Climatic Suitability for Haplodrassus rufipes in a Mediterranean Area: Linking a Predaceous Species to the Olive Grove

The use of natural enemies against crop pests has been promoted during the last decades. Among natural enemies, spiders are efficient generalist predators. An efficient pest limitation relies on the overlap of the predator and the pest in time and space. In Portugal, the cultivation of the olive tree (Olea europaea L.) represents a key economic and cultural activity. Previous works highlighted the ground hunter spider Haplodrassus rufipes (Lucas, 1846) (Araneae: Gnaphosidae) as a promising natural enemy against the olive fruit fly Bactrocera oleae (Rossi, 1790), the main pest of the olive tree in northeastern Portugal. The objectives of this work were (1) to approximate the distribution of H. rufipes throughout the whole Iberian Peninsula using the climatic suitability as surrogate of its potential distribution, and (2) compare it with the distribution of O. europaea to assess the match between the distributions of both species. The probability of occurrence of H. rufipes was approximated using a maxent (maximum entropy) algorithm based on presence-only data. Bioclimatic data was obtained from the WorldClim database at a 1 km resolution. The optimal model was selected using the checkerboard method for data partitioning. The distribution of O. europaea was visualized using a chorological map. The most contributing bioclimatic variables to the maxent model were the mean diurnal range, the temperature annual range, and the precipitation of the driest month. The distribution of O. europaea fairly overlapped the highest values of the bioclimatic suitability of H. rufipes (p > 0.6) throughout the Iberian Peninsula. Our results support further studies on the role of H. rufipes as a potential natural enemy in the olive grove agroecosystem.

The authors are grateful to the Foundation for Science and Technology (FCT, Portugal), for financial support through the project “Gestão dos serviços de ecossistema no olival utilizando modelos espaciais avançados - OLIVESIM” PTDC/ASP-PLA/30003/2017.