Behavioural and olfactory responses of &lt;i&gt;Sitophilus zeamais&lt;/i&gt; (Coleoptera: Curculionidae) to &lt;i&gt;Aframomum melegueta&lt;/i&gt; and &lt;i&gt;Zingiber officinale&lt;/i&gt; oleoresins.

D.A Ukeh,I.A Udo,S Umoetok,K Abdullah

doi:10.4314/gjpas.v16i1.62799

Abstract

The oleoresins extracted from the seeds of alligator pepper, Aframomum melegueta and ginger, Zingiber officinale rhizome using methanol, was evaluated for bioactivity against the maize weevil, Sitophilus zeamais in the laboratory. Using a 4-arm olfactometer, solutions of the oleoresins at a concentration of 1 mg/ml exhibited significant olfactory repellent activity against male and female S. zeamais when tested alone, and in combination with maize seeds. These findings provide a scientific basis for the observed repellent properties of the oleoresins and demonstrate the need for their development in stored product pest protection in Africa where these plants are readily available.KEYWORDS: Oleoresin, Aframomum melegueta, Zingiber officinale, Sitophilus zeamais, Olfactometer.

Highlights

The maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) is an important field to store pest of cereals in the tropics causing considerable losses estimated at about 96 million metric tonnes the world over (FAO, 1985; Throne, 1994)
Average dry weight losses of farm-stored maize for a storage period of 6 months caused by S. zeamais and Prostephanus truncatus (Horn.) (Coleoptera: Bostrichidae) in Togo has been estimated to range between 7% and 30% (Pantenius, 1988; Richter et al, 1997)
Insect culture Maize weevil was obtained from stock culture maintained by Central Science Laboratory, Sand Hutton, York, England, and reared on untreated Nigerian “Ikom white” maize, Zea mays (L.) and “local yellow” maize seeds in Kilner jars, at constant temperature and humidity (CTH) room running at 25 °C, 65% relative humidity on a 12:12 DL photoperiod

Summary

Introduction

The maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) is an important field to store pest of cereals in the tropics causing considerable losses estimated at about 96 million metric tonnes the world over (FAO, 1985; Throne, 1994). Average dry weight losses of farm-stored maize for a storage period of 6 months caused by S. zeamais and Prostephanus truncatus (Horn.) (Coleoptera: Bostrichidae) in Togo has been estimated to range between 7% and 30% (Pantenius, 1988; Richter et al, 1997). In Ethiopia in general, post-harvest losses caused by S. zeamais ranging from 20-30% are common, and studies in the Bako areas have shown grain damage levels up to 100% in some samples from farm stores after 6-8 months (Emana, 1999; Demissie et al, 2008). Weevils may gain access passively when other commodities are brought in from infested stores or by transportation on vehicles, farm equipment, sacks, and baskets or even on clothing (Cox and Collins, 2002)

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