Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/22/2008
Publication Date: 12/31/2008
Citation: Stoeva, A., Rector, B.G., Harizanova, V. 2008. Host-specificity testing on Leipothrix dipsacivagus (Acari: Eriophyidae), a candidate for biological control of Dipsacus spp.. Proceedings of the XII International Symposium on Biological Control of Weeds Interpretive Summary: Two invasive species of teasels (Dipsacus spp.) have become problem weeds in the USA and are the targets of a USDA-ARS classical biological control program. One candidate for biological control of teasels is a phytophagous mite, Leipothrix dipsacivagus, which is a new species that was discovered in Serbia in 2005 by an EBCL scientist and local collaborators. This study documents the host-range testing of this mite on various non-target plant species that are closely related to teasels. Infestation of the mite onto teasel and non-target plants in choice and no-choice tests revealed that the mite was only able to maintain colonies on the teasels and was unable to establish the closely related non-target plants. This mite causes serious damage to teasels and appears to have a very narrow host range. It has good potential as a biological control agent of invasive teasels in the USA.
Technical Abstract: Leipothrix dipsacivagus Petanovic & Rector is the first eriophyid mite recorded from hosts in the genus Dipsacus and is considered a potential candidate for biological control of invasive teasels (Dipsacaceae). Host-specificity testing on Leipothrix dipsacivagus (Acari: Eriophyidae) was carried out under insectary conditions for four months, from 19 April until the end of August, 2006. The laboratory colony of L. dipsacivagus was descended from mites collected on Dipsacus laciniatus L. in Klokotnitsa, Bulgaria. They were tested in choice and no-choice tests on D. fullonum L., Knautia arvensis L., Cephalaria sp., and Scabiosa sp. In the choice experiments, individual D. laciniatus plants infested with L. dipsacivagus were placed in cages with 1-2 plants of each test species. There were four replicates. Data were recorded at 10, 20, 30, 40, 60 and 90 days after infestation of test plants. After 10 days only D. laciniatus was infested. After 20 days mites were vagrant on all the plants except Scabiosa and colonies were established on all Dipsacus plants. Some Cephalaria and Scabiosa plants had vagrant mites at Day 20 and 30, respectively but all of these were dead by Day 30 and 40, respectively. By Day 60, all Knautia plants were colonized, although these colonies later died. The mite successfully colonized only D. laciniatus and D. fullonum and temporarily colonized Knautia arvensis. In the no-choice tests each of four plants of a given test species was infested with five mites/plant in a single cage. There were three replications (cages) for each test-plant species. Mites on plants other than Dipsacus spp. began to die after 10 days. Reproducing populations of L. dipsacivagus established only on D. laciniatus and D. fullonum.