School of Agriculture and Wine Sciences, Charles Sturt University, Orange Campus, Orange, New South Wales, Australia.
Council for Scientific and Industrial Research (CSIR), Crops Research Institute, Kumasi, Ghana.
Sci Rep. 2020 Apr 24;10(1):6951. doi: 10.1038/s41598-020-63709-x.
Besides providing food and shelter to natural enemies of crop pests, plants used in conservation biological control interventions potentially provide additional ecosystem services including providing botanical insecticides. Here we concurrently tested the strength of these two services from six non-crop plants in managing cabbage pests in Ghana over three successive field seasons. Crop margin plantings of Ageratum conyzoides, Tridax procumbens, Crotalaria juncea, Cymbopogon citratus, Lantana camara and Talinum triangulare were compared with a bare earth control in a three-way split plot design such that the crop in each plot was sprayed with either a 10% (w/v) aqueous extract from the border plant species, a negative control (water) and a positive control (emamectin benzoate 'Attack' insecticide). Pests were significantly less numerous in all unsprayed treatments with non-crop plant margins and in corresponding sprayed treatments (with botanical or synthetic insecticide positive control) while treatments with bare earth margin or sprayed with water (negative controls) had the highest pest densities. Numbers of predators were significantly depressed by synthetic insecticide but higher in other treatments whether unsprayed or sprayed with botanical insecticide. We conclude that some plant species have utility in both conservation biological control and as source of botanical insecticides that are relatively benign to natural enemies. In this crop system, however, the additional cost associated with using botanical insecticides was not justified by greater levels of pest suppression than achieved from border plants alone.
除了为作物害虫的天敌提供食物和住所外，用于保护生物防治干预的植物还可能提供其他生态系统服务，包括提供植物性杀虫剂。在这里，我们在加纳的三个连续田间季节中，同时测试了来自六种非作物植物的这两种服务的强度，以管理白菜害虫。在三边分割设计中，将 Ageratum conyzoides、Tridax procumbens、Crotalaria juncea、Cymbopogon citratus、Lantana camara 和 Talinum triangulare 等作物边缘植物与裸地对照进行比较，每个地块的作物都用 10%（w/v）的边界植物物种的水提取物、阴性对照（水）和阳性对照（emamectin benzoate 'Attack' 杀虫剂）进行喷雾处理。在所有未喷洒处理中，有非作物植物边缘的处理和相应的喷洒处理（用植物或合成杀虫剂阳性对照）中害虫数量明显减少，而裸地边缘或喷洒水（阴性对照）的处理中害虫密度最高。合成杀虫剂显著抑制了捕食者的数量，但在其他处理中，无论是未喷洒还是喷洒植物性杀虫剂，捕食者的数量都较高。我们得出结论，一些植物物种在保护生物防治和作为相对对天敌无害的植物性杀虫剂来源方面具有实用性。然而，在这种作物系统中，使用植物性杀虫剂所带来的额外成本并没有通过比单独使用边缘植物更有效地抑制害虫来证明是合理的。
