Arecanut Pest

Spindle bug, Carvalhoia arecae M. & C (Sucking insect)

Adult bugs are brightly coloured red and black.  They inhabit the inner most leaf axils, usually below the spindle.  This is a serious pest of young areca plantations of Kerala, Karnataka and parts of Tamil Nadu.  The light violet brown nymphs are greenish yellow with the border of body.            

Life cycle:  Eggs are laid singly  between the leaflets of the spindle. The eggs hatch in 9 days. There are five nymphal stages and it is completed in 15-24 days.

Phytophagous mites

   Mainly two species of mites colonise the palm.

      a)Cholam   or white mite Oligonychus indicus Hirst  (Acari: Tetranychidae): Adults and  nymphs of this spider mite colonise the lower surface of leaves.  The colony is found below a white web on the leaves.  Life cycle is of short duration.  The total duration of the immature stages varies from 6.5 to 9.0 days. 

(   b)Palm or red mite Raoiella indica Hirst  (Acari:  Tenuipalpidae):  Nymphs and adults of this mite are seen in large num­bers on the lower surface of leaves, in severe cases of infesta­tion they may be seen on the leaf stalks and on the spindles.  The life cycle lasts 12.9 days.  This mite also attacks palms like coconut, date and ornamentals. Population of both these mites start building up after the monsoon rains and reaches its maximum in April - May. Neglected and poorly irrigated gardens and nurseries, particularly those in exposed conditions are prone to severe infestation. Colonies of these mites start declining with the onset of rains in June.
 

Root grub, Leucopholis burmeisteri Brenske and L. lepidopho­ra Blan. (Coleoptera: Melolonthidae):

Root grubs or `white' grubs occur in low lying and clayey soils where the water table is high. They are voraceous feeders on areca roots and are found in the areca tracts of Kerala and Karnataka. Adult beetles (cockchafers) emerge during May-June after few days of premonsoon showers i.e., after 8-10 days of showers, between 6.30 to 7.30 PM. These beetles lay eggs in soil mostly up to 10 cm depth. Eggs hatch out in about three weeks. The early instar grubs feed on the roots of grasses and other humus.  The grub period with three instars is completed in 7 to 8 months. The pupation is in soil in cocoons of mud. This period lasts about one month. The adult beetle is chestnut brown in colour. The second and third instar grubs of these beetles feed on tender and mature roots of the palm, in severe cases of inci­dence, the bole of the palm is also eaten up. They feed on roots of grasses and intercrops like banana, cocoa, tapioca, yams etc.

In areca seedlings, the feeding on roots results in dropping and drying of leaves. Affected seedlings come off easily since the entire root system is usually eaten up. Palms with few years of infestation show a sickly appearance, with yellowing of leaves, tapering of stem, and reduction in yield. The  palms may topple in case of severe loss of root system.
 

Inflorescence caterpillar, Tirathaba mundella Walk (Lepidop­tera:  

     Pyralidae)

This is reported from Karnataka and Kerala. The adult moth lays eggs in the mechanically damaged portions of the spadices and the emerging caterpillars bore into the inside of the spadices. The egg period lasts five days and the larval period for about 26 days with five instars. Pupal period lasts for 9-11 days. The caterpillars feed on the inflorescences especially the tender female flowers and rachillae and web together the rachillae into a wet mass with silken threads formed by the caterpil­lars and take shelter in it. Mature caterpillars can damage newly opened inflorescences also. In severe cases of incidence, these bore into the tender buttons and tender nuts as well.

As a result of webbing and feeding the inflorescence is unable to exert the natural pressure on the spathe necessary for its opening and thus spathe opening is delayed. Yellowing of spadices, presence of small holes with frass and drying patches on the spathe are the external symptoms of  attack.

Pentatomid bug, Halymorpha marmorea (Hemiptera    Pentatomidae)

This bug causes tendernut drop in areca. Incidence of this bug is seen from March/April to July/August.  The later instar nymphs and adult bugs pierce the tendernuts of different maturity and suck the kernelsap. As a result of this feeding, the kernel dries up and the tendernuts drop. Char­acteristic pinprick black marks are seen at the point of feeding sites, which lead internally to the kernel.               

Minor pests

Stem weevil, Diocalandra stigmaticollis

Scale insects :Aonidiella orientalis (Homoptera:  Diaspidi­dae) and others

Sale insects colonise the leaves,  spathes, leaf sheaths and bunches and suck sap from the tissues.  Continuous  feeding on nuts results in pre-mature  yellowing of nuts and in severe infestation, the kernel may not develop and may turn black and shrivel up. The scale insects are present through out the year, but are more serious during October to February.

(Central Plantation Crops Research Institute, Kasaragod 671 124, Kerala, India)