Occurrence and density of the stink bug Antestiopsis thunbergii Gmelin 1790 (Heteroptera: Pentatomidae) and related egg-parasitoids in Burundi coffee agroecosystems

Antestiopsis thunbergii is the most important coffee pest in Burundi causing yield losses of up to 30%. The aim of this study was to estimate its occurrence and density and to assess the species diversity of native egg-parasitoids associated to this pest in coffee agroecosystems. Our study was carried out in four coffee growing agro-ecological zones of Burundi namely; the humid west escarpments, the humid central highlands, the sub-humid central highlands and the sub-humid southeastern and northern depressions. In total, 600 coffee trees, randomly selected in 40 coffee plots of 20 communes were investigated at three phenological stages of the crop viz. October 2019 (coffee was flowering), January 2020 (coffee berries were immature green) and April 2020 (coffee berries were mature green and red). The results showed a permanent presence of A. thunbergii with an increasing occurrence and density with time. Densities were above the economic threshold (one antestia bug per tree), except in the humid west escarpments. Differences were highly significant among the four agro-ecological zones at each time of sampling. The humid central highlands zone registered the highest densities with 1.55, 1.31 and 2.67 antestia bugs per tree in October, January and April, respectively. The humid west escarpments zone recorded lower densities of 0.38, 0.44 and 0.88 antestia bugs per tree, for the same periods respectively. From the 4,776 eggs collected from the field, 1,99 egg-parasitoids of A. thunbergii were obtained and identified, namely Trissolcus sp. (59.2%), Telenomus seychellensis (29.6%), Gryon fulviventre (2.9%), Anastatus sp. (8.1%) and Acroclisoides africanus (0.2%) .