Ixodiphagus hookeri wasps (Hymenoptera: Encyrtidae) in two sympatric tick species Ixodes ricinus and Haemaphysalis concinna (Ixodida: Ixodidae) in the Slovak Karst (Slovakia): ecological and biological considerations

Ixodiphagus hookeri (Hymenoptera: Encyrtidae) and Tick-Borne Pathogens in Ticks with Sympatric Occurrence (and Different Activities) in the Slovak Karst National Park (Slovakia), Central Europe

Ticks are involved in the transmission a plethora of pathogens. To effectively control ticks and mitigate the risks associated with tick-borne diseases, it is important to implement tick control measures. These may include the use of acaricides as well as the development and implementation of an alternative, environmentally friendly tick management program that include practices such as habitat modification or establishing biological control. Ixodiphagus hookeri Howard is a tick-specific parasitoid wasp that predates on several species of ixodid ticks and could contribute to the control of the tick population. This work aimed to detect the presence of parasitoid wasps in ticks (Ixodidae) using genetic approaches. Several tick species of the genera Ixodes, Haemaphysalis, and Dermacentor, with a sympatric occurrence in the Slovak Karst National Park in southeastern Slovakia, were screened for the presence of wasps of the genus Ixodiphagus. The DNA of the parasitoids was detected in four tick species from three genera. This work presents the first molecular detection of parasitoids in two Dermacentor tick species, as well as the first molecular identification of Ixodiphagus wasps in Ixodes ricinus and Haemaphysalis concinna ticks from the Karst area. In the given area, it was observed that I. ricinus and H. concinna ticks are hyper-parasitized by wasps. Moreover, it was observed that wasps here can parasitize several tick species, some of which are of less significance for human and animal health (as they transmit fewer pathogens).

The Role of Parasitoid Wasps, Ixodiphagus spp. (Hymenoptera: Encyrtidae), in Tick Control

Species of Ixodiphagus (Hymenoptera: Encyrtidae) are parasitoid wasps whose immature forms develop inside ixodid and argasid ticks (Acari: Ixodida). Following oviposition by adult female wasps into the idiosoma of ticks, larvae hatch and start feeding on their internal contents, eventually emerging as adult wasps from the body of the dead ticks. Species of Ixodiphagus have been reported as parasitoids of 21 species of ticks distributed across 7 genera. There are at least ten species described in the genus, with Ixodiphagus hookeri being the most studied as an agent for biological control of ticks. Although attempts of tick control by means of this parasitoid largely failed, in a small-scale study 150,000 specimens of I. hookeri were released over a 1-year period in a pasture where a small cattle population was kept, resulting in an overall reduction in the number of Amblyomma variegatum ticks per animal. This review discusses current scientific information about Ixodiphagus spp., focusing on the role of this parasitoid in the control of ticks. The interactions between these wasps and the ticks' population are also discussed, focusing on the many biological and logistical challenges, with limitations of this control method for reducing tick populations under natural conditions.

First record of the parasitoid wasp Ixodiphagus hookeri (Hymenoptera: Encyrtidae) infesting the tick Amblyomma nodosum (Acari: Ixodidae)

Ticks (Ixodida) are ecologically important ectoparasites that may impact human health and economic activities. Parasitoid wasps are natural enemies of ticks and a potential option for its biological control. In the present study, we recorded parasitism of the nymphs of the tick Amblyomma nodosum by the parasitoid wasp Ixodiphagus hookeri. The ticks, in turn, were parasitizing white-bearded manakins, Manacus manacus (Passeriformes: Pipridae) in the União Biological Reserve, one of the last major remnants of lowland rainforest in Rio de Janeiro state, southeastern Brazil. During the collection of ectoparasites from two manakins in this reserve, 20-30 parasitoid wasps hatched spontaneously from two of the ticks collected. The species of the tick nymphs and adult wasps were identified using morphological traits and molecular analyses. This record is the first documented case of I. hookeri parasitizing A. nodosum and the first time that parasitoid wasps have been found in ticks parasitizing birds in Brazil. This is also the first record of Ixodiphagus from southeastern Brazil in more than a century, with the only other record dating back to 1914. The record presented here provides valuable new information on the biology of this tick and its parasitoids, and new insights into this interspecific interaction. Further research on these vertebrate-tick-wasp interactions will be necessary to better understand the respective roles of the organisms involved in these processes.

First detection of Ixodiphagus hookeri (Hymenoptera: Encyrtidae) in Ixodes ricinus ticks (Acari: Ixodidae) from multiple locations in Hungary

The parasitoid wasp, Ixodiphagus hookeri (Hymenoptera: Encyrtidae), is the natural enemy of a wide range of hard and soft tick species. While these encyrtid wasps are supposed to be distributed worldwide, only a few studies report on their actual distribution around the globe. Within a shotgun sequencing-based metagenome analysis, the occurrence of I. hookeri was screened at multiple Ixodes ricinus (Acari: Ixodidae) tick sampling points in Hungary to contribute to the assessment of the distribution patterns of the parasitoid wasps in Central Europe. To our knowledge, the first report of the species in Hungary and the description of the southernmost I. hookeri associated geoposition in Central Europe took place within our study. I. hookeri infested I. ricinus nymphs were detected at five sampling points in Hungary. The results show that the exact distribution range of I. hookeri is still barely studied. At the same time, unprecedented public health issues being brought about by climate change might require steps toward the exploitation of the tick biocontrol potential and as an ecological bioindicator role of the parasitoid wasp in the future.

Perspectives of vector management in the control and elimination of vector-borne zoonoses

The complex transmission profiles of vector-borne zoonoses (VZB) and vector-borne infections with animal reservoirs (VBIAR) complicate efforts to break the transmission circuit of these infections. To control and eliminate VZB and VBIAR, insecticide application may not be conducted easily in all circumstances, particularly for infections with sylvatic transmission cycle. As a result, alternative approaches have been considered in the vector management against these infections. In this review, we highlighted differences among the environmental, chemical, and biological control approaches in vector management, from the perspectives of VZB and VBIAR. Concerns and knowledge gaps pertaining to the available control approaches were discussed to better understand the prospects of integrating these vector control approaches to synergistically break the transmission of VZB and VBIAR in humans, in line with the integrated vector management (IVM) developed by the World Health Organization (WHO) since 2004.