Assessment of the Real Rate of Senegalia macrostachya (Reichenb. ex DC.) Kyal. & Boatwr. Seeds Initial Infestation by Insect Pests in Spontaneous Vegetation, Using a Combination of Perforation and Dissection of These Seeds

Abstract

Background: Senegalia macrostachya is an edible wild legume in Burkina Faso whose seeds are affected by bruchid infestation before harvest. Aims: To assess the true initial infestation rate of Senegalia macrostachya seeds by bruchids in spontaneous vegetation by combining insect emergence and the dissection of healthy seeds. Study Design: S. macrostachya pods were harvested, insect emergence was monitored in the laboratory, and healthy seeds were dissected. Place and Duration of Study: Regional Direction for Environmental and Agricultural Research of the Centre/Saria Station and Joseph KI-ZERBO University, between November 2025 and April 2026. Methodology: Four samples, each consisting of 1,000 pods of S. macrostachya, were collected from the spontaneous vegetation at the INERA/Saria Research Station to form four replicates. After shelling, three different random subsamples of 100 seeds each were selected from each collected sample to carry out three different treatments. The perforated seeds from lot 1 were sorted and separated from the non-perforated seeds; the seeds from lot 2 were not sorted. These seeds were monitored in the laboratory for 70 days. The seeds from lot 3 were kept in the freezer. Following the monitoring of insect emergence, all non-perforated seeds were dissected. Results: At harvest, the mean number of perforated seeds was 2.5, 3.5, and 2 for lots 1, 2, and 3, respectively. After 70 days of monitoring, the number of perforated seeds in lots 1 and 2 increased significantly to 59.4 and 60.72. In lot 3, 43.6% of the healthy seeds contained at least one bruchid larva and/or nymph. The highest initial infestation rate (65.2 %) was recorded for seeds from lot 2. Bruchidius silaceus accounted for 87.21 % and 87.50 % of the insects that emerged from lots 1 and 2, respectively. Conclusion: Preventive measures must be developed to reduce egg-laying by bruchids on the pods of S. macrostachya in spontaneous vegetation.