L. Amadou

Triple bag hermetic technology for controlling a bruchid (Spermophagus sp.) (Coleoptera, Chrysomelidae) in stored Hibiscus sabdariffa grain

We assessed the performance of hermetic triple layer Purdue Improved Crop Storage (PICS) bags for protecting Hibiscus sabdariffa grain against storage insects. The major storage pest in the grain was a bruchid, Spermophagus sp.. When we stored infested H. sabdariffa grain for six months in the woven polypropylene bags typically used by farmers, the Spermophagus population increased 33-fold over that initially present. The mean number of emergence holes per 100 seeds increased from 3.3 holes to 35.4 holes during this time period, while grain held for the same length of time in PICS bags experienced no increase in the numbers of holes. Grain weight loss in the woven control bags was 8.6% while no weight loss was observed in the PICS bags. Seed germination rates of grain held in woven bags for six months dropped significantly while germination of grain held in PICS bags did not change from the initial value. PICS bags can be used to safely store Hibiscus grain after harvest to protect against a major insect pest.

Performance of PICS bags under extreme conditions in the sahel zone of Niger

Experiments in Niger assessed whether extreme environmental conditions including sunlight exposure affect the performance of triple-layer PICS bags in protecting cowpea grain against bruchids. Sets of PICS bags and woven polypropylene bags as controls containing 50 kg of naturally infested cowpea grain were held in the laboratory or outside with sun exposure for four and one-half months. PICS bags held either inside or outside exhibited no significant increase in insect damage and no loss in weight after 4.5 months of storage compared to the initial values. By contrast, woven bags stored inside or outside side by side with PICS bags showed several-fold increases in insects present in or on the grain and significant losses in grain weight. Grain stored inside in PICS bags showed no reduction in germination versus the initial value but there was a small but significant drop in germination of grain in PICS bags held outside (7.6%). Germination rates dropped substantially more in grain stored in woven bags inside (16.1%) and still more in woven bags stored outside (60%). PICS bags held inside and outside retained their ability to maintain internal reduced levels of oxygen and elevated levels of carbon dioxide. Exposure to extreme environmental conditions degraded the external polypropylene outer layer of the PICS triple-layer bag. Even so, the internal layers of polyethylene were more slowly degraded. The effects of exposure to sunlight, temperature and humidity variation within the sealed bags are described.

Field dispersal of the parasitoid wasp Habrobracon hebetor (Hymenoptera: Braconidae) following augmentative release against the millet head miner Heliocheilus albipunctella (Lepidoptera: Noctuidae) in the Sahel

ABSTRACT Pearl millet is one of the major staple food crops in Sub-Sahelian Africa, and the millet head miner (MHM) [Heliocheilus albipunctella] is its major pest, causing serious economic damage in the maturity period. We studied the dispersion patterns of the endogenous ectoparasitoid, Habrobracon hebetor (Hymenoptera: Braconidae), after augmentative releases in pearl millet fields for biological control of the MHM, in 2010 and 2011 in Burkina Faso and Niger. The parasitoids were released using 15 jute bags per release site. Parasitoid dispersion was indirectly monitored through weekly assessments of MHM parasitism by H. hebetor at different distances from release points (0, 3 and 5 km) and in control villages (15 km). Our findings indicate that the jute bags released approximately 900–1000 parasitoids per site over a period of three weeks. This initial parasitoid population led to higher parasitism of MHM larvae at the site of dissemination compared to farms at distances of 3 and 5 km. However, usually after five weeks, successive generations of H. hebetor dispersed up to 3 km, causing high levels of MHM larval mortality, which sometimes is similar to those of the release points. Based on these results, we recommend the release of parasitoids at sites spaced 3 km for timely and more efficient control of MHM populations.

PICS bags safely store unshelled and shelled groundnuts in Niger

We conducted an experiment in Niger to evaluate the performance of hermetic triple layer (Purdue Improved Crop Storage- PICS) bags for the preservation of shelled and unshelled groundnut Arachis hypogaea L. Naturally-infested groundnut was stored in PICS bags and woven bags for 6.7 months. After storage, the average oxygen level in the PICS bags fell from 21% to 18% (v/v) and 21%–15% (v/v) for unshelled and shelled groundnut, respectively. Identified pests present in the stored groundnuts were Tribolium castaneum (Herbst), Corcyra cephalonica (Stainton) and Cryptolestes ferrugineus (Stephens). After 6.7 months of storage, in the woven bag, there was a large increase in the pest population accompanied by a weight loss of 8.2% for unshelled groundnuts and 28.7% for shelled groundnut. In PICS bags for both shelled and unshelled groundnuts, by contrast, the density of insect pests did not increase, there was no weight loss, and the germination rate was the same compared to that recorded at the beginning of the experiment. Storing shelled groundnuts in PICS bags is the most cost-effective way as it increases the quantity of grain stored.

Les déterminants socioéconomiques de l’adoption des technologies améliorées de production du niébé diffusées par les champs écoles paysans dans les régions de Maradi et Zinder au Niger

Le niebe est une denree de base en Afrique subsaharienne. Le projet champ ecole paysan en a introduit des nouvelles technologies ameliorees afin d’accroitre son rendement dans les regions de Maradi et Zinder. Cette etude qui a concerne un echantillon de 300 producteurs a pour dessein d’identifier les contraintes entomologiques de la culture du niebe et de determiner les facteurs affectant l’adoption des technologies agricoles. Le modele de regression LOGIT a ete utilise comme outils d’analyse et les principaux resultats suivants ont ete obtenus : 1) la punaise brune ( Clavigralla tomensicollis Stall) et le puceron ( Aphis craccivora Koch) sont les principaux insectes ravageurs de la culture pour 53 a 61% des repondants ; 2) les taux moyens d’adoption par technologie sont de 74,9% pour les varietes ameliorees, 57,2% pour les pesticides chimiques, 20% pour la combinaison fumure organique/NPK ; 21.7% pour l’engrais NPK seul, 7,4% pour les biopesticides a base de graines de Neem et 5,7% pour le respect de la densite de semis. Ces ratios sont 2 a 16 fois plus eleves chez les producteurs formes par rapport aux non formes ; 3) les variables « formations par les champs ecoles paysans » et « l’acces au credit » ont influence positivement l’adoption des varietes ameliorees, des biopesticides et des fertilisants ; 4) le genre a ete positivement determinant dans le respect de la densite de semis et l’utilisation des fertilisants ; 5) l’âge des repondants a eu une influence significative dans le respect des ecartements entre les poquets. Ces donnees qui ont permis d’apprecier les niveaux d’utilisation des technologies de developpement de la culture du niebe pourraient aussi contribuer a ameliorer les programmes de vulgarisation des technologies agricoles en zone rurale. Mots cles : adoption, technologies ameliorees, niebe, champ ecoles paysans, Maradi, Zinder.