Survey Of Seasonal Foraging Activity And Feeding Preference Of Termites In The Field And Under Laboratory Conditions

Termites (Isoptera) are among the most important pest in China that cause serious damage to crops, plantations, forestry and buildings. The most pestiferous termites include Coptotermes formosanus (Shiraki), Odontotermes formosanus (Shiraki) and Reticulitermes flaviceps (Oshima). How to control efficiently for long term these economic pests is the main preoccupation of pest control agents. Among several control measures, bait strategies seem to hold more attention because of their environment friendly features. This study aimed to gain a further step in termite's management strategy with a special focus on termite's foraging pattern and the improvement of bait strategies. This include:(1) the determination of the yearly foraging activity to find the suitable period for termite control, (2) the determination of termites feeding preference, (3) the identification of wood factors that affect the feeding preference of termite, (4) the role of termite foraging preference on the inquilinisme.1. To examine the seasonal foraging activity of termites, a walking belt transects of 1 m wide was randomly laid every two weeks in four plots. Inside the frame of each plot,100 wood logs were examined for the presence or absence of termites during one year. To determine the effect of temperature on termite foraging activity, the relation between the monthly mean temperatures (maximum and minimum) and the termite foraging activity were analyzed. The effect of climate change on this activity was analyzed by comparing our results with a previous study. In our studying year, termites foraged throughout all the year. Their activities were low (but occurred) in winter. It increased remarkably in summer to reach its maximum in autumn (especially for O. formosanus). Odontotermes species are the most active termites in our study sites. The species of this genus attacked 23% of the examined wood logs. O. dimorphus was recorded for the first time in Hangzhou. The foraging activities of termites were positively correlated with air temperatures (mean maximum and mean minimum). The occurrence of termite activity in winter and that of O. dimorphus in our study sites could be a result of global warming. We suggest that any management strategy against termites in these sites should be carried out at the period of high foraging activity. 2. Baits made from the wood of eight different tree species (Cinnamomum camphora (L) Presl, Elaeocarpus glabripelalus Merr, Ligustrum licidum Aiton, Liquidamba formosana Hance, Magnolia denudata Desr, Ouercus variabilis Blume, Platanus orientalis L, and Populus bonatii Levl) were used to study the feeding preference of O. formosanus and conversely wood protection strategies of the tree species in order to find a suitable bait matrix. Three bait types were used to identify wood protection strategies:solid wood (SW) (physical and chemical protection), crude flour (CF) (chemical protection) made from ground wood and extracted flour (EF) (no protection) made by extracting crude flour with ethanol and toluene. Feeding preference was influenced by wood species and bait type. For solid wood M. denudata (75%) then E. glabripetalus (41%) were most preferred; for crude flour E. glabripetalus (97%) and Q. variabilis (92%) were most preferred; and for extracted flour there were no significant differences between wood species, demonstrating the influence of chemical defense. The greatest contrast between bait types was for P. orientalis, which was the least preferred as solid wood and crude flour, suggesting that chemical defense compounds are particularly important in this species. Solid wood consumption was inversely correlated with wood density. Extracted flour consumption was positively correlated with glucose concentration. There was no direct effect of holocellulose and other components tested. O. formosanus preferred to fed on soft wood with low chemical protection (M denudata); conversely trees protected their wood either physically (e.g. E. glabripetalus, O. variabilis, C. camphora and L. lucidum) or chemically (P bonati) or a combination of both strategies(L. formosana and P. orientalis).3. The feeding preference of C. formosanus and R. flaviceps were tested in choice and no choice bioassay with the same 8 wood species (C. camphora, E. glabripetalus, L. licidum, L. formosana, M. denudata, Q. variabilis, P. orientalis, and P. bonatii) using the same bait types (solid wood (SW), crude flour (CF) and extracted flour (EF)). These baits were offered to vigorous workers of these two species of termites. Their feeding preferences were determined by baits consumption rate. For SW and CF in both choice and no choice test, C. formosanus and R. flaviceps, showed a preference for respectively, L. formosana, P. bonatii, E. glabripetalus, and M. denudata. No clear pattern was found in bioassay (choice and no choice) with EF baits. No correlation was found between the consumption rate and holocellulose content. This result suggests that the four preferred wood species could be potentially regarded (equally) as a suitable bait matrix in bait strategies against C. formosanus and R. flaviceps.4. An analytically study was carry out with fungus combs of three inquilines Macrotermitinae termites including Macrofermes menglongensis Han, Odontoterm.es conignatus Xia & Fand, and Odontotermes gravelyi Silvestry to determine the role of feeding preference on this cohabitation. The content of sands, holocellulose (cellulose and hemicellulose), klason lignin and reducing sugar of all these three fungus combs were determined. The sand was found to be more important in amount (7% w/w) in O. conignatus fungus combs than the other two fungus combs. And among the lignocellulose components the content of klason lignin in M, menglongensis fungus combs (37% w/w) was different from that of the two Odontotermes species. Like the klason lignin, the highest content (0.15% w/w) of reducing sugar was also found in M. menglongensis fungus combs. This result suggests that the symbiotic fungi present in these fungus combs have different hydrolytic function. It also suggests that these termites have different feeding preferences.