Host range studies on Aceria sp. (Acari: Eriophyidae), a biocontrol candidate of Solanum elaeagnifolium in its native range

MARIEL GUALA; NICOLÁS A. SALINAS; FRANCO CHIARINI; CRISTINA ACOSTA; GREG LEFOE; ALEJANDRO JOAQUÍN SOSA

Puerto Iguazú

Simposio; XVI international symposium on biological control of weeds /; 2023

FUEDEI/CERZOS

Solanum elaeagnifolium Cav., silverleaf nightshade (Solannaceae), is a deep-rooted, summer-growing perennial herb, with an amphitropical native distribution (USA and Mexico, and the southern hemisphere, Argentina, Paraguay, Uruguay and Chile). In its invasive range in Australia, several options of management have been proposed, highlighting the necessity of biological control. The plant presents three clearly separated genetic lineages, two in South America with polyploid populations and a third with only diploids in North America and Australia. In Argentina the plant is present as diploid, tetraploid and hexaploid. Several natural enemies have been recorded in the weed native range, and proposed as potential biological control agents, one of them is Aceria bicornis Trotter (Acari: Eriophyidae). To search for this potential biocontrol agent, and to associate its occurrence with S. elaeagnifolium genetic variability, we conducted field trips in Argentina and preliminary field and laboratory host-range studies. During these trips, plants with mite-like damage were found at different localities. Moreover, we estimated mite field host range by checking other native Solanum for the presence of Aceria or other related mites and also were collected. In each site, plants and mites were collected for morphological identification and genetic analyses. For the mite identification, leaves with symptoms (galls) were collected and put in vials with ethanol (96%) and preserved for further morphological and molecular analysis. For rearing, S. elaeagnifolium plants with symptoms of Aceria were collected and taken to the laboratory. Leaves with galls were put in contact with asymptomatic plants of S. elaeagnifolium and 8 varieties of potato plant and eggplant in a non-choice design. Plants were potted and enclosed in fine-mesh cages for 2 months. Mites from field and laboratory tests were genetically analyzed using a fragment of the mitochondrial COI gene in order to identify mites found on S. elaeagnifolium, other native Solanum species and from host specificity tests without the need of morphological studies. The species found was Aceria sp, which was the same collected in each site. Aceria was collected only on the target weed in the field on only one plant lineage. In the laboratory host range study, it was found on the S. elaeagnifolium and on 2 plants of one variety of potato. The utilization of Aceria sp. as a potential agent against S. elaeagnifolium is still a challenge due to difficulties on mite identification and rearing.