A gall midge, Prodiplosis hirsuta Kolesik sp. nov., is described whose larvae feed on shoot tips of Jatropha gossypiifolia and Jatropha clavuligera in Paraguay and Bolivia. Morphology and the mitochondrial COI gene sequence of the new species are given. Field survey and preliminary no‐choice host specificity tests showed that the host plant range of P. hirsuta is confined to J. gossypiifolia and J. clavuligera. The apparent host specificity and the damage potential make P. hirsuta a prospective candidate for biological control of J. gossypiifolia in Australia.

Exotic water primroses are aggressive invaders in both aquatic and riparian ecosystems worldwide. Water primrose [Ludwigia hexapetala (Hook. & Arn.) Zardini, Gu & P. H. Raven], floating primrose-willow [Ludwigia peploides (Kunth) P. H. Raven subsp. peploides], floating primrose-willow [Ludwigia peploides (Kunth) P. H. Raven subsp. montevidensis (Spreng.) P. H. Raven], Uruguay waterprimrose [Ludwigia grandiflora (Michx.) Greuter & Burdet], and the winged waterprimrose (Ludwigia decurrens Walter) have naturalized in aquatic ecosystems in the United States and are the focus of this study. The only control tools available to resource managers for suppression of Ludwigia spp. are physical and chemical methods, but these options are often limited in effectiveness and by costs and regulatory constraints. Biological control is an alternative that can be used alone or in combination with traditional methods. The purposes of this study were to explore the feasibility of a biological control program targeting problematic Ludwigia spp. in the United States and to propose a list of plant species for consideration during host range studies of candidate herbivores. A variety of native insects feed on Ludwigia spp. in the United States; however, most are generalists and have no appreciable influence on plant growth or fitness. Foreign exploration for natural enemies of Ludwigia spp. in South America suggests that a rich herbivore fauna is associated with the plants in their native range. Candidate agents must have section-level host specificity because several Ludwigia spp. are also native to the United States. Therefore, the plant test list is designed to distinguish herbivore host ranges based on the phylogenetic relationships of the test plants. For those Ludwigia spp. for which eradication may no longer be possible because the weed is regionally abundant, biological control may be the primary control option when traditional methods are not feasible.

Hedychium coronarium (Zingiberales: Zingiberaceae), native to the Himalayas and southern China, has become an environmental weed in many countries around the world. Reported in several provinces of Argentina, H. coronarium constitutes a serious environmental problem especially in the wetlands of natural areas of Misiones Province, such as the Iguazú National Park, a World Heritage site. Hedychium coronarium does not have any specialist natural enemies in Argentina, and the Argentine flora does not have taxonomically closely related relatives to it. This suggests that it may be a prospective target for classical biological control in Argentina. Since 2008, the Centre for Agriculture and Bioscience International (CABI) (https://www.cabi.org) has been commissioned to find and evaluate biological control agents for the invasive Hedychium species complex for Hawaii and New Zealand. Surveys in the native range of Hedychium spp. have revealed a varied suite of potential biocontrol agents for H. coronarium. A cost-effective and streamlined biocontrol programme for H. coronarium could be developed for Argentina based on CABI’s ongoing biocontrol efforts on this species elsewhere in the world.

The host range of the thrips Liothrips ludwigi was investigated using single- and multi-generational no-choice nymphal development and oviposition tests. Development, oviposition, and egg viability were quantified when L. ludwigi were fed three exotic Ludwigia species and seven USA native plant species. Liothrips ludwigi completed development and oviposited viable eggs on sympatric native Ludwigia species and sustained multiple generations on test plant species under laboratory conditions. These results indicate that L. ludwigi is not sufficiently host-specific for further consideration as a biological control agent of exotic Ludwigia spp. in the USA and further testing is not warranted.