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Effect of olive surface waxes on oviposition by Bactrocera oleae (Diptera: Tephritidae)

Kombargi, W.S., Michelakis, S.E., Petrakis, C.A.
Journal of economic entomology 1998 v.91 no.4 pp. 993-998
Olea europaea, Bactrocera oleae, plant cuticle, waxes, triterpene acids, oleanolic acid, oviposition, cultivars, varietal resistance, seasonal variation, chemical constituents of plants, epicuticular wax
The amount of olive surface waxes obtained from fruits belonging to 5 Greek cultivars ranged from 11.6 to 152.9 mg/100 g fruit. It varied significant1y among varieties diuring fruit growth and maturation throughout the season, with 2 peaks around mid-August and the end of September upto mid-October. The 2 pentacyclic triterpene acids, oleanolic and maslinic, constituted the highest percentage of the total surface wax composition and were present in comparable amounts. The number of eggs oviposited varied significantly under treatments with different wax solutions compared with controls, which showed the highest mean in egg number (6.4 eggs per fruit). Highly significant negative correlations were detected among the concentrations of the oleanene acids and the number of eggs oviposited; the correlation factor (R) was -0.76 for oleanolic acid and -0.62 for maslinic acid. Oleanolic acid had a dominant effect over maslinic acid. Choice experiments showed that the degree of infestation of olive fruits by B. oleae was aflected by the type of cultivar and the degree of olive fruit maturation. The size of olive fruit was not significant in determining the preference of B. oleae for ovipositing.