Thrips (thysanoptera: Terebrantia) on flowers and fruit of citrus in New Zealand

Abstract

Thrips were collected from flowers, immature and mature fruit from commercial citrus orchards mainly in the Northland region of New Zealand and c. 23 000 were identified to species. Thrips obscuratus (Crawford) comprised 84–100% of all thrips recovered from flowers of all citrus varieties. Infestation levels of adults and larvae were commonly c. 20 thrips/flower but they were not associated with damage to the rind of fruit. Megalurothrips kellyanus (Bagnall) was also commonly found in flowers, usually in association with T. obscuratus. The highest infestations of M. kellyanus of 50 thrips/flower on lemons and 22 thrips/flower on tangelos occurred at times when T. obscuratus was present at a level of less than 1 thrips/flower. Approximately a third of M. kellyanus in flowers were larvae and the remainder were adults indicating that breeding occurred in the flowers. M. kellyanus larvae were commonly found on immature fruit of lemon, navel orange and tangelo, where their feeding caused scarring of the fruit. The low incidence of M. kellyanus on mandarin and Valencia orange flowers was reflected in low numbers of larvae on immature fruit and little evidence of damage. Heliothrips haemorrhoidalis (Bouche) was commonly found on mature fruit of all citrus varieties where their feeding activity caused a whitening of the rind. Fruit of Valencia orange were particularly susceptible to damage by this species of thrips, with mandarin, navel orange, and tangelo also damaged. The tubuliferan Nesothrips propinquus (Bagnall) was found on fruit of all citrus varieties, but there was no evidence of it producing any damage.