Dr. S.K. Dutta & Dr. Badal Bhattacharyya Department of Entomology Identification, symptoms and nature of damage: white grub, mole cricket and ants Dr. S.K. Dutta & Dr. Badal Bhattacharyya Department of Entomology Assam Agricultural University,Jorhat-13

White grubs: Identification: The adult beetles are dull brown, reddish or black in colour The larvae are “C” Shaped, white in colour with brown head and prominent thoracic legs. The grubs are generally found in the upper 5 to 10 cm layer of the soil Video: grubs of scarab beetles Video: Adult scarab beetles Source: AINP on White grubs, Department of Entomology, Assam Agricultural University, Jorhat-13

Symptoms: The damage becomes evident only when the entire potato plants dry up due to the grubs feeding on fibrous roots Fig. White grub infested potato plants Source: AINP on White grubs, Department of Entomology, Assam Agricultural University, Jorhat-13

Nature of Damage: Initially young grubs feed on mother tuber, roots of developing potato plants After tuber formation, the older second instar and third instar grubs feed on the under ground potato tubers by making large, shallow and circular holes into them and thus rendering them unfit for marketing They live concealed while feeding on tubers, and the plants continues to grow normally without any reflection of injury on aerial parts

Fig. White grub infested potato tubers Source: AINP on White grubs, Department of Entomology, Assam Agricultural University, Jorhat-13

Mole cricket: Identification: Adults are cylindrical, nearly 2.5-3.8 cm long and dull brown. Mole crickets have front legs enlarged, shovel-like and modified for digging They fly at night, can run quickly, but are poor jumpers. Nymphs resemble adults but are smaller and do not have fully developed wings Fig. Mole Cricket Source: AINP on White grubs, Department of Entomology, Assam Agricultural University, Jorhat-13

Symptoms: Cutting of seedlings and tunnelling in the soil Fig. Tunneling in fallow land by mole cricket Fig. Tunneling in field after sowing Source: http://insects.tamu.edu/extension/publications/epubs/eee_00039.cfm

Nature of Damage: Mole crickets can damage potato plants by feeding at night on above ground foliage or stem tissue and below ground on roots and tubers Seedlings may be girdled at the stems near the soil surface, though some plants may be completely severed and pulled into a tunnel to be eaten Mole cricket tunneling in the upper 25 cm of the soil dislodges plants or causes them to dry out. Reduction of plant stand is common Fig. Potato tubers infested by mole cricket Source: AINP on White grubs, Department of Entomology, Assam Agricultural University, Jorhat-13

Red ant: Identification: The red ants are reddish in colour and measures 1-1.5 cm in size Fig. Red ant Source: AINP on White grubs, Department of Entomology, Assam Agricultural University, Jorhat-13

Symptoms: Potato tubers show minute holes on the entire surface Fig. Potato tuber infested by red ant Source: AINP on White grubs, Department of Entomology, Assam Agricultural University, Jorhat-13

Nature of Damage: This ant attacks plant parts that are mostly underground Red ants are serious phytophagous pest of potato making galleries in tubers and their attack is characterised by presence of minute holes on the surface of tubers