Susceptibility of Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) to insecticides

African farmers operate traditional methods of integrated pest control when storing maize. They dry the maize well, store it on the cob in suitable structures and avoid protracted storage whenever possible. Such traditional methods are reasonably effective and studies have shown that under normal conditions they can keep losses down to less than 5% per year (Adams, 1977; Golob, 1981 a and 1981 b). Recent changes in farming systems have, however, interfered with traditional storage practices, resulting in the more frequent occurrence of serious losses. In particular, where high-yielding varieties of maize have been introduced, a dramatic increase in losses has often resulted. Other changes in farming systems have affected cropping patterns, causing farmers to store maize that is too wet, increasing its susceptibility to attack by insects and fungi.
The recent accidental introduction of the larger grain borer (Prostephanus truncatus) into Africa has added a new dimension to these problems, through its remarkable ability to damage well-dried maize, even when stored on the cob. This beetle is currently a more serious pest in parts of sub-Saharan Africa than in its native Central America, indicating that in Africa there are ecological, agricultural or socio-economic factors associated with maize storage which favour its success. Certainly, where P. truncatus has become established in Africa, it has commonly increased the loss levels sustained in traditional maize stores to a point at which intensified pest control by the farmer is an economic necessity (McFarlane, 1988). 
There is thus a need to revise recommended methods for the control of insect pests of maize in farm storage, taking into account the changes which have reduced the effectiveness of traditional practices. This bulletin attempts to summarize available data from studies of pest infestation in traditional maize stores, relevant to current and future research in this field. The emphasis on P. truncatus in parts of the text reflects the importance currently attached to the development of integrated pest management strategies for this pest, in order to limit its spread in maize-producing regions of Africa.

A review of insect infestation of maize in farm storage in Africa with special reference to the ecology and control of Prostephanus truncatus (NRI Bulletin No. 18)

Among the pests that attack stored maize and wheat grain, Sitophilus oryzae (L.) and S. zeamais Motsch (Coleoptera: Curculionidae) are the most destructive. This paper is aimed at the study of the insecticidal effect and the residual action of organophosphate fenitrothion, pyrethroid esfenvalerate, and the mixture of both on S. oryzae and S. zeamais in stored maize and wheat. Grains were treated in order to obtain theoretical concentrations of 10 and/or 0.5 mg·kg−1 fenitrothion and esfenvalerate, respectively. The effectiveness experiments were installed as of 15, and 30 days, and subsequently at monthly intervals as of 12 months after grain treatment, or until mortality ceased in the plots. After mortality evaluation happened all individuals were eliminated, either dead or alive, and grains were kept for 60 days to assess the number of emerged progeny. The comparison of mortality curves of the pest species within each combination of grain type and insecticide showed significant differences. In general, the mortality of S. oryzae decreased faster than that of S. zeamais considering the grain type-insecticide combination. Esfenvalerate was ineffective in all combinations. Higher mortality of both species was observed on wheat grains treated with fenitrothion and fenitrothion

/pdf/insecticidal-effect-and-residual-action-of-fenitrothion-and-2bnyi3b4gv.pdf

Insecticidal Effect and Residual Action of Fenitrothion and Esfenvalerate on Sitophilus oryzae and S. zeamais (Coleoptera: Curculionidae) in Stored Maize and Wheat

Simulation of natural air drying of maize in cribs

The biological activity of dry, ground plant parts (dust) and tablets of Zanthoxylum xanthoxyloides (Lam.) was assessed in both the laboratory and on the field against the maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) and the cowpea weevil, Callosobruchus maculatus (F.) (Coleoptera: Bruchidae). Dry ground leaves, bark and roots were prepared in various proportions of 60% leaves and 40% roots; 70% leaves and 30% roots; 80% leaves and 20% roots; 90% leaves and 10% roots; 60% leaves and 40% bark; 70% leaves and 30% bark; 80% leaves and 20% bark; 90% leaves and 10% bark, as well as 100% leaves, 100% bark and 100% roots. These proportions were mixed with 5 kg of grains at 5% (wt/wt) concentration to assess contact toxicity, grain protection, effect on eggs and immature stages and persistency. The biological activity of Z xanthoxyloides was also accessed using tablets made from different concentrations of 2.2ml leaves and 1.8ml roots; 2.4ml leaves and 1.6ml roots; 2.6ml leaves and 1.4ml roots; 2.8ml leaves and 1,2ml roots; 2.2ml leaves and 1.8ml bark; 2.4ml leaves and 1.6ml bark; 2.6ml leaves and 1.4ml bark and 2.8ml leaves and 1.2ml bark. Five tablets of each of the different concentrations were mixed with 5 kg of grains to assess toxicity or grain protection by fumigation, effect on eggs and immature stages persistency and repellency. University of Ghana http://ugspace.ug.edu.gh The effective combinations of dry ground dusts were 60% leaves and 40% roots; 70% leaves and 30% roots; 60% leaves and 40% bark and 70% leaves and 30% bark. These significantly (P<0.001) induced over 68 % mortality of both species of insects, provided about 96% protection to the grains, inhibited the development of eggs and immature stages and were persistent for 2 months. The effective tablet formulations were from concentrations of 2.2 ml: 1.8ml (v/v) leaves: roots; 2.4 ml: 1.6 ml (v/v) leaves: roots; 2.2 ml: 1.8ml (v/v) leaves: bark and 2.4 ml: 1.6ml (v/v) leaves: bark. These induced about 50% mortality, offered about 95% protection to the grains and evoked repellent actions against both insects. There was however, a rapid loss of activity after 7 days following treatment, irrespective of the dosage applied. Z xanthoxyloides, which is relatively safe to mammals because it is used for the treatment of ailments like tooth aches, stomach aches, leprous ulceration, and ulcers, syphilitic sores, fever, post-delivery pains while the leaves are fed to ruminants could be prepared into effective dry ground dust proportions as well as tablets for resource-poor farmers to protect their grains against some stored product pests. v University of Ghana http://ugspace.ug.edu.gh ACKNOWLEDGEMENT My greatest thanks go to God for helping me to carry out this research successfully. I wish to express my profound gratitude to my parents, especially my mother for the pain and responsibility they took in educating me this far. I render my sincere appreciation and gratitude to my supervisors Prof. J.N. Ayertey, Coordinator of the African Regional Postgraduate Programme in Insect Science and Dean of Graduate Studies, University of Ghana, Legon and Dr. Ebenezer Oduro Owusu of the Zoology Department, University of Ghana, Legon, for all their assistance, advice, constructive criticisms and encouragement in the supervision of this research work. I am very much grateful to Dr. Daniel Obeng-Ofori, Head of Crop Science Department, University of Ghana, Legon, for the numerous assistance, literature and encouragement he gave me at various stages of this work. I acknowledge with thanks the financial support, information and encouragement of Mr. John Manful of the Food Research Institute (C.S.I.R.) Accra, for this research work. I am very much indebted to Dr. Akuamoah of the Chemistry Department, University of Ghana, Mr. David Asiedu and Mr. Amoakoh, both of the Microbiology Department, Food Research Institute (C.S.I.R.) Accra, for providing literature, equipments, chemicals and assistance in the preparation of the Zanthoxylum xanthoxyloides tablets. v i University of Ghana http://ugspace.ug.edu.gh

On- Farm Evaluation of Candlewood Zanthoxylum Xanthoxyloides (Lam.) on Two Stored Product Pests.

Field trials to control insect pests of farm-stored maize in Zambia

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Field trials to control insect pests of farm-stored maize in Zambia