Browsing by Author "Dias, R.K.S."

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Aneuretus simoni emery occurrence and the ant community observed by multiple methods and repeated sampling in “Pompekelle”, Sri Lanka
(International Journal of Entomological Research, 2014) Dias, R.K.S.
The ant community of “Pompekelle” is of special interest due to the presence of island-endemic Aneuretus simoni Emery among them. Frequency of occurrence and proportional abundance of A. simoni workers and, species richness and composition of ant community were investigated using several sampling methods simultaneously on six visits to the forest from February to November 2004. Day time sampling of ants was carried out along ten, 100 m transects by mini-Winkler extraction, soil sifting, pitfall trapping, honey and canned fish baiting, leaf litter sifting, timed hand collection and beating tray method. Honey baits at 1 m height on trees and honey-baited pitfall traps on the ground were also set overnight. Aneuretus simoni workers were detected on all occasions. Honey baiting and litter sifting in day time caught the workers more often than canned fish baits, soil sifting, day time pitfall traps and night pitfall traps. Detectability of A. simoni was irregular in the ten transects but the frequency of occurrence ranged from 30-80 percent and the species comprised 1-6 percent of workers collected on each of the six occasions. It was a permanent minor component in the forest despite its absence in the area of transect 8. Fifty species of 36 genera in 11 subfamilies including the resident species, A. simoni, Anochetus sp., Anoplolepis gracilipes, Camponotus sp., Hypoponera sp. 2, Lophomyrmex quadrispinosus, Myrmicaria brunnea, Odontomachus simillimus, Pheidole sp. 7, Pheidologeton sp., Prenolepis sp., Solenopsis sp. and Technomyrmex albipes and other occasional ant species can be considered the first preliminary ant inventory of the forest.
The ant community observed by the repeated quadrat sampling in a selected region of the Meethirigala Forest Reserve, Sri Lanka
(Department of Zoology and Environmental Management, University of Kelaniya, 2015) Udayakantha, W.S.; Dias, R.K.S.
The Ants (Hymenoptera, Formicidae) of Sri Lanka: a taxonomic research summary and updated checklist
(ZooKeys 967, 2020) Dias, R.K.S.; Guénard, B.; Akbar, S.A.; Economo, E.P.; Udayakantha, W.S.; Wachkoo, A.A.
An updated checklist of the ants (Hymenoptera: Formicidae) of Sri Lanka is presented. These include representatives of eleven of the 17 known extant subfamilies with 341 valid ant species in 79 genera. Lioponera longitarsus Mayr, 1879 is reported as a new species country record for Sri Lanka. Notes about type localities, depositories, and relevant references to each species record are given. Accounts of the dubious and some undetermined species from Sri Lanka are also provided. 82 species (24%) are endemic whereas 18 species that are non-native to Sri Lanka are recorded. The list provides a synthesis of the regional taxonomical work carried out to date and will serve as a baseline for future studies on the ant fauna of this biodiversity hotspot.
Ants as Biological Indicators of Human Disturbance – evidence from Sinharaja forest and tea and rubber fields in Ratnapura district
(University of Kelaniya, 2006) Dias, R.K.S.; Perera, K.A.M.
Ants are a major group of insects in the forests as well as in agricultural fields in Sri Lanka. If the presence or absence of some ant taxa in disturbed areas differs from that of a forest reserve was investigated by sampling worker ants from tea and rubber fields in Godakawela and the primary and secondary forest regions in Sinharaja forest in September and October, 2005, respectively. Heavy rains prevailed during the sampling on both occasions. Honey baiting (25), soil sifting (10), hand collection (10) and litter sifting (10) during day time and pitfall trapping (10) at night along a 100 m transect were carried out in the forest while all of those methods except litter sifting were carried out in the tea and rubber fields. Depth of litter, soil moisture content and temperature and air temperature were also recorded. Worker ants belonging to seven subfamilies, Aneuretinae, Amblyoponinae, Cerapachyinae or Leptanillinae, Dolichoderinae, Formicinae, Myrmicinae and Ponerinae were recorded from the primary and secondary forest regions whereas five subfamilies, Dolichoderinae, Formicinae, Myrmicinae, Ponerinae and Pseudomyrmicinae were observed in both tea and rubber fields. Worker ants of subfamily Amblyoponinae were recorded from rubber fields but they were not observed in the tea fields. Thirty two morphospecies of ants from the primary forest region and twenty seven morphospecies from the secondary forest region were observed during this study. Thirty and thirty four morphospecies of ants were recorded from tea and rubber fields, respectively. Although Species Richness values did not show significant difference (p>0.05) for the four types of ecosystems, it was evident that Anoplolepis gracilipes (Jerdon), Diacamma rugosum Mayr, Meranoplus bicolor (Smith F.), Odontomachus simillimus Smith F., Oecophylla smaragdina Fabricius and Tetraponera rufonigra (Smith F.) could be considered as biological indicators of disturbance as they were restricted to tea and rubber fields. Also, Aneuretus simoni Emery, Technomyrmex bicolor Emery, Anochetus sp. and Leptogenys spp. were restricted to the two types of forest regions but further research would be carried out to confirm these observations.
Arboreal ant assemblages (Formicidae) and importance of Oecophylla smaragdina (Fabricius) occurrence in a wet zone cashew field in Sri Lanka
(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Dias, R.K.S.; Perera, A.P.S.
Many ant species (Hymenoptera, Formicidae) have the potential to control herbivore abundance, reducing the plant damage while increasing plant growth, reproduction and yield in agro-ecosystems. Ant assemblages on six cashew trees in Delgoda, Gampaha District were recorded throughout three phenological phases by visiting the field six times from March to June in 2015. Seven to 15 baited traps were set 25 cm apart on the branches of each small, medium and large tree and collected after three hours. Worker ants seen on the main trunk and four major branches of each tree during a five minute period were hand-collected 5 to 9 times from small to large trees on each occasion. Collected ants were preserved in 70% ethanol, identified and listed. Number of Oecophylla smaragdina (Fabricius) nests observed on the same trees was recorded from April to June in 2015. The materials carried by O. smaragdina workers on cashew tree branches were also collected, preserved in 70% ethanol and identified to the possible levels using a Low Power Stereo-microscope. Fourteen ant species in five subfamilies were recorded. Species richness observed on each occasion ranged from 7 – 11 while O. smaragdina was the only species on all cashew trees. Nests of the species of O. smaragdina were observed only on one or two large and medium-sized trees. Various plant and animal materials carried by O. smaragdina workers confirmed that the species is an omnivore and a generalist predator. Presence of ant assemblages on cashew trees in the absence of any insecticide application in the current cashew field may have contributed to an observed absence of serious damage by cashew insect pests elsewhere.
Colony demography in the differently colored leaf nests of Oecophylla smaragdina Fabricius collected from the premises of Kelaniya University, Sri Lanka
(Department of Zoology and Environmental Management, University of Kelaniya, 2015) Perera, A.P.S.; Dias, R.K.S.
Community composition of benthic insects of the Heen Ganga tributaries in the Knuckles region
(Proceedings of the Annual Research Symposium 2005-Faculty of Graduate Studies, University of Kelaniya, 2005) Weerasinghe, W M D; Silva, E I L; Dias, R.K.S.
Heen Ganga is a major tributary of river Mahaweli which drains through the Knuckles forest region in Sri Lanka. The community composition of benthic insects in four tributaries of Heen Ganga was investigated from June to September 2004 and in April 2005. Two of the tributaries were situated closer to the human settlements and the other two were relatively less disturbed. Another tributary in Galmal Oya was selected which is located at higher altitudes and with minimum disturbances, for the comparison. Two replicate samples were taken from each site using the Surber sampler (25 cm x 25 cm metal frame) while lifting the stones and manually stirring the bottom substrate demarcated by the frame for five minutes. Larvae and adult insects in the samples were sorted and examined under a stereo – microscope at suitable magnifications and the specimens were preserved in 70% alcohol and identified to the furthest possible taxonomic levels Insects belonging to seven orders were observed in the overall collection and Diptera (larvae only, 30 %), Coleoptera (larvae & adults , 28%), Ephemeroptera (larvae only , 21%) and Trichoptera (larvae only , 18%) dominated the orders, Odonata (larvae only, 1.8%), Plecoptera (larvae only, 1.06%) and Hemiptera (larvae only, 0.23%) observed at the Heen Ganga study sites. Also, among the six families of dipterans observed chironomids apparently dominated the other families, Tipulidae, Ceratopogonidae, Simuliidae, Athericidae and Psychodidae. Members of six families of Coleopterans, Psephenidae, Elmidae, Scirtidae, Gyrinidae , Lampyridae and Hydrophilidae and six families of ephemeropterans, Baetidae, Leptophlebiidae, Ephemeridae, Ephemerilidae , Caenidae & Prosopistomatidae were also identified. Trichopterans belonging to three suborders and eleven families, namely Glossosomatidae, Hydroptilidae , Dipseudopsidae, Ecnomidae , Hydropsychidae, Goeridae ,Calamoceratidae, Lepidostomatidae, Leptoceridae, Sericostomatidae and Helicopsychidae were observed while the members of Goeridae and Glossosomatidae were apparently dominant among them. At the Galmal Oya study site, coleopterans (33%) and dipterans (30%) were dominant while the trichopteran (26%) and ephemeropterans (8%) were observed in lower proportions. In addition, Hemiptera (1.6%) Plecoptera (1.2%) and Odonata (0.33%) were also observed. The values of diversity indices for morphospecies of common five orders indicated that there was not much difference between the diversity of benthic insect community in Heen Ganga tributaries (H’= - å pi ln pi =3.3) and the Galmal Oya study site. (H’=3.6).
Comparative study of the diversity and the community composition of the worker ants I a forest reserve and a secondary forest in Sri Lanka
(Sri Lanka Association for the Advancement of Science, 2005) Dias, R.K.S.; Perera, K.A.M.
Comparison of HPLC profiles of venom of Apis darsata fabricius (Giant Asian Honey Bee) and Apis mellifera Linnaeus (Western Honey bee)
(2016) Gunasekara, D.L.P.E.; Handunnetti, S.M.; Premawansa, S.; Dias, R.K.S.; Witharana, E.W.R.A.; Dassanayake, W.M.D.K.; Premakumara, G.A.K.; De Silva, N.R.
Culture of Moina maeroeopa straus using organic and inorganic inputs
(Sri Lanka Association for Fisheries and Aquatic Resources, 1998) Dias, R.K.S.; Yakupitiyage, A.
Discovery of Sri Lankan relict ant (Formicidae, Aneuretinae) and a preliminary ant inventory of Indikada-Mukalana Forest Reserve in Colombo district, Sri Lanka
(2016) Dias, R.K.S.; Udayakantha, W.S.
Discovery of the Sri Lankan Relict Ant, Aneuretus simoni Emery (Formicidae, Aneuretinae) and the nest density of the species in a selected region of Meethirigala Forest Reserve, Sri Lanka
(2016) Dias, R.K.S.; Udayakantha, W.S.
Discovery of three new Tetraponera species (Formicidae; Pseudomyrmecinae) from Sri Lanka.
(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Dias, R.K.S.; Udayakantha, W.S.; Thotagamuwa, A.; Fernando, K.S.S.D.; Madushani, N.
Tetraponera F. Smith is the sole genus of subfamily Pseudomyrmecinae recorded from Sri Lanka and very little is known about the diversity of the arboreal genus in the country. Nests of Tetraponera species were collected by checking the worker trails and locating them followed by severing the nests from the host trees. Colony members in (i) a nest in a cashew tree branch from Delgoda (7º 00.395´N and 80º 00.96´E) Udupila in Gampaha District in March, 2015 (ii) three nests of Tetraponera from two jack trees in the premises behind the Department of English language Teaching (6º58´ 35.94" N and 79º54´ 58.8"E), University of Kelaniya in March, 2015 and (iii) a nest in a dry rubber branch from Gulanakanda (6°35'01.7"N 80°00'36.7"E), Bombuwala, Kalutara in August, 2016 were preserved in 70 % ethanol for the identification and listing of Tetraponera species. Fifteen morphometric parameters of each adult caste of each species, if present, were measured using a calibrated micrometre eyepiece fixed to a stereo-microscope and total length of the adult castes were measured by a ruler in mm scale, which was kept under the stereo-microscope. Cephalic Index (CI=HW/HL), Scape Index (SI=SL/HW) and Relative Eye Length (REL=EL/HL) were also calculated. Worker ants were identified to the species level refering to the relevant literature; T. extenuata Ward, T. microcarpa Wu and Wang and T. modesta (F. Smith) in Tetraponera allaborans-group were identified from the nests (i), (ii) and (iii), respectively. Black or dark brownish black worker with the contrasting brownish orange post-petiole, tibiae, tarsi and scapes, taller and more slender propodeum and more convex and soft-edged pronotal margins characterized T. extenuata workers. Workers of T. microcarpa were of black or brownish black, with lighter brown petiole, post-petiole and appendages, bidentate median clypeal lobe, short and broad profemur and quadrat-shaped propodeum. Small size, orange-brownish colour of the body with lighter colour appendages and relatively slender profemur characterized T. modesta workers. Colony demography of each nest recorded by counting the number of each adult caste with the naked eye and that of larvae, pupae and eggs under the stereo-microscope indicated that workers generally had the highest percentage abundance whereas eggs or larvae were also present in higher percentages. Very low percentage of dealate queen was observed in each nest. Four Tetraponera species, T. rufonigra (Jerdon), T. allaborans (Walker), T. nigra (Jerdon) and T. nitida (Smith) recorded previously from Sri Lanka rose to seven with the current findings. A taxonomic key that distinguish all Tetraponera species recorded from Sri Lanka is prepared with the colour images to facilitate quick identification of workers of each species.
Diversity and community composition of the ground and lower canopy foraging worker ants in the Gilimale forest
(Proceedings of the Annual Research Symposium 2005-Faculty of Graduate Studies, University of Kelaniya, 2005) Dias, R.K.S.; Perera, K A M
Ants are a very important group of insects in the forests of Sri Lanka and their microhabitats vary from ground to the canopy. Worker ants on the ground and lower canopy of two sites in the Gilimale forest were sampled by several methods in April, June and August 2004. Worker ants were sampled along a 100 m transect in each site by the baited traps (honey and canned fish), manual collection, soil and litter sieving (Time unit method) and Winkler extraction. Branch clipping, beating and, five honey baited traps hanged at a height of 15 - 20 feet were used to sample ants on three Symplocos bractealis (Wal Bombu) and three Schumacheria castaneifolia (Kekiriwara) trees in April. Fifteen honey baited traps were hung on three of the each tree species in June. In August, five traps baited with honey, canned fish, desiccated coconut, ground peanut or paddy seeds (variety BG 11)) were hung on the same trees. Pitfall traps and baits on trees were set to collect ants that forage at dusk and the night. Worker ants were identified with the assistance of Bolton (1994) and the reference collection at the Department of Zoology, University of Kelaniya. Worker ants belonging to nine subfamilies and thirty five taxa (H = Ópi logpi = 2.56), Aenictus sp. (0.26%), Aneuretus simoni Emery (2.5%), Amblyopone sp. (0.15%), Anochetus (0.1%), Aphaenogaster sp. (25%), Calyptomyrmex sp. (0.3%), Camponotus sp. (4.7%), Cataulacus sp. (0.05%), Crematogaster sp. (9.4%), Cryptopone sp. (0.26%), Dolichoderus sp. (0.56%), Hypoponera sp. (0.1%), Leptanilla sp. (0.26%), Leptomyrmex sp. (1%), Leptogenys sp. (0.7%), Lophomyrmex sp. (0.26%), Meranoplus bicolor (0.77%), Monomorium sp. (1.1%), Myrmicaria sp. (10.4%), Odontomachus simillimus Smith (0.15%), Oligomyrmex sp. (13.4%), Paratrechina sp. (2.%), Pheidole sp. (4.5%), Pheidologeton sp. (8.4%), Polyrhachis sp. (1.2%), Ponera sp. (0.36%), Solenopsis sp. 1 (0.26%), Strumigenys sp. (0.05%), Tapinoma melanocephalum Forel (0.3%), Tapinoma indicum Forel (0.2%), Technomyrmex albipes Emery (2%), Technomyrmex bicolor Emery (2%), Tetramorium sp.1 (4.3%), Tetramorium bicarinatum Mayr (3.2%) and Tetraponera allaborans (0.05%) were recorded from the ground samples. Ten taxa (H = 1.73) of worker ants that belonging to Dolichoderinae, Formicinae and Myrmicinae, Aphaenogaster sp. (8%), Camponotus sp. (17%), Cataulacus sp. (1%), Crematogaster sp. (5%), Leptomyrmex sp. (1%), Myrmicaria sp. (1%), Polyrhachis sp. (8%), Solenopsis sp. 2 (12%), Technomyrmex albipes Emery (43%) and Tetramorium sp. 2 (4%) were identified from the lower canopy. Solenopsis sp. 2 and Tetramorium sp. 2 were observed only on the trees. Worker ants belonging to five subfamilies and fifteen morphospecies were observed in the night traps. Species Richness values recorded from both ground and the canopy in April, June and August were not significantly different (Chi-square, p > 0.05) and reached 24, 25 and 24, respectively. Presence or absence of some taxa and the proportional abundance of dominant taxa varied on the three occasions. Leptomyrmex sp. forages on the ground as well as on trees and is a new record from Sri Lanka.
Diversity and importance of soil dwelling ants
(Biodiversity Secretariat, 2013) Dias, R.K.S.
The diversity and some ecological aspects of Chironomid larvae in the Southwest segment of Beira Lake
(Sri Lanka Association for Fisheries and Aquatic Resources, 1999) Wickramasinghe, U.; Dias, R.K.S.
Diversity of Worker Ant Communities (Order: Hymenoptera; Family: Formicidae) in Non-Agricultural Lands in Ratnapura District
(University of Kelaniya, 2007) Dias, R.K.S.; Perera, K.A.M.
An ant survey (Jan., 2004 · Dec., 2005) conducted in the forests and some selected agricultural lands in Ratnapura district for the preparation of an inventory and to locate the habitats of the endemic ant, Aneuretus simoni Emery, was extended to nonagricultural lands in the district, from January to June in 2006. Worker ants were sampled along three transects laid in such a land in Kuruwita (January), Dumbaramanana (February), Godakawela (March), Ambilipitiya (April), Balangoda (June) and Nivithigala (June). Along each 100 m transect, twenty five honey baits were kept at four metre intervals and collected after an hour into bottles filled with 85% ethanol. In addition, ants sampled by soil sifting (20) and hand collection (1 0) at 4 m intervals were also preserved in 85% ethanol. Ants were sorted, identified to the possible taxonomic levels and enumerated in the laboratory. Air (23°- 35° C) and soil temperatures (22° - 33 °C), soil moisture content (17% - J7%) and soil organic matter (2% - 9%) of each site were also recorded. Although members of six subfamilies, Amblyoponinae, Cerapachyinae, Dolichoderinae, Formicinae, Myrmicinae and Ponerinae and, fifty six species and morphospecies of ants were recorded, Aneuretus simoni (Subfamily: Aneuretinae) was never observed during this study. Significantly different Species Richness values (chi square test; p< 0.05) were recorded for the lands in Kuruwita (18), Dumbaramanana (19), Godakawela (28), Ambilipitiya (17), Balangoda (29) and Nivithigala (26). Technomyrmex albipes (36.8%) dominated the Kuruwita ant community while Pachycondyla sp. 2, Monomorium sp." 2 and Paratrechina longicornis were observed in considerable (>5%) proportions. Pheidole sp. 2 was dominant in Dumbaramanana whereas Tapinoma melanocephalum (24.8%), Technomyrmex bicolor (12.6%), Myrmicaria brunnea (10.4%) and Technomyrmex albipes (5.9%) were also observed in considerable proportions. Tapinoma melanocephalum was the dominant species recorded from Godakawela (28.9%) and Nivithigala (27%) study sites. In addition, Pheidole sp. 2 (10.9%) and Pheidole sp. 3 (10.9%) in Godakawela and Camponotus sp. 2 (11.4%) & Paratrechina longicornis (9.3%) in Nivithigala were observed in considerable proportions. The dominant ant species observed in Ambilipitiya and Balangoda were Anoplolepis gracilipes (72.9%) and Pheidole sp. 2 (36.9%), respectively. Considerable proportions of Tetramorium bicarinatum (9%) in Ambilipitiya and Pheidole sp. 4 (12.9%) in Balangoda were also observed. Anoplolepis gracilipes and Meranoplus bicolor were the species common to six disturbed regions and this observation indicated that these species may have a value as biological indicators of disturbance. The ponerines, Anochetus spp., Cryptopone spp., Diacamma ceylonense, D. indicum, Hypoponera spp., Leptogenys spp., Odontomachus simillimus, Pachycondyla spp. and Platythyrea sp., when present, were always observed in very low proportions. Although the reasons for the presence of different ant communities in the six lands were not investigated in detail it is apparent that each ant community observed in each land could be a reflection of the environmental quality of each land. Members of Subfamily Aenictinae, which were recorded from forests in Ratnapura were not observed in these lands.
Diversity of Yala season diurnal ant community in two selected rice fields in the Wet Zone of Sri Lanka
(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Wickramasinghe, W.P.C.S.; Dias, R.K.S.
Studies on the ant communities of Wet Zone rice fields in Sri Lanka are scarce and the present study was conducted to determine the diversity and species composition of ants throughout Yala season. Worker ants were sampled within two, almost similar, rain-fed rice fields (18 x 20 m) in Mahadarawa, Gampaha District from February to September in 2017 encompassing post-harvest, seedling, tillering, flowering and mature grain stages. In each rice field, pitfall trapping (20), honey baiting (20) and hand collection (15) were employed along a 20 m line transect during daytime. The collected ants were preserved in 85% ethanol and identified to the possible taxonomic levels in the laboratory using the relevant references. Air temperature and light intensity varied between 32-360C and 14478-19983 Lux m-2, respectively. Eleven ant species, Anochetus graeffei Mayr, Anoplolepis gracilipes Smith F., Camponotus compressus Fabricius, Carebara diversa Jerdon, Diacamma rugosum Le Guillou, Meranoplus bicolor Guerin-Meneville, Monomorium floricola Jerdon, Odontomachus simillimus Smith F., Paratrechina longicornis Latreille, Tapinoma melanocephalum Fabricius and Tetramorium walshi Forel in 11 genera of 4 subfamilies, Dolichoderinae, Formicinae, Myrmicinae and Ponerinae were recorded from the two rice fields. The most speciose subfamily was Myrmicinae whereas Dolichoderinae contained only a single species. Species richness observed for seedling stage and post-harvest stage-2 was 9, while 11 species were observed on the other occasions. Higher Shannon-Wiener Diversity index value (H’= 2.093) was observed for tillering stage than that of the seedling stage (H’= 1.764). The highest mean percentage frequency of occurrence was observed for C. compressus followed by T. melanocephalum while A. graeffei had the lowest value. Significantly higher frequencies of C. compressus and T. melanocephalum were observed (Chi square test, p<0.05) at the ‘Field 1’ and ‘Field 2’ on all occasions. A diverse ant community consisting of 9 permanent inhabitant species occurred at the two fields irrespective of the presence of both wet and dry conditions. Carebara diversa was a nuisance to farmers because the workers carried away germinated rice seeds from the paddy fields. It appeared that O . simillimus was a predator of the rice pest, Gryllotalpa orientalis Burmeister (Oriental mole cricket).
Diversity, distribution and species composition of worker ants in tea and rubber fields in Ratnapura district
(Research Symposium 2009 - Faculty of Graduate Studies, University of Kelaniya, 2009) Dias, R.K.S.; Perera, K. A. M.
Very little is known about the diversity, distribution and species composition of ants, an economically important biotic component of tea and rubber fields, in Sri Lanka. Also, the endemic ant, Aneuretus simoni Emery, has been recorded from the forests of Ratnapura district but its presence or absence in the tea and rubber fields of the district has never been investigated earlier. A survey on worker ants was conducted by sampling worker ants from each tea and rubber field in Kuruwita (14 – 16, January), Nivithigala (28 – 30, March), Balangoda (24 – 26, May), Dumbaramanana (25 – 27, July) and Godakawela (28 – 30, September) in 2005. Honey baiting, (25), soil sifting (20), hand collection (10) at 10 m distance and pitfall trapping at night (10) were carried out along five, 100 m transects laid in each of the fields on each occasion. All samples were preserved in 70% ethanol in the field. Sorting of the samples and identification of ants to the furthest possible taxonomic levels was carried out under a low power stereo-microscope in the laboratory. Although significant differences in air temperatures were not evident in the tea and rubber fields at the other locations mean air temperature at the rubber field in Balangoda was significantly higher than that recorded from the tea field. Significant differences in soil temperatures and soil moisture% were noticeable (One Way ANOVA; p<0.05) between the tea and rubber fields at each of the locations. GPS co-ordinates of each location were also recorded. Species Richness of ants recorded from the tea field in Kuruwita was twenty five and it increased to 35, 41, 50 and 52 with the additional species recorded from the tea fields in Nivithigala, Balangoda, Dumbaramanana and Godakawela, respectively. Nineteen taxa recorded from the rubber field in Kuruwita increased to 33, 48, 56 and 64 with the addition of ant species and morphospecies from Nivithigala, Balangoda, Dumbaramanana and Godakawela rubber fields, respectively. Seventy three species and morphospecies of worker ants belonging to six subfamilies, Amblyoponinae (rubber only), Dolichoderinae, Formicinae, Myrmicinae, Ponerinae and Pseudomyrmecinae were recorded collectively from the tea and rubber fields. Aneuretus simoni was never observed in these fields. Forty three species and morphospecies of ants were common to both tea and rubber fields while eight taxa were observed only in tea fields and twenty one species and morphospecies were restricted to rubber fields. Species composition of ants observed at each field was unique and characteristic to environmental conditions existed at each of them.
Effects of a gel bait on the suppression of noxious Crematogaster rogenhoferi Mayr, 1879 (Formicidae: Myrmicinae) in Sri Lanka
(Caucasian Entomological Bulletin, Vol. 15. No.2., 2019) Dias, R.K.S.; Udeshika, K.G.I.
Crematogaster rogenhoferi Mayr, 1879 in a home garden in Sri Lanka was reported to cause health hazards and an investigation was conducted from February to November in 2016 to list the tree species bearing its nests and to record the nest structure, nest intensity and colony demography for the evaluation of its level of infestation and to recommend a method for the suppression of its population size. Three types of nests on 19 tree species were recognized. The largest nest had all life stages. The standard laboratory experiment conducted with the provision of 0.25 g of Optigard Ant Gel bait (OAG) showed 68% of mean mortality of workers. A field experiment conducted by applying separate 1 cm band of OAG and honey at 10 cm and 1 cm distance from three initial stage nests and a honey band only at 1 cm distance from three control nests recorded a significantly higher 89.2% of mean mortality of workers. Two mature nests treated with OAG similarly while two other similar nests served as simultaneous control nests resulted significantly higher 97.5% of mean mortality of workers and queens in OAG-treated nests, after 24 hours. Hence, application of 1 cm band of OAG on the tree trunk, if essential, is recommended as a method for suppressing the population size of C. rogenhoferi in a home garden.