Learn about the pests that damage plantation crops and its contol.
1. Arecanut Mirid Bug, Carvalhoia Arecae Miller & China (Hemiptera: Miridae):
This bug is one of the important pests of Areca catechu, A. lutescens and Loxococcus sp. in South India. The adult is a red and black bug measuring 6 mm long and 2.5 mm wide. The nymphs are greenish with reddish brown patches. The adults and the nymphs suck sap from central spindles and the young fronds.
Life-Cycle:
The pest is active during February. The female bug lays eggs singly into the tissues of the tender unopened leaves of the palm. The eggs are oval, 13.6 × 0.34 mm with two-bristle like structures arising from the operculum. The eggs hatch in nine days and the young nymphs suck cell sap from tender parts. The nymphs become adults in 2-3 weeks after undergoing 5 moultings.
Damage:
The adults and the nymphs suck sap from the tender leaves of arecanut palm. The bugs remain clustered together within the top-most of the leaf axils. In case of severe infestation, the leaves get shredded and stand erect. Continued attack over a number of years results in stunted growth of the palm and the yield is also reduced.
Control:
Spray 250 ml of monocrotophos 40EC or 375 ml of quinalphos 25EC in 250 litres of water per ha at monthly intervals especially on the spindles and young fronds.
2. Cashew Tree Borer, Ptocaederus Ferrugineus (Linnaeus) (Coleoptera: Cerambycidae):
This pest is the most important pest of the cashew-tree in South India. The adult is a medium- sized dark-brown beetle. In the grub stage, it feeds inside the tree trunk or branches, making tunnels.
Life-Cycle:
The beetle lays eggs under the loose bark on the trunk. The newly emerged grubs bore into the bark and feed on soft tissues, making tunnels in all directions. The grown-up grubs may also feed on wood. The openings of tunnels are seen plugged with a reddish mass of chewed fibre and excreta. When full-grown, the larva measures 7.5 cm and tunnels its way to the root region, where it forms a calcareous shell for pupation. The life-cycle is completed in more than a month and there are several overlapping generations in a year.
Damage:
The borers damage the cambial tissues and hence the flow of sap is arrested. The tree is weakened and if infestation continues it may die. Plantations over 15 years old are often seen infested with this pest.
Control:
(i) Remove the grubs by peeling the bark mechanically and destroy them.
(ii) Drench the basal trunk and the root region with 2.0 litres of chlorpyriphos 20EC in 250 litres of water per ha.
(iii) Inject carbon disulphide into the tunnels and plaster them with mud.
(iv) The badly infested trees should be uprooted and destroyed by burning.
3. Cashew Leafminer, Acrocerops Syngramma Meyrick (Lepidoptera: Gracillariidae):
This pest is distributed throughout the cashew growing areas. The adult is a silvery-grey moth. The freshly hatched caterpillars are pale white, turning to reddish-brown when fully grown.
Life-History:
The eggs are laid on very tender leaves. The larvae hatch in 2-3 days and mine into the leaves. Up to eight larvae are found to attack a single leaf. The larva becomes full-grown in two weeks. It drops to ground where it pupates for 7-9 days.
Damage:
The damage is done by the caterpillars by mining through the leaves. The thin epidermal peel swells up in the mined areas and appears as whitish blistered patches on the leaf- surface. In older leaves, these blisters dry and drop off leaving big holes.
Control:
Spray 2.0 kg of carbaryl 50WP or 1.25 litres of malathion 50EC or 1.5 litres of endosulfan 35EC in 625 litres of water/ha.
4. Rubber Bark Caterpillar, Aestherastis Circulate Meyrick (Lepidoptera: Hyponomentidae):
The pest is distributed in rubber growing areas like Tamil Nadu and Karnataka. The adult is small, white and black spotted moth. The larva is bright red flat caterpillar, measuring about 2.5 cm when full grown.
Life-Cycle:
The eggs are laid on the bark of the rubber tree. The eggs hatch in 2-4 days. The larva feeds under a web on the bark. It has duration of about three weeks and it pupates under a piece of bark in a web for 10 days. There are 2-3 generations in a year.
Damage:
The damage is done by the caterpillar by feeding on the bark of the tree, either on the renewing bark or on any other part of the tree but generally at a height of 90 cm from the ground and upto the region of the first branch. Usually the caterpillar feeds on the dead bark, but when it feeds on the renewing bark or tapping surface, it becomes troublesome.
Control:
(i) Application of tar on the bark surface prevents the attack.
(ii) The caterpillars can be brushed away with stiff brushes and destroyed.