Insect Pests of Fruit, Plantation, Medicinal & Aromatic Crops (2+1)

1. Rhinoceros beetle - Oryctes rhinoceros Linn. (Scarabaeidae: Coleoptera)

Damage

• The adult beetles cause severe damage to young as well as old trees. The beetles live in crevices between the leaf sheaths near the crown and burrow in to the softer portion feeding on the un opened fronds and inflorescence. The beetles chews the internal tissues and after injecting the juicy part throws out the fibrous part which comes out of holes is the indication for the presence of beetle in the crown. The infested fully opened fronds showing the characteristic 'v' shaped cuts on leaf lets. The young seedlings are often killed when the growing points are damaged. The repeated attack in old trees causes stunting of growth and present sickly appearance to the trees. Bore holes with chewed fibre sticking out at the base of central spindle is the typical symptom of attack.
Bionomics

• The adult beetle is black, stout measures 5 cm long and has a long horn projecting dorsally from the head. The horn is longer in male and shorter in female beetle. The female lays globular eggs singly in decaying organic matter such as manure pits, dead tree trunks compost heaps. The fecundity of the insect is 140-150 eggs per female. The egg period is 8-18 days. The newly hatched grub feeds on decaying organic matter. The grown up grub is stout, white, 'C shaped, sluggish and has a pale brown head. The larval period is 100-180 days. It pupates in earthern cells at a depth of 30-90 cm or more. The pupal stage last for 10-25 days. The adults make their way out and fly to the trees. The adult beetles lives for more than 200 days.





Management

• Remove and burn all dead coconut trees in the garden to maintain good sanitation.
• Collect and destroy the various bio-stages of beetles from the manure pit whenever the manure is lifted from pits.
• Incorporate entomopathogenic fungus, Metarrhizium anisopliae in manure pits.
• Keep the mud pots having soaked castor cake 1 kg in 5 litres of water to attack and kill the adults.
• Keep the toddy treated longitudinally split tender coconut stem and green petioles of fronds in the garden to attack and trap the adult beetles.
• Hook out the beetles using a long iron rod and kill them at the time of harvest.
• Apply three naphthalene balls /palm (weighing 35 g each) at base of interspace in leaf sheath in the 3 inner most leaves of the crown once in 45 days for the seedlings.
• Set up light traps following the first rain in summer and monsoon period to attract and kill the adult beetles.
• Set up aggregation pheromone (ethyl 4-methyl octonate) trap (bucket type trap).
• Release Baculovirus inoculated beetles in the garden to reduce the leaf and crown damage.
• Apply the mixture of neem seed kernel powder + sand (1:2) @ 150 kg per palm in the base of the 3 inner most leaves in the crown effectively control the beetle.