An-Najah Staff

This research demonstrated the possibility of conidial transmission of Penicillium expansum by the adult flies of Drosophila melanogaster to mature, sound nectarine and pear fruit. This transmission was accomplished by inserting the fungal conidia adhering either to mouthparts of the contaminated flies or to their abdominal tip into mature, sound nectarine and pear fruit, while making punctures in the fruit skin either for feeding or for oviposition. Accordingly, the mean number of typical P. expansum lesions that appeared due to this transmission per one nectarine or pear fruit subjected to contaminated flies was 4.7 and 2.5, respectively. Also, the mean diameter of these typical lesions was 5.3 and 3.2 mm on the same types of fruit, respectively. When the eggs laid by the contaminated females of D. melanogaster were left to develop until adult fly emergence, the mean number of the flies that emerged per fruit at the end of the life cycle was 48.3 and 24.3 on nectarine and pear fruit, respectively. Also, the mean life cycle duration for the emerged flies was 24.3 and 28.7 days on the same types of fruit, respectively. Moreover, viability of the pathogen conidia that either adhered externally to the various body parts of the contaminated flies or were introduced into their bodies was tested by plating the conidia onto oatmeal agar plates amended with chloramphenicol, following the release of the contaminated flies onto plates or the spread of their ground suspension in saline solution onto the same type of plates. The mean number of typical P. expansum colonies that appeared per plate was 5.3 for external contamination of the flies and 2.4 for internal contamination. The conidia of P. expansum adhering to the various body parts of contaminated flies were first localized on these parts and then photographed under the light microscope after they have been correctly identified. Overall results indicate the possibility of P. expansum conidial transmission by D. melanogaster adults into sound, mature nectarine and pear fruit through their feeding and oviposition punctures.

Control of primary postharvest diseases caused by Rhizopus stolonifer, Botrytis cinerea, and Penicillium expansum on a variety of fresh fruit was evaluated with an invert emulsion formulation of Trichoderma harzianum. Diseases evaluated were quantified by the period of protection conferred by the antagonist and the diameter of decay lesions. Treatment of the various fruit species with formulated T. harzianum conidia in an invert emulsion significantly (P ≤ 0.05) reduced the mean lesion diameters of R. stolonifer on apple, pear, peach and strawberry, B. cinerea on grape, pear, strawberry, and kiwifruit, and P. expansum on grape, pear, and kiwifruit in comparison with the control treatment. Significant differences (P ≤ 0.05) were obtained in the mean percent reduction in lesion diameter caused by the same postharvest pathogens on the same fruit species due to the treatment with the formulated T. harzianum conidia relative to control treatment. The greatest mean percent reduction (86.7%) was obtained on apple fruit for the infection with R. stolonifer. Significant differences (P ≤ 0.05) were also obtained in the mean durations of the minimum protection period due to treatment with the formulated T. harzianum against the infection with the same postharvest pathogens on the same fruit species. The longest mean duration of the minimum protection period (up to 59 days) was obtained for unwounded apple fruit against the infection with R. stolonifer. Overall, the results indicate that the treatment with the invert emulsion formulation of T. harzianum protected fruit from infection by the primary postharvest pathogens of the fruit tested for up to 2 months and reduced the diameters of decay lesion up to 86% and is a promising treatment to prolong the postharvest shelf-life of fresh fruit.