Cocoa borer until recently is still a serious problem faced by Indonesian cacao farmers. It can degrade the quality and quantity of cocoa production. Indonesia is the world’s third largest cocoa (Theobroma cacao L)- producing countries after the Ivory Coast and Ghana. This shows Indonesia has the potential to become the world’s leading producer of cocoa. Therefore, the breeding of resistant plant is very important in pest control so that this will not affect the quality and quantity of cocoa production, which contributes a great deal to the country’s foreign exchange.
Agung Wahyu Susilo, S.P, M.P, a staff researcher of Indonesian Coffee and Cocoa Research Centre, said that cocoa having layer of pods with dense trichome and high tannin granules frequency is resistant to the attack. "In the clones with high trichome density and high granule frequency, which are KW 514 and KW 411 with granular tannin frequency of 1.13 and 1.11/mm2 respectively there were found relatively few larva’s entrance holes," he explained to the board of examiners at the doctoral open exams promotion in the Faculty of Agriculture UGM, Wednesday (21/4).
In his dissertation entitled “Characteristic Study of Cacao Plant Resistance to Cacao Borer" Agung said the trichomes served to restrain the process of eating and laying eggs (antixenosis). Meanwhile, granular tannins play a role in the mechanism of antibiosis in the mesocarp of the fruit since tannin is toxic compounds for a number of pests. Tannin extract is proven to be able to prevent larvae movement.
Added by the man born in Kulon Progo, December 6, 1971, the resistant characteristic of cacao fruit borer is influenced by the development of fruit maturity. Trichome density and frequency levels of tannin granules tended to decrease along fruit maturity. The pattern of decrease apparently occurred at KW 411 and KW 514 for the frequency of tannin granule and KW 411 for trichome density when the fruit is 3.0-4.0 months old.
According to the husband of Fadma Puspitasari, S.I.P., and the father of Akmal’s Furqan Premudya and Ardi Faqih Metarum, a different pattern occurred in the sclerotic layer lignification which is intensively increasing along the fruit age. The resistant clones showed earlier sclerotic layer lignification than the clones that are less resistant and vulnerable. The more intense lignification and more compact layer structure appeared since three months old. "This shows that the optimal expression of cacao borer resistance characteristics occurs when the fruit is still as young as 3-4 months age," explained the man who graduated with cum laude achievement.