【作者】 姜渝；

【导师】 冯明光；

【作者基本信息】 浙江大学 ， 农业昆虫与害虫防治， 2006， 硕士

【摘要】 丝孢类昆虫病原真菌作为经典的害虫生防真菌,在农林害虫生物防治中发挥着重要作用。在本实验室若干前期工作的基础上,本研究有选择地测定了常用化学杀螨剂与两种有杀螨潜力的丝孢类生防真菌的短期和长期相容性,评价了生物相容性最佳的化学杀螨剂与杀螨真菌制剂协同互作对朱砂叶螨(Tetranychus cinnabarinus)的杀卵效果。主要研究结果总结如下: 常用化学杀螨剂与两种生防真菌孢子的短期相容性 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,两种生防真菌分生孢子与化学杀螨剂共处24h后,萌发率因杀螨剂品种及浓度而异。结果表明,活孢率的差异在10种杀螨剂的不同浓度下均以营养液萌发法更为灵敏。以24h内的孢子萌发率作为指标,供试杀螨剂的常规用药浓度(高)及其5倍(中)和10倍(低)稀释浓度对活孢率的影响在不同杀螨剂间差异极为显著(ρ<0.01),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,可与菌剂在田间混用。 球孢白僵菌与化学杀螨剂的长期相容性将速螨酮、克螨特和乐斯本三种短期相容性很好的化学杀螨剂分别按上述三种浓度与球孢白僵菌孢子悬乳剂混配后在4℃恒温和室内变温下进行长期共贮试验。通过定期抽样测定活孢率,发现三种杀螨剂对孢子活力的影响迥异。在室内变温下,克螨特的高、中、低浓度均在混贮1天后就使孢子完全失活;高、中、低浓度的速螨酮混贮时间分别不超过45天、90天和105天;高浓度与中浓度的乐斯本使菌剂中的孢子分别在第3天和第7天即全部失活,但低浓度混配菌剂可以贮存6.5个月。在4℃下冷贮期间,克螨特在高浓度下使孢子1天后全部失活,中浓度和低浓度下的孢子活力也仅延续1～3更多还原

【Abstract】 Entomopathogenic hyphomycetes are well known fungal biocontrol agents that play more and more important roles in microbial control of insect pests infesting crops or forests. To search for alternative measures for spider mite control, this study sought to test short-and long-term compatibility of common chemical acaricides with Beauveria bassiana and Paecilomyces fumosoroseus, and to evaluate quantitatively the interaction of a B. bassiana emulsifiable formulation with low application rates of chlorpyrifos, the most compatible acaricide, against the eggs of the carmine spider mite, Tetranychus cinnabarinus. The results are summarized below.Short-term compatibility of common chemical acaricides with two fungal agents. Ten commercial acaricides widely applied to mite control in China were assayed for their compatibility with the strains B. bassiana 2860 and P. fumosoroseus based on 24-h germination rates of their conidia on the plates of Sabouraud dextrose agar or in liquid medium (2% sucrose plus 0.5% peptone) containing a concentration labeled for field spray and its 5- and 10-fold dilution of each chemical. As a consequence, the 24-h viability varied significantly among the tested acaricides at the same level or among the concentrations of each in the plates or in the liquid medium. The liquid germination method resulted in less variation in conidial viability among the three replicates of each concentration and apparently was superior to the plate method. The responses of the two fungal agents to the acaricides also differed. The acaricides azocyclotin, liuyangmycin, dicofol and avermectin were found greatly inhibiting conidial germination of both fungi even at low concentration. However, several acaricides, including, hexythiazox and amitraz, were compatible quite well with the fungal agents and can be incorporated into fungal formulations for prompt spray in the field.Long-term compatibility of selected acaricides with B. bassiana. Threeacaricides, pyridaben, propargite and chlorpyrifos, with desired short-termcompatibility were separately incorporated into an oil-based, emulsifiable formulationof B. bassiana 2860 at the three concentrations as above and then stored at 4°C orambient temperature in dark for up to 12 months. Conidial viability determined bysamples at intervals during the storage differed largely over storage time among thethree acaricides. At the ambient temperature, no viable conidia were observed in thepropargite-inclusive fungal formulation, even at the low concentration, after one-daystorage. The formulations containing high, medium and low concentrations ofpyridaben were able to be stored at the ambient temperature for no more than 45, 90and 105 days, respectively. When the high or medium concentration of chlorpyrifoswas included in the fungal formulation, 100% viability loss was found on day 3 or day7. At the low concentration of this chemical, however, the fungal formulation did notsuffer from visible viability loss during a 6.5-month storage at the ambient temperature.While stored at 4°C, the propargite-inclusive fungal formulation lost its viability at thehigh concentration only after one day and maintained an acceptable viability for only1-3 weeks at the medium or low concentration. A viability of 94% was observed in thefungal formulation containing the low concentration of pyridaben after 12-monthstorage at 4°C. Safe periods of storage at 4°C for the chlorpyrifos-inclusive fungalformulation were 7 months at the high chemical concentration and over 12 months atthe low and medium concentrations because a viability of -90% was observed at theend of each period. The results indicate that the acaricide chlorpyrifos has the bestlong-term compatibility with B. bassiana conidia but still does not meet requirementsfor integration of it into the fungal formulation for normal storage.Lethal effect of fungal / chemical interaction on spider mite eggs. Fourindependent bioassays (Assays 1-4) were performed with a standard spray towermethod to quantify interaction of three conidial concentrations of B. bassiana 2860(low, medium and high: 58-67, 154-224 and 815-1036 conidia/mm2) with threeapplication rates of chlorpyrifos, equivalent to 5, 10 and 20% of its labeled rate,against the eggs of T. cinnabarinus on fava bean leaves in Petri dishes. Assay 1 includedthe fungal sprays only whereas the concentrations of 24, 48 and 96 ^ig/mL chlorpyrifoswere included in the fungal sprays of Assays 2-4, respectively. Each spray for atreatment consisted of four replicates and each replicated included 23-48 fresh miteeggs laid on a fava bean leaf. After exposure to the sprays, all Pertri dishes weremaintained at the regime of 25°C and 12L:12D and hatch rates of the mite eggssprayed were monitored daily until no more eggs hatched for three consecutive days.As a consequence, most of the mite eggs hatched on days 4-7 after spray and the hatchrates decrease with the increasing concentrations of fungal or chemical sprays or both.Mite egg mortalities attributed to the fungal infection (i.e., percentages of mycotizedeggs) in Assays 1-4 were estimated as 82.7, 90.6, 95.6 and 97.9% at the high conidialconcentration, 29.1, 50.6, 79.1 and 87.2% at the medium concentration, and 9.5, 19.6,58.6 and 60.5% at the low concentration, respectively. Based on the fitted linearrelationship between the egg mortalities and the egg mortalities, the LC50 with 95%confidence intervals of the B. bassiana formulation against the mite eggs wereestimated as 340 (276-433), 219 (186-259), 63 (35-91) and 77 (38-114) conidia/mm2 atthe dosages of 0, 24, 48 and 96 |ig/mL chlorpyrifos for interaction in Assays 1-4,respectively. In conclusion, inclusion of >48 ng/mL chlorpyrifos into the fungal spraysgreatly enhanced ovicidal activity of the fungal formulation against the spider mitepest with an LC50 less than 100 conidia/mm2. The acaricide applications rate includedis equivalent to only about 10% of its labeled rate for field application. The resultssuggest a high potential for the fungal / chemical interaction to be exploited for spider mite control.The results presented as above determined short- and long-term compatibility of the selected chemical acaricides with concerned fungal bicontrol agents. The discovery of the most compatible chlorpyrifos and its synergistic interaction with B. bassiana to kill spider mite eggs would help to facilitate incorporation of fungal formulations into mite pest management systems where application of chemical acaricides can be greatly reduced or minimized.更多还原