Delimiting survey
A delimiting survey (according to International Standards for Phytosanitary Measures, ISPM No. 6) was conducted for GAS in the major rice production areas of Kenya following its invasion of rice fields in Mwea. Besides the Mwea irrigation scheme, other schemes including Ahero, Hola, Bura and West Kano (Figure 2) were considered risk locations because they correspond to the risk activities for Pomacea spp. based on the suitability of habitats. With the help of scheme managers, field officers and lead farmers in these schemes and through trace-back information, points of invasion were identified and defined to begin the survey. The recommended approach was to survey the rice paddies, along the watercourses and other suitable habitats in the vicinity of the source of infestation within the potential spread distance estimated for the apple snails. Field surveys were conducted in these schemes in December 2020 and February 2022.