Transcript Document

Phoretic mites associated with Dendroctonus beetles and
their invertebrate predators
Richard W. Hofstetter, Elisabeth Alden, John C.
1
Moser ,
and Karen M.
2
Clancy
Northern Arizona University, Flagstaff, AZ 86011
1
2
USDA Forest Service, Pineville LA and Flagstaff AZ
Introduction
Mites are common associates of bark beetles and are known to
influence beetle reproduction and beetle-fungal relationships.
Mites may also affect beetle survival by preying on beetle eggs
and larvae. Many mite species introduce fungi into bark beetle
galleries and surrounding phloem (e.g. Tarsonemus mites;
Lombardero et al. 2003, Hofstetter et al. 2005). Mites travel from
tree to tree on beetles but cause no direct harm to the adult beetle
(termed “phoretic”).
fungal spores
Table 1. Phoretic mites on Dendroctonus species
MITE SPECIES
DENDROCTONUS
APPROXIMATUS
(N = 10)
X
Bauomia sp.
1
2
3
4
D.
BREVICOMIS
(N = 179)
D.
FRONTALIS
(N= 203)
Dendrolaelaps cuniculos
Dendrolaelaps neodisetus
X
X
Elattoma sp.
X
X
Tarsonemus spp.
7
X
Histiostoma sp.
X
Histiogaster anops
X
To identify and quantity mites that travel on Dendroctonus
beetles and their predators and competitors within Ponderosa pine
forests of Arizona.
Materials and Methods
8
9
Mexicheles virginatius
X
11
We collected live insects from baited funnel traps (see picture)
from June to October 2005 to estimate the prevalence of mites on
bark beetles and associated organisms in Arizona (USA). We
baited traps with synthetic lures designed to attract Dendroctonus
frontalis, D. mexicanus, D. brevicomis, D. pseudosugae, D. valens,
D. approximates and D. adjunctus bark beetles.
X
X
X
X
X
Proctolaelaps sp.
X
Proctolaelaps fiseri
X
X
Proctolaelaps
subcorticalus
Saproglyphus sp.
X
X
X
X
X
Tarsonemus krantzi
X
Tarsonemus terebrans
X
phoretic mites
Funnel trap
X
X
X
X
X
X
X
X
11
12
13
Overall, we collected 1500 insects and identified 1700 mites from
beetle exoskeletons.
Approximately 32 species of mite have been identified and one new
species (undescribed) was found on the predator, Temnochila
chloridia. Of the insects surveyed, D. valens, D. frontalis and D.
mexicanus had the greatest diversity of mites.
All insect species had phoretic mites. Predators and woodborers
tended to have the highest loads of mites, often greater than 150 per
insect. Although many of the Dendroctonus species and predators in
Arizona inhabit the same infested trees, some mite species were
associated with only one or two beetle species.
20% of the mite species identified were found only on predators and
competitors, and 34% were found only on Dendroctonus.
X
ÁCAROS
Anoetidae sp.
15
14
16
21
22
23
24
ENOCLARUS
SPHEGUS
X
TEMNOCHILLA
CHLORIDIA
PLATYSOMA
SP.
CORTECIUS
SP.
ELACATIS
SP.
CERAMBYCIDAE
SP.
Bouomia sp.
X
Dendrolaelaps cuniculos
X
Dendrolaelaps neodisetus
Histiostoma sp.
Histiogaster arborsignis
X
X
12
13
19
20
X
X
X
X
X
21 22
X
X
X
X
X
X
Histiogaster sp.
X
Narvacarus sp.
X
Pachlaelapidae sp.
X
Proctolaelaps fiseri
X
X
Saproglyphus sp.
X
X
Schwiebea sp.
X
X
X
X
23 24
X
Trichouropoda sp.
X
Trichouropoda hirsuta
X
Uroobuella orri
X
Winterschmidtia sp.
17
X
Schizostethes lyriformis
11
18
X
Proctolaelaps subcorticalus
8
9
10
X
20
Histiostoma sordida
5
15
16
7
9
X
19
Histiostoma varia
Results
8
X
Gamasina sp.
3
7
X
X
X
Trichouropoda hirsuta
Distribution of D. frontalis
6
X
Trichouropoda sp.
1
2
5
X
Schwiebea sp.
17
4
X
Table 2. Phoretic mites on Dendroctonus predators and competitors
Plots
(near Flagstaff, AZ)
3
X
X
Tarsonemus ips
10
X
X
Proctolaelaps hystrix
Objective
X
D.
PSEUDOTSUGAE
(N = 5)
X
Histiogaster sp.
6
D.
ADJUNCTUS
(N = 9)
X
Dendrolaelaps sp.
Iponemus truncatus
D.
MEXICANUS
(N=200)
2
X
Heterotarsonemus sp.
14
5
D.
VALENS
(N = 45)
1
X
X
X
X
X
X
X
Conclusions
The degree to which mite species affect bark beetle populations is unclear, but their high relative
abundances and diversity on bark beetles suggest that they may influence the dynamics within
infested trees and affect beetle fitness.
This research will continue to study the introduction and transfer of fungi by mites within beetle
infested trees and determine the effect this has on beetle population dynamics.
References:
Lombardero et al. 2003. Strong indirect interactions among Tarsonemus mites (Acarina: Tarsonemidae) and Dendroctonus frontalis. Oikos 102: 342-352.
Hofstetter et al. 2005. Seasonal dynamics of mites and fungi and interactions with southern pine beetle. Environmental Entomology (in press)
Hofstetter et al. 2005. Antagonisms, mutualisms and commensalisms affect outbreak dynamics of the southern pine beetle. Oecologia (in press).
Acknowledgements:
Support for this research was provided by USDA Forest Service and USDA Joint
Venture Agreement. Thanks to Stacy Bloomquist for assistance with lab work.