Effects of harvesting date on the level of initial infestation and damages caused by insect pests on the seeds of Acacia macrostachya Reichenb. ex DC., in the district of Boulkiemde in Burkina Faso

The seeds of A. macrostachya are increasingly consumed by the Burkinabe population, especially during customary and religious ceremonies. However, these seeds are rapidly degraded after harvest by insect pests, when no control method is undertaken. This study was therefore conducted to determine the level of initial infestation and damage caused by insect pests. The harvest of dry pods on 30 trees of Saria's spontaneous vegetation was carried out from November 2018 to January 2019. These pods were collected on 5 different dates at 10-day spacing. After shelling in the laboratory, the seeds obtained were placed in glass jars of 1-liter capacity. Monitoring of the 1st generation of insect emergences continued for 45 days. The results indicated that Bruchidius silaceus was the most dominant insect pests’ compared to Caryedon furcatus and Bruchidius sp. Seven parasitoid species also were recorded with Eupelmus sp. being the most abundant. The initial infestation rate ranged between 44.75 and 55.85%. The rates of seed perforation and weight loss increased from the 1st to the last harvest from 5.15 to 35.07% and 0.98 to 6.50% respectively. It is concluded from this study that timely and prompt harvest of pods of A. macrostachya are essential to lessen damage of the seeds by insect pests. Key words: Acacia macrostachya, Caryedon furcatus, Eupelmus sp., Bruchidius silaceus, Infestation level, Damage