Interactions variations climatiques – insectes ravageurs et perception des producteurs de cereales au sud Togo

La présente étude se propose d'établir les données de base relatives aux facteurs déterminants responsables de la structuration des espèces et procéder à des analyses qui permettront de déterminer la distribution des insectes ravageurs du maïs avec les prévisions actuelles des changements climatiques. De façon générale, le foreur de tige Sesamia calamistis a été l’espèce la plus rencontrée dans toutes les zones prospectées avec une abondance de 76,02% suivi de Busseola fusca (21,7%) et de Eldana saccharina (2,3%). Les projections d’une hausse des températures au Togo entraineraient de légères augmentations annuelles d’au moins + 0,23 des générations de S. calamistis et de E. saccharina. De plus l’analyse de la perception des agriculteurs indique l’apparition de «nouveaux» ravageurs tels que les termites, le criquet puant Zonocerus variegatus et une recrudescence des ravageurs de stock.Mots clés: Changements climatiques, Sesamia calamistis, maïs, générations, termitesEnglish Title: Climate variations-insect pests interactions and perception of cereal producers in southern TogoEnglish AbstractThe present study seeks to establish baseline data on the determinants responsible for the structuring of species and conduct analyzes that will determine the distribution of insect pests of maize under projected climate change. In general, stem borer Sesamia calamistis was the most important species found in all surveyed areas with an abundance of 76.02% followed by Busseola fusca (21.7%) and Eldana saccharina (2.3%). The result showed that projected increasing temperatures in Togo will probably lead to slight annual increases of at least +0.23 in number of S. calamistis and E. Saccharina generations. Further analysis of the perception of farmers indicates the proliferation of "new" pests such as termites, Zonocerus variegatus and an increase in storage insect pests.Keywords: Climate change, Sesamia calamistis, maize, generations, termite

Comparison of biological methods to control Aphis fabae Scopoli (Hemiptera: Aphididae) on kalanchoe crops in East Africa

Published online: 21 Dec 2020Aphids cause considerable damage to numerous crops all over the world and insecticides are the main means of controlling them, despite their detrimental impacts on human and environmental health. This study assessed the effectiveness of the parasitoid Aphidius colemani Viereck (Hymenoptera: Braconidae), a mixture of predatory ladybird beetles, Hippodamia variegata Goeze, Chilocorus calvus Chiccl, and Cheilomenes propinqua Mulsant (Coleoptera: Coccinellidae), and an entomopathogenic strain of Aspergillus flavus Link (Eurotiales: Trichocomaceae), collected locally in Tanzania, to control Aphis fabae Scopoli (Hemiptera: Aphididae). After assessing the predation and parasitism rates of these natural enemies at different aphid densities in laboratory experiments, their ability to control aphids on kalanchoe was assessed in a greenhouse experiment over two seasons. The largest number of A. fabae parasitized or consumed in the laboratory was found at a density of 160 aphids per predator, or parasitoid. At that density, an adult female of A. colemani parasitized 114 A. fabae per day, on average, and adults of C. calvus, H. variegata, and C. propinqua consumed 75, 72, and 85 aphids per day, respectively. A. flavus spores applied at 1 × 107 spores ml−1 reduced the aphid population by 7.9 and 12.6 times within 10 days in the first and second seasons of the greenhouse experiments, respectively, as opposed to 2.8 and 2.5 times by releasing a mixture of the ladybirds at a rate of 5 adults/m2, and by 3.3 and 9.5 times by releasing A. colemani at a rate of 2 adults/m2. This study confirmed the potential of these locally collected bio-control agents for controlling A. fabae. However, use of the isolated A. flavus strain was undermined by its production of aflatoxin. Further research is therefore required to tap into the potential of a non-toxic strain of A. flavus and/or other entomopathogenic fungi

Can black soldier fly larvae-Desmodium intortum based diets enhance the performance of Cobb500(R) broiler chickens and smallholder farmers' profit in Kenya?

Open Access Article; Published online: 19 Nov 2020This study aimed to evaluate the performance of broiler chickens fed on 3 black soldier fly larvae (BSFL) (Hermetia illucens) and Greenleaf desmodium (Desmodium intortum)-based meals. We evaluated growth performance, carcass quality, and profitability under various commercial pathways (doorstep, retail, whole, and assorted). Desmodium and BSFL powders were formulated into 3 ratios: T1 25:75, T2 50:50, and T3 75:25. A commercial feed was used as a control. One hundred and twenty mixed-sex 1-day-old broiler chicks (Cobb) were reared in pens for 42 d in a completely randomized design. The chickens were weighed weekly to monitor their growth rate. After the 42-day rearing period, they were slaughtered for carcass quality evaluation and recording of the weights of internal organs. During the initial growth phase (7–21 d), significant effects of fish meal replacement were found on the chickens' average weight (P < 0.001), average daily body weight gain (P < 0.001), average daily feed intake (P < 0.001), and feed conversion ratio (P < 0.001). However, during the second phase (21–42 d), no significant effect of the replacement was detected except on average daily feed intake (P = 0.003). No significant differences were found in terms of the relative weights of internal organs. It was found that Desmodium-BSFL-based feeds were more profitable than the control feed, and the assorted and retail modes of sale generated more revenue compared to when the chickens were sold at doorstep and on whole-chicken basis. The return on investment was higher for a push-pull adopter compared to a non-adopter. The study found that a BSFL-Desmodium mixture can be a valuable replacement for the protein component in conventional feed and would provide a new impetus for the adoption of push-pull