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Predicting the impact of temperature increase on the distribution of the variegated coffee bug, Antestiopsis thunbergii over an elevation gradient

Azrag A.G.A., Pirk C.W.W., Yusuf A.A., Niassy S., Babin R.. 2017. In : Omondi Aman Bonaventure (ed.), Kekeunou Sévilor (ed.), Ouali-N¿goran Mauricette (ed.), Salah Faiza Elgaili Elhassan (ed.), Tanga Mbi Chrysantus (ed.), Getu Emana (ed.), Zanou Elisabeth (ed.), Ayelo Pascal (ed.). Livre des résumés de la 22ème Réunion et Conférence de l¿Association Africaine des Entomologistes : ¿Vers une amélioration du bien-être humain grâce à la gestion de la diversité des insectes dans un monde en mutation¿. Wad Medani : AAIS, p. 32-33. 22nd Meeting and Conference of the African Association of Insect Scientists, 2017-10-23/2017-10-26, Wad Medani (Soudan).

The antestia bug Antestiopsis thunbergii (Gmelin 1790) is one of most damaging pests of Arabica coffee in eastern and southern Africa. It feeds on coffee vegetative parts and fruits, leading to yield and quality reduction. The present study aims to predict the impact of temperature increase on the distribution and abundance of A. thunbergii over an elevation gradient, ranging from 1000 to 1700 m asl, located on Mt. Kilimanjaro, Tanzania. Temperature-dependent phenology models were developed using a complete life table study at 7 constant temperatures. Three indices assessing infestation risk were computed and mapped over the elevation gradient using the phenology models and temperature data for year 2013 and predictions for 2055 (AFRICLIM database): 1) the establishment risk index (ERI), which characterizes the suitability of a geographical area for the insect establishment, 2) the generation index (GI), which estimates the mean number of generations per year, and 3) the activity index (AI), which indicates the population growth rate. Under 2055 temperature predictions, the ERI will decrease by 0.13 at elevations between 1000 and 1100 m asl, and increase by 0.24 between 1500 and 1700 m asl, indicating that high elevations will be more suitable for antestia bug establishment in the future. The number of generations per year will remain constant at elevations between 1000-1100 m asl, but will increase by one generation between 1500-1700 m asl. By 2055, the AI will increase by 1.71 at high elevations leading to higher population growth as a result of temperature rising. These results globally indicate a risk of increasing antestia bug infestation in the highest coffee producing areas of East Africa highlands in the coming decades. These areas are renowned for the high quality of their coffee and mitigation strategies against climate change are therefore needed to minimize the antestia bug risk. (Résumé d'auteur)

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