Some aspect of the life cycle and morphology of Anomis Leona SCHAUS (Lepidoptera: Noctuidae), an emerging pest of cocoa
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Some aspect of the life cycle and morphology of Anomis Leona SCHAUS (Lepidoptera: Noctuidae), an emerging pest of cocoa in Nigeria Olayiwola Maroof 1 & Idoko Joy Ejemen 2
&
Ofuya Thomas Inomisan 2
Received: 24 August 2019 / Accepted: 14 January 2020 # African Association of Insect Scientists 2020
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. Keywords Anomis Leona . Larval instars . Developmental period . Head capsule . Cocoa
Introduction The exploitation of vast land area for large scale agricultural farming had led to alternation in the ecosystem, resulting in pest outbreaks. In West Africa, cocoa suffers from incidence of pest outbreak more than anywhere else in the world (Mariau 1999; Anikwe 2009). Recently, there was an outbreak of Anomis leona Schaus (Lepidoptera: Noctuidae) a minor pest of cocoa seedlings and trees in some part of West Africa. The larval stages of the insect were implicated and they initially attacked the leaves on which the eggs were probably being laid Sarfo and Opoku (2006). The attack was * Idoko Joy Ejemen [email protected] 1
Cocoa Research Institute of Nigeria, P.M.B 5244, Idi-Ayunre, Ibadan, Oyo State, Nigeria
2
Crop, Soil and Pest Management Department, School of Agriculture and Agricultural Technology, Federal University of Technology, Akure, Nigeria
initially restricted to young and succulent leaves but extended into pods as the leaves aged and hardened. Green pods of all stages were attacked, even though cherelles and younger pods were more susceptible Sarfo and Opoku (2006). The pods were damaged as the larvae ate the pericarp and gradually bore through the endocarp to reach the beans, resulting in premature pod ripening and eventually wilting. Severe pods damage range from 30%–50%, and the larvae numbers per tree were between six and nine Sarfo and Opoku (2006). This situation was in line with observation of Omo
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