Insect Pests of Vegetable, Ornamental and Spice Crops (2+1)

Exercise: Pests of Beans
1. Black bean bug, Chauliops nigrescens distant ( Lygaeidae : Hemiptera

• The eggs are cylindrical, dark brown with chorion exhibiting fine reticulations. Eggs turn dark drown before hatching.
• Nymphs: Newly emerged nymphs are light orange in colour but after feeding, the thoracic part of the body becomes dark red while the abdomen turns red having light greenish tinge. Antennae are four segmented, stylets are transparent and the abdominal portion is slightly compressed. The first instar nymphs measure about 0.07 x 0.02 mm. The second instar is slightly light red but changes to red before moulting. The body shape is similar to that of first instar, but the average size and duration is about 1.0 x 0.6 mm and 3.5 days, respectively. Third instar nymphs are dark red in colour and during this stage the rudimentary wing pads can be seen under microscope, the size is 1.3 x 0.8 mm and the mean duration is about 3 days. Fourth instar nymphs are dull red and the wing pads are in the developing stage, abdominal segments are distinct. Average size is 1.9 x 0.9 mm and the mean duration is 4.3 days. Body colour of the fifth stage instar is dark brown, wing pads are visible, abdominal segments are more visible and this instar resembles the adult stage. Average size is 2.4 x 1.2 mm and the mean duration is 5.5 days. The average size of female and male is 2.75 x 1.00 and 2.85 x 1.25 mm, respectively.

2. Blister beetles

3. Pod borers, Adisura atkinsoni (Noctuidae: Lepidoptera)

• Damage: Caterpillars bore into developing pods and feed on ripening seeds, there by reducing the yield considerably.
• Eggs: Eggs are small and spherical.
• Larvae: Caterpillars are cylindrical, brownish green in colour, 25-33 mm long when full fed.
• Adults: Moths are medium sized and pale yellowish brown in colour. Fore wings are brown with grey tinge and outer margins pinkish. Hind wings are straw yellow in colour. Wing expanse is 30-35 mm.

4. Plume moth, Exelastis atomosa (Pterophoridae: Lepidoptera)

• Damage: Tiny caterpillar bore into the pods and feed on developing seeds, they do not bore completely, but the posterior abdominal portion remains out side the pods. Sometimes the caterpillars emerging from eggs laid on flower buds enter into these buds and feed inside.
• Eggs: Eggs are minute in size, about 0.5 mm long oval in shape and pale green in colour.
• Larvae: Full grown caterpillars are 10-14 mm long, moderately stout, greenish and covered with spine like hairs.

5. Legume pod borer or spotted pod borer, Maruca testulalis (Pyraustidae: Lepidoptera)

• Damage: Caterpillars feed on reproductive parts of the flower, and move from one flower to another damaging many flowers. Later they web the inflorescence with adjacent leaves and developing pods and then feed within by boring into the flowers and pods. Infested flowers do not develop into pods while the affected pods become malformed as they do not grow normally due to webbing and feeding of the pest. Occasionally the older caterpillars also bore into peduncles and stems.
• Eggs: Eggs are elongated oval in shape, less then 1mm in length, light yellow in colour.
• Larvae: Full grown caterpillars are 20mm long; light brown in colour with irregular brownish black dorsal, lateral and ventral spots.
• Adults: Adults are medium sized slender moths. Hind wings are semi hyaline white with a brown distal patch. Wing expanse is 20-30 mm fore wings are brown with white spots.

Hairy caterpillars:

6. Bihar hairy caterpillar, Spilarctia(Spilosoma) obliqua (Arctiidae: Lepidoptera)

• Damage: Damage is caused by the caterpillars by eating leaves and soft portions of stems and branches. In severe, infestation the entire plant can be defoliated.
• Eggs: Eggs are green, spherical laid in clusters on the under side of leaves.
• Larvae: The larvae are 40-45 mm when full grown and are covered profusely with grey hairs.
• Adults: Moths measure about 50 mm across the wings. The head, thorax and under side of the body are dull yellow. Antennae and eyes are black.

7. Red hairy caterpillar, Amsacta moorei (Arctiidae: Lepidoptera)

• Damage: Damage is caused by caterpillars. Young caterpillars prefer the growing points. The older ones have no such discrimination and feed voraciously on all types of vegetation. Moving army of caterpillars destroy field after field. Under sever infestations there can be complete failure of the Kharif crops.
• Eggs: Yellow spherical eggs are laid in clusters of 700-850 each on the under surface of the leaves of host plants.
• Larvae: Caterpillars measure about 25 mm in length. Their colour varies from reddish amber to olive green and the body is covered with numerous long hairs.
• Adults: Moths are stoutly built and have white wings with black spots. The outer margins of the fore wings, the anterior margin for the thorax and the entire abdomen is scarlet red. There are black bands and dots on the abdomen.