Oocyte maturation in the sloth’s giant tick Amblyomma varium (Acari: Ixodidae) in an ecological context

Abstract

The sloth's giant tick Amblyomma varium Koch, which is a neotropical species that inhabits tropical rainforests, is the largest tick reported to date. The adult stage of this tick parasitizes mammals from the families Bradypodidae and Magalonychidae (Xenarthra) nearly exclusively. This study aimed to describe morphological and histological features of the reproductive system and the oocyte maturation process of this tick species. The ovary of A. varium is a long single tubular organ that is horseshoe-shaped, winding and arranged in the posterior part of the body. Two oviducts are connected to the ovary on each side; these thicken at certain region forming the uterus (common oviduct), followed by a muscular connecting tube, vagina and genital aperture. A large number of oocytes at different stages of development are attached to the ovary wall by the pedicel, as they reach maturity they are released into the ovary lumen and from there to the genital aperture. These oocytes develop simultaneously and asynchronically along the ovary. Amblyomma varium oocytes were classified into five development stages (i.e., I-V), and specific characteristics were observed; the processes of yolk and chorion deposition begin early in oocytes stage II, and oocytes V exhibit a very thick chorion and eggs of a large size. These characteristics are likely adaptations that enhance the survival and the reproductive success of this extremely host-specific tick, which is limited to a particular environment.

Histopathological effects of the fruit extract of Citrullus colocynthis on the ovary of the tick Hyalomma dromedarii

“…Oocytes in the present study might be classified into oogonia and stages I, II, III, IV and V based on Roshdy ( 1969 ) and Balashov ( 1983 ) classifications. Similarly, oocytes were classified into five stages in Haemaphysalis longicornis (Yano et al 1989 ; Mihara et al 2018 ), Amblyomma cajennense (Denardi et al 2004 ), Rhipicephalus microplus (Saito et al 2005 ), R. sanguineus (Oliveira et al 2005 ; Sanches et al 2012a ), A. triste (Oliveira et al 2006 ), A. brasiliense (Sanches et al 2010 ), A. rotundatum (Sanches et al 2012b ), A. varium (Sanches et al 2014 )d annulatus (Kanapadinchareveetil et al 2015 , 2019 ).…”

development of oocytes of a dermacentor nuttalli tick

“…D. nuttalli (Olenev, 1928) хачгийг бэлчээрийн хачиг гэх бөгөөд малчид эрэгчин хачгийг цоохор нуруут, эмэгчин хачгийг алтан сэрвээт, эсвэл алтан толгойт хэмээн нэрлэдэг (Болдбаатар, Бямбаа, 2016б). Цус сорогч хачгийн өндгөвчний хэлбэр, ооцитын хөгжил, хэлбэр зүйн онцлогийн судалгаанууд Dermacentor andersoni, D. variabilis (Sonenshine, 1991), Amblyomma rotundatum (Sanches et al, 2012), A. cajennense (Denardi et al, 2004), A. triste (Olivera et al, 2006), A. brasiliense (Sanches et al, 2010), A. varium (Sanches et al, 2014), Rhipicephalus (Boophilus) microplus (Saito et al, 2005), R. sanguineus (Oliveira et al, 2005), Haemaphysalis longicornis (Mihara et al, 2018) хачгуудад судлагдсан байдаг. D. nuttalli хачиг нь туларемиа, ку-чичрэг, хачгийн риккетсиоз, хачигт энцефалит, адуу, үхрийн бабезиоз, хонины анаплазмозын үүсгэгчийн дамжуулагч вектор болдог (Бямбаа, 1994;Battsetseg et al, 2001Battsetseg et al, , 2002Болдбаатар, Бямбаа, 2016).…”

“…З.Үүрцайх ба бусад (2018) ХАА-н шинжлэх үхаан сэтгүүл №25 (03):[15][16][17][18][19][20][21][22][23][24] …”

loth's giant tick (Amblyomma varium) parasitizing free-ranging maned sloth (Bradypus torquatus) in the Atlantic Forest biome, Brazil

“…Amblyomma varium is a neotropical tick, distributed in the following Brazilian states: Pará, Acre, Amazonas, Rondônia, Paraíba, Pernambuco, Alagoas, Bahia, Mato Grosso, Espírito Santo, Minas Gerais, Rio de Janeiro, and São Paulo ( Acosta et al, 2016 ; Gruhn et al, 2019 ; Sanches et al, 2014 ; Witter et al, 2016 ;). Popularly known as the sloth’s giant tick, during the adult stage is found almost exclusively on mammals of the Bradypodidae and Megalonychidae families of the superorder Xenarthra ( Marques et al, 2002 ; Onofrio et al, 2008 ).…”