不同寄主植物对丽蚜小蜂寄生、发育、存活和增殖的影响

在人工气候箱内测定了5种寄主植物对丽蚜小蜂(Encarsia formosa Gahan)寄生、生长发育、存活以及增殖的影响。结果表明,不同寄主植物间丽蚜小蜂的寄生率差异显著,5种寄主植物中,丽蚜小蜂在番茄上的寄生率最高(84%),其次为菜豆、烟草、棉花,黄瓜上寄生率最低(26.9%)。不同寄主植物对丽蚜小蜂的生长发育、成虫寿命和产卵量均有较大影响,寄主植物间差异显著,但对其存活率影响不大。     

丽草蛉幼虫人工饲料的研究

分别以全脂蝇蛆粉、脱脂蝇蛆粉、猪肝粉、酵母粉作为主成分,再另外添加牛肉粉、鸡蛋黄、蜂蜜等成分探索丽草蛉幼虫的人工饲料配方.从2龄开始饲养,以1～2龄新菠萝灰粉蚧饲养丽草蛉作为对照,对丽草蛉生长阶段的各项发育指标进行观测与比较.结果表明:4种配方均能使丽草蛉完成1个世代,其中以脱脂蝇蛆粉作为饲料主成分饲养丽草蛉效果最佳,幼虫发育历期为9～14 d,幼虫存活率达到76.7％,羽化率达到66.7％.选取脱脂蝇蛆粉、猪肝粉、牛肉粉、蜂蜜、鸡蛋黄作为配方的主要成分,通过均匀设计法与SAS软件岭嵴分析得出其最佳配比为:脱脂蝇蛆粉6.0 g、牛肉粉4.0 g、猪肝粉1.6 g、蛋黄1.6 g、蜂蜜1.3 g.     

Effects of Teladorsagia (Ostertagia) circumcincta infection on lambs selected for high fleece weight

The physiological processes leading to the expression of the resilient phenotype, which allow animals to maintain a relatively higher production level during infection, have been investigated in lambs from a closed flock selected for 40 generations for high fleece weight (HFW), but with higher FEC and worm burdens than their unselected control (C) flock run in parallel. After recovery from surgery to implant abomasal cannulae, eight parasite-naïve lambs from each flock were infected intraruminally at 4.5 months-of-age with 50,000 Teladorsagia circumcincta L3. Blood, abomasal fluid and faecal samples were collected daily for measurement of serum gastrin and pepsinogen concentrations, blood eosinophils, abomasal pH and FEC. Four lambs from each flock were euthanased on Day 8 post-infection and the other four on Day 28 post-infection. At necropsy, abomasal contents and tissues were collected for worm counts, abomasal lymph nodes and fundic tissue for cytokine gene expression and fundic tissue for histopathology. Expression of resilience appeared to be age-dependent as there were no significant differences in either FEC or worm burden between lambs from the two flocks, unlike older HFW lambs in a previous study. Abomasal secretion did not differ between flocks. Histopathological changes were typical of parasitism: inflammatory cells, mainly eosinophils and lymphocytes, were numerous in nodular areas and there were fewer TGF-α positive parietal cells, many of which were vacuolated. By Day 28 p.i., globule leucocytes were present. Mucosal thickness was significantly greater on Day 8 than Day 28 p.i. (p = 0.000) and in C than HFW lambs. There were fewer parietal cells on Day 28 than on Day 8 p.i. (p = 0.003) for pooled data. Circulating eosinophil counts increased moderately in both groups, significantly less in the HFW lambs. Fewer tissue and blood eosinophils in the HFW than C group on Day 8 p.i. were consistent with cytokine gene expression patterns, particularly lower IL-5 levels. Worm count decreased by 90% by Day 28 p.i., along with declining tissue eosinophil counts and IL-13 gene expression and increasing IL-10 and IL-4 gene expression. Food intake was depressed less in the HFW lambs, suggesting that maintenance of appetite could be an important aspect of the physiological basis for resilience. Although the resilient phenotype was not apparent at the younger age, lesser effects on food intake, differences in ALN cytokine profiles and lower blood and tissue eosinophil numbers in the HFW lambs may lead to the expression of resilience when older.     

寄主密度对玉米螟赤眼蜂寄生及繁衍能力的影响

[目的]探讨寄主密度对玉米螟赤眼蜂寄生及繁衍能力的影响,为玉米螟赤眼蜂饲养技术的优化改良及其田间释放提供参考。[方法]采用卡方检验及回归分析对不同寄主密度下单头玉米螟赤眼蜂的寄生卵数、产卵数、产雌数、出蜂率和单卵出蜂数进行了研究。[结果]玉米螟赤眼蜂寄生卵数、产卵数及产雌数不会随着接卵量的增加而同等倍数的增长,寄主密度阈值为90粒/管;单卵出蜂数随着寄主密度增大而减少,当玉米螟赤眼蜂与接卵量之比为1∶160时可减少过寄生现象产生;寄主密度对玉米螟赤眼蜂的出蜂率无显著性影响。[结论]寄主密度能不同程度地影响玉米螟赤眼蜂的寄生、产卵及出蜂情况,在进行玉米螟赤眼蜂室内繁育及田间控害操作时需要特别留意寄主密度的选择,以增强其寄生及繁衍能力。     

生物因子对淡足侧沟茧蜂寄生的影响

研究了寄生蜂蜂龄、寄主密度和寄主饲料3个生物因子对淡足侧沟茧蜂寄生的影响。试验结果表明,1日龄和2日龄的淡足侧沟茧蜂寄生效果最好,寄生蜂和寄主按1：50寄生时寄生率最高。而由于不同寄主饲料水分和营养成分含量不同,对淡足侧沟茧蜂寄生也有明显的影响。     

Determinants of parasitoid assemblages of the diamondback moth,Plutella xylostella,in cabbage farmer fields in Senegal

Conservation biological control, which fosters the optimal use of indigenous natural enemies, is a promising way for reducing pesticide reliance in horticultural systems. A two-year field survey was conducted in the main cabbage-producing area in Senegal (Niayes) to assess the potential of indigenous parasitoids to control populations of Plutella xylostella (Lepidoptera, Plutellidae). Results showed an overall low level of parasitism (11.7%) which was independent of host abundance, but was highly variable among fields (0–50%). Parasitism was predominant in the late part of dry season. Insecticide use, mostly relying on broad-spectrum insecticides, had a negative effect on the overall parasitism rate. Observations conducted throughout the cabbage crop cycle showed that parasitism unexpectedly decreased with crop aging (from 41 to 60 days post transplanting), likely due to repeated insecticide applications. Four main parasitoid species including Oomyzus sokolowskii (Kurdjumov) (Eulophidae) (48.8%), Apanteles litae Nixon (Braconidae) (32.5%), Brachymeria sp. (Chalcididae) (11.3%), and Cotesia vestalis Haliday (Braconidae) (7.3%) were identified. Parasitism due to O. sokolowskii was greater during the first part of the dry season whereas parasitism due to A. litae was greater during the second part of the dry season. Parasitism due to Brachymeria sp. was not affected by time of season but was greater in the Centre and North than in the South of Niayes. Parasitism due to C. vestalis was equal in the three zones but was higher in the late part of the dry season. The diversity of parasitoids was constant across zones but was greater during the second part of dry season. A positive relationship between diversity (Shannon diversity index H′) and parasitism rate was observed, suggesting a positive effect of parasitoid diversity on natural pest control. Parasitoids have a promising role to play as biocontrol agents of P. xylostella populations in Senegal, provided significant changes to current insecticide use are made. Better knowledge of their resource requirements including crop and non-crop habitats, and provision of these in and around crops is also needed.     

布鲁氏菌胞内寄生的研究进展

布鲁氏菌是一种能够在哺乳动物巨噬细胞内生存和增殖的兼性厌氧菌。近年来,布鲁氏菌的研究主要集中在参与细胞内寄生过程中的毒力因子及其对宿主细胞的影响。主要论述布鲁氏菌如何逃避巨噬细胞的防御及其在细胞内寄生状况。     

蝇蛆寄生对家蚕血细胞和酚氧化酶活性的影响

为了探明蝇蛆寄生对家蚕免疫因子的影响,对家蚕追寄蝇(Exorista sorbillansW iedem ann)幼虫寄生的5龄家蚕血淋巴中血细胞数量的变化以及血淋巴酚氧化酶活性的变化进行了研究。结果表明:蝇蛆寄生家蚕后,家蚕血淋巴中颗粒细胞和浆细胞的数量急剧上升,在寄生后16~24 h,蝇蛆蚕血淋巴颗粒细胞和浆细胞数达到6.81×106/mL,比对照增加了4.76×106/mL;蝇蛆寄生导致血淋巴黑化反应加快,黑色素增加;蝇蛆蚕血淋巴酚氧化酶活性升高,在6 d内由7 U/mg上升到34 U/mg。     

穿刺巴斯德芽菌PPh01菌株鉴定及其对根结线虫的寄生性测定

从海南定安胡椒根部根结线虫体上分离到一株细菌PPh01,其形态特征与穿刺巴斯德芽菌相似。16S rDNA序列分析结果表明：该菌株与穿刺巴斯德芽菌的同源性达到99.3％,在发育树上聚为同一分支,亲缘关系最近,鉴定该菌株为穿刺巴斯德芽菌（Pasteuria penetrans）。寄生性试验结果表明：该菌株对南方根结线虫、爪哇根结线虫、花生根结线虫的2龄幼虫均具有寄生性和侵染能力。