米象金小蜂对玉米象种群控制作用研究

STUDY OF LARIOPHAGUS DISTINGUENSIS FOERSTER CONTROLLING MAIZE WEEVIL(SITOPHILUS ZEAMAIS MOSSCHUISKY)

研究明确了玉米象的寄生性天敌──米象金小蜂（Ｌａｒｉｏｐｈａｇｕｓ ｄｉｓｔｉｎｇｕｅｎｓｉｓ Ｆｏｅｒｓｔｅｒ）在山东省泰安地区室内变温条件下，一年发生５代，以老熟幼虫在寄主体内越 冬。在２６～３２℃、相对湿度７８％－８５％时，完成一代平均 １７．６ 天。当粮食中玉米象幼 虫虫口密度接近６００／ｋｇ时，分别接雌雄蜂１０和２０对以上，２个月后的控害效果依 次为７１．６３％和９０％以上。由此提出了益害比为１∶３０的该蜂保护利用指标。根据连 续两代蜂不同密度分别对玉米象控制后的残虫量，组建了相关模型。即：Ｙ_１＝９８．４８２９ －２．９１７７Ｘ_１；Ｙ_２＝４４７．８１３６－８．２４０５Ｘ_２。为预测不同蜂量的控害作用提供了科学依据。

Lariophagus distinguensis Foerster, an important endoparasitic wasp parasitising maize weevil larvae, has 5 generations in one year at changeable temperature in laboratory in Taian of Shandong Province. Its last instar larvae overwinters in maize weevil larvae. The average duration of one generation is 17. 6 days at 26 ~ 32℃ and 78% ~ 85% RH. When above 10 and 20 pairs (×) of the wasps were inoculated in wheat infested with maize weevil lar vae (1kg wheat contained 600 maize weevil larvae), the control effectiveness after 2 months was 71. 63 % and 94 .49% respectively. According to inoculation number of the wasps and the control effectiveness, the index protecting and utilizing the wasp is put forward, i. e the ratio of wasps to maize weevil larvae is 1∶30. Based on the inoculation number of the wasps (X) and the number of adult weevils (Y) after parasitism, the forecast models of two succes sive generations are established as follows: Y_1 = 98. 4829 - 2. 9177x_1, and Y_2 = 447. 8136 - 8.2405x_2. The modles can be used in forecasting the control effectiveness.