Depto. Agronomia, Área de Fitossanidade, Universidade Federal Rural de Pernambuco, Recife, PE 52171-900, Brazil.
Exp Appl Acarol. 2011 Aug;54(4):373-84. doi: 10.1007/s10493-011-9464-2. Epub 2011 Apr 10.
Aceria guerreronis Keifer (Acari: Eriophyidae) is considered a major pest of coconut in many countries in the Americas, Africa and parts of Asia. Neoseiulus baraki Athias-Henriot (Acari: Phytoseiidae) is one of the predatory mites most commonly found in association with A. guerreronis in parts of northeast Brazil. The objective of this work was to study the distribution of A. guerreronis and N. baraki among and within coconut bunches. The hypothesis was tested that A. guerreronis and N. baraki are homogenously distributed over the fruits in a bunch, independent of the fruits' age and position. Five collections of bunches, each corresponding to leaves 12-16 from apex (about 2-6 month-old), were conducted in each of three fields in northeastern Brazil, from February to October, 2007. A total of 1,986 fruits were examined. The number of mites, the percentage of fruits hosting them and the level of damage caused by A. guerreronis were evaluated. The highest density of A. guerreronis was observed on fruits of bunch 4 whereas the highest density of N. baraki was observed on bunch 5. Considering all fruits together, no significant differences were observed between densities of either A. guerreronis or N. baraki among the basal, median and apical thirds of the bunches. In younger bunches, fruits of the apical region tend to have lower densities of both mites than fruits of the basal region. This pattern, in association with a similar pattern for the percentage of fruits hosting N. baraki, suggests that the predator initially reaches the basal bunch region, from where it moves to the apical region. The results of the present study suggest that the pest population reduction in bunches older than bunch 4 could be due to (1) an effect of the predator, (2) reduction of the proportion of undamaged tissues amenable to attack, and/or (3) less favorable characteristics of the fruits to attack by A. guerreronis, as indicated by their increasing lignin content as they get older.
美洲、非洲和亚洲部分地区的许多国家都认为，叶瘿螨属的 guerreronis 螨（蜱螨目：瘿螨科）是椰子的主要害虫之一。巴氏新小绥螨（蜱螨目：植绥螨科）是在巴西东北部与 A. guerreronis 螨最常发现的捕食性螨虫之一。本工作的目的是研究 guerreronis 螨和 N. baraki 在椰子果穗内和之间的分布。该假说假设 guerreronis 螨和 N. baraki 在果穗中的果实上均匀分布，与果实的年龄和位置无关。2007 年 2 月至 10 月，在巴西东北部的三个地区，从叶尖第 12-16 片叶（约 2-6 个月龄）的每片叶采集 5 个果穗进行采集。共检查了 1986 个果实。评估了螨虫数量、有螨虫寄生果实的百分比和 guerreronis 螨造成的损害程度。在第 4 个果穗中观察到 guerreronis 螨的密度最高，而在第 5 个果穗中观察到 N. baraki 的密度最高。考虑到所有果实，在果穗的基部、中部和顶部三分之一之间，都没有观察到 guerreronis 螨或 N. baraki 的密度有显著差异。在较年轻的果穗中，与基部区域的果实相比，顶部区域的果实往往具有较低密度的两种螨虫。这种模式，以及与 N. baraki 螨寄生果实百分比相似的模式，表明捕食者最初到达基部果穗区域，然后从那里移动到顶部区域。本研究的结果表明，果穗超过第 4 个果穗的害虫种群减少可能是由于（1）捕食者的作用，（2）受损组织比例减少，以及/或（3）随着果实的老化，果实对 guerreronis 螨的攻击变得不那么有利，这表现为其木质素含量增加。
