Establishment, spread and impacts of Boreioglycaspis melaleucae, a biological control agent of the invasive tree Melaleuca quinquenervia.

Authors: Pratt, Paul; Center, Ted

Submitted to: Entomological Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 10/15/2006
Publication Date: 12/10/2006
Citation: Pratt, P.D., Center, T.D. 2006. Establishment, spread and impacts of Boreioglycaspis melaleucae, a biological control agent of the invasive tree Melaleuca quinquenervia.. Entomological Society of America Annual Meeting.

Interpretive Summary: We report the establishment and preliminary impacts of the melaleuca psyllid (Boreioglycaspis melaleucae Moore). Initially, eight sites were inoculated with 7000-10000 adult psyllids, with one exception where 2000 nymphs were released on seedlings. Psyllid populations established everywhere irrespective of colony source, site conditions, or the quantity released, although numbers released and, to a lesser degree, colony age influenced the numbers of colonies produced. Psyllid populations dispersed 2.2 to 10.0 km/yr, with the slower rates in dense, continuous melaleuca stands and faster rates in fragmented stands. Over 1.9 million psyllids had been redistributed to >100 locations as of May 2006. This species now occurs throughout the range of melaleuca in south Florida due to natural range expansion as well as anthropogenic dissemination. After inoculation of the psyllid in a field study, only 40% of seedlings survived herbivory treatments compared to 95% survival in controls. The resultant defoliation also reduced growth of the surviving seedlings. A weevil-induced decline at a site comprised mainly of coppicing stumps had slowed after a 70% reduction. Psyllids then colonized the site and 37% of the remaining coppices succumbed. The realized ecological host range of B. melaleucae was restricted to M. quinquenervia while 18 other non-target plant species predicted to be suboptimal or non-hosts during laboratory host range testing were unaffected when interspersed with psyllid-infested melaleuca trees in a common garden study. Evaluations are ongoing, but B. melaleucae is clearly reducing seedling recruitment and stump regrowth without adversely impacting other plant species.

Technical Abstract: We report the establishment and preliminary impacts of the melaleuca psyllid (Boreioglycaspis melaleucae Moore). Initially, eight sites were inoculated with 7000-10000 adult psyllids, with one exception where 2000 nymphs were released on seedlings. Psyllid populations established everywhere irrespective of colony source, site conditions, or the quantity released, although numbers released and, to a lesser degree, colony age influenced the numbers of colonies produced. Psyllid populations dispersed 2.2 to 10.0 km/yr, with the slower rates in dense, continuous melaleuca stands and faster rates in fragmented stands. Over 1.9 million psyllids had been redistributed to >100 locations as of May 2006. This species now occurs throughout the range of melaleuca in south Florida due to natural range expansion as well as anthropogenic dissemination. After inoculation of the psyllid in a field study, only 40% of seedlings survived herbivory treatments compared to 95% survival in controls. The resultant defoliation also reduced growth of the surviving seedlings. A weevil-induced decline at a site comprised mainly of coppicing stumps had slowed after a 70% reduction. Psyllids then colonized the site and 37% of the remaining coppices succumbed. The realized ecological host range of B. melaleucae was restricted to M. quinquenervia while 18 other non-target plant species predicted to be suboptimal or non-hosts during laboratory host range testing were unaffected when interspersed with psyllid-infested melaleuca trees in a common garden study. Evaluations are ongoing, but B. melaleucae is clearly reducing seedling recruitment and stump regrowth without adversely impacting other plant species.