Head Capsule Width and Population Densities of Overwintering Nymphal Stages of the Green Rice Leafhopper, Nephotettix cincticeps Uhler (Hemiptera: Cicadellidae)

월동 끝동매미충(Nephotettix cincticeps)의 약충태별 두폭크기 및 밀도변화

This study was conducted to investigate specific stages and distribution of overwintering nymphs of green rice leafhopper, Nephotettix cincticeps by measuring head capsule width. The nymphal head capsule width of the 1st instar to the 5th instar was 0.381, 0.502, 0.673, 0.979 and 1.128 mm, respectively. lts coefficient variation was 5.3, 4.0, 3.0, 4.5 and 5.3%, respectively. Growth ratio of each instar was not significantly different among 2nd to 4th instars as 1.31 to 1.34, but for the 5th instar it decreased as 1.28. The logarithm of the nymphal head capsule width was regressed as a function of the stage number of insects, resulting in LogY = 1.4627 + 0.1192X ($r^2= 0.9993$). Also fitness to the Dyar's law for the nymphal head capsule width of each instar was 98% or over and the Dyar's constant (K) was 1.316. The occurrence of N. cincticeps was maximum at the end of January with 195 individuals/0.25 $m^2$. The most abundant instar in the overwintering N. cincticeps population was 4th instar accounting for over 90%. Population of the 5th instar began to increase from mid-March, and adults began to occur in early April.

본 연구는 월동하는 끝동매미충의 충태별 분포를 두폭측정법을 활용하여 분석하였다. 끝동매미충 1령, 2령, 3령, 4령 및 5령 약충에 대한 두폭크기는 각각 0.381, 0.502, 0.673, 0.879 및 1.128mm였으며, 변이계수는 5.3, 4.0, 3.0, 4.5 및 5.3%였다. 성장률은 2령, 3령, 4령 약충에서는 1.31${\sim}$1.34로 큰 차이가 없었지만 5령에서 1.28로 약간 감소하였다. 두폭측정값의 회귀식을 구한 결과, LogY = 1.4627+0.1192X($r^2=0.9993$)으로 고도의 유의성이 인정되었고, Dyar 공식에 의한 적합도는 98% 이상으로 매우 적합하였으며, Dyar 계수(K)는 1.316이었다. 월동하는 끝동매미충의 밀도 및 충태 변화를 조사한 결과, 2006년 1월 하순에 0.25 $m^2$ 당 195마리가 채집되어 밀도가 가장 높았고, 월동 충태 조사에서는 90% 이상이 4령 약충이었다. 3월 중순부터 5령 약충의 발생량이 증가하였고, 월동 후 첫 성충발생은 4월 상순이었다.