Guava is a nutritious fruit that has perishable behavior during storage. We aimed to determine the influences of some edible coatings (namely, cactus pear stem (10%), moringa (10%), and henna leaf (3%) extracts incorporated with gum Arabic (10%)), on the guava fruits’ properties when stored under ambient and refrigeration temperatures for 7, 14, and 21 days. The results revealed that the coating with gum Arabic (10%) only, or combined with the natural plant extracts, exhibited a significant reduction in weight loss, decay, and rot ratio. Meanwhile, there were notable increases in marketability. Moreover, among all tested treatments, the application of gum Arabic (10%) + moringa extract (10%) was the superior treatment for most studied parameters, and exhibited for the highest values for maintaining firmness, total soluble solids, total sugars, and total antioxidant activity. Overall, it was suggested that coating guava with 10% gum Arabic combined with other plant extracts could maintain the postharvest storage quality of the cold-storage guava.
Laboratory trials of feeding potential of Chrysoperla carnea (Steph.) (No choice) were estimated at (25 ± 2 °C, 65± 5% R. H.). Data revealed that the larval stage of C. carnea (Steph.) fed on egg masses of Corcyra cephalonica (St.) Pectinophora gossypiella (Saund.) and Sitotroga cerealella (Oliv.) consuming all over its 3 larval instars an average of 493.6±50.32, 654.3±32.54and 673.9±31.52 eggs (total consumed) for the three prey species, respectively, with total larval corresponding periods 8.7 ± 0.94, 9.5 ± 0.97 and 9.6 ± 1.17 days. Statistical analysis of the obtained data obviously cleared that there were significance differences between the mean numbers of consumed C. cephalonica eggs and that of P. gossypiella and S. cerealella; on the other hand there was no significance of C. carnea total larval period when feeding upon each of the three preys. In addition, host preference (Free Choice) revealed that C. cephalonica was the most preferred host to C. carnea. The predator consumed (13.2 ± 6.01, 77.9 ± 31. 14 and 264.1 ± 68.8 eggs of C. cephalonica for the 1 st , 2 nd and 3 rd predator larval instars, respectively). S. cerealella was the least preferred host, whereas the respective predator larval instars consumed (0.8 ± 1.75, 27.9 ± 24.56 and 63.3 ± 47.2 eggs). Also, numbers of attacked eggs by the predator was recorded. Eggs of Rice moth were the highest attacked with Green Lacewing larvae while eggs of Angoumois grain moth were the least. This result needs more experimental efforts to earn its advantage in certain predacious performance.
Trials were conducted in a cotton field at Qaha Research Station, Qaluobia governorate, Egypt, to evaluate the dispersal ability and parasitism rate by the egg parasitoid Trichogramma evanescens West. (Hymenoptera: Trichogrammatidae), as well, to estimate the effect of parasitoid density from the releasing site on parasitism rate. Obtained data showed a limited dispersal ability for the parasitoid. The parasitism rates at 0, 50, 100, 150 and 200 cm. differed statistically from each other, being highest in the S. cerealella eggs placed at the shortest distance (43.03, 18.12, 10.92, 8.77 and 5.6%, respectively). The effect of releasing point and density on parasitism rate were also estimated. Increasing parasitoid density raised the rate of parasitism. When 2000, 3000 and 4000 parasitoids were released from the release point, the parasitism rates (mean percent ages for the whole 5 distances), were 33.21, 38.13 and 42.65%, respectively.
The present work was conducted in Qalubyia Governorate during 2010 to control the potato tuber moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelichiidae) in rustic farm storage and potato fields. Results showed that, double release of the parasitoid, Trichogramma evanescens Westwood and the predators, Chrysoperla carnea (Stephens) and Orius albidipennis (Reuter) were effective as biological agents against P. operculella under straw-cover heaps. The highest reduction percentage occurred with application of both T. evanescens and C. carnea, they reduced the infestation to 75.56% whereas application of both T. evanescens and O. albidipennis reduced the infestation to 56%. Application of O. albidipennis alone gave poor reduction percentage (5.1%). One release of O. albidipennis reduced the infestation to 21% in the field. However, application the agronomic cultural practices reduced rate of infestation to 45% at the trail end in the storge.
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