The Imtrader Ed.8 – Stigasis Weevil

The Australian Macadamia Nut (as reported by MPC) is on track for its biggest year to date in terms harvested nuts and revenue with around 52000 tonnes of nuts expected at a record $5.20/kg.  With this in mind pest management and in particular hard to kill pests capable of causing significant economic loss such as sigastus weevil need to be front of mind for all involved industry bodies and growers alike.

Sigastus is prevalent through the Northern Rivers region in NSW and Atherton Tablelands, as well as sporadic sightings in the Gympie area. According to the DPI, Sigastus has been thriving over the last 3 years for a range of reasons such as extended flowering and out of season nut set, neglected orchards, poor orchard hygiene, missing late fruit spotting bug spray allowing Sigastus to be highly productive most of the year.

Prior to shell hardening, the female weevil scarifies an area on the husk and prior to chewing off the stalk to promote the nut to drop, lays an egg which penetrates the kernel. Once hatched the larvae consumes the entire kernel and emerges as an adult. Damage caused by Segastus is not limited to prior to shell hardening. After the nut has progressed past shell hardening adult Sigastus feed on the outer green husk as well as leaves.

Sigastus weevil – ‘An emerging pest of macadamias in North Queensland’ by Fay et al, is known as the initial work on Sigastus weevil reporting 30% crop Loss in the Atherton tablelands with no treatments. Chemical treatments provided sufficient control in this trial work however now a much more comprehensive approach is necessary to obtain adequate control of Sigastus.

Macadamia nut close

There are several key factors in obtaining adequate control including but not limited to;

  • Orchard Hygiene
  • Chemical rotation
  • Timing of chemical application
  • Spray coverage

As part of Imtrade Australia’s vision to provide solutions to Australian farmers, work has commenced in seeking a solution with various products to assist in the control of Sigastus weevil. This work will add to our already established suite of products for the macadamia industry.

Click here to view our full range of Macadamia products.

There are several resources available for Sigastus