虫口密度和龄期对东亚飞蝗群居型向散居型转变的影响

采用笼养方法研究了东亚飞蝗虫口密度和龄期对其由群居型向散居型转变的影响。结果表明,不同密度条件下饲养的蝗虫其由群居型转变成散居型的速度不一样。密度越高,转变的速度越慢;当密度过高时,即使由三龄期开始隔离也无法转变其生态型。将处于三龄期群居型蝗蝻在低密度下隔离,到四龄时为过渡型,到五龄和成虫时为群居型;而四龄期的群居型蝗蝻经隔离后,在五龄和成虫时仅偏向于群居型;五龄期的群居型蝗蝻经隔离后,在成虫时仍为群居型。所以,三龄期可能是东亚飞蝗由群居型向散居型转变的临界期。超过三龄,即使在低密度下也不易发生生态型转变。

The impacts of nymph population densities and stadium of Locusta migratoria manilensis (Meyen) on the changes of its social type to the scattered type

Cage studies were carried out on the impacts of nymph population densities and stadium of locusta migratoria manilensis on the shift of its social type to the scattered type. The results showed that locust ecological type was different at different density conditions. The higher density, the slower change speed. When the density is too high, the locust ecological type could not change even if the locust started to be separated in the third nymph. If the social type nymphs were separated at the third age, the ecological type of locust was the medium type at the fourth age, and the scattered type at the fifth age and adult stage. If the social type nymph were separated at the fourth age, the ecological type of locust will develop to the social type at the fifth age and adult stage. If the social type nymph were separated at the fifth age, the ecological type of locust was still the social type at adult stage. The third age of nymph was suggested as the critical stage of the social type changed to the scattered type. Over the third age, locust ecological type was not easy to change.