How Dopamine Influences Survival and Cellular Immune Response of <i>Rhipicephalus microplus</i> Inoculated with <i>Metarhizium anisopliae</i>
2021
Thaís Almeida Corrêa | Jéssica Fiorotti | Emily Mesquita | Laura Nóbrega Meirelles | Mariana Guedes Camargo | Caio Junior Balduino Coutinho-Rodrigues | Allan Felipe Marciano | Vânia Rita Elias Pinheiro Bittencourt | Patrícia Silva Golo
Dopamine (DA) is a biogenic monoamine reported to modulate insect hemocytes. Although the immune functions of DA are known in insects, there is a lack of knowledge of DA’s role in the immune system of ticks. The use of <i>Metarhizium anisopliae</i> has been considered for tick control, driving studies on the immune response of these arthropods challenged with fungi. The present study evaluated the effect of DA on the cellular immune response and survival of <i>Rhipicephalus microplus</i> inoculated with <i>M. anisopliae</i> blastospores. Exogenous DA increased both ticks’ survival 72 h after <i>M. anisopliae</i> inoculation and the number of circulating hemocytes compared to the control group, 24 h after the treatment. The phagocytic index of tick hemocytes challenged with <i>M. anisopliae</i> did not change upon injection of exogenous DA. Phenoloxidase activity in the hemolymph of ticks injected with DA and the fungus or exclusively with DA was higher than in untreated ticks or ticks inoculated with the fungus alone, 72 h after treatment. DA was detected in the hemocytes of fungus-treated and untreated ticks. Unveiling the cellular immune response in ticks challenged with entomopathogenic fungi is important to improve strategies for the biological control of these ectoparasites.
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