Coleoptera

Seidel, Matthias, Arriaga-Varela, Emmanuel & Vondráček, Dominik, 2017, Abstracts of the Immature Beetles Meeting 2017, Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 57 (2), pp. 835-859 : 855

( Coleoptera : Scarabaeidae : Melolonthinae)

Kolla SREEDEVI

Division of Entomology, ICAR-Indian Agricultural Research Institute, New Delhi, India; e-mail: [e-mail]

The white grub, Brahmina coriacea (Hope) is a serious pest of potato in Himachal Pradesh, India, resulting in nearly 60–75% damage to the tubers in endemic areas. The pest is an annual belonging to Melolonthinae of Scarabaeidae (Coleoptera) . The immature stage viz., larvae feed on the roots and tubers of the plant resulting in initial drying of the plant and subsequent potato tuber damage. The adults are medium sized, black to dark reddish brown beetles whereas the larvae are dull white coloured and are the damaging stage. The identification of the white grub at larval stage itself facilitates the early initiation of pest management programmes. The description of larva of B. coriacea has not been attempted so far and hence a study has been conducted at Insect Systematics laboratory, Division of Entomology, ICAR-Indian Agricultural Research Institute, New Delhi during 2014–2016 to document and describe the morphological characters of the larvae. The adults were collected from Potato Research Station, Kheradar, Sirmaur dt, Himachal Pradesh, India (31°19′N Latitude; 77°10′E Longitude) through manual scouting during the night on their host plants, Robinia, Polygonum and Indigofera sp. The collected adults were brought to the laboratory, Division of Entomology, ICAR-Indian Agricultural Research Institute, New Delhi and reared in plastic jars. The eggs deposited in the moist soil were collected and transferred to Petri plates and the hatched neonates were later transferred to plastic jars containing cowpea seedlings. As the larvae grew, potato pieces were provided as food and reared till pupation. There were three larval stadia differentiated by moulted skin and size of the head capsule. The third instar larvae drawn from the rearing lot were used for the taxonomic studies. The third instar larva measured about 21–25 mm. Each larval specimen was studied for 54 characters and documented the characters specific to the species. Likewise five specimens were studied to record the consistency in the characters. The distinguishing characters included spiracle structure, anal slit, raster pattern, legs structure, mouth parts, etc. The mouth parts formed important diagnostic characters where antenna, epipharynx, mandibles and maxillae showed distinct characters that aid in species delineation. Antenna was four segmented and possessed one dorsal sensory spot and two ventral sensory spots in the terminal segment. The raster pattern observed is typical in distinguishing B. coriacea from other melolonthines. The palidium (comb like structure on last ventral segment) was shorter with wider septula with 9–10 linear long pali on each side of the central line. The pali were slender and pointed at the distal end. The pali of two linear palidia overlapped with each other at their distal ends. The stridulatory teeth on maxillae and characters in epipharynx were distinct for the species delineation. Proplegmatia were distinct and prominent in epipharynx with 6 to 10 plegmata on each side. The larval diagnostic characters of B. coriacea are described for the first time from India and discussed in detail.