Assessment of Two <i>Trichogramma</i>Species with <i>Bacillus thuringiensis</i>var. krustaki for the Control of the Tomato Leafminer <i>Tuta absoluta</i>Meyrick (Lepidoptera: Gelechiidae) in Iran

In this study, we investigated the efficiency of T. brassicae and T. embryophagum in combination with bacterial suspension of B. thuringiensis against the tomato leafminer T. absoluta eggs in cage inside greenhouse (semi field) experiments. Four treatments were used (T. brassicae or T. embryophagum + T. absoluta) (T1), (B. thuringiensis + T. absoluta) (T2), (T. brassicae or T. embryophagum + B. thuringiensis + T. absoluta) (T3) and control (T4). The lowest number of T. absoluta mines (6.1, 0.5 mine per plant) were recorded in T3 for T. brassicae and T. embryophagum were significantly lower than those of all other treatments which were followed by T1 and T2, while the highest number of mines per plant (50.70) were recorded in control (T4). In addition, the parasitism rate, adults’ emergence, the number of females and adult longevity of two parasitoids were investigated. According to the obtained results, the highest parasitism rate was obtained for T. embryophagum when treated with Bt reared in the T. absoluta eggs (31.18%). However, no significant differences were detected between T. brassicae and T. embryophagum in mortality and adult emergence rates were found when they were treated with/ without Bt reared in the T. absoluta eggs in cage inside greenhouse. Also, the longevity of T. embryophagum was significantly better than T. brassicae p = 0.000. This is the first study to investigate T. embryophagum in cage inside greenhouse for parasitizing the eggs of T. absoluta and results of present study suggested that T. embryophagum with Bt could be more efficient for biocontrol of T. absoluta.

孤雌产雌食胚赤眼蜂高温敏感阶段的研究

胞内共生菌Wolbachia可诱导赤眼蜂产雌孤雌生殖,而高温可使感染Wolbachia的赤眼蜂产雄比例增加。本文以感染Wolbachia孤雌产雌生殖的食胚赤眼蜂Trichogramma embryophagum为材料,采用30℃和35℃高温处理卵、幼虫、预蛹、蛹和成虫等不同发育阶段的虫体,统计子代蜂发育历期、寄生数、羽化率和性比。结果表明,与25℃对照相比,高温缩短了子代蜂各发育阶段的历期,其中蛹、成虫和全世代历期显著缩短。处理的发育阶段和持续时间不同,子代的出雄率不同,而且随着处理时间的延长,对食胚赤眼蜂子代的寄生和羽化有一定的影响。基于高温处理后子代出雄率指标分析,F3代卵和幼虫经高温处理后代子代雄蜂比率最高,达到了20.54%和23.78%,明显高于预蛹期和蛹期处理的雄蜂率。结果表明,高温处理后感染Wolbachia的食胚赤眼蜂生殖方式改变的敏感发育阶段为卵期和幼虫期,本研究可为进一步揭示Wolbachia调控赤眼蜂生殖的机理提供理论参考。

温度通过影响Wolbachia滴度调控赤眼蜂生殖方式

【目的】揭示温度对宿主体内Wolbachia滴度及其调控宿主生殖作用的影响。【方法】以感染Wolbachia且营孤雌产雌生殖的食胚赤眼蜂Trichogramma embryophagum为对象,在22,25,28和31℃4个梯度温度下连续培养5代,观察生殖方式、性比等生物学特性;采用实时荧光定量PCR以Wolbachia特异基因——外膜蛋白基因(wsp)、二磷酸果糖醛缩酶基因(fbp A)和酰胺转移酶基因(gat B)为靶标对内生菌进行定量分析。【结果】22和25℃条件下连续培养5代,食胚赤眼蜂生殖方式均未发生改变(无雄蜂出现),且5代赤眼蜂群体Wolbachia滴度没有明显差异;28℃下,食胚赤眼蜂在F3代开始有雄蜂出现,至F5代雄蜂比例明显增多,且体内Wolbachia滴度在F2代开始下降,至F5代显著下降;31℃下,F2代即有雄蜂出现,至F5代已经恢复成产雄孤雌生殖,体内Wolbachia滴度也在F2代开始下降,F3代开始显著降低,到F5代Wolbachia滴度极小甚至检测不到。【结论】高温可改变营孤雌产雌生殖赤眼蜂的生殖方式及体内Wolbachia滴度,且随着处理代数的增加以及温度的升高作用显著,即高温对营孤雌产雌生殖赤眼蜂生殖方式改变程度与其体内Wolbachia滴度呈负相关。