Symptoms are mostly visible at later stages of infestation. Flower buds and fruits are predominantly affected. Fruits will appear healthy at first, as the entry holes will be healed by the fruit juice. When the disease progresses, larval stage holes can be detected as they are being plugged by the end segment of the larvae. The fully grown the larvae exit the fruit by boring through the hard shell and spins a web, which ties the fruit or stalk to the main branch. The affected fruits are subsequently attacked by fungus and bacteria, thus resulting in rotting and ultimately dropping off. The fruits produce an obnoxious odour due to excreta of caterpillars. The excreta comes out of the entry holes and dries eventually, making the fruits unfit for human consumption.
Damage to Pomegranates is caused by larvae of Deudorix isocrates, which is commonly known as Anar Butterfly or Pomegranate Fruit Borer. It is the most destructive pest of the pomegranate fruit. The butterflies are active during the daytime and oviposit (laying eggs) singly on the fruits, tender leaves, flower buds and stalks. A female lays 20.5 eggs with an average of 6.35 eggs under controlled conditions. D. isocrates takes about 33 - 39 days to complete a life cycle from oviposition to adult emergence. After hatching, the larvae bore itself into the growing fruits, and feed on the pulp, developing seeds and tissues. Feeding damage is most likely to occur between 30 to 50 days of age. The incidence of pomegranate butterfly is most severe during July and shows a significant positive correlation with relative humidity. The incidence is less in March and steadily increases till it reaches its peak in September.
The parasitoid Trichogramma species is effective in controlling the pest. Release them @ 1.0 lakh/acre four times at 10 days interval. They can be placed in the middle and on the edges of the field. Predators of D. isocrates are lacewing, ladybird beetle, spider, red ant, dragonfly, robber fly, reduviid bug and praying mantis. Furthermore, species of wasps, big-eyed bug (Geocoris sp), earwig, ground beetle, pentatomid bug (Eocanthecona furcellata) are reportedly effective against the fruit borer. Bird species will also feed on the caterpillar. Calyx cup should be clipped off immediately after pollination as fruit borer lay eggs on calyx cup and this should be followed by applications of neem oil (3%) during the flowering stage. Set clean mud (heated by the sun) around the base of the fruit to protect it from the insect.
Always consider an integrated approach with preventive measures together with biological treatments. At flowering stage, spray Azadirachtin 1500ppm @3.0ml/lit of water at 15 days intervals commencing from initiation of flowering up to harvesting, subject to the presence of fruit borer. Spray one of the following chemicals: dimethoate (2 ml/lit), indoxacarb (1 g/lit), cypermethrin (1.5 ml/lit) or profenophos (2 ml/lit) at a fortnightly interval from flowering to fruit development. Chemical applications of lambda-cyhalothrin are also recommended for effective control of pomegranate fruit borer. Two sprays of emamectin benzoate 5 SG at the rate of 0.25 g/lit water or spinosad 45 SC at the rate of 0.20 ml/lit water record the highest reduction in fruit damage.