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United States Department of Agriculture

Agricultural Research Service

Research Project: Biological Control of Melaleuca and Other Invasive Plants

Location: Invasive Plant Research Laboratory

2010 Annual Report

1a.Objectives (from AD-416)
Develop safe and effective biological control agents of Melaleuca quinquenervia and other invasive weeds.

1b.Approach (from AD-416)
The following are the performance steps of a classical biological control investigation:

1. Survey and identify the pest's native range for list of herbivores that attack the pest plant.

2. Identify the best potential biocontrol agents based on field observations, preliminary lab tests, and information from local scientists.

3. Conduct preliminary host-range tests on most promising candidate in native country to obtain permission to import to U.S. quarantine.

4. Complete host-range tests in U.S. quarantine to ensure safety of the organism relative to local native plants, agricultural crops, and ornamental.

5. Petition Federal Technical Advisory Group for permission to release in the U.S. Also, obtain permission from necessary State agencies.

6. Culture agents that are approved to have sufficient numbers to release at field sites. Test release strategies to determine best method.

3.Progress Report

This research relates to the inhouse objective: Prioritizing and evaluating suitable target species for control; conducting surveys to discover natural enemies; studying the ecology of target species and determining the impact of their suppression on ecosystems; conducting risk analysis of potential biological control organisms; and releasing, establishing, evaluating, and transferring biological control agents against target species.

Australian Biological Control Activities: During Fiscal Year 2010 scientists improved rearing techniques for the Melaleuca weevil, Haplonyx multicolor to maintain a colony in case further shipments are required to the U.S. During surveys of H. multicolor in North Queensland an undescribed leaf-binding oecophorid moth was collected from Melaleuca colonised at ABCL. Initial host range testing indicates that this insect is not host specific to M. quinquenervia; several adults have been reared on Melaleuca alternifolia. An impact experiment was completed in early 2010 for the Melaleuca cecidomyiid fly, Lophodiplosis indentata, on Melaleuca quinquenervia. Overall L. indentata had a significant impact on M. quinquenervia in reducing the root and stem biomass as well as plant height. The leaf biomass increased dramatically causing the plants to droop from the extra weight of the galled tissue, but the overall total plant biomass was not significantly different to untreated plants. The experiment was conducted for two generations with an assessment after each and a six-fold increase in the number of pea galls was observed from the F1 to the F2 generation. Four shipments of ‘Sphaerococcus’ ferruginous galls, over 3,000 galls in total, were sent to IPRL in Ft. Lauderdale between February and June 2010 and attempts at colony establishment is underway in quarantine. No-choice host specificity testing in Australia is almost complete and as yet there has been no development of galls on any species including closely related broad-leaf Melaleucas. This insect appears to be highly specific despite observations of crawlers settling on test plants and attempting to feed. Biology studies are on-going.

Invasive Plant Research Lab, Gainesville Location Activities: We continued to rear the insect, Haplonyx multicolor, to maintain colonies and to use for host range tests. Numbers reared during the winter and spring months were low but slowly began rising in June 2010. Reasons for low numbers are undetermined; diapause or plant nutritional status are suspect. Studies of comparison of rearing adults on potted plants vs cuttings were initiated in May 2010. Longevity tests of H. multicolor males initiated in April 2009 were completed in June 2010. Host range test of the congener species and California ornamental, Melaleuca armillaris, initiated in April 2009, were completed in December 2009. Tests of number of generations of H. multicolor supported on Florida bottle brush species, initiated in July 2009, are ongoing. No choice and choice tests of other nontarget species continued. Completed host range data were summarized to include in a petition to USDA APHIS PPQ for release of H. multicolor.

Last Modified: 4/20/2014
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