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.