Brinjal Fruit and Shoot Borer [Leucinodes orbonalis]
Leucinodes orbonalis (Pyraustidae : Lepidoptera)
Egg: Adult females lay eggs on the leaves. The number of eggs laid by an average female varies from 80 to 253 . Eggs are laid during the night and eggs are laid singly on the lower surface of the young leaves, green stems, flower buds, or calyces of the fruits. Eggs are flattened, elliptical, and 0.5 mm in diameter. They are creamy-white soon after they are laid, but change to red before hatching. Eggs hatch in 3 to 6 days. Larva: Soon after hatching from eggs, young caterpillars search for and bore into tender shoots near the growing point, into flower buds, or into the fruits. Caterpillars prefer fruits over other plant parts. Larval period lasts 12 to 15 days in the summer and up to 22 days in the winter. Larval feeding in fruit and shoot is responsible for the damage to brinjal crop. A full-grown larva measures 18 to 23 mm in length. The larvae do not feed on or bore into brinjal fruit stalk (calyx) Pupa: Mature larvae come out of their feeding tunnels and pupate in tough silken cocoons among the fallen leaves and other plant debris on the soil surface near the base of eggplant plants. The color and texture of the cocoon matches the surroundings making it difficult to detect. The pupal period lasts 6 to 17 days depending upon temperature. Adult: Moths come out of pupal cocoons at night. Young adults are generally found on the lower leaf surfaces following emergence. Females are slightly bigger than males.
Damage: Within one hour after hatching, the larva bores into the nearest tender shoot, flower, or fruit. Soon after boring into shoots or fruits, they plug the entrance hole with excreta. In young plants, caterpillars are reported to bore inside petioles and midribs of large leaves. As a result, the affected leaves may drop off. Larval feeding inside shoots result in wilting of the young shoot. Presence of wilted shoots in an eggplant field is the surest sign of damage by this pest. The damaged shoots ultimately wither and drop off. This reduces plant growth, which in turn, reduces fruit number and size. New shoots can arise but this delays crop maturity and the newly formed shoots are also subject to larval damage. Larval feeding in flowers—a relatively rare occurrence—results in failure to form fruit from damaged flowers. Larval feeding inside the fruit results in destruction of fruit tissue. The feeding tunnels are often clogged with frass. This makes even slightly damaged fruit unfit for marketing. The yield loss varies from season to season and from location to location.
Natural enemies against BFSB reported in India:
Predators Campyloneura sp (a bug), Cheilomenes sexmaculata (a ladybird beetle), Coccinella septempunctata (seven spotted ladybird beetle), Brumoides suturalis (three striped ladybird) Parasitoids Pseudoperichaeta sp, Phanerotoma sp, Itamoplex sp, Eriborus argenteopilosus, Diadegma apostata Entomopathogens Fungus (Bipolaris tetramera), Baculovirus, Nuclear polyhedrosis virus
- Crop rotation is beneficial as the insect survives only on brinjal.
- Intercropping brinjal with other crops. as each crop has a characteristic odour, the adult moths are confused by various odours and that results in decreased infestation. Intercropping cowpea, maize, corainder improve the natural habitat for natural enemies (like spiders, lace wings, ladybirds etc) against the pest.
- The small and stout brinjals are more susceptible to the pest attack compared to long and slender varieties. It is better to go for the the lond and slender ones in the areas that are highly infested with the pest
- Collection, destruction of dried shoot tips and bored fruits. This is an efficient method because the larvae tend to pupate (transform into pupa and takes rest) in the plant residues itself. Burning of the infested parts and composting the crop remains is useful in preventing the build up of the moth populations in a given area
- Mass Trapping of adult male moths using pheromones Leucinodes (Brinjal FSB) being a monophagous (completes its life cycle on one single host) pest the female moths are obligated to lay eggs on brinjal plants. Understanding this behaviour, using pheromone traps in big numbers across brinjal fields is very efficient method to control the pest besides monitoring its population. Pheromones can be used in low-cost water-trough traps @ 40-60 traps per acre is very efficient in avoiding the pest in the first place. The pheromones traps trap the adult male moths (and not female ones) which reduces the fertilising the eggs of female moths.
Annual Report (2008) Biological control of rice and brinjal, National Research Centre for IPM, New Delhi Alam SN et.al (2003) Development of an IPM strategy for eggplant fruit and shoot borer in south asia, Technical Bulletin No-28, AVRDC-The World Vegetable Centre CSA (2003) Brinjal Fruit and Shoot Borer Management, NRI-CWS project Report Srinivasan R (2008) Integrated Pest Management for eggplant fruit and shoot borer (Leucinodes orbonalis) in south and south east Asia: Past, Present and Future, Journal of Biopesticides, 1(2):105 - 112 (2008) Su FC (2004) How to use sex pheromone for controlling egg plant fruit and shoot borer, AVRDC-The World Vegetable Centre Susveg Project –Natural Resources Institute, UK http://susveg-asia.nri.org/susvegasiabrinjalipm4.html http://susveg-asia.nri.org/susvegasiabrinjaltnau4.html http://susveg-asia.nri.org/susvegasianpm4.html Habitat Management for Conservation of Natural Enemies in Rice and Brinjal plots-NCIPM report