2012 Annual Report
1a.Objectives (from AD-416):
Parkinsonia (Caesalpinioideae) was planted in Australia mainly as an ornamental and shade tree. The detrimental effects include its propensity to form dense, thorny, impenetrable thickets along drainage lines, depressions, and ephemeral wetlands. Investigations into the potential biological control began in 1983. Two insects from the Sonoran Desert Region, Rhinacloa callicrates and Mimosestes ulkei were released since 1989 and a third insect from Argentina, the seed-feeding bruchid, Penthobruchus germaini, in 1995. Additional agents are needed. Recent genetic studies indicating very old dispersal events of P. aculeata in South America, stimulated interest in survey work in this area. Previous native-range surveys conducted in Argentina and Paraguay by ARS researchers revealed the existence of two prospective geometrid moths, Eueupithecia cisplatensis (Prout) and Euacidalia sp
1b.Approach (from AD-416):
• Focus searches on warmer semi-arid areas that match target climates in Australia.
• Collect young living plants of P. aculeata for growing at the Hurlingham laboratory.
• Transport living geometrid specimen to the Hurlingham laboratory.
• Rear the specimens to adult.
• Initiate a lab colony on the living plants of P. aculeata.
• Collect data on life cycle and basic biology.
• Compile a list of related species that could be collected as young plants and grown in pots in the lab for host specificity testing.
• Collect and grow these plants.
• Conduct host specificity tests. Use no-choice test design. Attempt to obtain mating and oviposition on test plant species and P. aculeata control and record larval development.
• If direct oviposition on plants is not possible, transfer eggs onto leaves of various species and record larval development.
• Variations to host testing to be discussed with Dr Tim Heard.
• While collecting geometrids, collect, preserve and label other insect herbivores.
• If geometrids cannot be found, transfer effort into the survey of other herbivorous species.
• If any other species appear promising, attempt rearing and specificity testing within the possibility of the available resources.
• Keep herbarium specimens of plants from all sites visited.
• Keep data sheets of characteristics of sites visited.
• If appropriate, collect geometrids from neighbouring legumes when populations found on P. aculeata.
Parkinsonia is used in Australia as an ornamental and shade tree; it forms thorny, impenetrable thickets in drainage lines, depressions, and wetlands. Two insects from the Sonoran Desert were released since 1989 and one from Argentina in 1995. Additional agents are needed.
Studies were focused on two leaf-feeding moths and a stem-galling midge. Five field trips were made in north-central Argentina for the plant and the natural enemies. larvae were collected by beating foliage and midge stem galls were collected by cutting braches. Collected material was held in plastic containers during the trip, provided with fresh leaves when necessary and transported to SABCL for subsequent emergence of adult specimens. The moth larvae collected were reared separately in controlled environmental chambers. Newly emerged adults were kept together to allow mating. After 2-3 days, females were separated in order to rear isofemale lines and breed pure colonies of the moth species. When dead, those females were dissected to investigate genitalia morphological differences. Collections from northern and from central Argentina corresponded to two different species. A culture of the species found in central Argentina is being raised at SABCL.
A total of 1,372 galls of the midge were collected in eight sites. Twenty to forty newly emerged adults were confined inside insect rearing sleeves wrapped around branches of potted Parkinsonia plants. None of the plants exposed to the insects registered stem galls development.
New findings: An unidentified moth larva was found feeding on Pakinsonia leaves. Adults of an unidentified moth were obtained from the midge stem gall samples. Specimens of both sites will be sent for identification to specialists at ARS-SEL. An unidentified stem miner was found in Salta Province on young shoots of Parkinsonia plants. An unidentified wasp was found parasitizing moth larvae.