寄主植物上喷药对大螟产卵选择性的影响

为明确稻田适量喷施保护性农药是否影响周边香根草对水稻螟虫的诱集效果,通过室内盆栽试验测定了在水稻和香根草上分别喷施氯虫苯甲酰胺对大螟成虫趋性及产卵选择性的影响。结果表明:在水稻上喷药后第1天,栖息在香根草上的大螟雌、雄成虫总量分别为4.2头和3.8头,显著高于水稻上雌、雄成虫的总量1.00头和0.60头;在水稻上喷药后1~3 d接入大螟,在水稻上不产卵,直到第6天才出现卵块;喷药后6 d和12 d接入大螟,在香根草上的卵粒数分别为287.2粒和309.2粒,显著高于其在水稻上的57.2粒和81.4粒,约为水稻上的5.0倍和3.8倍。在香根草上喷药后1~3 d接入大螟,成虫选择水稻居多,在香根草上的产卵量为0;喷药后6 d接入大螟,成虫对2种寄主植物的选择性无显著差异;喷药后12 d接入大螟,在香根草上的成虫数量为9.8头,约为水稻上的2.5倍,产卵量也约为水稻上的1.9倍,二者均差异显著。表明香根草喷施氯虫苯甲酰胺后其对大螟的诱集作用有一定影响,但这种影响会随着施药时间的延长而逐渐减弱。

The effect of spraying on host plants on the oviposition preference of Asiatic pink stem borer Sesamia inferens

To understand the effect of spraying pesticides on the trapping efficiency of vetiver grass on the Asiatic pink stem borer Sesamia inferens (Walker), the effect of chorantraniliprole application on adult tropism and oviposition preference of S. inferens were examined by using potted rice and vetiver grass. The results showed that, one day after chorantraniliprole spraying on the rice but not vetiver grass, the numbers of S. inferens female and male adults located on the vetiver grass and rice were 4.2 and 3.8, 1.0 and 0.6, respectively; there were 4.2- and 6.3-fold higher numbers on vetiver grass than on the rice, and there was no egg laid on the rice plants one to three days after spraying on rice. The egg masses on the rice six days after spraying on the rice and the egg numbers on vetiver grass were 287.2 and 309.2, respectively, approximately 5.0-and 3.8-fold higher than those on the rice six d-and 12 d-post spraying of chlorantraniliprole on the rice, in which egg numbers were 57.2 and 81.4, respectively. When vetiver grass but not rice was treated by chlorantraniliprole, most female adults of S. inferens selected rice as egg-laying host three days later and no egg was found on vetiver grass. There was no significant difference in location preference of S. inferens between rice and vetiver grass six days after spraying on vetiver grass. There were 9.8 adults on vetiver grass 12 days after spraying. Moreover, the number of S. inferens adults and eggs on vetiver grass were 2.5- and 1.9-fold higher than those on the rice. These results indicated that the application of chlorantraniliprole on vetiver grass weakened its trapping efficiency to some extent, but this impact decreased with time.