Identification, Symptoms and nature of damage: Stem borer, Shoot borer and Bark eating caterpillar of Mango

Mango stem borer Batocera rufomaculata (Cerambycidae: Coleoptera)

Introduction Stem borer is widely distributed in India and attacks a variety of fruit trees including mango. Damage is caused by the grub of this beetle as it feeds inside the stems boring upward resulting in drying of branches and in severe cases attained stem also dies.

Identification of Mango Stem Borer Grub - Full grown grubs are linear, fleshy, cream coloured, apodous with dark brown head and 90 x 20 mm in size. Adult - Grayish beetle, 35-50 mm in size, are stout with two pink dots and lateral spine   

Biology of Mango Stem Borer Female laid eggs either in the slits of tree trunk or in the cavities in main branches and stems covered with a viscous fluid. Eggs hatch in about 1 - 2 weeks. After hatching grub in the sap wood and feeding the vascular tissue. Grub feeds for 3 - 6 months. Pupation takes place inside the tunnel itself within the stem. The adult emerges in about 4 - 9 months in July-August. There is only one generation of the pest in a year.

Symptoms and Nature of Damage Grub tunnels in the sapwood on the trunk or branches Grub bore into the sap wood and making irregular tunnels. Feeding the vascular tissues interruption of nutrient and water transport on the tissue Drying of terminal shoot in early stage Frass comes out from several points and some time sap oozes out of the holes Wilting of branches or entire tree

Mango Shoot Borer Chlumetia transversa (Noctuidae: Lepidooptera)

Introduction Shoot Borer (Chlumetia transversa) is a serious pest of mango especially seedlings and young trees. Larvae eats developing leaves and tunnels into the midrib and terminal shoots. This pest is found all over the country. 

Identification Adult- Adult moths are stout grayish brown in colour with wings having wavy lines and measure about 17.5 mm with expanded wings. Hind wings are light in colour. Caterpillar-Young caterpillars are yellowish orange with dark brown prothoracic shield. Full grown caterpillars (20-24mm) are dark pink with dirty spots.

Symptoms Terminal shoots show tunnel from top to down wards. Stunting of seedlings with terminal bunchy appearance. Larvae of this moth bore into the young shoot resulting in dropping of leaves and wilting

Nature of Damage Female moths lay egg on tender leaves. After hatching, young larvae enter the midrib of leaves and then enter into young shoots through the growing points by tunneling downwards Larvae of this moth bore into the young shoot resulting in dropping of leaves and wilting of shoots. Larvae also bore into the inflorescence stalk. There are four overlapping generations of the pest in a year and it overwinters in pupal stage.

Bark eating caterpillar Indarbela tetraonis (Metarbalidae:Lepidoptera)

Introduction This pest is found damaging a variety of plants including a number of fruit trees, forest trees and ornamentals all over India. It attack trees of all ages, particularly the older ones, lowering their vitality. When severely infested, the entire branch or tree may die. old, shady and neglected orchards are more prone to attack by this pest. Larvae of this moth feed on the bark and weaken the tree.

Identification Adult: The moth is light grey in colour with dark brown dots and measures about 35-40 mm with expanded wings. Larvae: The full grown caterpillar is dirty brown in colour and is about 35-45 mm in length.

Symptoms The attack by this pest is characterized by the presence of long-winding, thick, blackish or brownish ribbon-like masses composed of small chips of wood and excreta. Young trees may succumb to the attack. Caterpillars bore into the trunk or junction of branches Caterpillars remain hidden in the tunnel during day time and come out at night, feed on the bark. By continuously devouring the tissues, as it tunnels through the stem and branches. This injury weakens the stem, resulting in drying of the branches and finally of the tree itself.

Nature of damage The attack by this pest is characterized by the presence of long-winding, thick, blackish or brownish ribbon-like masses composed of small chips of wood and excreta.

Summary Stem borer Batocera rufomaculata (Cerambycidae: Coleoptera) beetle attacks variety of fruit trees including mango. Grubs suck the sapwood and make irregular tunnels in the sapwood which cause wilting of braches or the entire tree. Shoot borer Chlumetia transversa belongs to order Lepidoptera. Adult moths are grayish brown. Larvae of moth bore in to young shoots and tunnels downwards, causing dropping of leaves and wilting of shoot . Bark eating caterpillar Indarbela tetraonis infests many trees including fruits, particularly older ones. Severely infested trees may die. Larvae bore into trunk and feed on bark during night.  

Reference Srivastava, R.P. (1997). Mango Insect Pest Management (first edition). Lucknow, India: International Book Distributing Co., 272 pp. Verma. L.R., Verma A.K and Gautam, D.C.(2004). Pest management in horticultural crops: Principles and practices.D.K Publishers. 544pp. Reddy P.Parvatha. Advances in integrated pest and diseases management in horticultural crops. Volume I Fruit crops . Studium press(India ) Pvt Ltd.359pp. Butani, D.K. (1993). Mango: Pest Problems. Delhi, India: Periodical Expert Book Agency, 290 pp. http://agropedia.iitk.ac.in/sites/default/files/litchi%20-bark%20eating%20caterpillar.jpg