No abstract

Fungus-growing termites are major contributors to litter decomposition and an agriculture pest in tropical and subtropical Africa and Asia. The foraging behavior of fungus-growing termites was hypothesized to be seasonal and may associate with climatic factors and the occurrence of natural enemies. In this study, we tested the effects of climatic factors and the presence of ants on the foraging activity of the fungus-growing termite Odontotermes formosanus (Shiraki) (Blattodea: Termitidae). Termite-foraging activities were quantified monthly based on the number of wood stakes occupied, amount of wood consumed, and foraging population size. The rate of wood-stake decomposition was measured by monitoring 484 wood stakes in a tropical forest over the course of nearly 6 yr. The results revealed that temperature and rainfall are the major climatic factors influencing the foraging seasonality of O. formosanus. Termites occupied fewer wood stakes during hot-wet seasons when fewer ants were present. The results of a path analysis supported that termite-foraging seasonality correlated mainly with climatic factors rather than the presence of ants. A new foraging hypothesis, the eat-and-run strategy, is proposed to explain the inconsistent seasonal foraging behaviors observed in fungus-growing termites.

Coptotermes gestroi(Wasmann), an invasive termite species in Taiwan, has been a major structural pest in southwestern Taiwan.C. gestroiwas recently reported to have infested living trees in a Taiwanese forest, showing its potential of becoming an invasive forest pest in Taiwan. To determine whetherC. gestroihave naturalized in the forests, we monitored their dispersal flights and estimated their colony development status on the basis of their worker and soldier morphology. The results showed that matureC. gestroicolonies occurred in forest, indicating thatC. gestroihas naturalized. The colony sizes ofC. gestroiwere estimated using a triple mark-release-recapture method. The three studied colonies contained 0.12-0.20 million individuals, which was smaller than that reported in previous studies conducted in urban environments. We speculate thatC. gestroipopulation is suppressed by ants and another dominant termite species,Odontotermes formosanus(Shiraki). Colony elimination was achieved four months after employing termite baits for controlling the three colonies ofC. gestroiin forest. In summary, althoughC. gestroihave naturalized in Taiwan, their further expansion in the forest has likely been restricted by ants and other termite species. Termite baits can be a practical option for controllingC. gestroiin the forests.

The black soldier fly (BSF, Hermetia illucens (Linnaeus), Diptera: Stratiomyidae) is an edible insect widely reared by using various types of organic wastes as its diet. Developing tools to evaluate the growth performance of BSF is crucial for improving its production. In this study, we monitored the daily growth of BSF larvae reared with 10 diets with diverse nutritional quality and compared 7 growth models for quantifying growth performance. We found that BSF generally exhibited an S-shaped growth curve and that the Richards model was the best-fitting growth model. We estimated asymptotic growth limit (W∞) and constructed a time-series curve of absolute growth rate (AGR) by using the Richards model. We used Gaussian functions to estimate AGR parameters (maximum AGR, m; timing of maximum AGR, T; the deviation of AGR, d) to evaluate whether these parameters adequately quantify the growth performance of BSF. Correlation analysis showed that the AGR parameters were mostly independent of W∞ but were correlated with the duration of the larval stage, indicating that W∞ and the AGR parameters respond to different dietary factors. The results of pairwise comparisons showed that the diets rich in carbohydrates and protein had high W∞, m, and d, and early T. The diets with low levels of carbohydrates had low W∞, and the diets with low levels of protein had low m and d and delayed T. We conclude that the parameters estimated by the Richards model could be effective indices for evaluating the growth performance of BSF and their diet quality.