Correlation between the infestation index of Anastrepha spp. (Diptera: Tephritidae) and the physico-chemical properties of guava fruits

The occurrence of fruit fly infestation is a limiting factor for the guava production and can cause losses up to 100% when the fruits are grown in organic systems. The infestation index (I.I.) of fruit flies Anastrepha spp. was determined for 13 guava genotypes cultivated in an organic system, and its correlation with the physical-chemical characteristics of the fruit was also determined. The fruits were weighed and placed in plastic cups containing vermiculite and covered with tulle to obtain pupae and adults. The means of the I.I. and the emerged adults were compared among the genotypes (Tukey, 5%). Simple correlations (Pearson) were carried out between the number of adult flies, I.I. and fruit characteristics: fruit mass (M), skin colour (SC), pulp colour (PC), firmness (F), soluble solids (SS), titratable acidity (TA), pH and ascorbic acid content (AA). The original data were standardized and submitted to multivariate analysis of principal components (PCA). Pupae of fruit fly were obtained in 100% of the collected guavas. The L2P6 genotype had a lower infestation rate (8.41 puparia kg(‑1) of fruit) and differed significantly from the L3P9 genotype (29.87). Significant and negative correlation was detected between I.I. and fruit SC (r=-0.5741*). It was observed that 83.1% of the total variation was explained by the three main components. The first principal component explained 46.1% of the total variance and represented a contrast between I.I., number of pupae and adults of Anastrepha spp. and fruit SC, F and TA. The distribution of the genotypes in the biplot graph confirmed the greater distance between the genotypes L2P6 and L3P9, and the multivariate analysis suggested that fruit infestation by fruit fly is inversely related to SC, F, SS and TA of guava fruits, characteristics related to fruit ripening.