FIELD AND LABORATORY STUDIES ON INFESTATION OF IMMATURE MANGO FRUITS BY THE PEACH FRUIT FLY, BACTROCERA ZONARA (SAUNDERS)

Abstract

the peach fruit fly, Bactrocerazonata, is one of the fruit flies thatattack mango fruits during maturity and ripening stages causing significant damage. This paper iscontribution for evaluation the role of dropped immature fruits as host of B. zonata through sampling dropped mango fruits of different varieties at different stages of maturity in different types of mango cultivations. Also, the study was extended to find an interpretation via laboratory investigation the ability of B. zonata females for egg laying on immature mango fruits after abscission for different periods (5, 10 and 15 days) comparing with freshly harvested fruits correlating with biochemical and physical fruit changes after abscission. The results indicated that the immature fruits that on the tree were free of infestation, while the infestation was observed on that were sampled under the trees. Percentages of infestation during the 1stseason (2014) for the early and mid-ripen season varieties were 7.83 and 9.14%, respectively and during the 2nd season(2015) were 5.18 and5.52%, respectively. The mean no. of obtained pupae/ infested fruit were 7.54 and 12.16 pupae/infested fruit, respectively, and 7.25 and 8.10 pupae / infested fruit, respectively during the second season(2015).The sampled immature fruits of late ripen varieties were free of infestation during the two season. The dropped immature mango fruits were firstly observed to be infested during the 4th week of May and the 1st week of June during the two seasons, respectively. The obtained data revealed that, the immature infestation percentages of early and mid-ripening season varieties were lower in comparison with those sampled during maturity and ripening stages. The laboratory study ensured the preference of B. zonatafemales for egg laying on the fruits that were abscised for 5, 10 and 15 days in percentages of 26.67, 46.67 and 53.33%, respectively, the pupation percentages were 80.85, 87.33 and 89.47%, respectively, adult emergence percentages were 63.16, 65.59 and 72.18%, respectively, while, the durations of total immature stages that reared on the mentioned abscised fruits were, 18.20, 16.98 and 16.79 days, respectively. The fruit phenological changes including increasing of total soluble sugars, total soluble solids(T.S.S), also reduction of fruit juice acidity and fruit firmness factor maybe play an important role in susceptibility of dropped immature mango fruits to the peach fruit fly attacks. Removal of such fruit becomes a necessity for avoiding such risk, also, attention should be paid for following and monitoring the fruit flies status in early times (after fruits setting) instead of later periods during June or July.