Population trend and fruit damage of Pezothrips kellyanus (Thysanoptera:Thripidae) in citrus groves in Valencia (Spain)

Abstract: Damage produced by thrips (Thysanoptera) has been traditionally consideredrare or absent in Spanish citrus orchards. However, Pezothrips kellyanus (Bagnall) was firstobserved in Alzira (Valencia province) in 2007 damaging citrus fruits. Since then, the pesthas extended to other citrus areas in eastern Spain causing important damage. Worldwide, P.kellyanus has emerged during the last decade as a pest of citrus fruits. Its presence and fruitscarringdamage in citrus orchards has been recorded since the 1990s in Australia, NewZealand and some Mediterranean countries. Nowadays, some basic aspects of its biology,which are necessary for the adequate management of the pest, still remain poorly understood.In order to study the relationship between the seasonal trend of its different developmentstages and fruit damage, P. kellyanus populations were monitored in several citrus orchardsusing different sampling methods (aerial and ground sticky traps, Berlese funnels and visualinspection), during 2008 and 2009. Seasonal trends in relative abundances of differentdevelopment stages were studied in oranges, lemons and jasmines. Our results show thatfruit damage is strongly correlated with number of larvae on young fruits and poorlycorrelated with number of adults on flowers or young fruits. The utility of different samplingmethods to estimate the number of generations and to predict the damage to fruits isdiscussed. Several species of soil dwelling predatory mites were identified in the soil aroundthrips-infested citrus and jasmine.