The Formosan subterranean termite, Coptotermes formosanus Shiraki, and the Asian subterranean termite, Coptotermes gestroi (Wasmann), are both pests of wood in service in Hawaii and Florida. We conducted a laboratory study using method modified from those described in standard E1-09 of the American Wood Protection Association (AWPA 2009) to assess the termite resistance of three commercially available wood species used in regions of the USA where both termite species occur: Douglas fir, Pseudotsuga menziessii, southern yellow pine, Pinus spp. and redwood, Sequoia sempervirens. A multiple-choice (three-choice) assay was used for four weeks (28 days) in order to simulate field conditions of food choice and assess termite feeding preferences under 28 °C and 72–80% RH. 400 termites (360 workers: 40 soldiers) were released into each test jar. Five replicates and two controls of each wood species were used with each termite species. Termite mortality was recorded at the end of the test; and wood wafers were oven-dried and weighed before and after termite exposure to determine the mass loss due to termite feeding, and rated visually on a 0 (failure) to 10 (sound) scale. There were significant differences in mean mass loss values among the three wood species and between two termite species. The mean mass loss value for redwood was significantly lower than Douglas fir and southern yellow pine with both termite species. However, C. formosanus showed increased feeding on Douglas fir and southern yellow pine compared to C. gestroi.

Tunneling behavior and the spatial dispersion of tunnels constructed by the subterranean termites Coptotermes formosanus Shiraki and Coptotermes gestroi (Wasmann) (formerly known as C. vastator Light) (Blattodea: Rhinotermitidae) were examined in foraging arenas. The results indicated that these two termite species construct quantitatively different tunnel systems, supporting visual observations made in earlier studies. Coptotermes gestroi constructed thin, highly branched tunnels, while C. formosanus tended to construct wider and less branched tunnels. Tunnels of C. gestroi showed more spatial dispersion than those of C. formosanus, and this species constructed a larger number of tunnels compared to C. formosanus. The presence or absence of food (wood) within the arena did not influence the tunneling pattern of either species. Although previous observations have suggested that these two termite species exhibit different tunneling behaviors; this is the first quantification of the differences. Comparative studies of the foraging behavior of subterranean termite species contribute to our understanding of their distribution and ecology and may help to improve pest management programs, particularly those based on placement of toxic baits. Moreover, differences in tunneling patterns may reflect different foraging strategies optimized for either tropical (C. gestroi) or subtropical/temperate (C. formosanus) environments.

Tunnel network construction and time to food (wood) discovery by Coptotermes formosanus Shiraki and Coptotermes gestroi (Wasmann) (Blattodea: Rhinotermitidae) (formerly known as Coptotermes vastator Light in the Pacific region) was examined when wood was present in a clumped distribution that mimics field conditions in the subtropical and temperate regions where C. formosanus naturally occurs. Previous research has noted that the tropical species C. gestroi constructs a highly branched tunnel network, while the subtropical C. formosanus constructs longer tunnels with few branches. Grace et al. (2004) hypothesized that this difference in tunneling behavior may relate to a more homogenous distribution of woody resources in the tropics vs. a disjunct and clumped distribution of fallen wood in the cooler subtropics. Thus, C. gestroi may exhibit a thorough search of the immediate area where wood is initially located, while it may be more energetically efficient for C. formosanus to tunnel greater distances in search of scattered resources. To test this hypothesis, we placed two wood resources at the opposite ends of laboratory foraging arenas, and released 1500 termites (1350 workers: 150 soldiers) into each arena. Arenas were observed every 24 hours for 14 days. We measured the total daily tunnel length, number of tunnels created in each quadrant of the arenas, and average time to discover food at both ends. Total daily tunnel length was relatively longer with C. formosanus and average time to discover food at either end was longer for C. gestroi. Although replication was limited in this study, these observations lend support to the hypothesis that C. formosanus is able to locate distant resources more efficiently than C. gestroi.

Field surveys were carried out from January 2010 to June 2011 to record the environmental properties of Coptotermes formosanus Shiraki and C. gestroi (Wasmann) (Blattodea: Rhinotermitidae) field sites on the island of Oahu, Hawaii; and to document seasonal patterns in C. formosanus and C. gestroi foraging activity. The two field sites selected differed in elevation, soil characteristics, vegetation, and mean temperature and humidity patterns. The C. formosanus colony was located on the Manoa campus of the University of Hawaii, near Miller Hall; while the C. gestroi colony was located 40 km away at the Barber's Point Horse Stables in Kalaeloa, Oahu (formerly Barber's Point Naval Housing). Mean temperature and humidity were recorded monthly at each field site using a Hobo® data logger (1000-1100h), soil samples were taken from each site and analyzed for physical properties, and vegetation type/s were observed, photographed, and samples brought to laboratory for identification. During each site visit, the number of active termite collection traps (termites present) out of a total of 22 traps per site were counted. The C. gestroi field site was generally warmer than that of C. formosanus. Both termite species exhibited irregular activity throughout the year, although C. formosanus was more active in general during cooler months (winter) than C. gestroi; while C. gestroi was generally more active during late spring and summer months. These results, as well as introduction histories, may help to explain C. gestroi distribution patterns in Hawaii.

Bamboo is widely grown and utilized as a construction material around the world, particularly in the tropics. At present, there are about 70 bamboo species and varieties recorded from Hawaii. The objective of our study was to determine the relative resistance of six Hawaii-grown bamboo species to attack by Coptotermes formosanus Shiraki and Coptotermes gestroi (Wasmann). Four-week laboratory feeding trials were performed as described in standard E1-09 of the American Wood Protection Association (AWPA 2009). Samples of each of the six bamboo species were individually exposed to 200 termites (with 10% soldiers); and termite mortality, wood mass loss, and visual appearance of the samples (on a scale of 0–10) were recorded at the conclusion of the trail. Mean mass losses of the six species as a result of termite feeding ranged from 13–29%; with the two most resistant bamboo species, Gigantocholoa pseudoarundinacea and Bambusa oldhamii, demonstrating significantly greater resistance to termite attack than the most susceptible bamboo species, Guadua anguistifolia, with both termite species. Dendrocalamus brandisii, Dendrocalamus latiflorus, and Bambusa hirose were intermediate in their termite resistance. Overall, we observed very little difference in wood preference between C. formosanus and C. gestroi. Although bamboo is a very promising construction material, and species clearly differ in their susceptibility to termite attack, all six species evaluated in the present study would require additional protection for use under conditions of high termite pressure.