Effect of Temperature on Hatchability of Overwintering Eggs and Nymphal Development of Pochazia shantungensis (Hemiptera: Ricaniidae)

This study investigates the hatching periods and hatchability of the eggs of Pochazia shantungensis at different collection times from 2011 to 2014, and the effect of temperature on the growth of P. shantungensis nymphs in an area of its outbreak. The hatchability of P. shantungensis eggs varies with their collection time; their hatchability in late November was higher than that in March of the next year, but no difference was observed in their hatching periods. The hatching periods of the eggs were 51.2, 31.3, 24.8, 19.4, 17.1, and 19.4 days at 15, 18, 21, 24, 27, and $30^{\circ}C$, respectively. The hatchability was above 70% at temperatures ranging from 18 to $27^{\circ}C$. The hatching time of the overwintered eggs in the Gurye region in Korea was reduced by 9 days from 2011 to 2014. The hatching rate was relatively higher when the average temperature in the winter season was relatively warmer. The dvelopmental periods of the first to fifth nymphs were 82.8, 58.0, 45.8, and 39.6 days at 18, 21, 24, and $27^{\circ}C$, respectively, at the relative humidity of 40~70%, and a photoperiod off 14 h light:10 h dark. The higher the temperature, the shorter the developmental period. At $30^{\circ}C$, all life stages after the fourth nymph died. Thus, the optimum growth temperature was estimated to be $27^{\circ}C$. For all life stages from the egg to the fourth nymph, the relationship between the temperature and developmental rate was expressed by the linear equation Y = 0.0015 X - 0.014. The lower developmental threshold was $9.3^{\circ}C$ and the effective cumulative temperature was 693.3 degree-days. The lower developmental threshold of approximately $3.8^{\circ}C$ was the lowest at the fourth nymph stage.

갈색날개매미충(Pochazia shantungensis) 월동알 부화와 약충 발육에 미치는 온도의 영향

본 실험은 갈색날개매미충의 난괴 채집시기별 부화율, 2011년부터 2014년까지 부화율과 부화시기, 그리고 발육에 미치는 온도의 영향을 조사하였다. 갈색날개매미충 알은 11월부터 익년 3월까지 채집시기가 늦어질수록 부화율이 높아지는 경향이며, 부화기간은 차이가 없었다. 온도별 부화 소요기간은 15, 18, 21, 24, 27, $30^{\circ}C$에서 각각 51.2, 31.3, 24.8, 19.4, 17.1, 19.4일이었으며 $18{\sim}27^{\circ}C$ 범위에서 70% 이상의 부화율을 보였다. 전남 구례지역에서 갈색날개매미충 월동 알의 부화시기는 2011년보다 2014년에 9일이 빨라졌으며, 겨울철 평균온도가 높았던 해에는 부화율이 높아지는 경향이었다. 부화약충부터 5령 약충까지 온도별 발육기간은 18, 21, 24, $27^{\circ}C$(습도 40~70%, 광조건 14L:10D)에서 각각 82.8, 58.0, 45.8, 39.6일로 온도가 높을수록 발육기간은 짧아졌는데, $30^{\circ}C$에서는 4령 이후 모두 사멸하여 시험온도중 약충의 발육최적온도는 $27^{\circ}C$이었다. 알에서부터 4령 약충까지의 온도와 발육속도와의 관계식은 Y = 0.0015 X - 0.014이며, 발육영점온도는 $9.3^{\circ}C$, 유효적산온도는 693.3일도였다. 발육영점온도는 4령 약충이 $3.8^{\circ}C$로 가장 낮았다.