Hubungan antara inhibitor enzim pada Sengon dengan pertumbuhan larva Boktor dalam Artificial Diet

Abstract

INTRODUCTION. Sengon (Paraserianthes falcataria (L) Nielsen) is widely planted for reforestation programs, especially in establishment of community forest as its timber is utilized for constrction, package box, lighter as well as raw material of pulp and paper. However, there is main problem in sengon plantation, which is boktor (Xystrocera festiva Pascoe) pest attact. In the midgut of boktor larvae it was detected trypsin and α-amylase enzymes activity. Whereas on sengon tree it was reported contains inhibitory substance against trypsin and α-amylase enzymes of boktor larvae. The inhibitory activity was assumed as defense mechanism of sengon tree against the pest attack. In order to clarify the assumption an investigation on the correlation between trypsin and α-amylase inhibitor of sengon with larval growth on an artificial diet is necessary. The experiments aimed at obtaining correlations between the activities of trypsin and α-amylase inhibitors of sengon tree with the growth of boktor larvae, with small (±1,5 cm) and big sizes (±3 cm) on an artificial diet containing respective sengon tree materials. METHODOLOGY. Plant material used was the wood and the bark of sengon trees made into powder by freeze drying. Two provenances were selected, i.e Kediri and Solomon, consisted of two conditions each i.e. healthy and heavily infested. Both small (±1,5 cm) and big sizes (±3 cm) of boktor larvae were put in a big test tubes filled with artificial diet, which contained powder of sengon wood and bark, as their main feed outside their natural habitat. Larvae growth parameters (weight, head diamaters, length and diet consumption) were observed and measured every two weeks. Data on trypsin and α-amylase inhibitors was obtained from biochemical analysis of wood and bark powders using a spectrophotometer. Two kinds of data, larval growth parameters and inhibitors activities, were then correlated using Pearson correlation in Microsoft Excel 2007. RESULTS AND CONCLUSION. Result of the experiments showed that correlation obtained between inhibitor activities of each tissue of each condition and corresponding larvae growth parameters was not all negative, as espected. Out of 64 observations about 35 are positive and about 29 are negatively correlated. In a healthy tree with high trypsin inhibitor activity small size boktor larvae do not prefer attacking. On the contrary similar larvae prefer heavily infested tree with low inhibitor activity. Healthy tree with high α-amylase inhibitor activity will be saved from big size boktor larvae preferences. The opposite accurs on heavily infested tree with low inhibitor activity, which is preferred by big size larvae. In order to obtain negative correlation for trypsin inhibitor it was suggested to do similar experiments using small size larvae, while for α-amylase inhibitor it was suggested using big size larvae.