Major findings

Trapping results from the 2015/16 season

The psyllid trapping program for the 2015/16 season has been completed. Trapping is continuing with a small number of traps currently being operated in Tasmania, Victoria and South Australia during spring. Trap numbers will be increased again for the 2016/17 potato growing season when planting begins in each region.

A summary of the results is given in Table 1.

Highlights were:

  • No tomato-potato psyllids (Bacticera cockerelli) were detected on 325 traps placed in the field during the 2015/16 season.
  • Over 1,753 native psyllids and 1,366 beneficial insects were caught.
  • Captures of native psyllids were highest in South Australia (average of 11.0 psyllids per trap) and lowest in eastern Tasmania (3.1 psyllids per trap).
  • None of the native psyllids caught are thought to feed on potato plants but were attracted to the yellow colour of the sticky traps from nearby vegetation, particularly Eucalyptus trees.
  • Over all locations, only 0.6% of all native psyllids caught belonged to the same family as the tomato-potato psyllid (Triozidae) making differentiation rapid based on wing venation (see: Tomato –potato psyllid Identification Key).
  • However, two triozids caught in north-western Tasmania in January 2016 were very similar in appearance to the tomato-potato psyllid and were later identified as a native species of Trioza.
  • Captures of beneficial insects were highest in Victoria (8.9 per trap) and lowest in eastern Tasmania (3.1 per trap).
  • Over 47% of beneficial insects caught were brown lacewings, while ladybirds constituted 25% of captures and hoverflies 26%.
  • As found in the 2014/15 season, there was no correlation between the number of native psyllids caught and the number of beneficial insects caught, as expected. The number of beneficial insects present in potato crops is most likely affected by the density of other prey insects, in particular aphids, and on agronomic practices (such as weed control and the number of insecticide sprays applied).

For more details of the trapping results for individual regions see: northern Tasmaniasouth-eastern TasmaniaVictoria, South AustraliaQueensland and NSW.

 

Table 1: Summary of 2015/16 trapping results

Region

Trapping period

Total no. traps

Total no. psyllids

Mean no. psyllids/trap

Total no. beneficials

Mean no. beneficials/trap

Tasmania northern

July-15-May-16

180

843

4.7

585

3.3

Tasmania eastern

Aug-15-May-16

74

226

3.1

231

3.1

Victoria

Dec-15-Jan-16

18

100

5.6

160

8.9

South Australia

Oct-15-Mar-16

53

584

11.0

390

7.4

All

 

325

1753

5.4

1366

4.2

Acknowledgments

We thank industry partners and Horticulture Innovation Australia for funding; all participating potato growers for allowing us to conduct trapping on their farms; and Dr Gary Taylor (University of Adelaide) for identifying the Trioza spp.