Morphometric Analysis of Coptotermes spp. Soldier Caste (Blattodea: Rhinotermitidae) in Indonesia and Evidence of Coptotermes gestroi Extreme Head-Capsule Shapes

Ultrastructure and distribution of sensory receptors on the nonolfactory organs of the soldier caste in subterranean termite (Coptotermes spp.)

The soldier caste of termites uses sensilla to sense pheromonal, tactile, and vibrational cues to communicate inside and outside their nest. Although sensilla with many modalities on the antennae of subterranean termites have been well explored, there remains a lack of information regarding sensillum characteristics and distribution of the nonolfactory organs of the soldier caste in the Coptotermes genus. In this study, the ultrastructure of sensilla from the soldier caste of three Coptotermes spp. (Coptotermes formosanus, Coptotermes curvignathus, and Coptotermes gestroi) was observed by scanning and transmission electron microscopy, and the putative function of each type was deduced. Six total sensillum types were observed, with two mechanoreceptive sensillum types (hair and plate). The long flexible-peg mechanoreceptive sensilla may work as contact-chemoreceptive sensilla due to their elongated dendritic outer segments and uniporous characteristics. There was a significant depletion of mechano-chemoreceptive sensillum numbers in C. gestroi, which was compensated by a high density of short-peg mechanoreceptive sensilla on the pronotum. Finally, cuticular and innervation characteristics of thermo-/hygrosensitive sensilla were observed for the first time on the labrum of the soldier caste of Coptotermes.

Geometric morphometrics versus DNA barcoding for the identification of malaria vectors Anopheles dirus and An. baimaii in the Thai-Cambodia border

Anopheles (Cellia) dirus Peyton & Harrison and Anopheles baimaii Sallum & Peyton are sibling species within the Dirus complex belonging to the Leucosphyrus group, and have been incriminated as primary vectors of malaria in Thailand. In the present study, DNA barcoding and geometric morphometrics were used to distinguish between An. dirus and An. baimaii in the international border areas, Trat Province, eastern Thailand. Our results revealed that DNA barcoding based on the cytochrome c oxidase subunit I gene could not be used to distinguish An. dirus from An. baimaii. The overlapping values between intra- and interspecific genetic divergence indicated no barcoding gap present for An. dirus and An. baimaii (ranging from 0 to 0.99%). However, the results of the geometric morphometric analysis based on the wing shape clearly distinguished An. dirus and An. baimaii, with 92.42% of specimens assigned to the correct species. We concluded that geometric morphometrics is an effective tool for the correct species identification of these two malaria vectors. Our findings could be used to make entomological surveillance information more accurate, leading to further effective mosquito control planning in Thailand and other countries in Southeast Asia.