Entomo Faune Floricole et son impact sur les rendements de Glycine Max (Fabaceae)

Abstract

In Cameroon, the demand on soya beans is high while its production is low due to the insufficiency know ledges on the relationships between the soya plant and the anthophilous insect. At Ngoa-Ekele (Yaoundé, Cameroon), from June to September 2015, Glycine max (Fabaceae) flowers were observed for the study of anthophilous insect activity and the determination of the impact of their activities on fruit and grain yields. For the period of studies, two treatments have been determined from the marking of six blocks. These treatments were differe nce by the presence or absence of protection vis a vis the visit of insect. The results show that ten species of insects visiting soybeans flowers for alimentation. Apis mellifera adansonii (45.74 %), Lipotriches collaris (35.63%) and Halictus sp. (13.82 %) respectively occupy the 1st, 2nd and 3rd rank. Apis mellifera adansonii, Lipotriches collaris and Halictus sp. visit flowers of this plant all day, with a peak between 12 h and 13 h for A. m. adansonii and L. collaris and 14 h and 15 h for Halictus sp. These insects intensely collect nectar. The average number of A. m. adansonii, L. collaris and Halictus sp. simultaneously in activities on 1000 flowers is 708, 215 and 113 respectively. The average duration of visit on flower for nectar harvest was 4.35 sec (A. m. Adansonii), 4.12 sec (L. collaris) and 4.65 sec (Halictus sp.). The workers of A. m. adansonii are faithful to G. max flower during foraging trips. They can classify this Fabaceae among highly nectariferous plants. Comparing the average yields of flowers submitted to the activity of anthophilous insects to those of flowers kept out of from those insects, it appears that the insect intervene to 26.20 % in increasing the rate of fruiting, 28.61 % increase in the percentage of seeds per pod, 31.49 % in the mass of the seed, 8.19 % and 6.66 % in the increase of equatorial and polar diameter of the seed and 5.30 % increase in the percentage of normal seeds. This yield improvement is justified by positive action on insects pollinate flowers the visit.