Endangered Nectar-Feeding Bat Detected by Environmental DNA on Flowers

Abstract

Leptonycteris nivalis (the Mexican long-nosed bat) is an endangered nectar-feeding bat species that follows “nectar corridors” as it migrates from Mexico to the southwestern United States. Locating these nectar corridors is key to their conservation and may be possible using environmental DNA (eDNA) from these bats. Hence, we developed and tested DNA metabarcoding and qPCR eDNA assays to determine whether L. nivalis could be detected by sampling the agave flowers on which it feeds. We sampled plants with known bat visitations in the Sierra Madre Oriental in Laguna de Sanchez (LS), Nuevo León, Mexico, and in the Chisos Mountains in Big Bend National Park, Texas, USA (CB). A total of 13 samples included both swabs of agave umbels and cuttings of individual flowers. DNA metabarcoding was performed as a PCR multiplex that targeted bats (SFF-COI), arthropods (ANML-COI), and plants (ITS2 and rbcL). We targeted arthropods and plants in parallel with bats because future metabarcoding studies may wish to examine all the pollinators and plants within the nectar corridor. We developed and tested the sensitivity and specificity of two qPCR assays. We found that both DNA metabarcoding and qPCR were highly successful at detecting L. nivalis (11 of 13 for DNA metabarcoding and 12 of 13 for qPCR). Swabs and flower cuttings and both qPCR assays detected the species over four replicates. We suggest that L. nivalis leaves substantial DNA behind as it forages for nectar. We also suggest that future studies examine the time since sampling to determine its effect on detection success. The DNA metabarcoding multiplex will be useful for parallel questions regarding pollination ecology, while, with further testing, the qPCR assays will be effective for large-scale sampling for the detection of migration corridors and foraging areas. This work may be relevant to other nectar-feeding bat species, which can likely be detected with similar methodologies.

Monitoring the birds and the bees: Environmental DNA metabarcoding of flowers detects plant–animal interactions

“…While the ability to detect insect visits to flowers using eDNA shows promise (Evans & Kitson, 2020; Gamonal Gomez et al, 2022; Harper et al, 2022; Thomsen & Sigsgaard, 2019), the technique has only recently been used to identify vertebrate flower visitors (Jønsson et al, 2023; Walker et al, 2022). Furthermore, while eDNA metabarcoding surveys have been shown to outperform the use of both visual (Barata et al, 2020) and camera trap (Leempoel et al, 2020) techniques in other contexts, there are limitations of the method, including limited knowledge on the deposition and persistence of eDNA on floral surfaces (Barnes & Turner, 2016; Harrison et al, 2019; Valentin et al, 2021).…”

Agave distribution and floral display influence foraging rates of an endangered pollinating bat and implications for conservation

“…New approaches, such as eDNA (environmental DNA) analysis to detect bat DNA from agave flowers, are being investigated as survey methods for L. nivalis and other nectarivorous bats (Walker et al., 2022). Our finding that bat visitation was more strongly related to lower flower position when umbels with open flowers were abundant can also be used to design optimal eDNA field sampling protocols, for example, targeting sample collection from the lowest umbels with open flowers on a stalk.…”

Out of thin air: surveying tropical bat roosts through air sampling of eDNA

“…Aquatic eDNA studies have detected rare and elusive fish ( Weltz et al, 2017 ; Nester et al, 2022 ), amphibians ( Plante et al, 2021 ), birds ( Neice & McRae, 2021 ) and marine mammals ( Ma et al, 2016 ; Juhel et al, 2021 ). Recently, eDNA left on agave flowers in Mexico and Texas ( Walker et al, 2022 ) and in guano deposits in Redwood tree hollows in California ( Armstrong et al, 2022 ) have been used to successfully detect roosting and migrating bats. To these methods we now add airborne eDNA detection of elusive bat species.…”