Detection of Philaenus (Hemiptera: Aphrophoridae) DNA in the gut of spiders, using PCR-based gut-content analysis

With the fast spread of Xylella fastidiosa throughout Europe, it is important to identify natural enemies of Philaenus spumarius (Hemiptera: Aphrophoridae), which is the main vector of this pathogen. Generalist predators, such as spiders, can play a key role in the control of P. spumarius. However, the determination of predation by spiders in the field is challenging. The use of PCR-based techniques may be a reliable approach to accurately detect these predation events. Here, a new set of 20 primers were designed and tested to detect the presence of Philaenus sp. DNA in the gut of spiders. Primers’ specificity was tested with species closely related and not related to P. spumarius and primer sensitivity was evaluated by using different concentrations of P. spumarius DNA. To estimate the digestion time at which prey DNA is detectable within the predator after ingestion, feeding trials with the spider Xysticus acerbus Thorell, 1872 (Thomisidae) were performed. One primer pair showed great sensitivity and specificity for Philaenus and when applied in the feeding assay the primer pair successfully amplified the degraded DNA of Philaenus in the gut of X. acerbus. According to the Probit regression, there is a 50% probability of detecting Philaenus DNA at 82 hours after being ingested by the spider. The practical applicability of this primer pair was validated by confirming, by DNA sequencing, the presence of consumed P. spumarius within spiders collected in field. This study demonstrates that this molecular-based diagnostic tool can provide an estimation of predator efficiency of spiders over Philaenus spp. in the field.PT; PPT; irodrigues@ipb.p