Introductory presentation on stick insects (Insecta: Phasmida) as pests of agriculture and forestry, with examples from the USA, Australia, Fiji and China. Cite as: Baker, Edward (2015): Phasmids as Pests of Agriculture and Forestry. figshare. http://dx.doi.org/10.6084/m9.figshare.1472902

1. Ed Baker
PHASMIDS AS PESTS OF
AGRICULTURE AND
FORESTRY

2.  USA (1870s-1970s)
Diapheromera femorata
 AUSTRALIA (1880s-1980s)
Didymuria violescens
Podacanthus wilkinsoni
Anchiale austrotessalata
 FIJI (1920s-Present)
Graeffea crouanii
 CHINA (1980s-Present)
Various spp.
MAJOR INFESTATIONS

3. REVIEW OF DIAPHEROMERA

4. “…eggs and fecal pellets are dropped to the
ground in great numbers, producing a pattering
sound, like rain, accompanied by a peculiar
seething sound of thousands of jaws chewing
the leaves.”
- Helfer (1963)
REVIEW OF DIAPHEROMERA

5. REVIEW OF DIAPHEROMERA
New York Outbreak (1870s)

6. Wisconsin Outbreak (1959-60s)
“Within seconds after a person stopped under
or near a tree, walkingsticks dropped onto and
crawled upon his body so that even to an
experienced entomologist it was an
uncomfortable, creepy feeling.”
Oatman (1965)
REVIEW OF DIAPHEROMERA

7. Michigan Outbreak (1930s)
REVIEW OF DIAPHEROMERA

8. Michigan Outbreak (1930s)
REVIEW OF DIAPHEROMERA

9. REVIEW OF AUSTRALIAN SPECIES

10. DIDYMURIA VIOLESCENS
Above: Female, David Rentz
Right: Male, Paul Brock
Phasmida Species File

11. PODACANTHUS WILKINSONI
Right: Female, Kennedy Harris
Below: Male (LT,PLT), ANIC (Paul Brock)
Phasmida Species File

12. ANCHIALE AUSTROTESSELLATA
Male, NHM, Paul Brock
Phasmida Species File

13. REVIEW OF AUSTRALIAN SPECIES
Habitat, Paul Brock
Phasmida Species File

14. REVIEW OF AUSTRALIAN SPECIES
Campbell and Hadlington (1967)

15.  Readshaw (1965) A Theory of Phasmatid Outbreak Release
 Campbell (1974) Factors Limiting the Distribution and
Abudance of the Three Species of Phasmatids (Phasmatodea:
Phasmatidae) Which Occur in Plague Numbers in forests of
South-Eastern Australia
 Readshaw (1990) Phasmatid Outbreaks Revisiting
CLASSIC LITERATURE

16.  Outbreaks are infrequent
 Semi-voltine life cycle
 Inability of predators and parasitoids to contain infestation
 High fecundity
 Slow migration
READSHAW’S CRITERIA

17. KENTROMORPHISM
 Individuals reared at
different densities have
different colouration and
morphology
 Potentially analogous
(homologous?) to density
dependence in plaguing
Orthoptera?

18. KENTROMORPHISM
http://davidavid.blogspot.co.uk/2006/11/just-phase.html

19. How general is this theory?
 Take the model of Australian outbreaks
 Apply it to other outbreaks
 See what breaks
TESTING THE THEORY OF PHASMATID
OUTBREAK RELEASE

20.  Expanded by Campbell to be require an absence of forest
catastrophe (mainly fire) for a period of 10-80 years
 No forest fires associated with D. femorata outbreaks…
… but they always seem to occur in plantations or second
growth forest
Conclusion:
Outbreaks are linked to habitat disturbance, whether that be
natural (forest fire) or anthropogenic (plantations)
OUTBREAKS ARE INFREQUENT

21.  Readshaw predicted this was important, as infestation levels
only occur every other year, preventing a rapid escalation in
predators/parasites
 D. femorata is generally uni-voltine. Some Chinese pest
species are up to tri-voltine.
Conclusion:
May be important in specific in cases, but more generally
phasmid outbreaks happen without this condition.
SEMI-VOLTINE LIFE CYCLE

22. Mymecomimesis semiglabra (Readshaw, 1965)
PREDATORS AND PARASITOIDS

23. Mymecomimesis semiglabra (Readshaw, 1965)
PREDATORS AND PARASITOIDS

24. Myna bird, introduced to Fiji to control Graeffea crouanii
Gerald McCormack
PREDATORS AND PARASITOIDS

25. Exova tunana, parasitoid of Eurycantha insularis
Kimsey, Dewhurst & Nyaure (2013)
PREDATORS AND PARASITOIDS

26. If there is an infestation – the stick insects are not being
predated or parasitised at a sufficient rate to control the
outbreak.
True by definition.
PREDATORS AND PARASITOIDS

27.  All species involved lay many times more eggs than would be
needed if no predators or parasitoids were present.
 This is true for all Phasmid species.
 Facilities outbreaks when population rise in phasmids is not
immediately followed by a rise in predators and parasites.
 Need to look at why this occurs. Given what else we know
habitat disturbance is likely (forest fires; altering of the forest
ecosystem; movement of phasmids into plantations)
HIGH FECUNDITY

28.  Diapheromera is wingless – movement confined to walking.
 Gravid females of Australian species can glide – limited flight.
Reports show that lighter males disperse more rapidly than
females. Concentration of eggs beneath females.
 Outbreaks generally occur in a very confined area, that
spreads over several years and may merge with others to form
widespread damage.
SLOW MIGRATION

29.  Not known in any phasmids besides the Australian ones
mentioned by Key.
 The Australian species come from forest that is subject to
natural forest fires, this could be an evolutionary adaption to
the effects of these.
KENTROMORPHISM

30.  Disturbance of forest (either natural or anthropogenic)
 Reduction in controlling species allows phasmid population to
rise more rapidly than their predators
 High fecundity and slow migration creates intense population
rises on limited scales (at least initially)
Rejected ideas:
 Semi-voltine life cycle
 Kentromorphism
GENERAL THEORY OF OUTBREAKS

31. GRAEFFEA CROUANII
CINHP, Gerald McCormack

32. GRAEFFEA CROUANII
Damage to coconut palm, Deesh, Swamy & Khan (2013)

33. GRAEFFEA CROUANII
Damage to coconut palm, Deesh, Swamy & Khan (2013)

34. BACULONISTRIA ALBA
Xiang Guowei in Hennemann et al (2008)
Defoliation of Cupressus funebris
FIGURES 7–9: Live insects
7. Baculonistria alba (Chen & He, 1990). on Cupressus funebris, Chon
8. Parapachymorpha sp. , Chongqing. (© Zhang Weiwei)
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