In a study published in Scientific Reports, researchers have found a highly effective, non-invasive method for monitoring biodiversity at the DeLuca Preserve in Osceola County, Florida. Spanning approximately 10,900 hectares, this preserve is a vital corridor for native and imperiled wildlife, yet traditional survey methods such as camera traps or direct observation are often limited by cost, labor, and taxonomic requirements. To overcome these hurdles, the research team investigated the use of invertebrate-derived DNA (iDNA) by analyzing the blood meals of local mosquitoes to detect a wide array of vertebrate species. This approach leverages the mosquito’s natural role as an “automated sampler” of the surrounding biological community, offering a snapshot of terrestrial life that is often missed by conventional surveying techniques.
The researchers conducted their field work over an eight-month period from January to August 2022, targeting four distinct habitats: forests, wetlands, Florida scrub, and citrus groves. To maximize the collection of blood-fed females, the team utilized large-diameter aspirators and resting shelters, which are specifically designed to capture mosquitoes as they digest their meals in shaded areas. Throughout the study, 54,637 mosquitoes were collected, with 3,508 (6.4%) identified as blood-fed. To preserve the genetic data, the blood meals were rolled onto Whatman FTA Classic Cards, and the team employed DNA barcoding to target the cytochrome c oxidase subunit I (COI) gene of vertebrates. The success of host identification was closely tied to the level of digestion, with “fresh” (BF1) blood meals yielding a 90% identification rate, while highly digested (BF3) samples dropped to just under 20%.
The results of this study were remarkably expansive, as the analysis of 2,051 blood meals across 21 mosquito species successfully detected 86 different vertebrate species. This assemblage represented all four terrestrial vertebrate classes and 22 different orders, including animals with diverse biological traits—ranging from nocturnal and diurnal to migratory, fossorial, and arboreal. Among the 86 species were 7 amphibians (all anurans), 57 birds (led by songbirds), 14 mammals, and 8 reptiles. Notably, the survey detected imperiled species like the gopher tortoise, as well as invasive species like the Cuban treefrog, and cryptic animals such as the American woodcock and barred owl. Four host species the white-tailed deer, green anole, wild turkey, and barred owl accounted for a significant portion of the detections, highlighting the dominance of a few common species within the preserve’s ecosystem.
A critical discovery of the research was that mosquito species do not contribute equally to biodiversity detection, leading the team to develop a metric known as “host detection efficiency“. This value represents the number of host species detected relative to the number of blood meals analyzed for a specific mosquito species. Culiseta melanura emerged as the most efficient sampler with a score of 7.47, specializing in avian hosts and detecting 28 different vertebrate species. Culex nigripalpus, the most abundant mosquito in the study, detected the highest richness with 63 host species, maintaining a high efficiency of 3.89. In contrast, species like Psorophora columbiae were found to be narrow specialists, with 91.3% of its blood meals derived from white-tailed deer, making them less useful for broad biodiversity characterization.
While mosquito-based iDNA provides a powerful tool for non-invasive monitoring, the researchers noted certain limitations and requirements for future applications. The study suggested that large sample sizes are necessary to overcome undersampling bias and detect rare or “singleton” species, as species accumulation curves for birds and reptiles had not yet reached an asymptote. Furthermore, certain groups such as fully aquatic animals, strictly fossorial species (like the Florida worm lizard), and bats remained largely undetected, likely because they do not frequently interact with host-seeking mosquitoes. The report concludes that for conservation efforts to be optimized, surveyors should target mosquito species with high host detection efficiency and utilize sampling methods tailored to the local mosquito community’s resting behaviors.
