不同寄主植物对马铃薯甲虫的引诱作用

随着马铃薯甲虫不断扩展其分布范围,其对寄主的适应性也在发生变化。在我国,马铃薯甲虫的主要寄主植物是马铃薯、茄子、番茄和天仙子。为进一步明确马铃薯甲虫对不同寄主植物的嗜食程度,研究了以上4种寄主植物对马铃薯甲虫的引诱作用,以及取食量的影响,同时进行了田间寄主选择性的调查。选择性试验结果表明:不同寄主植物对马铃薯甲虫的引诱作用差异显著,其中马铃薯、天仙子引诱作用显著高于茄子和番茄;取食量研究结果表明:马铃薯甲虫各龄期对不同寄主24 h取食量的大小依次为:马铃薯>茄子>天仙子>番茄;1—2龄幼虫取食量小,3—4龄幼虫及成虫暴食寄主叶片,是马铃薯甲虫造成危害的主要阶段。

Attraction effect of different host-plant to Colorado potato beetle Leptinotarsa decemlineata

The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), is one of the most destructive pests of potato crops and has expanded its range worldwide. CPB was first discovered in the foothills of the Rocky Mountains, where it originally fed on a native species, Solanum rostratum. Its shift to the potato, Solanum tuberosum L, is an outstanding example of a native insect attaining pest status by expanding its host range to include an introduced, cultivated plant. Such adaptation has enabled this species to expand its geographic range rapidly since the mid-19th century. CPBs have repeatedly adapted to new host plants as they have expanded their distribution. The CPB feeds on plants in the Solanaceae family (Solanales, Solanaceae), including potato, tomato (Solanum lycopersicum L.), eggplant (Solanum melongena L.), and nightshade (Solanum nigrum L.). When CPB invaded China from Kazakhstan in the 1990s, it did not feed on tomato crops in this region, unlike in the United States. Whether the host-plant adaptability of CPBs has changed in the 20 years since their colonization of northwestern China is unclear, as is which host plant they currently prefer. In this study, we performed several experiments to test the reactions of CPBs to four plants: potato, eggplant, tomato and henbane (Hyoscyamus niger L.). The research was conducted at the Institute of Plant Protection, Academy of Agricultural Sciences of Xinjiang Uygur Autonomous Region, China, from June to September 2011. Our study focused on: i) examining the appeal of different host plants to CPB adults in the laboratory; ii) CPB consumption levels during different development stages, including four larval instars and adults; and iii) a field survey of host selectivity among different host plants. The results indicated that there were significant differences (P < 0.001) in attraction among the four plants. In order of appeal to CPB, they were (from highest to lowest): potato > henbane > eggplant > tomato. Significant differences (P < 0.001) also existed among the four plant species in the amount of leaf consumption by CPBs. Consumption levels were ranked as follows (from highest to lowest): potato > henbane > eggplant > tomato. In addition, different development stages of CPB usually consumed different amount of food. First and second instar larvae consumed only small amounts of food, less than 50 mm² in 24 hours. The third and fourth instar larvae could consume much more leaf tissue. In 24 hours, they ate more than 300 mm² of potato, eggplant, and henbane leaves; however, they ate less than 200 mm² of tomato leaves in the same amount of time. The adult stage consumed the most leaf tissue, more than 500 mm² per day. The field host-selectivity survey also found significant differences (P < 0.01) among the four host plants; there were many more CPBs in fields of henbane and potato than in fields of eggplant and tomato. Based on the combined results of these laboratory and field experiments, we concluded that potato and henbane are the most suitable host plants for CPBs, consistent with an analysis done in the first year of their invasion of China in the 1990s. As a wild host plant of CPB, henbane's geographic distribution is less well known compared with those of potato, eggplant, and tomato. Therefore, understanding the role of henbane in the ecology CPB is essential to control this pest and to minimize its spread eastward into Gansu Province and Inner Mongolia Autonomous Region.