Some aspect of the life cycle and morphology of Anomis Leona SCHAUS (Lepidoptera: Noctuidae), an emerging pest of cocoa in Nigeria

Abstract

Recent field survey in the last 3 years at the Cocoa Research Institute of Nigeria (CRIN) showed that eight out of ten Lepidopteran caterpillars is Anomis Leona Schaus (Lepidoptera: Noctuidae). Some life cycle parameters of A. leona were investigated in the laboratory inside a growth chamber at an ambient temperature of 27 ± 3 °C and 70–80% relative humidity. The adult insect measures 15 – 20 mm in length with a dull brown colour and wings and the body are covered with scales. The detailed morphology of different larval stages of the insect was examined under binoculars microscope at every molt of the larvae. There were four larval instars and the forth instars exhibited marked colour polymorphism. The larvae measured 26.8 mm at full growth. The first and second larval instars feed on new reddish and green young cocoa leaves causing characteristic short holes on them while third and fourth larvae feed on entire leaves. The pupa is enclosed within a cocoon and when newly formed is purple in colour but later changed to a dark shinning brown colour. The insect undergo holometabolous development. The insect completed its life cycle in 26.3 days (range 24–30 days) from the egg stage.