Lifecycle of the invasive omnivore, Forficula auricularia, in Australian grain growing environments
BACKGROUND: The European earwig, Forficula auricularia(L.) (Dermaptera: Forficulidae), is regarded as an important beneficial in many orchard environments but has the potential to be a plant pest in other systems, including to grain crops. Due to its agricultural importance, the lifecycle of F. auriculariahas been widely studied in North America and Europe. However, much less is known in the southern hemisphere, including Australia where F. auriculariahas been present for over 170 years.
RESULTS: To elucidate the lifecycle of F. auricularia, we monitored five sites in grain-growing areas of southern Australia using two different trap types. Adults were found year-round, but most prevalent from late-spring to mid-winter. First instars were typically found from mid to late winter. Second, third and fourth instars occurred from winter through to late spring. The seasonal development of F. auriculariain Australia may be much earlier than observed in comparable North American studies. Degree day modelling highlights variation in development times across the active season for F. auricularia across our sites.
CONCLUSION: Forficula auriculariais well adapted to the Australian grain growing environments. The timing of egg hatching aligns closely with crop emergence, juveniles then develop alongside the crop, and adult development occurs by harvest time in late spring. These findings are important given that many of these crops (canola, lucerne, pulses) are vulnerable to attack by F. auricularia during emergence and development. They also suggest a phenotypic capacity of this species to adapt different phenology after introduction into a novel environment.
Is what you see what you get? The relationship between field observed and laboratory observed aphid parasitism rates in canola fields
Background: Estimating parasitoid abundance in the field can be difficult, even more so when attempting to quantify parasitism rates and the ecosystem service of biological control that parasitoids can provide.To understand how 'field observed' parasitism rates (in-field mummy counts) of the green peach aphid,Myzus persicae (Sulzer) (Hemiptera: Aphididae) translate to'laboratory observed'parasitism rates (laboratory-reared parasitoid counts), field work was undertaken in Australian canola fields, over the winter growing season.
Results: Overall, laboratory observed parasitism was on average 2.4 times higher than field observed parasitism, with rates an average of four-fold higher in fields from South Australia. Total field observed and laboratory observed parasitism rates (OPRs) of M. persicae varied considerably across regions, but less so among fields within regions. As crop growth stage progressed, the incidence of field observed mummies increased. The incidence of total parasitoids reared also increased with crop growth stage, averaging 3.4% during flowering and reaching 14.4% during podding/senescing. Although there was a greater diversity of reared parasitoid species at later crop growth stages, the laboratory OPR was unaffected by parasitoid species. Diaeretiella rapae was the most commonly reared parasitoid, increasing in absolute abundance with crop growth stage.
Conclusion: These findings indicate that field mummy counts alone do not provide a clear representation of parasitism within canola fields.
Life stages of the non-native Ommatoiulus moreleti (Lucas, 1860) (Julida, Julidae) in Australian small grain systems
1.The Portuguese millipede, Ommatoiulus moreleti (Lucas, 1860), is increasingly a pest of grains crops in Australian agricultural ecosystems. With the rapid uptake of minimum-tillage practices, habitat quality has been enhanced for several species of soil dwelling invertebrates, in particular O. moreleti.
2.To understand the population dynamics of O. moreleti in Australian grains crops, populations were sampled at multiple sites for more than 2 years using pitfall traps and cardboard roll traps. Specimens were dissected to investigate reproductive status and developmental stage.
3.Millipede trapping rates varied between sites and across the year, and tended to be lower when soil water content (m3/m3) was high. Both sexes were active year round, however females were relatively more abundant when ground temperatures were higher.
4.Males in a copulatory state and females with mature eggs were collected year round although females lacking mature eggs were more common when ground temperatures were higher and the soil was drier, and female egg load was higher under cooler conditions. Females at a stadium 9 or later carried mature eggs and copulatory males tended to be from stadium 8 or later. Different developmental stages could be recovered at all times of the year.
5.These findings indicate persistent populations of O. moreleti across fields throughout the year, with a key breeding period in autumn but likely opportunistic breeding all year. Control of millipedes will need to focus on increasing the impact of biological agents, decreasing suitable habitat for millipede breeding and intensive control at susceptible crop periods.
Biology, ecology and management of Diuraphis noxia (Hemiptera: Aphididae) in Australia
The Russian wheat aphid,Diuraphis noxia(Mordvilko ex Kurdjumov), is one of the world's most economically important pests of grain crops and has been recorded from at least 140 grass species within Poaceae. It has rapidly dispersed from its native origin of Central Asia into most major grain-producing regions of the world including Africa, Asia, Europe, the Middle East, North America and South America.Diuraphis noxia was first found in Australia in a wheat crop in the mid-north of South Australia in May 2016. Since then,D. noxia has been recorded throughout grain-growing regions of South Australia, Victoria, New South Wales and Tasmania. The distribution will continue to expand, with climatic suitability modelling suggesting D. noxia can persist in all key grain regions, including large parts of Western Australia and Queensland. Australian populations of D. noxia appear to be anholocyclic, with no sexual stages being observed. The aphids can reproduce year round as long as host plants are available. Australian farmers have generally adopted prophylactic insecticide seed treatments and/or foliar sprays to manage D. noxia. Research is required to fully understand yield impacts, host preferences and host plant resistance associated with D. noxia. Cultural control through managing alternate host plants over summer, agro-nomic crop management, biological control and developments in host plant resistance should provide considerable future benefits.