Population dynamics and economic threshold of the nematodes Radopholus similis and Pratylenchus goodeyi on banana in Australia

To help banana growers to decide when to apply nematicide, economic thresholds were determined for tropical north Queensland, subtropical south-east Queensland and northern New South Wales, Australia. This was done by monitoring nematode populations, root damage and growth parameters of bunching pseudostems in several commercial crops for several years. There was no significant consistent change in the disease index in consecutive years in any of the regions, although there was great variation between crops. However, on two crops in the tropics, the disease index of roots increased. To reduce the risk of not applying nematicide when required, the economic threshold was adjusted down to allow for this increase on some crops. In the tropics with a crop value of $25 000 ha^?1 year^?1, the economic threshold occurred at a root disease index = 9.2-15.6. In the subtropics with a crop value of $10 000-15 000, the economic threshold occurred at a root disease index = 20.5-35.5. In the subtropics, Radopholus similis (burrowing nematode) was as pathogenic as Pratylenchus goodeyi (lesion nematode) as measured by root necrosis. However, both nematodes were less pathogenic in the subtropics than was R. similis in the tropics. In the subtropics, R. similis tended to be more numerous in warmer months and P. goodeyi in cooler months.     

黄猄蚁史料及其用于柑桔害虫防治的研究

黄蚁是柑桔害虫的重要天敌。 1 70 0年前我国就开始利用其防治害虫 ,是世界上生物防治最古老的实例。本文简述我国利用该天敌的早期文献 ,以及其生物学和防治害虫技术的研究结果。     

Implications of on-farm research for local knowledge related to fruit flies and the weaver ant Oecophylla longinoda in mango production

We interviewed half of the mango-growers in northern Benin, including 15 farmers involved in a regional fruit fly project, and held focus group discussions with women fruit-pickers. They were asked about pest management and their knowledge of a weaver ant, Oecophylla longinoda. All considered low yields due to fruit flies to be the principal constraint upon mango production, estimating economic losses to be between 20 and 45%. None could recognize damage during the first 2 days after fruit fly egg deposition. On-farm research persuaded farmers to stop using insecticides and it also changed negative perceptions of Oecophylla. Over 80% of the farmers involved in on-farm research, compared to 25% of those not involved, reported Oecophylla to be beneficial. All fruit-pickers knew that ants protected mango from fruit flies, with 60% attributing better mango quality in terms of appearance, shelf-life and sweetness to the presence of Oecophylla. Nevertheless, 40% of the pickers still considered weaver ants a nuisance pest during harvest. Ways of reducing this nuisance need to be developed for Oecophylla to gain wider acceptance by mango-growers.     

黄猄蚁饥渴耐受能力的初步研究

在实验室恒温条件下,通过完全饥渴、清水和蜂蜜水处理3种方式对黄猄蚁工蚁进行了饥渴耐受能力的测定。结果表明,完全饥渴处理的黄猄蚁工蚁平均存活时间为81.38h(24～132h),清水处理的黄猄蚁工蚁平均存活时间为92.25h(48～156h),两者差异显著(P<0.05)。蜂蜜水处理死亡的黄猄蚁工蚁平均存活时间为118.43h(60～156h),与完全饥渴和清水处理的黄猄蚁工蚁存活时间差异极显著(P<0.01)。在试验观察结束(156h)时,完全饥渴和清水处理的黄猄蚁工蚁全部死亡,而蜂蜜水处理的黄猄蚁工蚁仍有75存活。     

淡色生赤壳菌Bo-1菌株拮抗物质的分离纯化、解析及活性分析

从浙江省金华市郊水稻内生菌中筛选到1株拮抗水稻白叶枯病菌（Xanthomonas oryzae pv.oryzae,Xoo） P6生理小种的淡色生赤壳菌Bionectria ochroleuca Bo-1菌株。该菌株的菌体和发酵液对Xoo P6生理小种均表现出较强的拮抗能力。以P6生理小种作为指示菌进行活性跟踪,通过分步萃取、硅胶柱层析、高效液相色谱等,分离纯化获得拮抗活性物质结晶;对所获得的结晶物进行核磁共振氢谱分析和质谱分析,通过解析与比对,该物质分子量为344.0835,分子式为C₁₈H₁₆O₇,鉴定为松萝酸（usnic acid）。将纯化的松萝酸以20%叶枯唑（bismerthiazol）和3%中生菌素（zhongshengmycin）为对照,采用96孔板法测定对Xoo P6生理小种的抑菌活性,最低抑制浓度为200 μg/mL,表明松萝酸具有较强的抑菌活性,但较中生菌素弱,与20%叶枯唑效果相近。