Pure evil? Tick sometimes gets eaten and has parasites too

Ticks are, for example, a source of proteins for various animals. "They can easily fall prey to predators especially after feeding when they are filled with blood and become larger, more visible" - noted in an interview with PAP Krzysztof Dudek from the Institute of Zoology of the University of Life Sciences in Poznań.

Tick fall prey to invertebrates, such as ants and beetles. Tick predator is, for example, one of flies, that also lives in our climate.

Larger animals also prey on ticks, for example toads, which was confirmed by observations carried out in the USA and Brazil, as well as rodents - shrews, mice and rats. But their most important natural enemies are birds. Some of them, such as African red-billed oxpecker, specialize in cleaning parasites (including ticks) from livestock and wildlife, for example antelopes and rhinos. In a similar manner prey cattle egrets, for which ticks can be an important part of the diet.

Even chickens do not despise ticks, as confirmed by studies conducted in Kenya, on a cattle farm. Smaller birds of other, for example passerine species also hunt ticks on a smaller scale.

Although they are parasites themselves, ticks can also serve as hosts for other parasites. These include certain viruses, bacteria, fungi and nematodes.

Natural enemies of ticks also include bugs, larvae of butterflies and mites, which are arachnids related to ticks.

There are few scientific papers devoted to the natural enemies of ticks, the naturalist from the University of Life Sciences in Poznań noted. "Researchers who study ticks usually focus on their impact on other organisms than on how they themselves become prey. But perhaps in time we will find that some organisms may be useful in the fight against these mites, as was the case with slugs in horticulture, which today are commonly combated with nematodes" - he said.

The reasons why we avoid ticks define their function in the ecosystem. "Like any parasite, ticks have a regulatory role in the environment: they carry diseases that can affect the weakened individuals and limit the populations of some organisms" - explained Krzysztof Dudek.

The level of infection of ticks with pathogens dangerous for humans (such as Borrelia that causes Lyme disease) depends on the region and the type of ecosystem. "Research conducted in different parts of Poland shows that in the total population of ticks, a few to several tens of percent of the ticks carry Lyme disease, usually - a dozen. One review study indicated that in the ecosystem in the area of Katowice even more than 30 percent ticks may be infected" - reported Krzysztof Dudek.

"Studies conducted in Germany show that in recent decades the number of infected ticks living there has increased greatly. Between the 1980s an the present day the prevalence of Borrelia in ticks more than doubled" - he added.

One of the most important causes of the problem may be the warming climate, which is conducive to both ticks and pathogens they carry. "Some experts believe that higher temperatures may facilitate the survival of the Borrelia spirochete and tick-borne encephalitis. And vice versa - very low winter temperatures can neutralize these pathogens" - said Krzysztof Dudek.

He also suggested that the larger scale of pathogens among ticks living in Poland may be related to the level of biodiversity, which in recent years has been observed in the American forest ecosystems. According to researchers from the University of Life Sciences in Poznań the theory may be true that the greater the diversity of species in the environment - the less ticks become carriers of pathogens.

"The most important reservoir of pathogens are rodents, which are found in any, even heavily degraded environment. Ticks living in such places basically have no alternative. When they are hungry and waiting for a host, they usually encounter rodents, such as mice or voles, which are often carriers of harmful micro-organisms. This means a high probability of infection" - he explained.

In more diverse environments, where alongside rodents live also other mammals, birds and reptiles, ticks are more likely to encounter, for example, lizards, which are poor reservoirs of pathogenic microorganisms. "Our previous research showed that only approx. 4 percent lizards have tick-borne pathogens in their bodies, and more specifically - Lyme disease. At the same time lizards, are often hosts of ticks. Record lizard we studied by had 66 ticks on it!" - said the zoologist.

The study, which will check whether ticks in the environment with greater biological diversity have less Lyme spirochetes in their organisms, is being carried out at the University of Life Sciences in Poznań. The results of the study undertaken within the framework of a National Science Centre will be presented in two years or later.

PAP - Science and Scholarship in Poland

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