Residual insecticides, inert dusts and botanicals for the protection of durable stored products against pest infestation in developing countries

Insect pests associated with durable grains and processed food cause considerable quantitative and qualitative losses throughout the world. Insect infestation can occur just prior to harvest, during storage in traditional storage structures, cribs, metal or concrete bins, and in warehouses, food handling facilities, retail grocery stores as well as in-transit. Many tools are available for managing insects associated with grains and processed food. Although pest management strategies are changing to meet consumer’s demand for food free of insecticide residues, address concerns about safety of insecticides to humans, delay insecticide resistance development in insects and comply with stricter insecticide regulations, the use of synthetic residual insecticides will continue to be a major component of stored-product pest management programmes. Selective use of residual insecticides requires a through understanding and evaluation of risks, costs and benefits. The use of plant and inert materials may be a safe, cost-effective and environmentally friendly method of grain preservation against pest infestation among low-resource poor farmers who store small amounts of grains. There is a dearth of information on the use of plant materials by rural farmers in Africa for stored-product protection. The most promising candidate plant materials for future utilization as grain protectants are Azadirachta, Acorus, Chenopodium, Eucalyptus, Mentha, Ocimum, Piper and Tetradenia together with vegetable oils from various sources. Neem is the only plant from which several commercial products have been developed worldwide. However, unlike synthetic insecticides these alternatives often do not provide effective or rapid suppression of pest populations and may not be effective against all species of pests. These alternatives are also more expensive than synthetic insecticides, and have not been tested extensively under field conditions in the tropics. This paper focuses on the current state of the utilization of residual insecticides, inert dusts and botanicals by resource-poor farmers for protection of durable stored produce against pest infestation in Africa. A major research priority is a well designed on-farm trials to validate the efficacy of botanicals and inert dusts for stored-product protection using standard procedures and formulations that can be transferred to other communities. Key words: Botanicals, Residual insecticides, Inert dusts, Grain storage, Storage pests, Stored product

Field evaluation of non-synthetic insecticides for the management of insect pests of okra Abelmoschus esculentus (L.) Moench in Ghana

In a two-year study, aqueous seed extracts of the neem tree Azadirachta indica A. Juss (Meliaceae) and Bacillus thurigiensis (Bt) were evaluated in the field for the management of pests of okra, Abelmoschus esculentus (L.) Moench. The aqueous neem seed extracts were applied at the rate of 30, 50, 75 and 100 g/l and B.thurigiensis was applied at the rate 1.0 g/l of water. Actellic 25 EC, a synthetic insecticide, was applied at the rate of 2 ml/l as standard check. Arthropod fauna on okra were sampled using traps, sweep nets, aspirators and handpicking. The nature of damage caused to the stems, leaves, flowers and fruit was assessed by visual observation. The major insect pests of okra collected were Podagrica uniformis Jac, Aphis gossypii Glov, Sylepta derogata (F.), Spodoptera litoralis Boisd, Prodenia litura (F.), Dysdercus superstitiosus (F.), Epilachna similis (F.), Bemisia tabaci (Genn.) and Zonocerus variegatus (F.). These pests were observed attacking mainly the leaves of okra. Some of the minor pests identified were Lagria villosa (F.), L. cuprina Thoms, Mylabris temporalis Wellni, M. trifasciata (Thumb.), Lapidognatha sp and Empoasca devastans (D.). Actellic, neem seed extract and Bt significantly reduced the population and damage caused by the major insect pests of okra recorded at Legon, Ghana compared to the untreated. Actellic and aqueous neem seed extracts were equally effective against the pests of okra and caused a significant reduction in insect damage to the leaves, flowers and fruit of the crop. There were no significant differences among the different dosages of neem seed extract on all the parameters assessed, with the exception of the final fruit yield. Actellic, neem extracts or Bt produced higher yield of marketable fruit of okra than untreated plants. Neem seed extract applied at the rate of 30 g/l of water to okra plants produced lower fruit yield than those treated with 50 g or more. Aqueous neem seed extracts and Bt can be used effectively by farmers as a component of integrated management of pests of okra in Ghana. Key words/phrases: Bacillus thurigiensis (Bt), insect pests, neem seed extract, non-synthetic insecticides, okra SINET: Ethiopian Journal of Science Vol.26(2) 2003: 145-15

Some aspects of the biology and behaviour of Sesamia nonagrioides botanephaga Tams and Bowden (Lepidoptera: Noctuidae), a major stem borer pest of maize in Southern Ghana

Studies were conducted on the stemborer, Sesamia nonagrioides botanephaga Tams and Bowden (Lepidoptera: Noctuidae), which is a pest of increasing importance on maize in Ghana, to elucidate some aspects of its biology and behaviour in southern Ghana. The pest was more abundant in the minor season than in the major season. The life cycle revealed 10 developmental stages, namely the egg, six larval instars, prepupa and pupa. A female S. n. botanephaga laid eggs within a period of 5 days. The eggs were deposited on the inner side of the leaf sheath fitting tightly onto the maize stem. The mated females laid more eggs per female (330 + 17.7 eggs) than the virgin females (268 + 9.2 eggs). The incubation period of the eggs was 5.23 + 0.03 (5-7) days. The mean larval duration was 29 days and the prepupal period lasted for 1–3 days. The first instar larvae dispersed within 1–3 days after hatching. The third, fourth, fifth, and sixth instar larvae fed actively on maize stalk producing large quantities of frass. The pupal period varied from 6 to 10 days. The life cycle was completed in an average of 35.2 (26-51) days. Adults of S. n. botanephaga lived for between 4–10 days. The adults reared in the laboratory showed a sex ratio of 2:3 (male : female), which was significantly different from the expected ratio (1:1). The implications of these findings are discussed in relation to the effective management of the pest in Ghana

Bioactivities of crude extracts of the candlewood Zanthoxylum xanthoxyloides Lam. (Rutaceae) against the cowpea beetle Callosobruchus maculatus (Walp)

The efficacy of petroleum-ether crude extracts of the candlewood, Zanthoxylum xanthoxyloides Lam. was assessed for their contact toxicity, feeding and oviposition deterrence to the cowpea beetle Callosobruchus maculatus (Walp). Percent mortality, number of progeny produced and damage caused to were dose– dependent. Root extracts was the most effective as toxicant to the beetles. The LD50 in 24 h topical application of root extracts was 4.98 μg. The LD50 (96 h toxicity in grain) suggests that root extract was highly toxic to C. maculatus. Development of eggs and larvae within grain kernels, as well as progeny emergence were significantly inhibited in treated grains. There were no progeny produced by C. maculatus in grains treated with dosage ³ 0.4 g per 100 g of grain. Root extracts provided the greatest protection of cowpea against feeding by C. maculatus with no observable feeding damage to grains treated with the highest dosages of the three materials. Extracts were repelled C. maculatus but with considerable variation in their repellent action. Z. xanthoxyloides contains phytochemicals, and crude extracts could be used as a botanical insecticide in alternative control strategies against C. maculatus. Keywords: Antifeedant, Bruchids, Botanical insecticides, Reproduction retardant, Toxicity. Int. J. Biol. Chem. Sci. Vol. 2 (3) 2008: pp. 316-32

Toxicity, growth regulatory and repellent activities of medicinal plant extracts on Musca domestica L. (Diptera: Muscidea)

Housefly, Musca domestica, is a major vector for many medical and veterinary pathogenic organisms. The development of naturally occurring insecticides, represent one of the most promising approachesfor their ecochemical control. Petroleum-ether extracts of Griffonia simplicifolia and Zanthoxylum xanthoxyloides were assessed for their toxicity, growth regulatory and repellency to the housefly. Percent mortality and index of repellency induced by the extracts against the insects were found to be dose-dependent. Seed extracts of G. simplicifolia and root extracts of Z. xanthoxyloides were the mosteffective as toxicants and repellents against the fly. The LD50 in 24 h topical application of seed extracts of G. simplicifolia and root extracts of Z. xanthoxyloides were 0.28 and 0.35 ìg, respectively. Seed extracts of G. simplicifolia evoked a very strong regulatory effect against the second larval instar of the housefly. The RD50 of crude extracts of G. simplicifolia and Z. xanthoxyloides against housefly ranged from 1.0 to 6.8 and 1.3 to 1.7 ìg cm–2, respectively. Extracts of the two plant species may be useful as insecticides for controlling the housefly and should be exploited as a component of integrated vector control strategies or could be useful in the search of new larvicidal naturalcompounds

Compensatory and susceptive responses of cowpea genotypes to infestation by aphis Craccivora koch.

The aim of the study was to estimate yield loss to10 selected genotypes of cowpea as a result of Aphis craccivora infestation during the vegetative phase of the crop. There were two trials with four replications. The first trial serving as the control was sprayed at the seedling, flowering andpodding stages against insect pests with lambda cyhalothrin (PAWA®). The other trial was sprayed only at flowering and podding stages. The cowpea seedlings of the second trial were infested with five four-day-old aphids per seedling two weeks after planting. The aphids were allowed to form colonies and fed on the seedlings until symptoms of damage were observed. When the susceptible seedlings became stunted with distorted leaves and yellowing of leaves at two weeks after infestation (28 days after planting), aphids were controlled. The results showed that aphids’ infestation delayed flowering and maturity of genotypes of cowpea. With the exception of early flowering genotypes all the medium to late flowering genotypes produced higher dry grain yield in infested plots than the control plots. The trend was not different from the production of dry biomass. The results of the present study implies that control of aphids infestation inearly maturing cowpea genotypes should not be delayed up to two weeks after infestation or 28 days after planting. Aphid’s infestation period for studies in susceptive response in medium to late maturing genotypes should go beyond 28 days after planting probably up to 35 days afterplanting

Management of insect pest complex of cowpea (Vigna unguiculata) with phosphorous-enriched soil and aqueous neem seed extract

The study determined the major insect fauna of cowpea and evaluated the effectiveness of neem seed water extract (NSWE) and soil amendments in managing insect pest complex of cowpea at Juaboso in the Western Region. Phospho-compost was applied at the rate of 560 g plot-1 (865 kg ha-1). The NSWE was applied at the rate of 50 g 1-1 (15 kg ha-1). The phosphate rock and cymethoate were applied at the rate of 195 g plot-1 (300 kg ha-1) and 2.5 ml 1-1 (750 ml ha-1), respectively. Insect fauna belonging to eight orders were found associated with cowpea in the field. The major insect pests were Aphis craccivora (Koch), Spodoptera littoralis (F), Empoasca spp., Ootheca mutabilis (Sahlberg), Zonocerus variegatus (L.), Megalurothrips sjostedti (Trybom), Maruca vitrata (Fabricius), and Anoplocnemis curvipes (Fab.). Neem seed extract and cymethoate (synthetic insecticide) significantly reduced the incidence of these insect pests, thereby reducing the damage caused to the leaves and pods in treated plots. The incidence of beneficial insects was higher on NSWE-treated plots than on cymethoate- treated plots. These included Mantis mantis, species of Bombus, Crematogaster and Coccinella, and dragonfly. This suggests that NSWE was less harmful to beneficial insects than cymethoate. The phospho-compost-NSWE treatment recorded grain yield of 1.168 tonnes ha-1, which was 68.5 per cent higher than the no soil amendment-no insecticide treatment (0.368 tonnes ha-1). The phospho- compost-NSWE insecticide treatment had a profit margin of ¢1,804,000.00 ($212.2), whilst the no soil amendment-no insecticide treatment had a loss of ¢373,000.00 ($43.9). The use of phospho-compost and neem seed extract may represent an important component of the integrated crop and pest management strategy in traditional farming systems in Ghana.Des études étaient entreprises à Juaboso dans la région ouest du Ghana pour déterminer la faune d'insecte majeure de dolique et pour évaluer l'efficacité de l'extrait d'eau de la graine de margousier (EEGM) et d'amendements du sol dans la lutte contre l'ensemble d'insectes ravageurs de dolique. Le phospho-compost était appliqué à la proportion de 560 g lot-1 (865 kg ha-1). Le EEGM était appliqué à la proportion de 50 g l-1 (15 kg ha-1). La roche de phosphate et la cyméthoate étaient appliquées à la proportion de 195 g lot-1 (300 kg ha-1) et 2.5 ml l-1 (750 ml ha-1), respectivement. La faune d'insecte appartenant à huit ordres était trouvée d'être associé avec la dolique au champ. Les insectes ravageurs majeures étaient Aphis craccivora (Koch); Spodoptera littoralis (F), Empoasca spp., Ootheca mutabilis (Sahlberg), Zonocerus variegatus (L.), Megalurothrips sjostedti (Trybom), Maruca vitrata (Fabricius), et Anoplocnemis curvipes (Fab.). L'extrait de la graine de margousier et la cyméthoate (insecticide sythétique) provoquait une réduction considérable de la fréquence de ces insectes ravageurs avec une réduction qui en a résulté aux ravages faits aux feuilles et aux cosses dans les lots traités. La fréquence d'insectes bénéfiques était plus élevée sur les lots traités d'EEGM que sur les lots traités de cyméthoate. Parmi ceux étaient Mantis mantis, espèces de Bombus, Crematogaster, Coccinella et la libellule. Ceci suggère qu'EEGM était moins nuisible aux insectes bénéfiques que la cyméthoate. Le traitement de phosphocompost – EEGM enregistrait un rendement de grain de 1.168 tonnes ha-1 qui était 68.5 pour cent plus élevé que le traitement de sans-amendement de sol–sans-insecticide (0.368 tonnes ha-1). Le traitement de phospho compost - EEGM avait une marge bénéficiaire de 1,804,000 cedis ($212.2) alors que le traitement de sans-amendement de sol–sans-insecticide avait une perte de 373,000 cedis ($43.9). L'utilisation de phospho-compost et d'extrait de la graine de margousier pourrait représenter un élément important de la stratégie intégrée de l'amenagement de culture et de la lutte contre les ravageurs dans les systèmes d'agriculture traditionnelle au Ghana. Ghana Journal of Agricultural Science Vol. 39 (1) 2006: pp. 10

Field studies on the susceptibility of six plantain cultivars to infestation by the banana weevil, Cosmopolites sordidus Germar (Coleoptera: Curculionidae) in Ghana

Field studies were used to identify plantain cultivars that were less susceptible to infestation by the banana weevil Cosmopolites sordidus Germar (Coleoptera: Curculionidae). Six plantain cultivars, Osoboaso, Borodewuio, Apantu-pa, Asamienu, Agbagba and Obino L\'Ewai, were evaluated between October 1997 and September 1998. The results indicated that all the cultivars were susceptible to weevil damage in weevil oviposition, egg hatchability, and larval growth and development. Weevil population was not significantly different among the cultivars, but differences in the corm damage were significant. Agbagba and Borodewuio were significantly more susceptible to borer attack than Obino L\'Ewai and Osoboaso, Asamienu and Apantu-pa were intermediate in their susceptibility to borer attack. Cultivating Obino L\'Ewai, Osoboaso, Asamienu and Apantu-pa, using good management practices, may increase plantain yields and enhance the sustainability of plantain production in Ghana.Cosmopolites sordidus (Germar) (Coléoptères: Curculionidés) au Ghana. Des études sur le terrain étaient faites pour identifier les variétés de plantain qui étaient moins prédisposées à l\'infestation par le charançon de banane Cosmopolites sordidus Germar. Six variétés de plantain c.-à-d., Osoboaso, Borodewuio, Apantu-pa, Asamienu, Agbagba et Obino L\'Ewai étaient évaluées entre Octobre 1997 et Septembre 1998. Les résultats indiquaient que toutes les variétés étaient prédisposées aux ravages de charançon sous l\'angle de la ponte du charançon, la capacité d\'éclore l\'oeuf, la croissance et le développement larvaire. La population de charançon n\'était pas considérablement différente parmi les variétés mais les différences entre les dégâts de bulbe étaient considérables. Agbagba et Borodewuio étaient considérablement plus prédisposées à l\'attaque d\'insecte térébrant qu\'Obino L\'Ewai et Osoboaso. Asamienu et Apantu-pa étaient intermédiaires en leur prédisposition à l\'attaque d\'insecte térébrant. La culture d\'Obino L\'Ewai, Osoboaso, Asamienu et Apantu-pa en adoptant les pratiques de bonne exploitation, peut augmenter les rendements de plantain et améliorer la durabilité de la production de plantain au Ghana. Ghana Journal of Agricultural Science Vol. 40 (2) 2008: pp. 177-18

Effect of phospho-compost on growth and yield of cowpea (Vigna unguiculata)

The effect of phospho-compost on the growth and yield of cowpea (Vigna unguiculata) was studied at Juaboso in the Western Region of Ghana. It was a factorial experiment arranged in a randomized complete block design with four replications. Phospho-compost, prepared from phosphate rock, cocoa pod husk, sawdust and poultry manure, was applied at the rate of 560 g plot-1 (875 kg ha-1) and worked into soil before planting. Phosphate rock was applied at the rate of 195 g plot-1 (300 kg ha-1) 1 week before planting. The triple superphosphate was applied as band placement of 90 g plot-1 (130 kg ha-1), 7 days after sowing. These application rates were equal to 60 kg P205 ha-1. Phospho-compost significantly (P < 0.05) increased number of leaves, number of nodules, plant biomass, number of pods per plant, and grain yield more than the control. Grain yield on the phospho-compost-treated plot was 25.8 per cent higher than the control. Phospho-compost treatment had a profit margin of ¢3,295,000.00 ($387.65). This figure compared favourably with the treatment using conventional triple superphosphate fertilizer, which recorded ¢3,422,000.00 ($402.59) profit. The controls had a profit margin of ¢2,515,000.00 ($295.88). The results of the study indicate that the use of phosphocompost (which is locally prepared) can significantly increase the yield of cowpea. Resource-poor farmers can use phospho-compost to improve the fertility of soil for higher productivity of cowpea.Une étude était entreprise à Juaboso dans la région de l'Ouest du Ghana pour faire des recherches de l'effet de phosphocompost sur la croissance et le rendement de dolique. C'était une expérience factorielle arrangée dans un dessin de bloc complet choisi au hasard avec quatre réplications. Phospho-compost, préparé de roche du phosphate, de l'écale de cosse de cacao, de sciure de bois et de fumier de volaille, étaient appliqués à raison de 560 g/lot (875 kg/ ha) et mélangés avec le sol avant la plantation. La roche du phosphate était appliquée à raison de 195 g/lot (300 kg/ha) une semaine avant la plantation. La triple superphosphate était appliquée comme un placement en bande de 90 g/lot (130 kg/ha), sept jours après les semailles. Ces taux d'application étaient équivalent à 60 kg P2 O5/ ha. Phospho-compost augmentait considérablement (P < 0.05) le nombre de feuilles, nombre de nodules, biomasse de plante, nombre de cosse par plante et le rendement de graine plus que le contrôle. Le rendement de graine sur le lot traité de phospho-compost était 25.8$387.65) et ce chiffre se comparait favorablement avec le traitement appliquant l'engrais conventionnel la triple superphosphate, qui donnait un bénéfice de ¢3,422,000.00 ($402.59). Les lots de contrôle avaient une marge bénéficiaire de ¢2,515,000.00 ($295.88). Les résultats de l'étude indiquent que l'application de phospho-compost (qui est préparé localement) peut augmenter considérablement le rendement de dolique. Les pauvres agriculteurs ingénieux peuvent appliquer phospho-compost pour améliorer la fertilité du sol pour une productivité plus élevée de dolique. Ghana Journal of Agricultural Science Vol. 40 (2) 2008: pp. 169-17