TETRAGONULA IRIDIPENNIS SMITH in NORTH-WESTERN PLAINS of INDIA Amit Choudhary* Jaspal Singh Pardeep K

DOI: 10.2478/JAS-2021-0003 J. APIC. SCI. VOL. 65 NO. 1 2021J. APIC. SCI. Vol. 65 No. 1 2021 Original Article NEST ARCHITECTURE AND NESTING SITE PREFERENCE OF TETRAGONULA IRIDIPENNIS SMITH IN NORTH-WESTERN PLAINS OF INDIA Amit Choudhary* Jaspal Singh Pardeep K. Chhuneja Punjab Agricultural University, Ludhiana, India *corresponding author: [email protected] Received: 15 April 2019; accepted: 20 November 2020 Abstract Stingless bees constitute an important group of bee diversity providing a vital ecological service i.e. pollination. From India, nine species of stingless bees have been reported out of which Tetragonula iridipennis Smith is widely distributed. Studies revealed that the majority (86.67%) of these bees’ nests were present in brick walls and the remaining (13.33%) were in cavities of hollow tree trunks. Most of the colonies nested at a height of 3.50 m from the ground. Most of the nests (56.67%) had entrances oriented to the east. No distinct entrance tube was observed in 26.92 per cent of the colonies. Overall average entrance tube dimensions (longer side diameter x shorter side diameter x tube length) were 11.62 x 11.73 x 14.04 mm. In all the nests, brood area was surrounded by pollen pots and a few honey pots. The mean dimensions (depth x width) of brood cells, honey pots and pollen pots were 2.79 x 2.62 mm, 5.33 x 4.52 mm and 6.93 x 5.19 mm, respectively. All of the sixty colonies whether in brick/ stone walls or in hollow tree trunks overwintered successfully. Our results can be useful for developing conservation measures for T. iridipennis and its augmentation for crop pollination. Keywords: nest architecture, nesting site, stingless bee, Tetragonula iridipennis INTRODUCTION Tetragonula bengalensis (Cameron), Tetragonula gressitti (Sakagami), Tetragonula iridipennis More than 503 species of stingless bees (Apidae: (Smith), Tetragonula ruficornis (Smith) and Meliponini) occur worldwide (Ascher & Pickering, Tetragonula fuscobalteata Cameron. 2017), and the majority are confined to tropical or In North-west India, only two species, namely subtropical regions (Michener, 2007). The genus T. iridipennis and T. laeviceps have been Tetragonula Moure, 1961, is the largest group reported to exist in which T. iridipennis is widely of Indo-pacific stingless bees (Rahman et al., distributed (Rahman et al., 2013). Stingless bees, 2013) comprising thirty valid species worldwide like honey bees, are highly social insects living (Ascher & Pickering, 2017), but Sakagami (1978) in perennial colonies. Their nests are located and Rasmussen (2008) described only six mostly in concealed places, and colonies may species belonging to three genera from India. accommodate from a few dozen to more than Since then, the total number of species has 100 000 workers (Michener, 2007). Like other been raised to nine (Rasmussen, 2013; Ascher hive bees, these bees are also important because & Pickering, 2017) with the latest recording of their honey offers a peculiar aroma and taste a new species, Tetragonula gressitti (Sakagami), and reported to possess some medicinal value from Arunachal Pradesh by Rathor et al. (2013). (Rao et al., 2016). In addition, stingless bees The nine species reported from India are provide the vital ecological service of pollination Lepidotrigona arcifera (Cockerell), Lisotrigona in many crops grown under protected cultivation cacciae (Nurse), Lisotrigona mohandasi Jobiraj including strawberries (Malagodi-Braga, 2002), & Narendran, Tetragonula aff. laeviceps (Smith), brinjal (Amano, 2004), sweet peppers (Cruz et 49 Choudhary et AL. Nesting behaviour of Tetragonula iridipennis al., 2005) and cucumbers (Santos et al., 2008). the Punjab state. Most of the area is cultivated This shows the immense potential of these tiny or under permanent structures. The main ag- bees to be used as important and effective pol- ricultural crops are rapeseed and mustard, linators of many crop species (Slaa et al., 2006). cotton, maize, sunflower, linseed, sesamum Successful hiving of stingless bees is an age-old and fodder crops as clover and pearl millet, and practice in India. Kani tribe members in Western pulses as pigeon pea, chickpea and green gram. Ghats, India rear this bee in bamboo stems (Ø Vegetable crops grown in the area are chiefly 30-35 cm, length 80-85 cm), while the people cucurbits (cucumber, bitter gourd, squashes, of Naga tribes in Nagaland, India use such sponge gourd, ridge gourd etc.), crucifers (cauli- various structures as log wood hives (Ø 11-38 flower, cabbage, radish, turnip etc.), solanaceous cm, length 43-128 cm) and rectangular wooden crops (tomato, brinjal, capsicum and chillies) boxes (length 25-32 X width 18-26 X height and umbelliferous (carrots and fennel). Horti- 20-64 cm) as reported by Kumar et al. (2012) cultural plantations like pears, peaches, plums, and Singh (2016), respectively. In Punjab, Makkar guavas, gooseberries, kinnows and mangoes, et al. (2016) characterized morphologically and and landscape plantations like mountain-ebony, molecularly the stingless bees of the region to golden shower, flamboyant tree, silver oak and be T. iridipennis. Several reports are available dinner plate tree. on various aspects of the biology and rearing of T. iridipennis, and the majority of them are Climatic conditions the outcome of work conducted under tropical The mean maximum and minimum tempera- conditions on nesting preference (Pavithra et al., tures of the area fluctuate considerably during 2013), spatial distribution (Sheetal & Basavara- summer and winter seasons. The long term jappa, 2009) and nest structure (Dannaraddi weekly mean maximum and minimum tempera- et al., 2009). However, there is still no report tures of Ludhiana were 39.7 and 5.4°C, respec- available on the biological aspects including tively. However, on certain days, the maximum scientific rearing under the current ecological temperature reached 45°C and the minimum conditions which are characterized by subtropi- 0°C. The average rainfall was 400-1300 mm cal semi-arid climate with very hot summers with approximately 80% of the rainfall received and very cold winters. The present study will during July to September (Kaur et al., 2016). help in understanding how this species persists in such harsh climatic conditions, which will Data collection form a basis to develop a species-specific con- T. iridipennis colonies of were searched in and servation strategy. This bee can be utilized in around the PAU, Ludhiana campus between 2013 managed pollination programmes, which ne- and 2015. Search operations were conducted cessitate the hiving in artificial hives for easy in various localities following an all-out search multiplication. Therefore, the present study method through ocular vision (Sheetal & Ba- has been conducted to understand the nesting savarajappa, 2009). Data on various variables site preference and nest architecture of the as enlisted by Roubik (2006) for the study of stingless bee in North-west India for the first nesting biology of stingless bees were recorded. time. Nesting site MATERIAL AND METHODS Regular surveys were done in the study area and nests of T. iridipennis were searched visually Study area around human-made structures including resi- The study area, the Punjab Agricultural dential buildings, educational buildings and University, Ludhiana, is situated at 30°-56´N and roadsides and natural vegetation including 75°-52´E at an elevation of 247 m above mean trees and shrubs. The data was also recorded sea level in the central plain agro-climatic zone of on nesting in either brick or stone walls. 50 J. APIC. SCI. Vol. 65 No. 1 2021 Nest aggregation twenty-six colonies (only those which were in Data was recorded visually on twenty-eight reach) were observed. Observations were also different sites, walls of residential buildings, recorded of the number of entrances per tube accommodating 48 live colonies of stingless and the presence of any defensive structure bees to know the aggregation of T. iridipennis deployed at the entrance. colonies. Colony defence behaviour Height from the ground level The number of guard bees present at the The height of a colony was recorded with the entrance gate during different time intervals of help of a measuring tape, but when a colony a day was also recorded and then averaged. was too high to observe, black markings were recorded to locate the colony (Fig. 1). These Nest architecture black markings, usually present on brick walls, The nest architecture of only those colonies were associated with the presence of a colony. present in the trees was studied because it was After that, the location was ascertained through not possible to break open brick or stone wall the observation of bee movement. The height with a nest inside. Four colonies were retrieved of such colonies was measured by counting the from the mulberry trees. The hollow stems number of brick lines and multiplying it by the containing T. iridipennis colonies were cut and average height of a brick line. Observations were opened carefully with the help of chisel and saw. also taken on the occurrence of T. iridipennis Such observed aspects of nest architecture as colony with the ant or termite nests. the placement of brood and food stores, size and shape of brood and food cells, pillars size and shape were recorded. Afterwards the whole content of a nest was transferred in a mating nucleus of Apis mellifera Linnaeus. Overwintering success A layout was made depicting the placement of the colonies. Monthly observations were recorded for a year to know the overwintering success. This was ascertained only through the recording of bee activity at the entrance. Data analysis The collected data were compiled for various Fig. 1. Black markings associated with the Tetragonula variables and wherever necessary. A general iridipennis nests. descriptive analysis was performed while the Z-test was employed to determine variations in colony characteristics and dimensions. Nest orientation Nest orientation was recorded using a standard RESULTS compass.

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