Population distribution and density of Antestiopsis thunbergii (Hemiptera: Pentatomidae) in the coffee growing regions of Rwanda in relation to climatic variables

Abstract

Antestia bug, Antestiopsis thunbergii (Gmelin, 1970) (Hemiptera: Pentatomidae) is one of the most damaging pests of coffee (Coffea arabica, L.) worldwide, except in central and south America. A two – year study was conducted to assess the distribution and the density of Antestia bug in the coffee growing regions of Rwanda, and to determine the effects of climatic variables on density of Antestia bug. 205 farms were surveyed in 2016 and 191 farms in 2017. The density and damage of Antestia bug were quantified and climatic variables including temperature, rainfall, wind speed and relative humidity were recorded. Antestia bug was distributed in all coffee growing regions of Rwanda, during both study periods. Over both years, the highest density was recorded in the northern region of the country while the lowest was recorded in the eastern region. The economic damage due to Antestia bug ranged from 0 to 92% and from 0 to 81% in 2016 and 2017, respectively. Stepwise multiple linear regression analysis indicated that temperature and rainfall significantly influenced pest density. However, wind speed was not significantly associated with the density of Antestia bug. Principal component analysis (PCA) indicated three distinct groupings. Coffee regions that received higher, regular rains had a higher population of Antestia bug than where rains were erratic. Similarly, the areas where temperature was consistently high had high densities of Antestia bug. Wind speed was highly and negatively related to principal component one. This study indicated the need to intensify control measures against Antestia bug. Furthermore, the impact of climate change on density and damage of Antestia bug and other coffee pests needs further research.