Ants as predators of the Spinose Ear Tick, Otobius megnini (Dugès) in Sri Lanka G.C.P. Diyes, N.B. Karunarathna, T.H.S.E. Silva, W.A.I.P. Karunaratne, R.S. Rajakaruna To cite this version: G.C.P. Diyes, N.B. Karunarathna, T.H.S.E. Silva, W.A.I.P. Karunaratne, R.S. Rajakaruna. Ants as predators of the Spinose Ear Tick, Otobius megnini (Dugès) in Sri Lanka. Acarologia, Acarologia, 2017, 57 (4), pp.747-753. 10.1051/acarologia/20174200. hal-01598294 HAL Id: hal-01598294 https://hal.archives-ouvertes.fr/hal-01598294 Submitted on 29 Sep 2017 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. 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Subscriptions: Year 2017 (Volume 57): 380 € http://www1.montpellier.inra.fr/CBGP/acarologia/subscribe.php Previous volumes (2010-2015): 250 € / year (4 issues) Acarologia, CBGP, CS 30016, 34988 MONTFERRIER-sur-LEZ Cedex, France The digitalization of Acarologia papers prior to 2000 was supported by Agropolis Fondation under the reference ID 1500-024 through the « Investissements d’avenir » programme (Labex Agro: ANR-10-LABX-0001-01) Acarologia is under free license and distributed under the terms of the Creative Commons-BY-NC-ND which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited. Acarologia 57(4): 747-753 (2017) DOI: 10.1051/acarologia/20174200 Ants as predators of the Spinose Ear Tick, Otobius megnini (Dugés) in Sri Lanka G.C.P. DIYES, N.B. KARUNARATHNA, T.H.S.E. SILVA, W.A.I.P. KARUNARATNE and R.S. RAJAKARUNAB (Received 28 August 2016; accepted 11 February 2017; published online 06 July 2017; edited by Karen MCCOY) Department of Zoology, University of Peradeniya, Peradeniya, 20400, Sri Lanka. [email protected], [email protected], [email protected], [email protected], (B) [email protected] ABSTRACT — Many pathogens, parasitoids and predators have been documented as natural enemies of ticks, but their impact on tick populations are rarely evaluated. Here, we report the predatory behaviour of ants on the spinose ear tick, Otobius megnini. Ticks were collected from the ear canal of stabled horses in Nuwara Eliya racecourse and were brought to the laboratory. Eggs, unfed and engorged larvae, engorged nymphs and adults were naturally exposed to ants under laboratory conditions and the predatory behaviour of the different species and their feeding preferences were observed. Five ant species were found feeding on different life stages of O. megnini including eggs, larvae (fed/unfed) and adults; ants did not feed on the nymphal stages. Ant species were identified as Tapinoma melanocephalum, two species of Monomorium, one species of Pheidole and one species of Crematogaster. The predatory preference differed among the five ant species, with T. melanocephalum being identified as the best predator as it fed on eggs and adults, the non-parasitic stages of O. megnini. Different strategies have been used to control the infestations of O. megnini in the stabled horses but none of them were successful. Although we cannot extrapolate our empirical findings to a natural context, observations suggest that these ant species may be potential bio-suppressors of this tick species. KEYWORDS — Ant predators; bio-suppressors; spinose ear tick INTRODUCTION health with negative effects on non-target organ- isms and poor quality animal products (e.g., milk, Tick infestations are very hard to control owing to meat and hide; Rajput et al., 2006). Other control the wide distribution of certain species, their re- methods such as vaccination (Willadsen, 1995), se- markable longevity, seasonal dynamics and off-host lection of resistant host breeds (Samish et al., 2004; development (Sonenshine, 1993). The most widely Shyma et al., 2015) and pasture spelling which in- used and currently effective method is the use volves rotating livestock among paddocks for peri- of chemical acaricides like carbamate, organophos- ods of 3-4 months to starve the larval ticks (Wilkin- phate, synthetic pyrethroid, formamidine, macro- son, 1957) have been practiced, particularly for con- cyclic lactone and pyrazole (Lovis et al., 2011). Al- trolling the cattle tick, Rhipicephalus microplus. Ap- though effective, intensive use can result in the de- plication of acaricide substitutes such as extracts velopment of resistance (Foil et al., 2004; Guerrero of plants like Azadirachta indica, Calotropis procera, et al., 2012), impaired environmental and human http://www1.montpellier.inra.fr/CBGP/acarologia/ 747 ISSN 0044-586-X (print). ISSN 2107-7207 (electronic) Diyes G.C.P. et al. Nicotiana tabacum (Zaman et al., 2012) are being dida: Argasidae) is a soft tick of medical and vet- promoted. Moreover, in Sri Lanka, local reme- erinary importance that feeds in the ear canals dies are widely being used among the rural peo- of wide range of domesticated animals including ple to remove or to repel ticks from livestock and horses (Diyes and Rajakaruna, 2016a), and occa- pets. Some of these methods include: use of co- sionally humans, causing otoacariasis in Sri Lanka conut oil, citronella oil, neem (Azadirachta indica) (Ariyarathne et al., 2016). When present in the ear oil/leaves/seeds, marigold plant leaves and use of canal, they can cause paralysis, irritations, toxic mothballs (Personal communications with villagers conditions, allergies, eardrum perforation, muscle and livestock farmers). spasms, severe otitis and act as vectors of Q fever (Jellison et al., 1948; Madigan et al., 1995; Estrada- Numerous potential biological control agents of Peña and Jongejan, 1999). Larvae and nymphs of ticks including pathogens, parasitoids and preda- the spinose ear tick are parasitic while adults (males tors have been documented (Jenkins 1964; Mwangi and females) and unfed larvae are free-living and and Kaaya 1997; Samish and Rehacek, 1999; Kaaya, found in cracks and crevices in the immediate vicin- 2003). Pathogens like bacteria, fungi and nematodes ity of the host (Sonenshine, 1993). Here we present that infect and kill ticks, parasitoids that deposit the first report of predatory behavior of four genera their eggs in ticks or predators like birds and ants of ants on O. megnini in Sri Lanka. have been suggested as potential candidates for controlling some hard and soft tick species under field and laboratory conditions (Samish et al., 2004). MATERIALS AND METHODS Predator-tick relationships of 28 arthropod fami- Larvae and nymphs of Otobius megnini infesting the lies have been identified, of which, many are ants ear canals of stabled horses at the Nuwara Eliya race (Hymenoptera: Formicidae), followed by carabid course (GPS: 6.962829N, 80.769207E) were collected beetles (Coleoptera: Carabidae) and some spiders onto small pieces of white open-wove cotton ban- (Araneae: Lycosidae; Samish and Alekseev, 2001). dage. The ground cover materials in stables were Among ants, Aphaenogaster, Formica, Iridomyrmex, brushed carefully using a soft bristle duster to col- Monomorium, Notoncus, Pheidole, Pogonomyrmex, lect the free-living adults. Live ticks were brought Rhytidoponera and Solenopsis are some of the genera to the Parasitology Laboratory in the Department that occasionally target ticks as their food source of Zoology, University of Peradeniya and were (Samish and Rehacek, 1999). Ants that feed on counted, weighed and separated according to life ticks are considered as bio-suppressors (Samish et stage. Some of the field-caught engorged nymphs al., 2004). They are generalist predators that feed were allowed to moult into adults. Field-caught on ticks occasionally and may affect the size of a adults were allowed to mate and lay eggs. Some tick population in nature, but using them as biologi- of these eggs were kept in perforated Eppendorf® cal control agents may have negative consequences tubes (1.5 ml each containing 100 eggs) to obtain un- as it requires a large increase in the ant population fed larvae. The rest of the eggs were placed in per- which could lead to changes in non-target species forated Eppendorf® tubes (1.5 ml each containing (Symondson et al., 2002) or result in the ant becom- 100 eggs) and were kept on a microcentrifuge rack. ing a pest (Barbosa, 1998; Bellows and Fisher, 1999). Field caught engorged larvae and nymphs, and the Gleim et al. (2013) discussed the potential use of laboratory moulted adults were placed in quadran- Solenopsis invicta against tick species: Amblyomma gular plastic grid plates (25 wells in each plate and americanum and Amblyomma maculatum populations three ticks per well). The grid plates were covered in burned habitats. However, few studies have ex- with a plastic mesh which allowed ants to enter but amined the exact effect of ants on tick population excluded flies (e.g., the scuttle fly, Megaselia scalaris; dynamics. Hence, the importance of ants in biologi- Diyes et al., 2015) and other larger predators. Larvae cal control is still controversial (Barbosa, 1998). and nymphs with fungal infections were removed The spinose ear tick, Otobius megnini (Acari: Ixo- from the collection. Eppendorf® tubes containing 748 Acarologia 57(4): 747-753 (2017) TABLE 1: Developmental stage of Otobius megnini and the feeding preferences of the five predatory ant species under different experi- mental set up No.