Traits and Damage of Carambola Fruit by Bactrocera dorsalis

Stepwise regression and path analyses,as well as the decision-making factor calculation,were used to evaluate the correlation between the traits of carambola(Averrhoa carambola Linn.) and the severity of damage on the fruits infested by Bactrocera dorsalis Hensel.The results showed that the number of the insect larvae on the infested fruits increased with the maturity,soluble solids content and softness of the fruits.The correlations decreased in the order of:fruit firmness(X4)>tartaric acid(X7)>reductive sugar(X3)>pH value(X2)>total amino acid content(X5)>oxalic acid(X6)>crude protein(X1).The regression equation of the correlation was∶ Y=459.2219 + 91.6060X1-91.2226X2-100.8494X4 + 0.4432X11(citric acid),with a correlation coefficient of 99.98%.The decision coefficients of the 4 studied traits were found to be:fruit firmness(X4)>crude protein(X1)>pH value(X1)>citric acid(X11).Hence,the main decision-making factors on the fruit damage by B.dorsalis were fruit firmness and crude protein content,the primary restricted trait was pH value,and the appropriate restricted trait was citric acid.The results could help better determine the timing for effective pest control of B.dorsalis larvae.