BioResources FSB Project - BLOG
ANASTATUS UPDATE DEC 2013
18 December 2013
Anastatus Project Update Dec 2013
The last Anastatus Update back in July was a roundup of the first season of on-farm Anastatus releases. Some sites had much lower bug damage than previous years and things were looking very promising. For details and comments from growers, go to the previous blogs. And in late August we had begun another season of releases. !
However, over the last couple of months we have had a major issue with the mass rearing of Anastatus that relates to the condition of the frozen silkworm eggs that we use for raising the wasps.
BioResources' task within the HAL Multi-Industry FSB Project was to try and develop a commercially available biocontrol agent for FSB. This involves rearing large numbers of wasps very efficiently.
It may take another 12 months to resolve the host egg quality issue and back in September, we were not sure we could reliably supply wasps for trial sites and consequently assess them appropriately within the HAL Project's limited timeframe and resources.
The uncertainty that these issues have created for the Industry contributors and for BioResources resulted in BioResources deciding to withdraw from the HAL fruitspotting bug project.
We will however, continue with the work but in a low-key fashion under our own steam. We think Anastatus can make an important contribution to bug control so we will stick at it and try and resolve the mass rearing problems and get going again with field releases as soon as we can.
When we have a set back, I remind myself that the developers of antibiotics initially took months to produce enough penicillin to treat a mouse! And closer to home, ten years ago we didn't think we could produce MacTrix wasps as efficiently as we are doing today.
Send comments and bug observations to:
Richard Llewellyn
richard@bioresources.com.au
Above: Closeups of Anastatus. When running around on a leaf they are hard to tell from ants. Their wings may reflect some light and note the boomerang shaped clear section in the wings.
The problem
The current problem stems from the seasonality of supply of silkworm eggs used as a host for the wasps. The eggs we have been recently presenting to the wasps have been in the freezer since March and now seem to be past their “best by” date. The low yield of wasps we are getting means that we cannot efficiently and reliably produce enough wasps at present. We still have a fairly large culture but we need to maintain a large culture in anticipation of getting more fresh eggs from China in late February.
To mass rear insects on a commercial scale one needs a steady supply of suitable food or eggs for the natural enemy. Early in the HAL project we built up our fruit spotting bug culture and were getting about 3,000 bug eggs per week. This is good for research purposes but way short of what is required for a commercial product where we talk in the millions.
We then turned to using silkworm eggs imported from China. For many years, the Chinese have been rearing large numbers of a closely related species of Anastatus for release into lychees for control of lychee stink bug. Fortunately for the Chinese, the supply window of fresh silkworm eggs coincides with the optimum time slot to rear wasps for the the field so that they do not need long term storage. With fruit spotting bug we would like to make releases more evenly through the year so this means we must store the eggs, in various ways, for later use
What we can do
There are a number of things that we can do that should help us get around this problem - a combination of logistical changes as well as different handling and storage of the wasps in the rearing process. At this stage, it looks like we may end up with two major release periods per year: one from March to April and another from August to October. We aim to use a combination methods: eggs stored for up to a month but not frozen; frozen eggs using different packing materials and cold stored parasitised eggs. On the latter, we have some data already but we need to refine the process and run through it again when we get more fresh eggs in February. We are confident that by experimenting with different storage procedures and packing materials we can get around these issues.
Timeframe
It will take another 12 months before we know if we can resolve the rearing issues and whether it looks like it's successful enough for longer term commercial viability. There are plenty of good natural enemies out there but it's quite another thing to mass rear them efficiently and cost effectively, so that many growers can benefit from them, not just a few.
We’d like thank all those who have encouraged and supported this work and we hope that we can be back on track soon.
Before mounting an egg to insert their ovipositor, Anastatus females, check to see if “the coast is clear”, inspect the egg carefully, to see if its a suitable host and detect if another wasp has already parasitised the egg.
