Detection of Lampropeltis californiae in environmental DNA samples

Invasive snakes are some of the most challenging invaders worldwide due to their exceptionally low detection probability and grave ecological impacts. Environmental DNA (eDNA) detection offers substantial opportunities for invasive snake management programs, yet these have only been tested for two aquatic species so far and its application for terrestrial invasive snakes remains unexplored. We analyzed the applicability of eDNA detection for the invasive California kingsnake (<i>Lampropeltis californiae</i>) in Gran Canaria (Canary Islands, Spain) by (1) designing specific primers to differentiate the species from co-existing reptiles, (2) evaluating snake eDNA detectability in the field using various artificial cover objects (ACOs), soil samples collected under these ACOs, and soil samples collected at random using different sampling protocols, (3) and determining snake eDNA degradation over time under controlled conditions. <i>Lampropeltis californiae </i>primers amplified snake samples but none of the co-existing endemic reptiles. We found that sampling <i>L. californiae </i>eDNA detection varied among sampling protocols, which overall detected snakes in 9.31% of all swab samples, 2.22% of soil samples under the ACOs and none of the randomly collected soil ones. We detected no evidence of snake eDNA degradation seven days after snake removal from their terraria. Our study provides critical insights for the implementation of eDNA detection techniques in the management of <i>L. californiae </i>in the Canary Islands and illustrate the applicability of these techniques for the management of the numerous invasive snakes worldwide.