In vivo production of recombinant protein by a baculovirus vector inoculated perorally to the prefinal instar larvae of Bombyx mori L. (Lep., Bombycidae) aided by an optical brightener, Tinopal UNPA-GX

Abstract: Budded particles of nucleopolyhedrovirus (NPV) were found to infect perorally the 4th (prefinal) instar larvae of Bombyx mori L. that were treated by an optical brightener, Tinopal UNPA-GX (Tinopal). Host larvae were fed a diet containing 0.3% (w/w) Tinopal on day 1 in the 4th instar and then fed a diet contaminated by budded particles of NPV (1.0 × 10⁶ TCID₅₀ U/larva) that was pathogenic to B . mori (BmNPV) on day 2 (inoculation schedule 1). Another set of host larvae was fed a diet containing BmNPV budded particles (2.5 × 10⁶ TCID₅₀ U/larva) together with 0.3% (w/w) Tinopal on day 1 in the 4th instar (inoculation schedule 2). Host larvae treated by both schedules died of viral infection. The operation of schedule 2 is simpler than that of schedule 1, although the former required higher doses of the virus for satisfactory infection. We inoculated a baculovirus vector carrying human serum albumin (HSA) gene into 4th instar B . mori larvae by schedule 1. Recombinant HSA was detected in the homogenate of host larvae 4 days after inoculation. The peroral inoculation of BmNPV budded particles aided by Tinopal may thus lead to industrial pharmaceutical production using a baculovirus vector for large numbers of insect hosts.     

Effects of Diflubenzuron on the Development of Bombyx mori (Lepidoptera: Bombycidae)

ABSTRACT This study was conducted to determine the effects of diflubenzuron (DFB) on the growth and development of the silkworm, Bombyx mori (L.). The DFB treatment extended abnormally the larval duration and affected negatively on larval spinning of the 5th instar. All the larvae treated with high DFB concentration (2.5 × 10^-1 and 2.5x 10^-1μg/μl) lost their spinning capability and finally died, whereas 62% of larvae treated with low DFB concentration (2.5 × 10^-1μg/μl)) spinned cocoon. The larval weights depended sensitively on the DFB treatment period rather than on the DFB concentration. The DFB treatment decreased the larval maturity less than 6% without regard to the concentration and treatment period. All the larva, when treated with DFB before the 5th days of the 5th instar, were not matured.     

Effects of environmental factors on virulence of the entomopathogenic fungus, Nomuraea rileyi, against the corn earworm, Helicoverpa armigera (Lep., Noctuidae)

The effects of environmental factors on infection of the entomopathogenic fungus, Nomuraea rileyi , isolated from the corn earworm, Helicoverpa armigera , in Taiwan, to its host insect were studied in the laboratory. The fungus caused higher larval mortality at 20°C than at 30°C when 5 × 10⁶ conidia/ml were sprayed on the fourth instar. However, mortality of the fifth instar injected with 1 × 10³ conidia/larva was not significantly different when the inoculated larvae were incubated from 15 to 30°C. The fungal development in inoculated larvae was best at 20 and 25°C after shifting from 20°C to either lower or higher temperatures. The germination rate was higher at 20 and 25°C than at 30 or 35°C. Conidial germination was better on the wash-off of insect cuticle than on Sabouraud maltose agar with yeast extract. Sporulation on chill-dried cadavers was maximal at 95 or 100% relative humidity than at lower levels of relative humidity. The time required for sporulation was 2 days less at 100% than at 95% relative humidity. Although photoperiod did not affect fifth instar mortality caused by N. rileyi , the median lethal time (LT₅₀) values were shorter upon incubating under light than in darkness. Incubation of infected cadavers under 12 or 24 h light resulted in 20-fold more conidial production than under full darkness. Therefore, illumination is necessary for development of this isolate on insect cadavers.     

麻疯树蛀梢斑螟生物学特性观察及其防治药剂筛选

本文对攀西地区麻疯树(Jatropha curcasL.)人工林中的麻疯树蛀梢斑螟Oncocera faecella Zeller进行了生物学特性观察及其防治药剂筛选的研究。结果表明:该虫在攀西地区1年发生5代,每雌产卵量为(29±17.05)个,卵期(7±1)d,孵化率93.23%;幼虫共4龄,1、2龄取食量小,占整个幼虫生长阶段的10.6%,3、4龄幼虫取食量大,占整个幼虫生长阶段的89.4%;蛹期(13.11±1.05)d,雌雄比为1.04(F)∶1(M),羽化率88.96%。成虫寿命为6～8d。初孵幼虫仅取食叶肉,后缀嫩叶为害梢头,老熟幼虫在叶片上或枯枝落叶中织茧化蛹;以老熟幼虫越冬。对2龄和3龄幼虫进行防治药剂筛选,表明4.5%高效氯氰菊酯1.0×103mg·L-1和0.5×103mg·L-1、30%乙酰甲胺磷乳油0.5×103mg·L-1和0.25×103mg·L-1有很好的防治效果。     

Isolation and phenotypical identification of spore-forming Bacillus species from Jordanian habitats with larvicidal activity against Drosophila melanogaster

Spore-forming Bacillus isolates were recovered from different Jordanian habitats. Of 37 samples, 187 colonies were selected. Forty-six (24·6%) of them were pathogenic to the third instar larvae of Drosophila melanogaster . Larvicidal activity of the isolates was from 0% (non-cultivated soil) to 83·3% (decomposed animal residues). The total spore count per gram weight varied from 0·1 × 10⁵–18 × 10⁵ among the 37 tested samples. Morphological and microscopical identification of the isolates showed the presence of 16 different Bacillus species. The pathogenic isolates were B. thuringiensis (44) and B. sphaericus (2).     

BIOLOGICAL ACTIVITY OF EXTRACT OF STELLERA CHAMAEJASME AGAINST FIVE PEST INSECTS

Abstract Biological activity of an extract of the root of Stellera chameajasme with ethanol by dip (SCEE) against 5 insect pests, Pieris rapae, Plutella xylostella, Spodoptera litura, Myzus persicae , and Ostrina fumalis as tested. The LD, of stomach poison of SCEE against the fifth instar larvae of P. rapae was 12. 32 μarvae day 2 after treatment. With SCEE at concentration of 5, 2. 5 and 50 mg/mL, the fifth instar larvae of P. rapae , the third instar larvae of P. xylostella , and the third instar larvae of S. litura by disc leaf dipped method, had corrected mortalities of 100%, 31. 03 % and 16. 67 % 7 days after treatment respectively. The LC₅₀ of SCEE against M. persicae was 0. 599 2 mg/mL after day 2 treatment by leaf dipped method. With SCEE at 10 mg/mL for the third instar larvae of O. furnucalis by mixture pesticide method, the corrected mortalities of 65. 52% and 85. 72% days 7 and day 14 after treatments respectively. The results showed that SCEE possessed strong biological activity to P. rapae, O. furnacalis , and M. persicae , while possessed weak biological activity to S. litura and P. xylostella .     

亚洲玉米螟幼虫应对大肠杆菌注射的血淋巴免疫应激反应

为研究大肠杆菌Escherichia coli侵染引发亚洲玉米螟Ostrinia furnacalis Guenée幼虫免疫应激反应的机理,本实验测定了分别注射生理盐水以及3×10³,3×10⁴,3×10⁵和3×10⁶个细胞/mL大肠杆菌后亚洲玉米螟5龄幼虫血淋巴中血细胞总数（THC）、颗粒细胞和浆血细胞数量,血清中酚氧化酶（PO）、谷胱甘肽过氧化物酶（GSH-px）、谷胱甘肽还原酶(GR)和谷胱甘肽-S-转移酶(GST)的活性,通过流式细胞仪分析了血细胞活性氧自由基(ROS)水平的动态变化。结果表明：与对照组相比,注射3×10⁵和3×10⁶个细胞/mL大肠杆菌细胞后12 h,可引起亚洲玉米螟5龄幼虫THC及浆血细胞、颗粒细胞数量明显上升(P<0.01),同时应激产生大量ROS。3×10⁴,3×10⁵和3×10⁶个细胞/mL大肠杆菌3个不同浓度处理组均引起幼虫体内PO活性显著升高(P<0.01),诱导幼虫血清中GSH-px,GST及GR的活性上升(P<0.01)。这些结果表明, 亚洲玉米螟幼虫受到大肠杆菌侵染后,其血淋巴细胞免疫和体液免疫能力受到显著影响, 可诱导血清中GSH-px,GST和GR活性升高以清除过多的ROS, 防止其毒害。     

影响蜜蜂球囊菌侵染蜜蜂幼虫的因素及侵染过程观察

为探究蜜蜂球囊菌Ascosphaera apis只侵染封盖前后蜜蜂幼虫的原因及相关侵染机制, 本研究利用实验室饲养的意大利蜜蜂Apis mellifera ligustica幼虫, 给其接种球囊菌孢子, 探究不同接种量（0, 1.0×10², 1.0×10³, 1.0×10⁴, 1.0×10⁵ 和1.0×10⁶ 孢子/mL）、 接种时期（3, 4, 5和6龄幼虫）以及28℃低温处理6 h对蜜蜂球囊菌侵染的影响。同时对处于不同侵染阶段的蜜蜂幼虫做病理学切片, 探究球囊菌侵染的过程。结果显示： 球囊菌孢子接种量与蜜蜂的发病率密切相关（r=0.9883）, 蜜蜂幼虫对低于1.0×10³孢子/mL的侵染有抗性, 与不接孢子的对照组差异不显著（P>0.05）。蜜蜂不同龄期接种发病率的差异是因不同龄幼虫食量不同导致的摄入孢子剂量的不同引起的, 28℃低温处理能够显著提高处于幼虫到蛹转化期蜜蜂的发病率（P<0.05）, 而对取食阶段的蜜蜂幼虫没有影响。病理学研究表明, 在整个幼虫期, 摄入的孢子因中肠没有氧气不生长, 对幼虫没有致病性, 幼虫的取食和发育过程正常, 至幼虫期结束进入蛹期后, 蜜蜂的中后肠接通, 摄入的孢子伴随蜜蜂的蛹便进入后肠并在此迅速萌发生长, 在1~2 d内菌丝即突破体表, 导致蜜蜂死亡。蜜蜂球囊菌选择营养物质储存最多而防御能力较低的幼虫到蛹转化期侵染, 降低了侵染成本, 提高成功率。该研究阐明了蜜蜂球囊菌侵染蜜蜂的机制, 丰富了昆虫与病原菌之间相互作用的内容。     

Effects of azadirachtin on insect cytochrome P-450 dependent ecdysone 20-monooxygenase activity

The effects of the insect growth and ecdysis inhibitor azadirachtin on ecdysone 20-monooxygenase activity were examined in three insect species. Homogenates of wandering stage third instar larvae of Drosophila melanogaster, or abdomens from adult female Aedes aegypti, or fat body or midgut from last instar larvae of Manduca sexta were incubated with radiolabelled ecdysone and increasing concentrations of azadirachtin and the ecdysone 20-monoxygenase activity quantified by radioassay. Azadirachtin was found to inhibit in a dose-response fashion the ecdysone 20-monooxygenase activity associated with all the insect preparations. The concentration of azadirachtin required to elicit approximately 50% inhibition of the ecdysone 20-monooxygenase activity ranged from a low of 1 x 10(-4) M for Drosophila to a high of 4 x 10(-4) M for Manduca midgut.     

Effect of 20-hydroxyecdysone agonist, tebufenozide, on pre-and post-diapause larvae of Dendrolimus pini (L.)(Lep., Lasiocampidae)

Studies of the effects of a novel insect growth regulator (tebufenozide, RH 5992) in pest lepidopterans are extended to its influence on pre- and post-diapause larvae of the pine-tree lappet, Dendrolimus pini (L.) (Lep., Lasiocampidae). Larval diapause was induced under experimental conditions. The relation between the width of head capsule and each larval instar of the experimental populations is presented. The toxicity of tebufenozide applied topically and per os (orally), and its effects on feeding activity were examined. High doses and concentrations (≥100 ng/larva and ≥0.001%) of tebufenozide were toxic and reduced the feeding intensity in larvae of D. pini , however, post-diapause larvae were less sensitive to oral treatment with tebufenozide then pre-diapause insects. In pre-diapausing insects of the fourth instar a greater than four-fold fall in mortality was observed among the insects treated with low doses/ concentrations (0.1–10 ng/larva and 0.00001%–0.001%, respectively). A remarkable stimulatory effect on feeding behaviour was observed in pre-diapausing IV instar larvae when treated with tebufenozide topically, in a dose of 10 ng/larva. A possible ecdysteroid mimicking effect of tebufenozide onto feeding and mortality among diapause-destined D. pini is discussed.     

Food consumption by Chilo partellus (Lepidoptera: Pyralidae) larvae infected with Beauveria bassiana and Metarhizium anisopliae and effects of feeding natural versus artificial diets on mortality and mycosis

Second and third instar Chilo partellus larvae were infected with Beauveria bassiana and Metarhizium anisopliae (both at 1x10(8)conidia/ml) and daily consumption of maize leaves was measured. Infection by the fungi was associated with reduced mean daily food consumption. Reduction in food consumption became evident 3-4 days after treatment with the fungi for second instar larvae and 4-5 days for third instar larvae. Four conidial concentrations, 1x10(5), 1x10(6), 1x10(7), and 1x10(8)conidia/ml, were tested against second instar larvae. Food consumption dropped by 70-85% when the second instar larvae were treated with the fungi at 1x10(8)conidia/ml. Reduction in food consumption by C. partellus larvae infected with B. bassiana and M. anisopliae may offset the slow speed of kill of the fungi. The effect of artificial versus natural diets on mortality and mycoses of second instar larvae treated with the fungi at 1x10(8)conidia/ml was determined. Larvae provided with artificial diet suffered little mortality and mycoses than larvae provided with maize leaves. The LT(50) was longer for larvae provided with artificial diet.     

Experimental Infection of Nosema sp. Ghose in an Unnatural Host Lesioderma sericorne

ABSTRACT. Various doses of a microsporan parasite, Nosema sp., were fed to third and fourth instar larvae of Lesioderma sericorne that infested different types of stored grains. A spore dose of 3 × 10³ spores/individual resulted in a 39% infection rate, reduction in larval and adult weights, and mean spore concentrations of 1.28 ± 0.2 × 10⁸ spores/larva and 1.1 ± 0.2 × 10⁸ spores/adult. At the above dose, mortality was not well marked (about 35% in larvae and 25% in adults). At 3 × 10⁴ spores/individual, the rate of mortality increases to 80% in larvae and 60% in adults. However, more of the pest population (88% of larvae and 73% of adults) died at a dose of 3 × 10⁵ spores/individual. This dose produced mean spore concentrations of 3.91 ± 0.2 × 10⁸ spores/larva and 2.89 ± 0.2 × 10⁸ spores/adult. Insect death was caused by heavy damage to gut epithelia and fat bodies.     

Generation Time and Growth Rate of the Human Intestinal Parasite Blastocystis hominis

ABSTRACT. Blastocystis hominis , an anaerobic intestinal protozoan parasite of man, has a generation time (GT) in axenic culture of 8.5–19.4 h, depending on the strain tested. Average GT of the eight strains was 11.7 h. Zero growth time cell counts of 5.0 × 10⁵/ml to 2.0 × 10⁶/ml rose in 3–5 days to 1 × 10⁷ or 1 × 10⁸ cells/ml. The GT was determined for the 24-h period during which the most rapid growth occurred; about 2% of the B. hominis cells were in division during this time. Division under the culture conditions provided was by binary fission, the usual mode for B. hominis in vitro as well as in vivo. Division times were determined also by direct observation of individual dividing cells in slide cultures. These were usually ca. 40–60 min but sometimes as low as 20 min.     

孢悬液浓度和宿主体型大小对球孢白僵菌对松墨天牛幼虫的致病力的影响

【目的】球孢白僵菌Beauveria bassiana是一种被广泛用于害虫生物防治的生防菌。本研究探讨了孢悬液浓度和宿主体型大小对球孢白僵菌对松墨天牛Monochamus alternatus 幼虫的致病力的影响,旨在为松墨天牛的生物防治提供科学基础。【方法】分别用0.5% 吐温-80(CK)以及1×10⁵, 1×10⁶, 1×10⁷, 1×10⁸和1×10⁹孢子/mL的球孢白僵菌孢悬液接种松墨天牛4龄幼虫,统计接种后15 d内幼虫死亡率和染菌率。同时用最佳浓度(1×10⁹孢子/mL)的球孢白僵菌孢悬液接种体型大小分别为100~150, 200~220, 300~320, 400~420, 500~520和600~650 mg/头的松墨天牛幼虫,测定接种后20 d内幼虫的死亡率和染菌率。【结果】接种1×10⁵~1×10⁹孢子/mL的球孢白僵菌后,松墨天牛4龄幼虫起初活动自如,后在头部出现烧灼状伤并且体色逐渐变红,最后周身长满菌丝。不同浓度下,随球孢白僵菌孢子浓度升高,松墨天牛4龄幼虫校正死亡率和校正染菌率增加。接种1×10⁶~1×10⁹孢子/mL球孢白僵菌孢悬液15 d的松墨天牛4龄幼虫累计校正死亡率均可达到100%,1×10⁷, 1×10⁸和1×10⁹孢子/mL浓度下,松墨天牛达到100%校正死亡率所需时间最少。接种0 (CK), 1×10⁵, 1×10⁶, 1×10⁷, 1×10⁸和1×10⁹孢子/mL球孢白僵菌孢悬液的松墨天牛4龄幼虫校正染菌率在第15天分别为0, 20.00%, 86.67%, 90.00%, 96.67%和100.00%,表现为白僵菌孢子浓度越高,染菌率越高。1×10⁹孢子/mL的接种浓度下,松墨天牛幼虫个体越大,天牛幼虫死亡率和染菌率越高。表现在第20天时,体型大小为100~150, 200~220, 300~320, 400~420, 500~520和600~650 mg/头的幼虫的死亡率分别为76.67%, 76.67%, 66.67%, 93.33%, 100.00%和100.00%,染菌率分别为60.00%, 63.33%, 60.00%, 86.67%, 96.67%和100.00%。【结论】球孢白僵菌悬浮液浓度对松墨天牛幼虫的死亡和侵染有显著影响,表现为随孢子浓度的增加而增加;同时,松墨天牛幼虫个体越大,死亡率和染菌率越高。研究结果对开展利用球孢白僵菌防治松墨天牛具重要借鉴和指导意义。     

一株玫烟色虫草对草地贪夜蛾的致病性研究

草地贪夜蛾Spodoptera frugiperda(J.E Smith)是我国新发现的一种重要外来入侵害虫。为了寻找对草地贪夜蛾有致病性的昆虫病原真菌,本实验采用浸虫法研究了玫烟色虫草Cordyceps(=Isaria)fumosorosea SCAU-IFCF01对草地贪夜蛾1~6龄幼虫的致病力,通过体视镜观察了幼虫感菌后侵染症状和体表病变过程。结果表明:菌株IFCF01可侵染草地贪夜蛾6个龄期的幼虫。4龄幼虫接种后48 h,虫体出现缩短、强直等形态变化;接种后72 h,幼虫死亡且体外形成菌丝层;接种后120 h,虫体被浅玫烟色的分生孢子覆盖。随孢子浓度的升高,幼虫的感病死亡率增加,当浓度达到1×109孢子/mL时,1~3龄幼虫的累计死亡率均为100%,4龄幼虫和5龄幼虫也达到了98.9%和50%,6龄幼虫仅21.1%。5 d后1~5龄幼虫的LC 50值分别为3.74×104、1.17×105、1.86×105、8.09×105和3.03×108孢子/mL。幼虫LT 50值随孢子浓度增加而递减,在浓度为1.0×105~1.0×109孢子/mL的范围内,1龄幼虫和2龄幼虫的LT 50值分别为3.62~1.37 d和4.51~1.65 d;在1.0×106~1.0×109孢子/mL时,对3龄幼虫的LT 50为4.03~1.82 d;浓度为1.0×107~1.0×109孢子/mL时,对4龄幼虫的LT 50为3.47~2.52 d。浓度为1.0×109孢子/mL时,5龄幼虫的LT 50为4.74 d。本研究结果表明,玫烟色虫草菌株IFCF01对草地贪夜蛾幼虫具有较强的致病力,为今后草地贪夜蛾微生物防治提供重要的有效真菌。     

环丙氨嗪对鸡粪中亮斑扁角水虻生长的影响及添加活性炭对环丙氨嗪的解毒作用

【目的】研究环丙氨嗪对鸡粪中亮斑扁角水虻Hermetia illucens幼虫生长发育的影响及添加活性炭对环丙氨嗪的解毒作用。【方法】使用含不同浓度(0, 0.1, 0.25, 0.5, 1, 2.5, 5, 10和15 mg/kg)环丙氨嗪的鸡粪分别饲养3, 4和5龄亮斑扁角水虻幼虫,统计幼虫的生长发育(体重和死亡率)变化;在鸡粪中添加不同浓度(0, 10, 30, 50, 100和150 g/kg)活性炭饲养亮斑扁角水虻3龄幼虫,测定活性炭对其生长发育的影响以及对环丙氨嗪的解毒作用。【结果】在用含一定浓度环丙氨嗪的鸡粪饲养后,亮斑扁角水虻3, 4和5龄幼虫均表现出体节伸长,停止进食,直至死亡。鸡粪中环丙氨嗪对亮斑扁角水虻3, 4和5龄幼虫的致死中浓度(medium lethal concentration, LC₅₀)值分别为0.18, 1.39和6.45 mg/kg。在鸡粪中添加量为30~100 g/kg的活性炭可以显著促进亮斑扁角水虻3龄幼虫的生长发育,并且能够解除环丙 氨嗪对3龄幼虫的毒性,95%有效剂量(95% effective dose, ED₉₅)值为51.83 g/kg。【结论】随着亮斑扁角水虻幼虫龄期增长,其对鸡粪中环丙氨嗪的敏感性逐渐降低。活性炭可用于解除鸡粪中环丙氨嗪对亮斑扁角水虻幼虫的毒性,为生产上应用亮斑扁角水虻处理含环丙氨嗪的鸡粪提供解决方案。     

Larvae of lycaenid butterflies that parasitize ant colonies provide exceptions to normal insect growth rules

Fourth instar larvae of Maculinea species of lycaenid butterfly live as social parasites inside Myrmica ant nests. They show highly unusual growth patterns, with small but regular growth in early phytophagous instars, followed by >10 times the growth predicted by extrapolating the early growth rate (following Dyar's rule) during the final carnivorous instar. This produces striking allometry between head and body size in full-grown larvae (ratios of 4–5% compared with 8–10%). Larvae of the Myrmica ant hosts have a similar growth. Data for c. 150 other lycaenid species showed that species with similar life-histories exhibit the same unusual growth pattern (Phengaris spp., Lepidochrysops spp., Niphanda fused); all others have regular growth throughout their larval life, including the carnivorous species that are parasitic on ants from the first instar. It is suggested that Maculinea-type growth pattern has arisen convergently in at least three unrelated lineages of lycaenids. Selection pressures might include the need for reduced early growth to produce late instars that are small enough to be integrated as brood mimics into ant social systems, combined with the need to achieve at least the same adult size as the ancestral species. Trophic pressures that operate on both sedentary ant and butterfly larvae, which must survive long periods of starvation and grow rapidly when food is abundant, may also be involved.     

一株球孢白僵菌的分离鉴定及其对草地贪夜蛾的致病性

草地贪夜蛾Spodoptera frugiperda(J. E.Smith)是我国于2019年新发现的一种迁飞性重大害虫。为了寻找对草地贪夜蛾有高致病性的昆虫病原真菌,本实验对采自广东省广州市华南农业大学湿地的感菌稻黑蝽Scotinophara lurida若虫僵虫进行了室内分离培养,结合形态学和rDNA-ITS序列分析,采用浸虫法研究了该菌对草地贪夜蛾各龄幼虫的致病力。鉴定结果表明该病原真菌为球孢白僵菌Beauveria bassiana,编号为GZSL-1菌株。菌株GZSL-1可侵染草地贪夜蛾6个龄期的幼虫,随孢子浓度的升高,草地贪夜蛾幼虫感病死亡率增加,当浓度达到1×10~8孢子/mL时,1～3龄幼虫的累计校正死亡率皆为100%,4龄和5龄幼虫也达到57.47%和55.06%,6龄仅25.28%。接菌6 d后1～5龄幼虫的LC_(50)值分别为1.32×10~3、3.42×10~3、1.01×10~4、1.61×10~5和1.23×10~7孢子/mL。幼虫LT_(50)值随孢子悬浮液浓度增加而递减,在孢子浓度为1.0×10~4～1.0×10~8孢子/mL范围内,1龄、2龄和3龄幼虫的LT_(50)值分别为3.58～1.69 d、4.30～1.78 d和5.70～3.12 d;浓度为1.0×10~5～1.0×10~8孢子/mL时,对4龄幼虫的LT_(50)为5.45～4.85 d;浓度为1.0×10~7～1.0×10~8孢子/mL时,对5龄幼虫的LT_(50)为5.04～5.02 d。上述研究结果表明,鉴定的球孢白僵菌菌株GZSL-1对草地贪夜蛾幼虫具有较强致病性,可为草地贪夜蛾微生物防治提供候选菌种资源。     

Growth performance of Epirrita autumnata (Lepidoptera: Geometridae) on mountain birch: trees,broods, and tree x brood interactions

Summary The outcome of herbivore-host plant interactions is partly a function of variation within the two populations. We partitioned variance in herbivore growth performance into components attributable to differences between trees, differences between (full-sib) insect broods, and tree x brood interactions. Growth performance of Epirrita larvae feeding on a small (0.25 ha) population of mountain birch was greatly influenced by differences between individual trees. Up to 49% of the variation in insect growth rate was due to tree effects; 5th instar growth rates ranged from 0.38 to 0.56 mg·mg^-1·day^-1 across a sample of 8 trees. About 25% of the variation in pupal weights and larval periods was due to tree effects; on low quality trees larvae required a longer time to attain lower pupal weights. Differences between trees were also evident in physical and chemical characteristics of the leaves. Insect broods differed in the duration of the larval period (15% of the variance) which led to differences in the pupal weight attained (13% of the variance). However, brood-specific differences in growth rate were modest (6% in the 4th instar) or nonexistent (5th instar). There was no evidence for tree x brood interactions, which refutes the possibility of fine scale adaptation to particular tree phenotypes. Hypotheses to explain the existence of this variability, and to predict its evolutionary and ecological consequences, are advanced.     

Attempts to control cabbage root flies Delia radicum L. and Delia floralis (Fall.) (Dipt., Anthomyiidae) with entomopathogenic fungi: laboratory and greenhouse tests

One laboratory and three greenhouse experiments were conducted to study the pathogenicity and efficacy of Finnish isolates of entomopathogenic hyphemycetous fungi against cabbage root flies. In Petri dishes, exposure to 1.5 × 10¹⁰ spores of Metarhizium anisopliae per dish caused 40–50% mortality of undifferentiated second- and third-stage larvae of Delia floralis , and 1 × 10⁷ spores per dish caused 40–50% mortality of Delia radicum larvae. In one greenhouse test, 1 × 10⁸ and 1 × 10⁹ spores of M. anisopliae and Paecilomyces fumosoroseus reduced the root damage of head cabbage by 20–70% compared with untreated controls, although this was not accompanied by significant reductions in the number of pupae. Only M. anisopliae consistently grew out of larvae and pupae of D. floralis during incubation that followed their recovery from the soil at the end of an experiment testing different formulations of M. anisopliae and Beauveria bassiana , but the frequency of the latent infections of the pest by M. anisopliae was not associated with reduced severity of damage to seedlings of head cabbage.