| heal.abstract |
Closterotomus trivialis (Costa) (Hemiptera Miridae) is widespread in olive groves in the Mediterranean basin. This species feeds on flowers and it has been reported to reduce fruit setting due to flower abortion. However, there is contradictory evidence and its damage potential has not been clarified. The related species Aphanosoma italicum Costa is also commonly recorded on olive trees in the study area. The aim of this study was to investigate the potential of C. trivialis and A. italicum to impact adversely on olive fruit setting. Their damage potential was investigated at different stages of flower development, as this could constitute a critical factor in the damage incidence of these insects and thus being a key issue in unravelling the puzzle evidence. Shoots on the trees were enclosed in cages into which 3 or 6 adults in spring 2007 or 8 nymphs or adults in spring 2008 were introduced. In 2007 the introduction took place on 29 March. In 2008, the damage potential was investigated in 3 periods extending from early flower emergence to the start of the blooming period (placement of the cages on 7 and 27 March and 18 April). Records showed that in the cages where C. trivialis or A. italicum had been enclosed a high percentage of the fruiting organs dropped (99 and 91%, in each species, respectively). In the controls, the respective percentages were 63 and 64%. This high reduction in fruit setting was mostly attributed to bud abortion. The damage potential of both species was affected by the time of the infestation. Damage of C. trivialis can be severe from the early period of inflorescence development before they develop well and start blooming, whereas A. italicum showed a comparatively lower damage potential. In any case, at the period of blooming damage does not seem to be important. Thus, C. trivialis can cause serious fruit abortion. This knowledge can substantially contribute to the development of appropriate control programs of this pest in olive groves. |
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