Title

Detection of five polymorphic populations of Boophilus microplus (family Ixodidae) infesting cattle in two pastures with different management practices in Cavite, Philippines

College

College of Science

Department/Unit

Biology

Document Type

Archival Material/Manuscript

Abstract

Species diversity and intensity of ticks infesting cattle in two pastures [Imus abattoir pasture (IAP) and Trece Martires Victoria cattle farm (TMVCF)] with different management practices in the providence of Cavite were assessed for six months from December 2009 to May 2010. The cattle examined (male=98, female=119) comprised the Brahman, Holstein and Sahiwal breeds. In TMVCF, where the cattle were subjected to acaricidal treatment, lower infestation (56.5%) and contamination of the pasture (38%) were recorded. Highest infestation was recorded among the 4-6 year old Brahman cattle (84%), and infestation was higher among males in IAP (60.6%) and females in TMVCF (85.7%). A total of 1993 ixodid ticks representing larvae, nymphs and adults were plucked out of the different body parts of 144 infested cattle. Two ixodid tick species Boophilus microplus and Rhipicephalus sanguineus were identified. Boophilus microplus accounted for 99.4% of all the ticks collected in both study sites. Interestingly, differences in the adanal and accessory plates in 1393 non-engorged male B. microplus revealed five distinct morphs, with morph-1 being the most common (34%) and morph-4 the least frequent (13.9%). All the five morphs were identified during the six month period, with increasing numbers during the warmer months. Warburton (1912) had proposed the clustering of Boophilus and Rhipicephalus ticks under one genus. Also, based on molecular findings, Barker and Murrell (2002) and Beati and Keirans (2001) are convinced of Boophilus as monophyletic and arose within one Rhipicephalus lineage. In our study however, Boophilus and Rhipicephalus were identified as two separate genera based on the apparent differences in their mouthparts, body shape and punctations, presence and absence of festoons and anal groove. More importantly, we observed among the non-engorged mal B. microplus marked differences in their reproductive adanal and accessory plates. This may account for polymorphism attributable to the simultaneous occurrence of several discountinuous phenotypes or genes in a population, with the frequency even of the rarest type higher than can be maintained by recurrent mutation (Mayr, 1969). While the five morphs do not warrant formal taxonomic recognition for now, considering that the changes are manifested by accessory reproductive organs, it may be safe to infer these gene mutations as indicative of a process to subspeciation. Further evaluation of the five morphs using morphometric data analysis vis-a-vis the use of scanning electron microscopy and gene sequence analysis should be pursued.

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Disciplines

Biology

Keywords

Boophilus microplus—Philippines—Cavite; Cattle—Parasites—Philippines—Cavite

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