Seasonal Prevalence of Ovarian Development in Macropterous Females of Whitebacked Planthopper, Sogatella furcifera (HORVÁTH) (Hemiptera: Delphacidae) in Paddy Fields

Abstract

The seasonal ovarian development in macropterous females of the Whitebacked Planthopper, Sogatella furcifera was observed in paddy fields in 1990, 1992, and 1993. Very few first-generation macropters developed ovaries and emigrated from the field in 1990. By contrast, a fraction (5% to 30%) of first-generation macropters did not emigrate but had complete eggs in most ovarioles in 1992 and 1993. Second-generation nymphal density was high in these two years. Analysis of synoptic weather conditions associated with peak catches in light traps showed that non-migratory first-generation macropters contributed to the second-generation occurrence in 1992. A laboratory experiment showed that ovarian development in macropters is delayed when rearing densities are high, suggesting that crowding is an important factor in determining ovarian development of macropters. However, in paddy fields, there was no noticeable relationship between adult density and ovarian development in first-generation macropters. The effects of other factors on ovarian development such as the growth stage of rice plants should be clarified in the future.