Feeding, oviposition and survival of overwintered rice water weevil (Coleoptera: Curculionidae) adults in response to nitrogen fertilization of rice at seedling stage

Abstract

Overwintered adults of the rice water weevil, Lissorhoptrus oryzophilus Kuschel, were used to examine the impacts of nitrogen (N) fertilization on their feeding, oviposition and survival. Rice plants (cultivar Shanyou 63) were fertilized with urea at 20 days after sowing at rates 0, 30, 60, 90, and 120 kgN/ha, respectively. Plants were initially used the day after fertilization to determine adult performance, and used at 3, 9 and 16 days after transplantation (23, 29 and 36 days old, respectively) to test adult feeding and oviposition preference. Feeding, oviposition period, fecundity and survival duration increased significantly as fertilization increased from 30 to 60 kgN/ha, and from 60 to 90 kgN/ha (except for fecundity), while they no longer increased significantly as fertilization increased further to 120 kgN/ha. When provided with 29-d-old plants, adults preferred to feed on the plants fertilized at 60 kgN/ha rather than on those fertilized at higher levels, while for 36-d-old plants, the results were strikingly reversed. On 23-d-old plants, adults preferred to deposit eggs on those fertilized at 60 kgN/ha; on 29- and 36-d-old plants, however, plants fertilized at 90 and 120 kgN/ha were significantly more preferred for oviposition.