Species Composition Of Ants (hymenoptera Formicidae) And Thermal Tolerance Along Environmental Gradient In The Bale Mountains National Park (bmnp) Ethiopia

This study was conducted to investigate the species composition of ants (Hymenoptera:rnFormicidea) and thermal tolerance of Camponotus negus and Camponotus acvapimensisrnin the Bale Mountains National Park (BMNP), Ethiopia. Ants were collected fromrndifferent altitudes and habitats using manual search, baits and pitfall traps fromrnDecember 14, 2013 to October 08, 2015. Heat and cold tolerance of ant colonies (C.rnnegus) from different altitudes of the BMNP (Gaysay and Sanetti) and from Dilla (C.rnacvapimensis) was determined. The time taken (minutes) by ant colonies to lose mobilityrnat a stressfully high temperature (knock-down resistance) of colonies were measuredrnfrom each site as an index of heat tolerance. For heat tolerance experiment 10 to 12rnindividuals from each colony (for a minimum of 24 individuals per colony) were placedrninto two Petri dishes in identical water baths (Stuart digital water bath, RE300DB, KeisonrnInternational Ltd, UK). Initially the temperature in both baths was set and maintained atrn45 °C for 90 minutes. After 90 minutes, the temperature was raised by 5 °C, andrncontinued to rise by 5 °C every 30 minutes thereafter until all ants had succumbed to heatrnstress. Time was recorded starting from the time the first ant completely lost mobility tillrnthe last ant stopped moving. The time required for an individual to recover from exposurernto extremely low temperatures (chill-coma recovery) was used to assess cold tolerance ofrnants. For cold tolerance experiments, 24 to 27 ants from each colony were placed in arnPetri dish covered in ice for 20 minutes. Then the time for each individual to recoverrnfrom chill-comma was recorded. From a total of 162 sample collections made, 16 speciesrnunder 8 genera and 4 subfamilies namely; Dorylinae, Formicinae, Myrmicinae andrnPonerinae were identified. Subfamily Myrmicinae was the most diverse with nine speciesrniv | P a g ern(56.25%) and the genus Tetramorium was the most speciose containing five species. C.rnnegus was the most abundant species of 54.12% of the samples collected. The highest antrnspecies diversity was observed in the altitude range of 2000– 2500 m followed by 3000–rn3500 m and the lowest was in the altitude range of 2500– 3000 m and 3500–4000 m.rnThus there was no clear pattern of species diversity with elevation. The highest antrnspecies diversity was recorded from the rainforest. C. negus from Sanetti (3970 m) hadrnhigh heat tolerance (143.52 ± 1.80 minutes) than from Gaysay (3040 m) (98.30 ± 1.82)rnminutes, but cold tolerance did not differ between the two sites. Colonies from Sanetti onrnaverage tolerated heat for additional 45 minutes compared to Gaysay. C. acvapimensisrnhad similar heat tolerance as C. negus from Sanetti but it had very low cold tolerancernwhich took 549.79 ± 18.77 seconds to recover from chill-comma compared to C. negusrnfrom both Gaysay and Sanetti which were 113.94 ± 19.40 and 84.04 ± 18.77 secondsrnrespectively. C. acvapimensis needed nearly 5 times more time to recover from chillcomarncompared to colonies of C. negus from Gaysay and 6 times than C. negus fromrnSanetti. Hence C. negus from Sanetti had higher heat and cold tolerance and may havernhigher potential to survive in the changing climate of BMNP. In conclusion, there was nornclear pattern of species diversity with elevation and the diversity was the highest in thernrainforest. C. negus from Sanetti had higher heat and cold tolerance and may has higherrnchance of survival in the changing climate.rnKey words: ants, diversity, climate change, thermal tolerance, Camponotus negus,rnCamponotus acvapimensis, Bale Mountains National Park

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