MANGO SEED BORER
SCIENTIFIC NAME: Mangifera indica
FAMILY: Anacardiaceae
The following information was brought to our attention by John Brace, of Mindanao in the Philippines. It is based on an article, by Ramiro C. Alvares, that appeared in the December 4th issue of the Manilla Bulletin, The article was entitled, "Effective Control Against Mango Seed Borer Found".
BACKGROUND
The mango is an important commercial crop in the Philippines. The Province of Guimaras, for example, had 8,000 hectares planted with mangos in 1989. This is about a thousand more trees than are planted in Pangasinan and twice as much as are found in Bulacan, both being provinces of Luzon.
During this same year, the harvest amounted to 80,000,000 kilograms (176 million pounds) valued at P$400 million. The author notes, however, that if it weren't for the seed borer, the harvest could have reached 200 million kilograms with a value of about P$1 billion.
THE SEED BORER
The mango seed borer, according to the article, first appeared in India in 1902, and since then has made its way to Indonesia, Australia and Thailand. It wasn't until the late 1960s that its presence was noted in the Philippines. It gathered its strength slowly and in 1975, "...an epidemic of mango seed borer hit Southern Tagalog...." At that time there was no defence against this pest.
The insect, which is a moth, lays its eggs on the apex or pointed end of the young fruit. When the eggs hatch, the larvae bore holes in the fruit and make their way to the seed, which is still immature and therefore soft enough for the larvae to enter. From this point on, the larvae literally eat their way out of the fruit, a course that the grower is not aware of because he can't guess what is going on. It is only sometime after the seed has been consumed that "...holes in the mango fruit burst out and the fruit drops to the ground." By this time, the larvae have been transformed into pupae, from whence they will emerge as adult moths and thus repeat the cycle.
Dr. Hermani Golez, who has been studying the mango borer since 1987, notes that the larvae often work their way out of the fruit, and let themselves hang down spider-like on a silken thread, which permits the wind to blow them to another fruit which is also damaged.
CONTROLS
Dr. Golez recommends that the spreading of the insect can be partially controlled both by the regular pruning of existing groves of mango trees and by properly spacing trees when a new planting is made.
For full control, spraying with an insecticide is necessary. The article does not mention which insecticide Dr. Golez recommends, but he is definite about the spraying schedule. The initial spraying should begin "... 60 days after the formation of the mango seed. This is followed by spraying on the 75th, 90th and 105th day."
DATE: May 1991
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