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Sigastus Weevil

In the last five years, Sigastus has emerged as a very serious pest in Northern Rivers of NSW. We have begun collecting information about the Sigastus Weevil problem and have conducted a survey of growers to help us get a better picture of the problem.

  • Chemical use has increased but this is unlikely to be a long term solution.
  • How can we halt the increasing use of chemicals for this pest?
  • A number of tactics are likely to be required.
  • Can we make farms more resistant to this pest and stop it spreading?
  • How can we conserve and encourage the natural enemies that are there?
  • A clearer picture of Sigastus larvae development times at different temperatures would also help with management.
  • We also need a better undersatnding of how and where it carries over from one season to the next. This season consultants have frequently observed Sigastus adults through the harvest period as well as infested nut.
  • Entomopathogenic nematodes may be useful in high pressure areas or hot spots so we are screening for effectiveness.
  • Consultants and growers need better monitoring methods to get the best timing of sprays.
  • NSW DPI is working with the Beauvarea fungus which kill sigastus under the right conditions.
  • Providing a favourable environment for natural enemies (including Beauvarea) during the harvest period to help reduce overwintering populations.

A Report will be distributed within the next couple of months but it is likely to take years to answer these important questions.

Link to Preliminary Sigastus Report

Links:

AMS Sigastus Fact Sheet (2014)

Article by Harry Fay Qld DAF

MPC Sigastus article May 2014

Natural Enemies of Sigastus Weevil

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Sigastus adult and external damage and egg laying site.

Sigastus weevil damage to husk and pulled back to reveal sigastus egg

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Parasitoid of Sigastus weevil

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Assassin bug nymph attacking a weevil (this weevil is not Sigastus)(Pic by J Coates)

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Parasitoid larva feeding on of Sigastus weevil larva - Species. unknown at this stage (Pic by J Coates)

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Sigastus weevil parasitoids are out there. These were caught overnight in a plate trap - water plus some detergent.

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Assassin bug moving in on a cluster of sigastsus weevils. (Jarrah Coates)

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Sigastus larva in macadamia nut (Jarrah Coates)

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Tachinid fly maggot feeding on a Sigastus weevil larva - Species. unknown at this stage (Photo, J. Coates)

Magpies have also been observed feeing on Sigastus adults.