Journal of Advanced Agricultural Technologies Vol. 1, No. 1, June 2014 Foraging Polyethism in Odontotermes Formosanus Shiraki E. Soleymaninejadian1, B. Z. Ji1, S. W. Liu2, J. J. Yang1, and X. W. Zhang1 1College of Forest Resources and Environment, Institute of Forest Protection Nanjing Forestry University, Nanjing 210037, China 2The Administration Bureau of Dr.Sun Yat-sen，s Mausoleum, Nanjing 210014, China Email: [email protected]; [email protected]; {liushuwen2006, brocadeyang} @126.com; [email protected] Abstract—South of China is always invaded by showed that workers with different sizes have different Odontotermes formosanus Shiraki. In this paper Polyethism roles in construction behavior. He divided workers into of foragers in O.formosanus Shiraki have been investigated. two small workers (SW1, SW2) and three large workers Foragers of Thirty nests in Nanjing Forestry University (LW1, LW2. LW3) based on a research was done by have been studied, 4782 workers and soldiers captured. We McMahan (1970) [14]. Building behavior of all of them realize that workers with head width of medium (MW) are the main foragers. According to frequency of head width had been analyzed by him. He found that SW1 and LW3 and resulted peaks, foragers have been divided into Very are moderate in abundance at the gallery repair site, they small workers (VSW), Small Workers (SW), Medium are vigorous yet. In spite, the SW2 are the active builders. Workers (MW), Large Workers (LW), and Very Large Also, LW3 are taking part in grooming [15]. As well Workers (VLW). Studying each nest separately showed that McMahan et al. (1984) attested that 96% of small all the above groups are not available in foraging behavior workers are attending in queen chamber on the contrary of one nest. We found three groups of soldiers among 99% of large workers take part in foraging and 70% of foragers, Small Soldiers (SS), Medium Soldiers (MS), and them can be found around swarming sites exit holes [16]. Large Soldiers (LS). In this case, MS were the main groups Campora, and Grace (2004) mentioned that the size plays of soldiers. In addition, foraging polyethism in different tree species has been investigated Cinnamonum camphora was a critical role in tunneling galleries. They analyzed their the main target for this species. At the end it became data using ANOVA and regression analysis. The research obvious that however some of other groups taking part in confirmed that large workers can make wide with less foraging in different nests, but workers and soldiers with segmentation tunnels, while the small worker are good medium head width have a key role in foraging behavior by enough to make tunnels with more segmentation still less this kind of termite. width [9]. Size polyethism is not involved only among the workers, small and large soldiers of N. exitiosus act Index Terms—termite, isoptera, odontotermes formosanus differently in facing with enemies. In this species small shiraki, size polyethism, foragers soldiers are more attracted to the intruders and they use their frontal gland to secret and repel the invaders. In contrast, large soldiers are non combative and flee at the I. INTRODUCTION time of danger. Non combative large soldiers may serve During the evolution of social insects polyethism is as messenger and make the nest ready by raising the one of the key phenomenons [1]. Polyethism makes the danger signals [17], [18]. Furthermore, one study on N. colony works harmoniously. To put it in a nutshell, costalis has shown that soldiers have a key role in polyethism means division of duties among the insect foraging by recruiting other soldiers and large workers to colony member. As Evans (2006) revealed in his paper, the source of food [19]. This phenomenon is called in Nasutitermes exitiosus, worker shifted their work from chemical regulation of polyethism during foraging [20]. foraging to building behavior and vice versa very rarely. It was cleared that large instar workers have bigger This research has shown that duties are somehow divided sternal glands than soldiers, subsequently produce more in different individuals in a fix manner [2]. Recent trail pheromone to recruit more foragers [21], [20]. studies have shown that age [3]-[7] size [8]-[11] and sex In this paper O.formosanus Shiraki has been studied to [12] or combination of them [13] are the fundamental see polyethism among foragers. Foraging polyethism of criteria in polyethism. 30 nests has been studied. Furthermore, polyethism has Size of the termites especially workers is one of the been studied among different tree species. To indicate important morphological characters that confirm the this phenomenon, the head width of foragers measured activity of the workers. Jones (1980) studied the and put into different groups. Then, major groups construction behavior of Nasutitermes costalis. He involving in foraging have been demonstrated. II. MATERIALS AND METHODS Manuscript received March 12, 2014; revised May 22, 2014. ©2014 Engineering and Technology Publishing 32 doi: 10.12720/joaat.1.1.32-42 Journal of Advanced Agricultural Technologies Vol. 1, No. 1, June 2014 Nanjing Forestry University (NFU), located in the east To measure head width (exactly after antenna toward of Nanjing, at the foot of Zijin Mountain and east of back side of the head Fig. 1) of the samples, JSZ6S Xuanwu Lake (32° 4′ 50.66″ N, 118° 48′ 41.06″ E), was (20030568) microscope (manufactured by Nanjing the study site. All the termites captured in a sunny day Jiangnan Novel Optics Co.,Ltd) with a camera (JIFEI) between 10Am-2 Pm with temperature of 20, humidity of (manufactured by Nanjing JIFEI Technology Co.,Ltd) 50 and a breeze blowing (0.5 Km/H). Hot damp summers assembled on it has been used. The microscope was and cold damp winters with short spring and fall are the connected with a computer. JIFEI software helped us to main characteristic seasons in Nanjing. Finding shelter measure and capture photos in the computer. Microsoft tubes on the trees considered as a sign of foragers of a Excel has been used to calculate Average and Standard nests. Making a breach in the tube gently (tweezers can Error. After measuring the head width, the data has been be used) and then by the means of smooth painting brush loaded into Microsoft Excel and column charts made samples collected into a plastic container (11 cm in using head width and frequency of them as x and y axis diameter, 4 cm high) with a moist filter paper in it. respectively. Based on the peaks, workers and soldiers Foragers of each nests collected into one plastic container. have been classified into different groups [10], [22]-[24]. After collecting the samples, name of the invaded species For division of the groups we consider a gradual rise recorded. ended with a peak and a gradual down. So a sudden rises Samples taken to the lab and mud particles removed or falls did not consider as groups. Also, lowest peak is from them, then transferred into glass vials containing reflected as starting of one group. FAA (37% formalin: acetic acid: ethanol=6:1:16). In the case of studying polyethism among trees, the Foragers kept into FAA over night. Then replace the nests divided based on the tree they had been hosted. FAA with 70% alcohol. Then, head width measured and similar criteria used to divide the foragers. Figure 1. The black line is stretched from side to side of head is the place was used to measure head width foragers with medium head width are the most abundant III. RESULTS ones in the 30 nests. Foragers with Head width of 1.42 are the majority of the foragers. Average of head width Foragers of 30 nests have been studied in this paper. and Standard Error for 30 nests was calculated in Total number of foragers caught was 4782, 4747 workers Microsoft Excel and they were 1.45 and 0.001 and 35 soldiers. As it can be seen in the Fig. 2 head width respectively. of workers vary from 0.4-1.72 millimeters (mm). All the sizes in this paper are based on mm. It is cleared that Figure 2. Distribution of foragers based on head width measurement. X axis is the head width and Y axis is the number of foragers. Foragers with head width of 0.4-1.26 were classified as Very Small Workers (VSW), 1.27-1.38 Small Workers (SW), 1.39-1.48 Medium Workers (MW), 1.49-1.59 Large Workers (LW), and 1.6-1.72 Very Large Workers (VLW) Borders of each group are highlighted in black. ©2014 Engineering and Technology Publishing 33 Journal of Advanced Agricultural Technologies Vol. 1, No. 1, June 2014 Based on the peaks in the graphs foragers have been Medium Workers (MW), 1.49-1.59 Large Workers (LW), classified into different groups. Foragers with head width and 1.6-1.72 Very Large Workers (VLW). Percentage of of 0.4-1.26 were classified as Very Small Workers each group can be seen in the Fig. 3. (VSW), 1.27-1.38 Small Workers (SW), 1.39-1.48 Figure 3. Percentages of different groups of workers among foragers of 30 nests in total. As it can be seen less than 1% of foragers are VSW. Most abundant workers among foragers are MW with 41% followed by LW (30%), SW (21%), and VLW with 8%. Only 0.75 % of all the foragers were soldiers. From 35 they also can be classified as Small Soldiers (SS), 1.24- foraging soldiers, soldiers with head width of 1.34 are the 1.33, Medium Soldiers (MS), 1.34-1.44, and Large most abundant ones (Fig.