The effects of temperature on the development of the immature stages of the Cassava Mealybug, Phenacoccus manihoti Mat-Ferr. (Homoptera, Pseudococcidae)

The durations of eggs, nymphs and immature adults of the cassava mealybug, Phenacoccus manihoti Mat-Ferr. were determined at 3–4 constant temperatures. The duration of development of each stage decreased with increase in temperature. The rate of development was slowest in the egg and fastest in the second instar nymph. The calculated lower threshold temperatures were 14 °C (egg), 20 °C (instar I), 19 °C (instar II), 19.5 °C (instar III), 17 °C (immature adult), and 20 °C (egg-adult). The sums of effective temperatures were for eggs 131.4 degree-days, instar I 34.1 degree-days, instar II 33.0 degree-days, instar III 32.5 degree-days, immature adult 58.5 degree-days and egg-mature adult 260.9 degree-days above their respective thresholds.