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United States Department of Agriculture

Agricultural Research Service

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Location: Invasive Plant Research Laboratory

2013 Annual Report

1a. Objectives (from AD-416):
1. Complete host testing for Bikasha collaris in Gainesville quarantine on North American plant species. 2. Determine the identity of the stem-gall wasp and establish colonies. 3. Colonize and rear Gadirtha inexacta in quarantine and initiate host range tests on North American plant species. 4. Colonize the stem galling wasp, Eulophidae, Testrastichini.

1b. Approach (from AD-416):
Conduct quarantine host testing to determine safety of potential agents for biological control.

3. Progress Report:
This research directly related to inhouse objective 4 - Conduct risk analysis to determine environmental safety of new and existing potential biological control agents for weeds such as air potato, melaleuca, Brazilian pepper, lygodium, downy rose myrtle, Chinese tallow, waterlettuce and skunk vine. During the past 6 months we initiated testing of a third insect from China, the defoliating caterpillar Gadirtha n. sp. (Lepidoptera: Noctuidae). Testing of the defoliating caterpillar indicates that in no-choice tests, larvae are specific to the target weed. Nearly all the larvae died when placed in no choice tests on the non targets. The exceptions include two of 14 larvae fed Euphorbia (=C.) hypericifolia and one of 13 larvae fed Gymnanthes lucida emerged to the adult stage. Consumption of tallow averaged 226.1 cm2 whereas that consumed by the larvae fed E. hypericifolia was 194.9 cm2and G. lucida was 169.1 cm2. Pupal weights of individuals fed tallow averaged 0.42 and 0.38 g for females and males, respectively, whereas those fed E. hypericifolia weighed 0.39 g and G. lucida 0.30 g (both females), respectively. Therefore, with these few exceptions these results indicate that this insect will be a safe for release. More research is needed to finish testing this species on more test plants and with additional testing protocols to confirm our results.

4. Accomplishments

Last Modified: 06/22/2017
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