Molecular detection of wasps parasitizing nymphal cattle fever ticks towards the study of temporal pattern of tick-parasitoid interactions

Authors: BON, MARIE-CLAUDE - European Biological Control Laboratory (EBCL); KASHEFI, JAVID - European Biological Control Laboratory (EBCL); GUERMACHE, FATIHA - European Biological Control Laboratory (EBCL); MEDIANNIKOV, OLEG - Institute For Research And Development (IRD)

Submitted to: International Symposium on Biological Control of Arthropods
Publication Type: Proceedings
Publication Acceptance Date: 2/11/2022
Publication Date: 3/15/2022
Citation: Bon, M., Kashefi, J., Guermache, F., Mediannikov, O. 2022. Molecular detection of wasps parasitizing nymphal cattle fever ticks towards the study of temporal pattern of tick-parasitoid interactions. International Symposium on Biological Control of Arthropods. 5.6-5.9. http://dx.doi.org/10.6084/m9.figshare.19349348.
DOI: https://doi.org/10.6084/m9.figshare.19349348

Interpretive Summary: Cattle Fever Ticks are a growing concern for livestock producers, property owners, and wildlife managers. Their presence on property, livestock and wildlife in Texas subject owners to quarantine and treatments to eliminate ticks in the prevention of Texas Cattle Fever (also named bovine babesiosis), a highly fatal disease for infested animals. Recent expansion of Cattle Fever Tick infestations has resulted in quarantines in Texas counties away from the Mexico border which comprises the permanent fever tick quarantine zone. Increasing prevalence of tick hosts among native and exotic ungulates, widespread tick acaracide resistance, and climate change, undermine efforts to control bovine babesiosis. Biological control using minute parasitoid wasps is seen as an alternative method of controlling cattle fever ticks One species of the two cattle fever ticks is most prevalent in the Balkan region where populations of this species were found genetically similar to the Texas tick populations. Searching for ticks parasitized by wasps in the Balkan region using conventional method is like looking for a needle in a haystack as prevalence of the wasps emerging from the ticks could be extremely low (3%). Molecular methods which have revolutionized the field of diagnostics could have routine applications in the detection of a parasitoid wasp within its tick host. A sensitive DNA-based method is being optimized to detect wasp parasitoids in the tick populations occurring in the Balkan region and hence would help streamline the search of benefical wasp populations for tick control.

Technical Abstract: Cattle fever ticks, Rhipicephalus (Boophilus) annulatus (Say) and R. (B.) microplus (Canestrini) (Ixodida: Ixodidae) are vectors of hemoprotozoan diseases of veterinary importance such as babesiosis and anaplasmosis in cattle. Hymenopteran wasps have been targeted as biocontrol agents against cattle fever ticks in Texas due to their ability to parasitize and kill ticks. However, these wasps which mainly belong to the Ixodiphagus genus are known to emerge from engorged nymphs of some tick species, which are very small and difficult to collect. As a consequence of this, parasitism of ticks using conventional methods may have gone unoticed in the native range or overly underestimated. This is particularly true when the parasitoid wasp is at its early developmental stage, like egg, inside questing larval and young nymphal ticks. To circumvent this problem, we used a DNA-based method already developed to detect the presence of hymenopteran wasps including Ixodiphagus hookeri within adult ticks using Hymenopteran-specific primers which target the 28S RNA region. We optimized this method using quantitative PCR in order to detect inside questing larval and young nymphal ticks what little parasitoid wasp DNA could be found in eggs. The sensitivity of the method was tested in vitro with success before being applied to 32 young nymphal Rhipicephalus annulatus ticks collected in the Balkan region (Northern Greece and Crete). None of them tested positive for parasitoid wasps, indicating that they were not parasitized. No definitive conclusions can yet be made, although results remain encouraging. This pilot study should be pursued as there is a need for an efficient tool to track parasitized juvenile tick populations in the field.