Check fruit for red banded caterpillar

Red banded mango caterpillar (RBMC; Deanolis sublimbalis) is considered a serious threat to Australia’s mango industry. Though, RBMC has not reached any commercial mango plantations in Australia and poses no immediate threat to the mango industry, the pest has caused commercial losses in the order of 10-15% in tropical parts of Asia. It has also been detected at several locations near the northern tip of Cape York Peninsula. 

Above: Cut fruit open to expose the inside of the seed to inspect for RBMC larvae which have distinctive dark red bands and a black cap.  Photo: DEEDI.

Above: Cut fruit open to expose the inside of the seed to inspect for RBMC larvae which have distinctive dark red bands and a black cap.
Photo: DEEDI.

Officers from Biosecurity Queensland regularly survey Cape York Peninsula for RBMC, however, it is also important that growers keep watch for it given the potential impact of this pest. The best time to look for red banded mango caterpillar is during the fruiting period.

Adult RBMC are fawn coloured moths which lay their eggs on the stalk of the fruit. After 7-8 days the eggs hatch into larvae and tunnel into the flesh of the mango.

RBMC larvae are plump and glossy with distinctive bright white and dark red bands. They also have a black collar near the head. 

Larvae feed for 15-20 days and pupate in the soil for around 20 days, before emerging as the adult moth which can lay more eggs. 

It can be hard to find early signs of infestation, but there may be small darkened boreholes on the fruit caused by entering larvae.

A more obvious sign of infestation is liquid leaking from the mouth of the caterpillar tunnel that trickles down to the tip of the fruit and accumulates. Although almost clear when fresh, the liquid darkens and appears as a dark streak on the skin leading to a dark spot at the fruit tip. 

The dark streaks on the mango skin can look like those caused by mango pulp weevil (Sternochetus frigidus) and mango seed weevil (Sternochetus mangiferae).

Damaged fruit may then be attacked by fruit flies or decay organisms and fall from the tree prematurely. 

To inspect for RBMC, cut fruit open to expose the inside of the seed. More than one larva can be present in each fruit and they will most likely be seen tunnelling in the seed but can also be present in the flesh. 

Adult moths are fawn coloured. Photo: Pest and Diseases Image Library, Bugwood.org.

Adult moths are fawn coloured. Photo: Pest and Diseases Image Library, Bugwood.org.

Darkened borehole on the fruit caused by entering larvae. Photo: DEEDI.

Darkened borehole on the fruit caused by entering larvae. Photo: DEEDI.

As well as being observant and monitoring your mangoes for anything unusual there are several things you can do to protect your mangoes from RBMC. 

The pest is spread through the movement of infested plant material, so it is important to get plant material only from clean certified sources.

On-farm biosecurity practices such as ensuring that vehicles and equipment are washed before entering your property and keeping records of who enters and leaves your farm may also reduce the spread of pests and diseases to your property.

If you think you have seen RBMC or anything else unusual report it to the Exotic Plant Pest Hotline on 1800 084 881.

Article supplied by Plant Health Australia. For further information visit: planthealthaustralia.com.au.