Bryan R P, Kerr J D
CSIRO, Division of Tropical Animal Science, Rockhampton, Australia.
Vet Parasitol. 1989 Mar;30(4):315-26. doi: 10.1016/0304-4017(89)90101-5.
Faecal pats containing parasitic nematode eggs were deposited monthly on worm-free pasture, from mid-1975 to early in 1979, near Rockhampton in central Queensland. Pasture samples were collected monthly from beside these pats and the number of infective larvae on the samples was counted. Cooperia spp. were the most numerous larvae on pasture all year round and Haemonchus placei were commonly present in low numbers. Small numbers of Oesophagostomum radiatum larvae were found, mostly during summer. Dung beetle activity and rainfall influenced larval populations on pasture, but temperature did not. Beetles were not active in winter, and pats deposited in spring, summer and autumn when beetles were active yielded only 42, 44 and 26%, respectively, as many larvae per 1000 eggs deposited as winter pats. Pats in which beetle activity was minimal (feeding only), moderate and intense (complete destruction), yielded 43, 10 and 6%, respectively, as many larvae per 1000 eggs as intact pats. Larval densities on pasture were highest after the first saturating rains during the spring-summer period and most of these larvae migrated from unattacked pats deposited in winter. Beetle numbers and activity increased with the summer rains and so few larvae were available to migrate onto pasture during late summer and autumn when the highest falls of rain were recorded. The regression of larval recovery on rainfall was positive and statistically significant when data collected soon after these very heavy rainfall periods were omitted from the analysis. In 1977, drought-breaking rains increased the normal larval density on pasture 10-fold because larvae in pats deposited in the last 4 months of the drought migrated onto pasture immediately after the rains. This work suggests that in summer rainfall areas where dung beetles are active, helminth control may be achieved by reducing the worm egg output from cattle during the winter.
1975年年中至1979年初，在昆士兰州中部罗克汉普顿附近，每月将含有寄生线虫卵的粪便堆放置在未感染蠕虫的牧场上。每月从这些粪便堆旁边采集牧场样本，并对样本上感染性幼虫的数量进行计数。全年库珀属线虫是牧场上数量最多的幼虫，而少量的捻转血矛线虫也普遍存在。发现少量辐射食道口线虫幼虫，主要在夏季。蜣螂活动和降雨影响牧场上的幼虫数量，但温度没有影响。冬季蜣螂不活跃，在蜣螂活跃的春季、夏季和秋季放置的粪便堆，每沉积1000个卵产生的幼虫数量分别仅为冬季粪便堆的42%、44%和26%。蜣螂活动极少（仅取食）、中等和强烈（完全破坏）的粪便堆，每1000个卵产生的幼虫数量分别为完整粪便堆的43%、10%和6%。春夏季第一次饱和降雨后，牧场上的幼虫密度最高，其中大部分幼虫从冬季放置的未受攻击的粪便堆迁移而来。随着夏季降雨，蜣螂数量和活动增加，因此在夏季末和秋季降雨最多时，可供迁移到牧场上的幼虫很少。当分析中省略这些暴雨期后不久收集的数据时，幼虫回收率与降雨量的回归呈正且具有统计学意义。1977年，暴雨打破了干旱，使牧场上正常的幼虫密度增加了10倍。因为在干旱的最后4个月放置的粪便堆中的幼虫在雨后立即迁移到了牧场上。这项研究表明，在蜣螂活跃的夏季降雨地区，通过减少冬季牛的蠕虫卵产量，可以实现蠕虫控制。
