ABSTRACT
A survey of nematodes associated with the red palm weevil Rhynchophorus ferrugineus was conducted in southern Italy in 2015 and 2016 in order to create a species inventory and obtain data about nematode biodiversity. A total of 70 insect samples (pupae and adults) were collected from infested Phoenix canariensis, Phoenix dactylifera, and Chamaerops humilis palms in three Italian Regions: sampling took place at 11 locations in Apulia, 1 in Basilicata, and 1 in Sardinia regions. Individual insects were dissected to determine nematode presence, and different nematode species were also recovered from red palm weevil cocoons collected at the sites in Apulia. Individual nematodes were molecularly identified by sequencing the ITS, D2-D3 expansion domains of the 28SrRNA gene and the mitochondrial COI and inferring the phylogenetic relationships. The insect-associated nematofauna identified belonged to the families Rhabditidae, Cephalobidae, and Diplogastridae. Just two nematode species, Teratorhabditis synpapillata and Mononchoides macrospiculum, were always found in association with adult insects and cocoons taken from all sampling sites. This paper reports on the biodiversity of the nematodes associated with R. ferrugineus and on current knowledge of the specific habitat of specialized and divergent entomophilic nematodes.
ABSTRACT
Two different nematode species were recovered from pomegranate decaying fruit in two localities in Southern Italy: the mycetophagus nematode Sheraphelenchus sucus and a bacterial feeder nematode belonging to the Panagrolaimidae (Rhabditida) family. Morphometrics of the Italian population of S. sucus closely resemble that of the type population, whereas some differences were found when compared with another population from Iran. Molecular characterization of the Italian S. sucus using the 18S rRNA gene, D2-D3 expansion domains of the 28S rDNA, the ITS region, and the partial mitochondrial COI were carried out. Sequences of the 18S rRNA gene, the D2-D3 domains, and the ITS were analyzed using several methods for inferring phylogeny to reconstruct the relationships among Sheraphelenchus and Bursaphelenchus species. The bacterial feeder Panagrellus sp. was characterized at the molecular level only. The D2-D3 expansion domains and ITS sequences of this Italian panagrolaimid were determined. The D2-D3 sequences of the Italian panagrolaimid showed 99% similarity with the corresponding sequence of Panagrellus sp. associated with Rhynchophorus ferrugineus. This is the first report on the tritrophic association of S. sucus and Rhabditida that uses both insects and pomegranate fruit as hosts.
