Diclidophlebia smithi (Hemiptera: Psyllidae), a potential biocontrol agent for Miconia calvescens in the Pacific: Population dynamics, climate-match, host-specificity, host-damage and natural enemies

Abstract

Diclidophlebia smithi (Hemiptera: Psyllidae) has been proposed as a candidate biological control agent for Miconia calvescens (Melastomataceae), a neotropical tree regarded as one of the worst threats to the rainforest ecosystems of several Pacific islands. Populations of D. smithi monitored over three years at three sites in the state of Minas Gerais, Brazil were found to peak during the cooler, drier months from April to July, with air temperatures as the factor most strongly correlated (negatively) with population density. A biologically significant match of climate conditions (+0.7 CMI, using CLIMEX regional matching) was found between the study region in Brazil and 3 of 9 weather stations in the potential release area of Hawaii. This result coupled with the wide variation in climatic conditions under which D. smithi populations have been found in Brazil suggest that D. smithi has good potential to establish in at least some regions of Hawaii. No significant predator, parasitoids or entomopathogens were found attacking D. smithi in its native range. No nymphs or adults of D. smithi were found on any plant belonging to a list of 102 species of 58 plant families growing in the vicinity of colonized M. calvescens individuals. Conversely, potted sentinel plants of the Hawaiian biotype of M. calvescens were readily colonized by D. smithi during an experimental six-month field exposure. Greenhouse no-choice tests with nine species of Melastomataceae also demonstrated that D. smithi has a host-range restricted to M. calvescens. A study of the morphological changes caused on tissues of M. calvescens by D. smithi showed that attack on leaves caused a collapse in the epidermis, cell disorganization and degeneration of the vascular system. This study confirms that D. smithi has significant potential as a biocontrol agent for M. calvescens.