Studies on the biology of the palm aphid, Cerataphis variabilis (Homoptera: Pemphigidae), on Raphia hookeri–1: Developmental period of the immatures, fecundity and longevity of the apterous adults

Abstract

AbstractThe biology of the aphid, Cerataphis variabilis H.R.L., on Raphia hookeri Mann & Wendl., was studied in the laboratory and the field using a ‘clip-on’ cage and a sleeve cage. The first instar lasted 5.1 days. The second and third instars each lasted 2.45 days, while the fourth instar lasted 2.4 days. The total developmental period of the nymphs was 11.3 days at 26.4 ± 1.43°C and r.h. 83 ± 1.46%; 11.6 days at 26.4 ± 1.63°C and r.h. 85 ± 1.19%; 12.9 days at 27.9 ± 1.04°C and r.h. 75.5 ± 1.64%; 12.95 days at 27.8 ± 0.33°C and r.h. 69 ± 1.23%; 15 days at 21.4 ± 0.58°C and r.h. 45 ± 1.77%. These periods were significantly different at 5% level (LSD = 0.59 days). The higher the temperature and relative humidity the shorter the developmental period (with temperature: r = −0.69, 20.8–28.9°C; r.h.: r = −0.97, 43.2–86.2%). The number of progeny per adult ranged from 54 to 60 in a period of 28–31 days. The longevity ranged from 31 to 34 days.