In memory of Gary Bauchan: Integrated taxonomy of soil predatory mites in farming systems

Authors: RUEDA-RAMÍREZ, DIANA - Humboldt University; Carta, Lynn; Mowery, Joseph; Bauchan, Gary; Ochoa, Ronald - Ron; YOUNG, MONICA - University Of Guelph; PALEVSKY, ERIC - Agricultural Research Organization Of Israel

Submitted to: Systematic and Applied Acarology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2021
Publication Date: 1/12/2022
Citation: Rueda-Ramírez, D., Carta, L.K., Mowery, J.D., Bauchan, G.R., Ochoa, R., Young, M., Palevsky, E. 2022. In memory of Gary Bauchan: Integrated taxonomy of soil predatory mites in farming systems. Systematic and Applied Acarology. 27(2):181–208. https://doi.org/10.11158/saa.27.2.3.
DOI: https://doi.org/10.11158/saa.27.2.3

Interpretive Summary: Conservation biological control programs in agricultural systems are critical to reduce pesticide use and depend on careful identification and enumeration of key invertebrate taxa in soil food webs. Nematodes are commonly found in soils and serve as prey for many families of soil predatory mites. In this study, soil samples were collected at the USDA ARS Farming Systems Project (FSP) at the Beltsville Agricultural Research Center. The samples were either incubated with alfalfa or bean plant amendments or not. Predatory mites were identified using anatomical features with light and scanning electron microscopes and molecular markers. Fifteen species among 2 classification categories known as orders, plus a new species yet to be described were found. This study will be important to plant protection officers, extension workers, agriculture scientists, entomologists, soil ecologists, nematologists and soil conservation programs.

Technical Abstract: Current and future legislation requiring the reduction of pesticides use, coupled with global initiatives for the promotion of soil health and conservation of soil biodiversity are creating opportunities for studies aimed at highlighting ecosystem services provided by functioning soil food webs in agricultural systems, including soil predatory mites. However, the key personnel for performing such studies are expert taxonomists, who are already spread very thin. To meet this demand, we propose an integrative approach where scientists (without expertise in taxonomy) play a significant role in supporting expert taxonomists. Soil samples were collected at the USDA ARS Farming Systems Project (FSP) at the Beltsville Agricultural Research Center, either incubated or not, followed by extraction of mites and nematodes. Improved modified Berlese funnels and an extraction protocol were utilized to improve sequencing success. Incubation dramatically enhanced the number of extracted individuals per sample whilst the daily freezing of extracted mites substantially improved the sequencing success rate compared to previous studies. Taken together, this led to the addition of six Mesostigmata and eight Oribatida sequences to BOLD (Barcode of Life Database). Fifteen species of Mesostigmata species were found, with three dominant species, C. diviortus, L. youcefi and a new species of Gamasellodes. LTSEM imaging followed by molecular identification contributed further details to the published descriptions of C. diviortus and L. youcefi. In line with our general aim, collecting, extracting, identification to morpho-species, sample preparation for DNA barcoding and uploading relevant information to BOLD was performed by trained personnel, but without taxonomic expertise. Whereas our skilled taxonomists focused on the morphological identifications using light microscopy, expanding on existing descriptions using LTSEM images and in a subsequent manuscript the description of a new species. We believe this division of tasks and labor will set the stage for further collaborative integrated studies between ecologists, biocontrol specialists and expert taxonomists for the identification, evaluation and description of known and novel soil acarine BCAs.