Emergence season of Hypoderma lineatum warbles in southern Punjab, Pakistan

Scanning electron microscopy of antennal sensory organs of the cattle grub, Hypoderma lineatum (Diptera: Oestridae)

Hypoderma lineatum (Villers, 1789) (Diptera: Oestridae) is a hypodermosis fly that has resulted in great economic losses worldwide. The antennae of cattle grub males and females were examined through stereoscopic microscopy and scanning electron microscopy to reveal the general morphology, combined with distribution, type, size, and ultrastructure of the antennal sensilla. All of the three antennal segments (antennal scape, pedicel, and funiculus) possess microtrichiae on their surface. Mechanoreceptors only exist on the antennal scape and pedicel. The antennal funiculus presents four types of antennal sensilla: trichoid, basiconic, coeloconic, and clavate sensilla. Three distinctive characters of H. lineatum are obvious: (1) the relatively slender, flexible, and equal-height mechanoreceptors; (2) the enlarged antennal pedicel, and numerous antennal sensory pits and pit sensilla on the antennal funiculus; and (3) all types of antennal sensilla clustered in sensory pits, respectively. Additionally, the enlarged antennal pedicel and abundant sensory pits and pit sensilla might facilitate odor detection, enhance olfactory sensitivity and accuracy, and also protect the fragile antennal sensilla from mechanical irritation or damage.

Cutaneous myiasis caused by Hypoderma lineatum

Cutaneous myiasis is a temporary parasitic infestation of the skin of domestic and wild animals and occasionally of humans by the larvae of flies. Larvae of many flies from various geographic areas can cause myiasis: in Central and South America, human cutaneous myiasis is mainly caused by the larvae of Dermatobia hominis; in Africa, by the larvae of Cordylobia anthropophaga; in the northern hemisphere (North America, Europe, Africa and Asia), by the larvae of Hypoderma spp. A case of cutaneous myiasis in a 47-year-old woman, co-author of the present report, is described. She returned to Slovenia from a three-week trip to Ladakh in Northern India. The parasite, nested in tumor-like swelling about 1-2 cm in diameter and 0.5 cm high in her neck, was removed. The parasite was identified by its morphological characteristics as the larva of Hypoderma lineatum. After the removal of the larva, which was yellowish-white, oval-shaped and about 6 mm long and 1.5 mm wide, the lesion healed in two weeks without further treatment. Clinical and laboratory staff will need to be alert in the future, not only to myiasis caused by Dermatobia and Cordylobia larvae from tropical and subtropical areas but also to Hypoderma larvae from the Himalayan area from where the patient returned to Slovenia.