Application to release the microhymenopteran parasitoid Tachardiaephagus somervillei for the control of the invasive scale insect Tachardina aurantiaca on Christmas Island, Indian Ocean Prepared by Peter T. Green, Dennis J. O’Dowd and Gabor Neumann (La Trobe University, Kingsbury Drive, Bundoora 3086) on behalf the Director of National Parks. Submitted by The Director of National Parks, for assessment by the Australian Government Department of Agriculture 1 December 2014 Contents Executive Summary ………………………………………………………………………………………………………………………………..iii Preamble ………………………………………………………………………………………………………………………………………………. vi Acknowledgments ……………………………………………………………………………………………………………………………… viii 1. Information on the target species, the yellow lac scale Tachardina aurantiaca ……………………………. 1 1.1 Taxonomy ………………………………………………………………………………………………………………………….. 1 1.2 Description ………………………………………………………………………………………………………………………… 1 1.3 Distribution ……………………………………………………………………………………………………………………….. 1 1.4 Australian Range ………………………………………………………………………………………………………………… 2 1.5 Ecology ………………………………………………………………………………………………………………………………. 2 1.6 Impacts ……………………………………………………………………………………………………………………………. 3 1.7 Information on all other relevant Commonwealth, State and Territory legislative controls of the target species …………………………………………………………………………… 7 1.8 When the target was approved for biological control ………………………………………………………. 7 1.9 History of biological control ……………………………………………………………………………………………… 7 2. Information on the potential agent Tachardiaephagus somervillei …………………………………………….. 8 2.1 Taxonomy ………………………………………………………………………………………………………………………… 8 2.2 Description ………………………………………………………………………………………………………………………. 8 2.3 Distribution, biology, behavior and life cycle of the agent ……………………………………………….. 10 2.4 Host range of the agent and related species – a database analysis of host specificity and potential for non-target impacts ………………………………………………………………..12 2.5 Report on host specificity testing ……………………………………………………………………………………… 14 2.6 The agent’s potential for establishment on Christmas Island …………………………………………… 19 2.7 The agent’s potential for control of the target …………………………………………………………………. 20 2.8 Information and results of any other assessments of the agent ….……………………………………. 23 2.9 Possible interactions with existing biological control programs (of same or related targets and other targets) ……………………………………………………………………………………. 23 2.10 Possible indirect effects of the agent ……………………………………………………………………………….. 24 2.11 Environmental risk assessments undertaken on the species both in Australia and overseas ……………………………………………………………………………………………………… 25 2.12 The proposed source of the agent, sanitary procedures and arrangements for its release on Christmas Island ………………………………………………………………………………….. 27 2.13 Where, when and how the initial release from the rearing facility will be made ……………… 30 2.14 Establishment and evaluation ………………………………………………………………………………………….. 31 Literature cited …………………………………………………………………………………………………………………………………….. 33 Tables ……………………………………………………………………………………………………………………………………………………39 Figures …………………………………………………………………………………………………………………………………………………. 60 ii Executive Summary The invasive, non-native scale insect, the yellow lac scale Tachardina aurantiaca (Kerriidae) has been listed as a Target for biological control on Christmas Island (Indian Ocean), mainly because of the role it plays in the dynamics of supercolony formation of another invasive species, the yellow crazy ant Anoplolepis gracilipes. Invasion and supercolony formation by the yellow crazy ant is Listed as Threatening Process under the EPBC Act, because of the direct and indirect negative impacts it has on native biota. The yellow lac scale occurs in extremely high densities in supercolonies, and supplies a large fraction of the honeydew required to maintain ecologically damaging, high densities of this ant. This proposal is to introduce a microhymenopteran parasitoid to control the yellow lac scale on Christmas Island. In its native range in Southeast Asia, the yellow lac scale is very rare and patchily distributed, has a diverse assemblage of natural enemies, and is heavily parasitized. On Christmas Island, the species is abundant (especially so in association with yellow crazy ant supercolonies), and the females are not parasitized by any of the few natural enemies associated with the species on the Island. Introduction of a host-specific parasitoid could bring the yellow lac scale under control and indirectly suppress supercolony formation by the yellow crazy ant, with immediate and long- lasting benefits to biodiversity on Christmas Island The proposed agent is Tachardiaephagus somervillei (Mahdihassan 1923), an encyrtid endoparasitoid with a broad native geographic range (India, Thailand and Peninsular Malaysia, as well as Sarawak and Sabah in Borneo) and a broad climatic range (from consistently warm and wet in the aseasonal tropics of Southeast Asia to much drier and seasonally cool climates in India). Several lines of evidence indicate that T. somervillei has a very narrow host range restricted to species in the lac scale family Kerriidae, and that the probability of non-target impacts on other scale insects on Christmas Island is extremely low; 1. Historical data indicate this species is known from just five host species in a single family, the Kerriidae. This includes the target species T. aurantiaca, and four species in Kerria, the lac genus of commerce. 2. Database records further indicate that the genus Tachardiaephagus is narrowly specialized on lac scale insects; all seven species of Tachardiaephagus are known only from kerriid hosts (Tachardina, Kerria, and Paratachardina). 3. No-choice host-specificity tests conducted under field conditions within the native range of the agent confirm this degree of specificity. Only the known host T. aurantiaca was heavily parasitized by T. somervillei, while eight test species − four species of soft scales (Coccidae), one species of armoured scale (Diaspididae) and three species of mealybugs (Pseudococcidae) − were not parasitized at all. 4. There are no native or endemic, non-target scale insect species on Christmas Island. More than 400 hours of structured field survey over three years along with targeted search on 14 of 18 known endemic plant species did not detect any endemic scale species. Paratachardina pseudolobata (Kerriidae) occurs on Christmas Island and could possibly be parasitized by T. somervillei, but this species is not native to the island and is a significant environmental pest in its own right. iii There are seven endemic species or subspecies in the Order Hemiptera known on Christmas Island, but three lines of evidence indicate the risk posed by T. somervillei to these species is extremely low. 1. Parasitoids from the Encyrtidae, the family to which T. somervillei belongs, are very uncommon parasitoids of the families containing the endemics; four of the seven families to which the endemic hemipterans belong have no known encyrtid parasitoids, and the remaining three families are attacked by just 15 encyrtid parasitoid species, despite great diversity (3735 species) in that group. 2. Most encyrtid parasitoid species known to attack scale insects in the Kerridae, the family to which the yellow lac scale belongs, are restricted to hosts in that family. The host ranges of the remaining encyrtid species are restricted to the Superfamily Coccoidea. This suggests that any encyrtid parasitoid that attacks host taxa within the Kerriidae is highly unlikely to attack any hosts other than scale insects. 3. All of the endemic hemipteran species on Christmas Island occur in different suborders (either Suborder Auchenorrhyncha or Heteroptera) to the yellow lac scale (Suborder Sternorrhyncha). Thus, any potential for non-target impacts by T. somervillei on these endemic Hemiptera would require a host range that bridges this very substantial phylogenetic distance. No encyrtid parasitoid species that uses kerriid lac scales is known to bridge this phylogenetic distance. There are no morphological or genetic differences between populations of yellow lac scales in the native range in Malaysia and on Christmas Island. Further, there are no morphological or genetic differences between populations of the agent T. somervillei in the Southeast Asian part of its native range. This obviates the need to consider matching populations when selecting the source of the agent for introduction. The founder population of T. somervillei will be sourced from Kuala Lumpur in Malaysia. This location is climatically well matched to Christmas Island, nearby an established rearing facility at the Forestry Research Institute of Malaysia, and close to an international airport. At the time of writing, it is likely the agent will be transported to Christmas Island from Kuala Lumpur via Perth, Western Australia. A quarantine facility does not exist on Christmas Island, so the transport of T. somervillei to Christmas Island should conservatively be treated as the “release from containment” that would normally occur on the mainland. Therefore, sanitary procedures to ensure the agent is free of pathogens and hyperparasitoids will be conducted at the Forest Research Institute of Malaysia. Only adults of T. somervillei will be introduced, minimizing the possibility of co-introducing any hyperparasitoid. A dedicated screen house production facility is being built by Parks Australia on Christmas Island to mass-rear T. somervillei for field release. This involves the production of