- Thylacoptila paurosema Meyrick (Lepidoptera)
- Hyalospila leuconeurella Ragonet
- Nephopteryx sp.
- Anarsia epotias M.
Cashew apples are attracted by many insect pests during different developmental stages. Apart from the above mentioned common species, larvae of Orthaga exvinacea, Lamida moncusalis and Euproctis spp. also damage tender nuts and apples, however, they are considered to be external feeders.
H. leuconeurella: Female moth lays eggs in the grooves near the junction of nut and apple. Freshly laid eggs are whitish in colour, turn dark red before hatching. Caterpillars are reddish with a light brown head.
Nephopteryx sp. : Adult moth is medium sized with dark forewing and pale hindwings.
- Eggs of T. paurosema are laid on the fruits and the incubation period is 3-5 days.
- The caterpillars are very active, dark pink in colour, measures 2-2.5 cm length and the larval period lasts for 15-20 days.
- The egg, larval and pupal period of H. leuconeurella last for 4-5, 12-17 and 9-12 days respectively.
- The adult is dark-brown moth with a wing expanse of 16 mm.
- A female moth lays 50-60 eggs singly or in groups of 10-20. The egg period lasts for 3-4 days.
- Pupation takes place in larval tunnels of the attacked shoot, in crevices of the branches, twigs, at the cut end of branches or within the galleries in the dry apples.
- Pupal period is 7-10 days and the total life cycle is completed within 27-29 days.
- Larval period is 15-33 days.
- Full grown larvae are 2-2.5 cm in length, pink having short setae.
- Pupation takes place in earthern cocoon and the pupal period lasts 8-10 days.
- In one fruit, up to 5 larvae are found.
During flowering and fruiting period (January-May) but severe during April- May.
- Nephopteryx sp. – mango (M. indica),
- T. paurosema – Cassia fistula.
Symptoms of damage
- Larvae initially damage flowers by webbing the panicles and feed the unopened flower buds.
- Then they bore inside the tender nuts and developing apples resulting in shrivelling and premature fall.
- In the developed green nuts and apples, larvae tunnel near the junction of apple and nut and the bore holes are plugged with frass and excreta.
- Usually, these damaged apple and the nuts shrivel and fall prematurely. Damaged fruits can be easily located as they have frass hanging externally at fruit and nut joint.
- Larvae bore through the apple from one end to the other and remain inside the apple till the fruit drops.
- Attacked apples generally fall down from the trees.
- Nuts when attacked become severely deformed.
- The larva binds dry inflorescences to the side of the apples or nuts hanging adjacently and nibbles them continuously.
- The infestation is manifested by the presence of dry inflorescences touching cashew fruits. In the progressive stages of injury, the caterpillars even make galleries inside the nut.
- Larvae scrape the epidermis of tender nuts and apples.
- The young larvae move to the point of attachment of nut and apple, scrap the epidermis and bore into apples and nuts.
- The entry hole is minute and plugged with the excreta.
- The infestation spoils the apples and nuts, larvae also feed on the kernel.
- The fruits shrivel and drop prematurely, while, the nuts do not develop and dry up.
- Removal and destruction of infested panicles having larvae can be followed to prevent spread of the pest.
- Three larval parasitoids viz., Panerotoma sp., (Braconidae) and Trathala flavorbitalis (Ichneumonidae) and one unidentified tiny dipteran fly occur on apple and nut borers and a maximum of 46.2 to 50 per cent parasitism has been recorded under field conditions.
- Spraying of lambda cyhalothrin (0.6 ml/lit) or dichlorvos (1 ml/lit) is found effective for apple and nut borers.
Trathala flavorbitalis, a parasitoid of T. paurosema