Compatibility of Beauveria bassiana with Neoseiulus barkeri for Control of Frankliniella occidentalis

The entomopathogenic fungus Beauveria bassiana （Balsamo） Vuillemin and predatory mite Neoseiulus barked Hughes are effective biological control agents of Frankliniella occidentalis Pergande （Thysanoptera： Thripidae）, one of the most important pests of ornamentals and vegetables world-wide. Combined application of both may enhance control efficiency. The functional response for N. barked on the first instar larvae of western flower thrips which were infected by B. bassiana for 12 and 24 h in the laboratory （（25＋1）℃, （70＋5）% RH, L：D=16 h：8 h） was determined. The virulence of B. bassiana against the second instar and pupae of the thrips attacked by N. barked were also tested. The results showed that N. barked exhibited a Holling type II functional response on treated thrips. After having been treated with the fungus for 12 h and then offered to the predator, thrips were more vulnerable to be killed by N. barked. The second instar larvae and pupae of the thrips which had been attacked by predatory mites were markedly more susceptible to B. bassiana infection than normal thrips; the cumulative corrected mortality of B. bassiana of the second instar and pupae which were attacked by N. barked were 57 and 94%, respectively, compared to 35 and 80% in controls on the day 8. These findings highlight the potential use of B. bassiana in combination with N. barkeri to control F. occidentalis.

Quantitative impact of mating duration on reproduction and offspring sex ratio of Phytoseiulus persimilis(Acari: Phytoseiidae)

Phytoseiulus persimilis is an important biological control agent, commercially produced worldwide. To increase understandings of its reproduction, herein we provided quantitative descriptions of the inflation and deflation of its spermathecae as a function of time and copulation duration, and the quantitative impact of copulation termination on volume of spermatheca vesicle, fecundity, and offspring sex ratio. After mating started, at least one spermatheca started to inflate immediately, but no egg was produced until spermatheca volume reached 1 021 μm3. Beyond this size, cumulative fecundity was linearly correlated with vesicle volume. Producing one egg required 36 μm3 volume increase of the vesicle. Each spermatheca vesicle reached its peak size at the end of mating duration(ca. 2.38 h after mating started), and started to shrink immediately. In 24 h, ca. 71% individuals had one completely shriveled spermatheca, while in 72 h all individuals had at least one shriveled spermatheca. The estimated maximum cumulative fecundity per female after a single mating is(69.4±7.7) eggs. No significant impact of mating termination on offspring sex ratio was observed after mating duration reached 60 min, while higher proportion of male offspring was observed when mating duration is 15 or 30 min. This study is the first step to investigate possible male impact on offspring sex ratio in P. persimilis. Our results suggested the number of sperms received during mating be a restriction factor of P. persimilis offspring sex ratio regulation.

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。