Bruchid control with traditionally used insecticidal plants Hyptis spicigera and Cassia nigricans

Abstract

Losses of stored seed to insects in the tropics have reached levels of major concern. Synthetic insecticides, while effective, are generally very expensive for small fanners. The efficacy of two plants, Hyptis spicigera and Cassia nigricans, used by farmers to control insect infestation in stored cowpeas was determined. The oviposition and hatching of bean weevils {Acanthoscelides obtectus), under controlled environmental conditions, were reduced following treatment with EtOH extracts (1 g plant material 1 ml EtOH) at low application rates with EC 50 between 0.3 and 14 n\ extract/g bean. Further field studies are proposed to determine if such natural products can be further exploited to reduce stored legume losses.Resume-Les pertes causees par les insectes aux graines entreposees ont atteint un niveau d'alerte. Les insectcides synthetiques bien qu'efflcaces sont generalement tres couteux pour les petits planteurs. On a determine l'efficacite de deux plantes Hyptis spicigera et Cassia nigricans utilisees par les planteurs pour lutter contre les infestations d'insectes attaquant les pois blancs. L'oviposition et l'eclosion des charancons (Acanthoscelides objectus) a des conditions d'elevage controlees a ete reduite suite a un traitement d'extraits alcooliques (un g/ml) a des doses faibles ayant une CE,,, de 0.3-14 ^1 d'extrait par gramme de pois. Nous proposons des evaluations sur le terrain pour determiner si Ton peut envisager l'utilisation de ce genre de produit naturel pour reduire les pertes en legumineuses emmagasinees.

Comparative susceptibility of different legume seeds to infestation by cowpea bruchid Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae)

“…In a no-choice experiment, 24 h after infestation, the number of laid eggs on different treatments was counted following the method as described by Lambert et al (1985).…”

“…Subsistence agriculture requires that the farmer store a percentage of staple food to feed his family and livestock between harvests (Hindmarsh et al 1978). The largest quantity of food in the tropics is stored in traditional farmer's granaries and in most cases under one roof (Lambert et al 1985;Stathers et al 2002).…”

Effect of Site Location and Collecting Period on the Chemical Composition ofHyptis SpicigeraLam. an Insecticidal Essential Oil from North-Cameroon

“…In Central and eastern Africa, and also in Guinea, H. spicigera is cultivated and the oleaginous seeds are eaten like sesame. It is also recognized as a valuable bio-pesticide, because when mixed with grains (3g of dried leaves powder for 1kg of grains), H. spicigera exhibits strong insecticidal and repellent activities against insects devastating stored grains (3). Within a large ethnobotanical survey carried out in northern Cameroon, Ngamo and Mapongmetsem (personal communication, 2004) highlighted that H. spicigera is traditionally used by some ethnic groups (Guiziga, Massa, Mofu, Musgum, Mundang…) to protect cowpeas and sorghum against insects infestation.…”

“…Within a large ethnobotanical survey carried out in northern Cameroon, Ngamo and Mapongmetsem (personal communication, 2004) highlighted that H. spicigera is traditionally used by some ethnic groups (Guiziga, Massa, Mofu, Musgum, Mundang…) to protect cowpeas and sorghum against insects infestation. The insecticidal potentiality of H. spicigera has been emphasized by some authors (3,4). Lambert et al (3) managed to control the oviposition and the hatching of weevils by treatment of peas with alcoholic extracts of H. spicigera.…”

Applied evolutionary ecology of insects of the subfamily Bruchinae (Coleoptera: Chrysomelidae)

“…Alternatively, parasitoids (e.g., a trichogrammatid egg parasitoid Uscana, larval-pupal parasitoids, pteromalid Dinarmus, Anisopteromalus, an eupelmid Eupelmus, and a braconid Heterospilus; e.g., Southgate, 1979;Steffan, 1981;Fujii and Wai, 1990;Mitsunaga and Fujii, 1999;Schmale et al, 2001;Tuda et al, 2001;Kobayashi et al, 2003;Jaloux et al, 2004;Tuda and Shimada, 2005;Wu et al, 2005;Vamosi, Hollander and Tuda, unpublished) and plant extracts (e.g., Lambert, 1985;Rahman, 1990) have been actively explored for biological control (see Huis, 1991 for review). In addition to biological and botanical control, controlled temperature (e.g., Rahman, 1990), mechanical control (e.g., Quentin et al, 1991), controlled atmosphere (e.g., Oosthuzien and Schmidth, 1942) and radiation (e.g., Kiyoku and Tsukuda, 1968;Hossain et al, 1972;Reddy et al, 2006) have been proposed as effective control methodology (see also Highley et al, 1994).…”