Potential use of essential oils from local Cameroonian plants for the control of red flour weevil Tribolium castaneum (Herbst.) (Coleoptera : Tenebrionidae)

Animal feed is food constituted for breeding stock animals because it possesses vital nutrients for animal growth. Animal feed or their ingredients as constituted by cereal flour and are stored after formulation for ulterior breeds. These provender or cereal grains used are commonly attacked by storage insects principally of the genus Tribolium. Firstly, contact and ingestion test by two essential oils of aromatics plants Ocimum gratissimum L (Lamiaceae) and Xylopia aethiopica Dunal A. Rich (Annonaceae) were done firstly on adults and aged larvae of Tribolium castaneun. Secondly, the contact and inhalation test by three essential oils of the aromatic plants Annona senegalensis L. (Annonaceae), Lippia rugosa L.  (Lamiaceae) and Hyptis spicigera Lam. (Verbenaceae) were done for the control larvae, young and aged adults of the red flour weevil Tribolium castaneum Herbst (Coleoptera : Tenebrionidae) very resistant pest to chemical pesticides. Essential oils of Ocimum gratissimum and Xylopia aethiopica have no contact and  ingestion effect on adults of Tribolium castaneum; their insecticidal activity is characterized mostly by their inhibition of the  nymphosis of aged larvae of the same species. On the other hand contact and inhalation tests with crude essential oils of Lippia rugosa and Hyptis spicigera are the most promising because of their efficacy on the other life stages. They are more efficient, with 100% mortality, on larvae at early  stages and young adults. On resistant aged larvae and adults, the insecticidal  efficacy decreases but remains significant. Since this insect, Tribolium castaneum is the major pest of stored flours and provender, the incorporation of these  promising essential oils in flours or in storage formulations of these foods for animals could contribute to their better cereal food conservation. The important and indispensable element of cereals for storage, growth and reproduction animal feed could be preserved from insects attack by use of natural product and may  contribute to diminish toxicity of feeder, environmental pollution and the resistance phenomenon of insects.Key words: Essential oils, Tribolium castaneum, Pesticides

Potential of Anisopteromalus calandrae (Hymenoptera: Pteromalidae) as biocontrol agent of Callosobruchus maculatus (F.) (Coleopetera: Bruchidae)

The bruchid Callosobruchus maculatus (F.) (Coleopetera: Bruchidae) is a major pest of stored cowpea Vigna unguiculata (Walp.) in Africa and particularly in northern Cameroon. Anisopteromalus calandrae (Hymenoptera: Pteromalidae) parasitoid of its larval stages, could be used in the biological control of this grain pest. In field conditions, 5 months samples in small holder granaries established the phenological relationship between this parasitoid and its host. Large amount of A. calandrae may efficiently control C. maculatus infestations. Laboratory assays made an evidence of the preference of A. calandrae to parasitise 4th instar larvae of C. maculatus. To estimate the suitable density of the infesting population of parasitoid, other experiments pointed out that one mated female induced reduction of 4.97% of emergence of C. maculatus while 4 females performed more. The reduction of emergence observed was 42.34%. In suitable density, A. calandrae may play an important role in the biological control of C. maculatus on cowpea during storage

Toxicity Of Some Terpenoids Of Essential Oils Of Xylopia Aethiopica From Cameroon Against Sitophilus Zeamais Motschulsky

The acute toxicity of essential oils from the whole fruit (EF) or from the fibres of the fruit (FF) of the local aromatic plants Xylopiα αethiopicα Dunal (Annonaceae) collected in north Cameroon was evaluated on Sitophilus zeαmαis adults. A concentration of 1 ml of essential oil per 100 g of maize seeds was tested to determine weevil mortality after 24 h of exposure. Under these conditions, the essential oil derived from both EF and FF of X. αethiopicα led to 100% mortality. In a second step, proportions of active compounds present in the oil of both EF and FF of X. αethiopicα were quantified. The toxicity of the four main compounds was tested against S. zeαmαis: α-pinene, β-pinene, -3-carene and terpinen-4-ol according to their proportion in the essential oil of the concerned plant part. β-pinene and terpinen-4-ol were responsible for 50% of the mortality at the proportion found in EF and FF essential oils respectively. When mixed, a synergic effect of the compounds was observed that restored the mortality percentage observed for the crude oil. It appears that X. αethiopicα essential oil could be a potential source of natural and low-cost insecticide to control storage pests

The use of plant extracts for stored product protection

A wide range of plant extracts have been used alternatively to chemical insecticides against stored product insect pest species. These substances could be used alone or in combination with other alternatives or synthetic insecticides in order to enhance their action. Botanicals can be applied with the same techniques that are used for the application of traditional contact insecticides or fumigants. Given that stored product insects exhibit different levels of sensitivity or tolerance to plant extracts, a wide screening of these substances has been carried out to widen the available tools against these harmful organisms with interesting results. © 2014 Springer India. All rights reserved