Abstract:

Objective To describe and compare the morphological characteristics of Triatoma rubrofasciata at different developmental stages. Methods Adult T. rubrofasciata were captured and fed to obtain eggs and nymphs, which were then observed under a dissecting microscope to measure egg length, egg middle width, egg lid width, and egg lid middle height. For nymph and adult T. rubrofasciata, the following were measured: body length, head length, head width, length of anteocular part, length of postocular part, distance between ommateums, distance between ocelli, length of antennal joints, length of rostral segments, length of pronotum, length of anterior lobe of pronotum, length of posterior lobe of pronotum, maximum width of throax, maximum width of abdomen and length of forewing bud/hemelytron. Morphological comparisons were made between the adult T. rubrofasciata observed in this study and those of Panstrongylus, Rhodnius, and Triatoma sinica recorded in Medical Entomology and Chinese Bug Identification Manual. Results The life history of T. rubrofasciata includes egg, nymphⅠ-Ⅴ and adult stages. The eggs had a long oval shape, sized 1.838 mm × 0.976 mm on average, with an egg lid. The eyespot emerged in the late development stage. The body length increased from nymph to adult stage, being 2.546 mm, 4.834 mm, 7.127 mm, 10.258 mm, 17.062 mm and 21.787 mm at nymphⅠ-Ⅴ and adult stages, respectively. The wing buds grew out at nymph Ⅲ and then elongated gradually, which finally developed into wings at the adult stage. The average lengths of forewing bud/hemelytron from nymphⅢ to adult were 0.584 mm, 1.261 mm, 3.832 mm and 13.359 mm, respectively. The ocelli did not develop from nymphⅠ to nymphⅣ, showed a trace at nymphⅤ and finally developed into ocellus pair at adult. T. rubrofasciata could be differentiated from the genera of Panstrongylus and Rhodnius based on the shape of the head and the location of the antennae. The T. rubrofasciata had a moderate head length, and antennas between eyes and the clypeus. In contrast, the Panstrongylus had a thick and short head, and antennas located rightly ahead of the eyes. The Rhodnius had a narrow and long head and antennas located at the anterior region of the head, close to the clypeus. T. rubrofasciata could be differentiated from T. sinica based on the presence of particles on the head and the pronotum, and the morphological characteristics of the front angles of the pronotum and the angulus parielis of the scutel. For T. rubrofasciata, there were many particles on the head and the pronotum. The front angles of the pronotum were long and the angulus parielis of the scutel was needle-like. For T. sinica, there were no particles but wrinkles on the head and the pronotum. The front angles of the pronotum were short and the angulus parielis of the scutel did not appear needle-like. Conclusion The T. rubrofasciata had distinct morphological characteristics at different developmental stages. The morphological characteristics of adult T. rubrofasciata can be differentiated from those of Panstrongylus and Rhodnius genera as well as T. sinica.

Key words: Triatoma rubrofasciata, Nymph, Morphological characteristic