Understanding and managing insects on pistachio orchards (PS16000)
What’s it all about?
Contracted in September 2017, this two-year project is responsible for increasing knowledge about pest and beneficial species of insects and mites in Australian pistachio orchards. In its course, it will help the industry better understand the pests that currently pose a risk to pistachio production, or that have the potential to move into orchards. The work will also help the industry prioritise future research in pest management.
Field work in the project has now been conducted over two full growing seasons. In the second season of research, the focus was on beneficial insects – which were far more common than pest species in the first year of orchard observations.
In this second year of study, some 40 different ‘morphospecies’ of beneficials were identified across field visits at three observation sites, in October and November 2018, and January 2019. That is, there were 40 categories of insects with wholly different physical characteristics (the project team note they used this categorisation approach to indicate different species, “without undertaking the lengthy process of identifying all samples to genus and species level”).
The range of different beneficial insects reduced over the season, and the species composition varied over time. More spiders and wasps were seen early in the season, while there were greater numbers of ladybirds and lacewings later in the season. By late season, the variety of beneficials narrowed markedly.
In the first season of work, the researchers identified light brown apple moth early as an early season pest that may cause damage that interferes with nut set. The researchers were set to investigate it further in the second season, however as trapping began extremely low numbers were found – potentially due to the very dry winter prior. The researchers concluded that while pests are being found, none are at damaging levels.
Meanwhile, the researchers continued to find synergies with almond pest research. They teamed up with the Hort Innovation Almond Fund investment An integrated pest management program for the Australian almond industry (AL16009) to assess mummy nuts. They were looking to see if these offered a refuge for Carpophilus beetles and carob moths. The researchers note that while pistachio orchards are clearly a host for several species, crops do not appear to be damaged by them – “it is significant, though, that mummies left of the orchard floor can support other damaging species,” they said. “This highlights the need to maintain good orchard hygiene.”
Back in November 2018, an update on the project was presented at the industry’s Tech Group meetings, run under the investment Technology transfer for pistachio growers (PS17002). You can access the slides from the presentation here.
In March, the project wrapped up its first season of field work at orchards in Kyalite in New South Wales, Robinvale in Victoria, and Pinnaroo in South Australia. A monitoring protocol was developed, and included placement of pheromone traps and yellow sticky traps, visual assessments and beat sampling at 10 sites across the three orchards to gather information on the presence of key pests of interest, as well as to see what other beneficials and potential pests are in pistachio orchards.
From this first season of work, the researchers report that the pest status of pistachio orchards is very low. “By far the highest number of significant insects noted were beneficials – predators and parasitoids were very common,” they note. High beneficial numbers are thought to be a potential flow-on effect of the low pest pressure, which has reduced the need for in-season pesticides.
Of the pests that were identified, Carpophilus beetle, carob moth, light brown apple moth, small bugs and weevils were identified as being of interest for further assessment.
The project team notes that, in the case of Carpophilus and carob moth, there are synergies to be found with current projects taking place in the Hort Innovation Almond Fund and collaboration has begun. Working together, at the time of writing the teams were to undertake a joint field trip to make assessments of overwintering populations of the insects during June.
Light brown apple moth and small bugs were both identified as potential early season pests that may have an impact on nut set (damaging flower/nut clusters and causing some nut abortion). “Although the impact of this is likely to be small, some further assessments of this will be conducted in year two of the project,” the researchers report.
They also note that low levels of nut piercing damage later in the crop’s development was observed, but no clear link between this and any specific pest was possible. Based on work conducted in California, large bugs (for example, stink bugs) are a likely candidate for this damage, but levels of these pests in the three orchards were extremely low – averaging less than one bug per site.
A revised monitoring program for the project’s second year of the field work is currently under development. Look for details as the project progresses.
This project is a strategic levy investment in the Hort Innovation Pistachio Fund.