EFFICACY OF VEGETABLE OIL EXTRACTS FOR CONTROL OF INSECT PESTS OF TOMATO IN SOUTHERN BENIN

Pests are a menace to production of tomato ( Lycopersicon esculentum Mill.) in sub-Sahara Africa. The objective of this study was to evaluate the efficacy of oil extracts of selected common plants for control of pests of tomato in Benin. The study was carried out on the Togba market garden sites in Benin. The botanical pesticides ( Tephrosia purpurea , Ricinus communis , Thevetia neriifolia and Cashew Nut Shell Cold Liquid (CNSL cold) were compared with a biological insecticide (Topbio), a synthetic insecticide (Lambda cyhalothrin) and an untreated negative control. The fish model and the generalised linear mixed or fixed effects model were used to explain the number of caterpillars per plot as a function of the products tested during the different plant phases. Tephrosia purpurea oil, cold CNSL, Topbio and lambda cyhalothrin treatments significantly reduced H. armigera, S. littoralis and T. absoluta populations. The average yields of marketable tomato ranged from 7.20 \ub1 0.89 t ha-1 for the controls and 21.14 \ub1 3.56 and 20.46\ub11.98 t ha-1 for the plots treated with Tephrosia purpurea and CNSL cold on tomato, respectively. Plots treated with the synthetic insecticide lambda cyhalothrin gave the best yields (31.15\ub13.20 t ha-1). Of all the extracts tested, cold extracted CNSL and T. purpurea oil showed very high larvicidal activity at doses of 10%, compared to R. communis and T. neriifolia oil on the farm. The larvicidal activity of the extracts observed at low doses on H. armigera and S. littoralis larvae seems to offer an alternative advantage for the control of tomato pests.Les ravageurs sont une menace pour la production de tomate (Lycopersicon esculentum Mill.) en Afrique sub-saharienne. L\u2019objectif de cette \ue9tude \ue9tait d\u2019\ue9valuer l\u2019efficacit\ue9 des extraits d\u2019huile de Tephrosia purpurea, Ricinus communis, Thevetia neriifolia et Cashew Nut Shell Cold Liquid (CNSL cold) pour le contr\uf4le des ravageurs de la tomate. L\u2019\ue9tude a \ue9t\ue9 r\ue9alis\ue9e sur les sites mara\ueechers de Togba au B\ue9nin. Les pesticides botaniques ont \ue9t\ue9 compar\ue9s \ue0 un insecticide biologique (Topbio), un insecticide de synth\ue8se (Lambda cyhalothrine) et un t\ue9moin n\ue9gatif non trait\ue9. Le mod\ue8le poisson z\ue8bre et le mod\ue8le lin\ue9aire g\ue9n\ue9ralis\ue9 \ue0 effets mixtes ou fixes ont \ue9t\ue9 utilis\ue9s pour expliquer le nombre de chenilles par parcelle \ue9l\ue9mentaire en fonction des produits test\ue9s lors des diff\ue9rentes phases de la plante. Les traitements \ue0 l\u2019huile de Tephrosia purpurea, au CNSL cold, au Topbio et \ue0 la lambda cyhalothrine ont significativement r\ue9duit les populations de H. armigera, S. littoralis et T. absoluta. 20,46\ub11,98 t ha-1 pour les parcelles trait\ue9es respectivement avec Tephrosia purpurea et CNSL cold sur tomate. Les parcelles trait\ue9es avec l\u2019insecticide de synth\ue8se lambda cyhalothrine ont donn\ue9 les meilleurs rendements (31,15\ub13,20 t ha-1). De tous les extraits test\ue9s, l\u2019huile de CNSL cold et de T. Purpurea extraite a montr\ue9 une activit\ue9 larvicide tr\ue8s \ue9lev\ue9e \ue0 des doses de 10% par rapport \ue0 l\u2019huile de R. communis et de T. neriifolia \ue0 la ferme. L\u2019activit\ue9 larvicide des extraits observ\ue9e \ue0 faible dose sur les larves de H. armigera et S. littoralis semble offrir un avantage alternatif pour la lutte contre les ravageurs de la tomate

Source of resistance among cowpea accessions to bruchid, Callosobruchus maculatus F. Coleoptera: Chrysomelidae, in Benin

Post-harvest loss in cowpea ( Vigna unguiculata L.) is essentially caused by bruchid (Callosobruchus maculatus F.), the most damaging storage pest causing up to 95% loss of produce kept for long in non-treated conditions. In managing storage pests, host plant resistance proves to be a better approach than chemicals control, especially for food produce. However, no investigation in Benin has tackled resistance of cowpea germplasm to bruchid. The obective of this study was to identify sources of resistance to cowpea bruchid in Benin. A total of 174 cowpea accessions were evaluated in storage. Fourteen cowpea accessions were found resistant to bruchid including: IT06K-123-1, ALEGI*SECOW3B, IT86D-1038, WC35B, IT86D-1033, TOUMKALAM, KPLOBEROUGE, WC66*NE50, IT06K-270, IT84S-2246-4, WC36, TVU1471, TVU-1367-7 and WC66*5T with respective Dobie susceptibility indices of : 2.96, 2.71, 2.67, 2.58, 2.55, 2.49, 2.46, 2.36, 2.11, 1.42, 1.15, 0.53, 0.00 and 0.00. Pest tolerance of cowpea (0.00 to 100.00%) varied according to the resistance and susceptibility statuses of accessions screened. Correlations showed that seed damage, number of adult emerged, weight loss and Dobie susceptibility index, could be considered essential while selecting bruchid tolerant accessions. The resistant accessions observed during this experiment can serve as parental lines in breeding programmes.Le ni\ue9b\ue9 ( Vigna unguiculata L.) est fortement attaqu\ue9 par les bruches du ni\ue9b\ue9 ( Callosobruchus maculatus F.) causant 95% de d\ue9g\ue2ts. L\u2019usage des plantes r\ue9sistantes constitue une alternative aux produits chimiques. Ainsi, au B\ue9nin, en absence d\u2019\ue9tudes ant\ue9rieures sur la r\ue9sistance du ni\ue9b\ue9 aux bruches les accessions susceptibles sont toujours cultiv\ue9es. L\u2019objectif g\ue9n\ue9ral de cette \ue9tude est l\u2019\ue9valuation de la r\ue9sistance des diff\ue9rentes accessions de ni\ue9b\ue9 cultiv\ue9 au B\ue9nin. En effet, 174 accessions de ni\ue9b\ue9 ont \ue9t\ue9 \ue9valu\ue9es en stock. Plusieurs param\ue8tres ont \ue9t\ue9 d\ue9termin\ue9s : poids initial et final des graines; pourcentage d\u2019insecte \ue9merg\ue9; pourcentage de perte de poids, de graines endommag\ue9es et de tol\ue9rance des insectes; p\ue9riode m\ue9diane de d\ue9veloppement; indice de susceptibilit\ue9 de Dobie; indice de croissance; nombre moyen de trous, nombre moyen d\u2019\u153ufs pondus. Les donn\ue9es collect\ue9es ont \ue9t\ue9 soumises \ue0 ANOVA One-way, corr\ue9lation de Pearson et \ue0 une r\ue9gression lin\ue9aire multiple. Quatorze accessions \ue9taient r\ue9sistantes aux bruches \ue0 savoir\ua0: IT06K-123-1, ALEGI*SECOW3B, IT86D-1038, WC35B, IT86D-1033, TOUMKALAM, KPLOBEROUGE, WC66*NE50, IT06K-270, IT84S-2246-4, WC36, TVU1471, TVU-1367-7 et WC66*5T respectivement avec la susceptibilit\ue9 de Dobie: 2.96, 2.71, 2.67, 2.58, 2.55, 2.49, 2.46, 2.36, 2.11, 1.42, 1.15, 0.53, 0.00 et 0.00. La corr\ue9lation de Pearson montre que pourcentage de graine endommag\ue9e, nombres d\u2019insectes \ue9merg\ue9s, la perte de poids et l\u2019indice de susceptibilit\ue9 de Dobie sont les param\ue8tres \ue0 prendre en compte dans un processus de s\ue9lection des accessions r\ue9sistantes aux bruches. En cons\ue9quence, les accessions r\ue9sistantes observ\ue9es dans ce travail peuvent \ueatre utilis\ue9es dans des programmes d\u2019am\ue9lioration

Efficacy of vegetable oil extracts for control of insect pests of tomato in Southern Benin

Pests are a menace to production of tomato (Lycopersicon esculentum Mill.) in sub-Sahara Africa. The objective of this study was to evaluate the efficacy of oil extracts of selected common plants for control of pests of tomato in Benin. The study was carried out on the Togba market garden sites in Benin. The botanical pesticides (Tephrosia purpurea, Ricinus communis, Thevetia neriifolia and Cashew Nut Shell Cold Liquid (CNSL cold) were compared with a biological insecticide (Topbio), a synthetic insecticide (Lambda cyhalothrin) and an untreated negative control. The fish model and the generalised linear mixed or fixed effects model were used to explain the number of caterpillars per plot as a function of the products tested during the different plant phases. Tephrosia purpurea oil, cold CNSL, Topbio and lambda cyhalothrin treatments significantly reduced H. armigera, S. littoralis and T. absoluta populations. The average yields of marketable tomato ranged from 7.20 ± 0.89 t ha-1 for the controls and 21.14 ± 3.56 and 20.46±1.98 t ha-1 for the plots treated with Tephrosia purpurea and CNSL cold on tomato, respectively. Plots treated with the synthetic insecticide lambda cyhalothrin gave the best yields (31.15±3.20 t ha-1). Of all the extracts tested, cold extracted CNSL and T. purpurea oil showed very high larvicidal activity at doses of 10%, compared to R. communis and T. neriifolia oil on the farm. The larvicidal activity of the extracts observed at low doses on H. armigera and S. littoralis larvae seems to offer an alternative advantage for the control of tomato pests

Susceptibility of some Rice Varieties to the Lesser Grain Borer, Rhyzopertha dominica Fab. (Coleoptera: Bostrichidae) in Benin

The lesser grain borer, Rhyzopertha dominica, is a major primary insect of stored cereals worldwide. In Benin, it causes serious damages on paddy rice stored in rural zones. Nowadays, there is a big interest in developing alternative measures included the use of resistant varieties for controlling this key pest. For this purpose, a study was conducted at Africa Rice Center in 2008 to establish the resistance of 17 improved rice varieties included 13 NERICA, 2 Oryza sativa and 2 Oryza glaberrima to this pest. The varieties were artificially infested under laboratory conditions. The results showed that CG14, WAB56-50, WAB56-104 and NERICA4 had good resistance against the attack of Rhyzopertha dominica while NERICA10 and NERICA8 were highly susceptible. The most tolerant cultivars investigated from this study could be recommended for safe storage to reduce pest and economic losses in all endemic zones where R. dominica represents a major threat