化的要求差距较大.乐斯本的长期相容性相对较优,与菌剂低浓度混配可在常温下贮存6.5个月,中浓度和低浓度混配在4 ℃下可贮存12个月.     

两种杀虫真菌制剂对茶小绿叶蝉的田间防效评价

于2002年盛夏在浙江遂昌一高山茶园对茶小绿叶蝉(Empoasca spp．)进行了真菌杀虫剂的田间药效试验。所用菌剂为球孢白僵菌(Beauveria bassiana)和玫烟色拟青霉(Paecilomyces fumosoroseus)的纯孢子悬乳剂及其与3％吡虫啉10％可湿剂的混配剂．各菌剂稀释500倍喷雾2次,间隔12d．结果表明。两种真菌的混配剂明显优于纯菌剂,其中球孢白僵菌混配剂的最高防效达83．4％,而玫烟色拟青霉的最高防效为71．3％．根据25d期间历次调查结果计算平均防效,球孢白僵菌混配剂达66．8％,玫烟色拟青霉混配剂为62．1％,含微量吡虫啉的矿物油为50．3％,球孢白僵菌和玫烟色拟青霉的纯菌剂分别为49．5％和19．0％,结合试验期间气候及田间种群结构特征,讨论了各处理问差异的来源及提高真菌杀虫剂控制茶小绿叶蝉效果的可能途径。     

Factors affecting sporulation and germination of Pandora nouryi (Entomophthorales: Entomophthoraecae), a pathogen of Myzus persicae (Homoptera: Aphididae)

Pandora nouryi discharged large numbers of primary conidia between 8 and 25°C from cadavers on the surface of water-agar. At 8°C conidial discharge lasted for 120 h, but most conidia were produced within 48 h when temperature was >15°C. Saturated humidity alone was not enough to allow for sporulation to occur freely and where RH?<?95%, no conidia were discharged. Light did not affect the pattern of conidial production nor the total number of conidia. Germination percentages of conidia on the surface of water-agar were 40 and 66% at 8 and 30°C, respectively, and were significantly lower than that at 15–25°C where germination was >95%. Conidia on leaves germinated well when RH?>?74%, while no germination occurred when RH?<?100% on cover slips. All eight insecticides tested entirely inhibited conidial germination at recommended doses (R), in particular, both the organophosphorus pesticides Lorsben (chlorpyrifos) and the organochlorine pesticides Thiodan (endosulfan) completely inhibited conidial germination even at 0.2R dose.     

The entomopathogenic fungus Beauveria bassiana and its compatibility with triflumuron: effects on the twospotted spider mite Tetranychus urticae

Laboratory studies were conducted to determine the effects of the mycoinsecticide Naturalis-L (Beauveria bassiana conidial formulation) on the twospotted spider mite Tetranychus urticae. Compatibility of B. bassiana with triflumuron (benzoylphenyl urea typically used as an insecticide, but also with acaricide effects), was also investigated in order to incorporate both in the control of this pest. For each juvenile stage, 180–22,800 viable conidia/mL on deutonymphs, 380–12,160 viable conidia/mL on protonymphs, and 712–7480 viable conidia/mL on larvae were evaluated. For the adult stage, the concentrations ranged from 213 to 54,720 viable conidia/mL. The mortality data used in the analysis were those accumulated after 5 days of treatment for deutonymphs and protonymphs, 7 days for larvae and 9 days for adults. The lethal concentration to kill 50% (LC₅₀) for the juvenile stages was 3184 viable conidia/mL (their probit-log concentration regression lines were the same), and 1949 viable conidia/mL for adults. No significant differences in mortality were observed among egg age classes (24-, 48-, 72-, and 96-h-old eggs) at the tested concentrations (1400–22,800 viable conidia/mL). When B. bassiana was combined with 0.25 g Alsystin (25% triflumuron as a wettable powder)/L, mite egg mortality decreased significantly. Triflumuron reduced mycelial growth but not conidial germination of B. bassiana. This fungus is a possible candidate to be included in integrated pest management programs with triflumuron of T. urticae. In such programs, the possible antagonist effects of triflumuron should be considered.     

Effect of formulated Metarhizium anisopliae on eggs and eclosing nymphs of Triatoma infestans

Little is known about the ovicidal effects of fungi that attack nymphs and adults of triatomine vectors. A combined formulation of Metarhizium anisopliae IP 46 conidia prepared with diatomaceous earth (DE) and vegetable oil was tested against eggs of Triatoma infestans. Eggs were highly susceptible to fungal infection at relative humidity close to saturation [>98% relative humidity (RH)] but not at 75% RH regardless of the formulation applied. Susceptibility of eggs decreased with longer post‐ovipositional embryonation periods before treatments. The eventual eclosion of nymphs was best suppressed by application of conidia prepared with DE + oil and at a >98% RH incubation. Moreover, nymphs were less affected by the fungus when exposed for only a 24‐h period after eclosion to a treated surface than individuals that were in constant contact with the conidia. These findings contribute to a better understanding of the potential of M. anisopliae as an agent against all developmental stages of T. infestans.     

蝉拟青霉LB菌株的生物学特性

本文研究碳源、氮源、温度、湿度、pH值和光照等对蝉拟青霉LB菌株生长、产孢和孢子萌发的影响.结果表明,适合该菌株菌落生长和产孢的最佳碳源是可溶性淀粉和蔗糖,最佳氮源为蛋白胨;菌丝生长和孢子萌发的最适温度范围是25℃～27℃,产生分生孢子的最适温度是25℃;分生孢子萌发所需湿度范围是RH 90%～100%,当RH低于90%时很难萌发;在pH值4～10的范围内该菌能生长和产孢,菌丝生长最适pH为6,产生分生孢子和孢子萌发最适pH范围为6-7;光照处理对该菌产孢有一定的影响;分生孢子的致死条件为55℃ 10min.生物学特性显示,蝉拟青霉LB菌株是一株对营养要求不高、对环境适应能力较强的昆虫病原真菌.     

Reproductive bionomics of the soft tick, Ornithodoros turicata (Acari: Argasidae)

The effects of different temperatures and relative humidities (RHs) were tested on various reproductive parameters of Ornithodoros turicata, an argasid tick that inhabits gopher tortoise burrows in Florida, USA. The pre-oviposition, oviposition and incubation periods of the ticks decreased as temperature increased. These periods were also affected by the RH. The number of eggs oviposited was affected significantly by the combined effect of temperature and RH. Fewer eggs were laid by ticks in the 24°C regimes and the 27°C/95%RH regime compared to those in the other temperature/RH groups. There was an inverse relationship between the number of eggs oviposited and the percentage of hatched larvae that was correlated with the temperature and RH. Ticks reared at 27°C/90%RH and 30°C/90%RH laid more eggs than those reared in the other combinations of temperature and humidity but fewer larvae hatched from these eggs. The reproductive fitness index (RFI) values were highest in females held in the 24°C groups and the 30°C/95%RH group, although significantly more larvae hatched at the lower temperatures. The optimum reproductive conditions for O. turicata under laboratory conditions appear to be 24°C and 90–95%RH. While mating occurred at all temperatures, none of the females laid eggs at 22°C. The ticks may move preferentially to low temperatures when not feeding to remain above the critical equilibrium humidity and/or below the critical metabolic level necessary for prolonged survival. However, most female ticks oviposited after 45 days when moved to 27°C/95%RH. Ornithodoros turicata females may have a limited capability to delay oviposition until an optimal microenvironment for egg deposition can be located in the burrow.     

Hirsutella thompsonii and Metarhizium anisopliae as potential microbial control agents of Varroa destructor,a honey bee parasite

The potential of Hirsutella thompsonii Fisher and Metarhizium anisopliae (Metschinkoff) as biological control agents of the parasitic mite, Varroa destructor Anderson and Trueman was evaluated in the laboratory and in observation hives. In the laboratory, time required for 90% cumulative mortality of mites (LT(90)) was 4.16 (3.98-4.42) days for H. thompsonii and 5.85 (5.48-7.43) days for M. anisopliae at 1.1 x 10(3) conidia mm(-2). At a temperature (34+/-1 degrees C) similar to that of the broodnest in a honey bee colony, Apis mellifera L., H. thompsonii [LC(90)=9.90 x 10(1) (5.86-19.35) conidia mm(-2) at Day 7] and M. anisopliae [LC(90)=7.13 x 10(3) (2.80-23.45) conidia mm(-2) at Day 7] both showed significant virulence against V. destructor. The applications of H. thompsonii to observation hives resulted in significant mortality of mites, and reduction of the number of mites per bee 21 and 42 days post-treatments. The treatments did not significantly affect the mite population in sealed brood. However, the fungus must have persisted because infected mites were still observed [82.97+/-(0.6)%] 42 days post-treatment. In addition, the fungus was found to sporulate on the host. A small percentage [2.86+/-(0.2)%] of dead mites found in the control hives also showed fungal infection, suggesting that adult bees drifted between hives and disseminated the fungus. H. thompsonii was harmless to the honey bees at the concentrations applied and did not have any deleterious effects on the fecundity of the queens. Microbial control with fungal pathogens provides promising new avenues for control of V. destructor and could be a useful component of an integrated pest management program for the honey bee industry.     

Effects of Temperature and Relative Humidity on Development,Reproduction, and Predation in Feltiella acarisuga (Vallot) (Diptera: Cecidomyiidae)

The predatory gall midge Feltiella acarisuga (Vallot) (Diptera: Cecidomyiidae) is a biological control agent for twospotted spider mites on greenhouse vegetable crops. Effects of temperature and relative humidity (RH) on development of immatures, reproduction, and prey capture were determined in order to confirm the suitability of F. acarisuga for use in greenhouses. Developmental time ranged from 10 days at 27°C to 34 days at 15°C. At 20°C, developmental time was significantly shorter at 96% RH than at 84% RH. There was very poor survival of immatures at 64% RH and none at 36%. Lifespan of adult females decreased with increasing temperature, but temperature had no significant effect on number of eggs laid. At 20°C, lifespan was longer at 84 and 96% RH than at 64 or 36% RH. The number of spider mites attacked by 3-day-old larvae over 8 h increased with increasing temperature from 15 to 27°C. The number of mites attacked also increased with increasing RH at 27°C. We conclude that F. acarisuga will complete its life cycle and reproduce under conditions typically found in vegetable greenhouses in northern temperate climates. However, extended periods of low RH (<60% RH) could reduce reproduction and survivorship sufficiently to impair the predator's action against spider mite populations.