Beti J A, Phillips T W, Smalley E B
Department of Plant Pathology, University of Wisconsin-Madison 53706, USA.
J Econ Entomol. 1995 Dec;88(6):1776-82. doi: 10.1093/jee/88.6.1776.
Insects play an important role as facilitators of the aflatoxin-producing fungus, Aspergillus flavus Link, in both preharvest and postharvest corn. The current study investigated the role of maize weevils, Sitophilus zeamais Motschulsky, in enhancing aflatoxin B1 content in stored corn. In laboratory experiments, aflatoxin B1 was quantified with an indirect enzyme-linked immunosorbent assay (ELISA) on corn following artificial infestation with adult weevils that had each been topically treated with 100 spores of A. flavus. Corn kernels infested with A. flavus-contaminated weevils had significantly higher levels of aflatoxin B1 than A. flavus-inoculated corn without weevils. The presence of maize weevils resulted in increased kernel moisture content during incubation, and grain moisture was positively correlated with aflatoxin content across treatments receiving spores. Aflatoxin B1 levels were higher in corn treated with fungus-contaminated weevils compared with corn that was mechanically damaged and inoculated with spores, which in turn had more aflatoxin than undamaged corn treated with spores. Aflatoxin B1 content in corn increased with time of weevil exposure from 7 to 21 d, but decreased after 28 d of exposure. Aflatoxin levels in infested corn increased significantly with increased numbers of A. flavus-contaminated weevils. Maize weevils carried spores both internally and externally; however, substantial numbers of spores were intimately associated with the exoskeleton of adult weevils. These findings indicate that maize weevils facilitate the growth of A. flavus and aflatoxin production in corn by increasing surface area susceptible to fungal infection and increasing moisture content as a result of weevil metabolic activity.(ABSTRACT TRUNCATED AT 250 WORDS)
在收获前和收获后的玉米中，昆虫作为产黄曲霉毒素的真菌——黄曲霉（Aspergillus flavus Link）的传播媒介发挥着重要作用。当前的研究调查了玉米象（Sitophilus zeamais Motschulsky）在提高储存玉米中黄曲霉毒素B1含量方面的作用。在实验室实验中，在用100个黄曲霉菌孢子对成虫进行局部处理后，对人工感染成虫的玉米进行间接酶联免疫吸附测定（ELISA）来定量黄曲霉毒素B1。被黄曲霉污染的玉米象侵染的玉米粒中黄曲霉毒素B1的含量显著高于接种了黄曲霉但没有玉米象的玉米。玉米象的存在导致孵化期间玉米粒的水分含量增加，并且在接受孢子处理的各处理中，谷物水分与黄曲霉毒素含量呈正相关。与机械损伤并接种孢子的玉米相比，用被真菌污染的玉米象处理的玉米中黄曲霉毒素B1水平更高，而机械损伤并接种孢子的玉米又比未损伤但接种孢子的玉米含有更多的黄曲霉毒素。玉米中黄曲霉毒素B1的含量随着玉米象暴露时间从7天增加到21天而增加，但在暴露28天后下降。受侵染玉米中的黄曲霉毒素水平随着被黄曲霉污染的玉米象数量增加而显著增加。玉米象在体内外都携带孢子；然而，大量孢子与成虫的外骨骼紧密相连。这些发现表明，玉米象通过增加易受真菌感染的表面积以及因玉米象代谢活动而增加水分含量，促进了玉米中黄曲霉的生长和黄曲霉毒素的产生。（摘要截选至250词）
