The Sweep Net

The  GRDC funded Sweep Net insect identification service and Integrated Pest Management support for northern NSW Grains ceases business on Sunday 30th June 2012.  Staff from The Sweep Net would like to thank everyone who made use of the service over the past three years and wish everyone luck in their pursuit of further sustainable insect pest management.  Similar ongoing support, funded by the GRDC, will be provided in the form of insect identification workshops, insect identification smartphone apps and regional demonstration sites.  To access this support if you are in the northern NSW region, keep an eye on The Beat Sheet, GRDC Diary Dates and newsletters and promotions from ICAN.

The Sweep Net will be running a free insect Identification workshop at Moree next tuesday (May 8th).  The workshop is for Agronomists of grain crops – interested growers are also welcome.  The session will be at the Moree TAFE Agskills Campus (about 7km’s north of Moree on the Newell Hwy) beginning at 9am.  It will run for 3 – 3.5 hours and content includes basic insect biology and then looks in greater detail at the groups of insects that are of relevance to grain crops and the differences between these groups.  Specific examples of crop insects are looked at in detail and many examples (including microscopic ones) are brought along to the workshop for people to familiarize themselves with.

If you are interested in attending please contact Rachel Waugh on 02 6773 2338, or insect.ID@une.edu.au by this friday afternoon (May 4th).

Cantharid larvae

Larvae of Soldier beetles (Chauliognathous spp.) are predaceous in the soil, while adults are generalist predators above ground.  The adult beetles forage on vegetation and around flowers for small prey items such as bug and moth eggs, small caterpillars, aphids, mealybugs and thrips.  Larval diet will be discussed below.  A few comments have arisen recently with large numbers of soldier beetles present in some crops, especially Mungbeans, that the adult beetles may be eating plant material.  This is not the case, where the confusion may come in is when the adult beetles are actively searching for prey around flowers and the growing tips of plants.   Very occasionally however, they may take a small amount of pollen and nectar but rarely vegetative plant material.

Springtail from Liverpool Plains soil - family Isotomidae

The larvae of soldier beetles are soil dwelling.  They consume detritus eating invertebrates such as Collembolans (Springtails) (see image at left) which seem to be their main prey, while very small earthworms are taken to a lesser extent.  It has also been shown that they play a role in the suppression of aphid populations.

From egg to adult stage Cantharid beetles take approximately ten months with larvae present in the soil during winter, emerging throughout summer as adults, often en mass; adult longevity is thought to be about 2-3 months.

It is known that populations of Springtails increase dramatically where soils are augmented with lots of organic matter such as compost.  Reports have come into The Sweep Net recently (see recent post) of very large populations of soldier beetles in crops where compost has been applied.  In one of these crops very large numbers of Springtails were found in a brief survey of soil litter insects by Rachel Waugh from The Sweep Net in 2010.

Carabid beetles and Staphylinid beetles are also predaceous beetles that have their larval stage in the soil, including litter from crop stubble.

An insect identification morning was held for soybean growers from the Glen Innes district on Feb 17^th.  The morning was organised by Landmark agronomist, Greg Nies and hosted by John and Maryanne Bower at their property west of Glen Innes.  After a BBQ breakfast and short discussion about insect ID and pest and beneficial insects in soy crops we took the group into the crop to look at what insects were present and to talk about monitoring for threshold calculations.  Although insect activity was generally low, some green vegetable bugs (including a couple that had been parasitised by the introduced Trichopoda fly), a brown bean bug and some soybean loopers were found, there was also some mirid activity (Australian Crop Mirid).  There were a number of predators present in the crop also including glossy shield bugs, damsel bugs, parasitic wasps and spiders.  At this stage there was certainly no need for any action against insects, although levels green vege bugs and mirids will need ongoing monitoring through the pod-fill stage.  The growers who attended this day indicated an increased level of confidence about the ID of both pest and beneficial insects in their soy crops.  Thanks to Greg Nies, Landmark and John and Maryanne Bower for hosting the day.

Soldier beetles are present in large numbers at this time of year and are often present in grain crops. There have also been reports in the media by curious gardeners etc. Soldier beetles are large green and yellow beetles (approx. 15mm) and belong to the family Cantharidae. They are predaceous as both adults and larvae and although the adults do occasionally feed on pollen and small amounts of foliage, they are a beneficial insect. John Hosking, Liverpool Plains agronomist, has commented that they are present in particularly high numbers where growers are using a lot of compost as fertilizer. The reason for this is likely to be that the soil dwelling, predaceous larvae have an abundant food source due to the relatively high levels of soil invertebrate activity in soils managed in this way. The practice of composting may therefore be having a previously unrecognised indirect effect on pest control by assisting with the suppression of populations of insect pest species such as aphids, Heliothis and other caterpillars and bugs.

Black Field Cricket. Photo Copyright George Novak, Flickr.com

Mick Duncan, Northern Agriculture has reported finding large numbers of crickets (Teleogryllus sp.)  in an emerging oat crop near Walcha, NSW.  Field crickets feed on a wide variety of plant matter and they lay their eggs individually in the soil, generally in warm, wet conditions between spring and autumn.  Although field crickets have only one generation per year, the lifestages can overlap considerably.  They can be especially abundant in cracking soils and where plant stubble is present as these conditions provide shelter for the crickets.  Birds (and very likely bats and other native carnivorous wildlife) are natural predators of crickets but need to be present in high numbers to have a significant impact on cricket populations – more reasons to have native vegetation around.  There are a variety of other natural controls for crickets such as tachinid flies, egg parasitoids, various predatory beetles and spiders.  Although these are known control agents, the degree of control possible by these organisms is unverified.

There are also naturally occurring diseases of crickets, notable ones are a particular virus and also a strain of the fungus Metarhizium anisopliae. Various strains of Metarhizium are effective biological control agents for a number of agricultural pests and research trials for cricket control by Metarhizium on crickets were conducted by the CSIRO  in the mid-1990’s. They showed effective control, but unfortunately no Metarhizium is not registered for the control of crickets currently.

Cricket populations are best monitored at dusk or in the evening when crickets are actively feeding.  This can be done best by placing hessian bags at regular intervals in the crop and in the morning checking for the presence of crickets sheltering under the bags.  Obviously, general cricket populations can also be monitored by keeping an eye on lights at night.

On friday 17th Feb, Rachel Waugh from The Sweep Net will be assisting a group of soybean growers from Glen Innes with insect identification in their soy crops.  The field day follows on from an IPM and insect identification workshop which Rachel co-hosted with Hugh Brier from DEEDI in November.  Similar insect ID sessions within crops are welcomed by northern NSW growers and advisors.  Please contact Rachel at insect.ID@une.edu.au or on: 02 6773 2338 if you would like to know more about the session on friday, or would like to arrange an alternative insect identification session.

A free insect identification workshop will be run by The Sweep Net on December 15^th at Mullaley Hall. The workshop will start at 8:30am and run for the morning. The workshop will cover basic insect biology, insect collection techniques and look in more detail at groups of insects of particular agricultural significance. Specific insects relevant to local crops will also be displayed and aspects of IPM in grain crops will be discussed. If you would like to attend, please email Rachel Waugh at: insect.ID@une.edu.au

Check out some detailed information on The Beat Sheet: http://thebeatsheet.com.au/sorghum/helicoverpa-and-npv-in-sorghum-%E2%80%93-current-issues-4/ about using NPV for the control of Helicoverpa in flowering sorghum

The APVMA has suspended the use of dimethoate on a number of food crops due to potential dietary risks. New restrictions have been put in place that allow the use of dimethoate only on certain horticultural and field crops and also restricts its use in home gardens.

Information on the APVMA website states that:

“The suspension will last for 12 months while the APVMA completes further assessments on the chemical. The suspension prohibits:

· use of dimethoate on certain horticultural crops

· use on all food producing plants in the home garden

· supply and possession of dimethoate products unless they carry the new instructions for use.

‘Possession and use on some crops can continue provided the products carry the new instructions for use. Product registrants are requested to inform all parts of the supply chain that new instructions have been issued by the APVMA. All products in the supply chain and the marketplace must contain the new instructions prior to sale.’

The announcement follows the release of the 2011 Dimethoate Residues and Dietary Risk Assessment Report (August) which found that its use on many crops could exceed the recommended public health standard (the Acute Reference Dose).

‘Some of the estimated exposures for consumers are above the Acute Reference Dose, reducing, but not breaching, the margins of safety that are normally in place to protect consumers,’ said Dr Raj Bhula, Pesticides Program Manager.

‘These safety margins, built into the APVMA’s risk assessment, provide a protective buffer to ensure that consumers will not actually be exposed to high levels of residues in food.

‘If our risk assessment shows that these standards could be exceeded, the APVMA must remove or modify the use of the chemical on the crop so that consumption remains in line with the public health standard.’

A link to the APVMA announcement follows:

http://www.apvma.gov.au/news_media/media_releases/2011/mr2011-04.php