The biology, ecology and control of Phalanta phalanta Drury (Lepidoptera: Nymphalidae), a defoliator of Populus spp. in Nigeria.
Poplars (Populus spp.) have recently been introduced into Nigeria where the young trees suffer defoliation by larvae of Phalanta phalantha (Dru.), a Nymphalid that has not previously been of pest status locally. The results of investigations of its biology in the field and laboratory in 1967-70 are reported. In the field, adults were associated with the flowers of the weed Tridax procumbens. In a nursery site where fertilisers and insecticides were applied to poplars of a hybrid clone (Populus deltoides X P. nigra) as routine measures, adults were seen but no damage. On Populus in an unprotected nursery in another area defoliation was severe. Eggs were found in the field in every month of the year, and the rate of hatching varied from 13.0 to 51.6%. There were five larval instars, and in the laboratory at 23-29 deg C the duration of the larval stage was 10-13 days. In the field and outdoor cages, the duration was 1-2 days less. The pupal stage lasted 5-7 days, and the adults lived for up to 41 days in outdoor cages [cf. RAE/A 56, 1253]. In the course of rearing, three adults of the parasite Brachymeria kivuensis (Schmitz) emerged from pupae and one of Palexorista sp. from a larva of the Nymphalid. For control on young poplars (which are more vulnerable than older trees), clearance of T. procumbens and the encouragement of fast growth by application of fertilisers are recommended; sprays of 0.01% aldrin (Aldrex) or 0.005% dieldrin (Dieldrex) used against termites protect against Phalanta.