Natural History, Ecology and Evolution of Aedes aegypti and Aedes albopictus with Special Reference to Florida
Natural History, Ecology and Evolution of Aedes aegypti and Aedes albopictus with Special Reference to Florida
P Lounibos, Univ. of Florida, Florida ...
Natural History, Ecology and Evolution of Aedes aegypti and Aedes albopictus with Special Reference to Florida
P Lounibos, Univ. of Florida, Florida Medical Entomology Lab
Part I: Invasion Biology & Competitive Displacement Part II: Natural History & Ecology of Life Stages in Florida Part III: A Resurgence of A. aegypti in Florida?
Major range expansion of Aedes albopictus occurred in the past 40 years from Asia 1991
1985
1991
1985
Enserink. 2008. Science
These two species both frequent container habitats provided by humans and, as adults, mate in association with host-seeking
Rapid disappearance of A. aegypti in Bermuda after establishment of A. albopictus Ex Kaplan et al. (2010) Biological Invasions
Decline of A. aegypti after the arrival of A. albopictus in Florida
Lake city Gainesville Ocala Leesburg
Apopka
Orlando Kissimmee St. Cloud Yeehaw Junction Okeechobee
Modified from O’Meara et al. J. Med. Entomol. 1995
Surveillance in south Florida cemeteries since 1990 documented rapid displacement and led to testing hypotheses of proposed mechanisms
Patterns of exclusion and co-existence in south Florida cemeteries (modified ex Lounibos et al. 2010 An. Entomol. Soc. Am.)
Larval densities, leaf litter, and species were manipulated in experiments in tires and plastic cups in Vero Beach, Florida and Rio de Janeiro, Brazil
2004 (Braks et al. 2004)
Auto salvage yards harbor sympatric A. albopictus and A. aegypti in south Florida
Evidence of interspecific mating among field-collected females Sperm from
Collection Site M& K Auto
Species aegypti
Mean No. (SE) Per Coll 73.4 (18.7)
(n=7)
albopictus
Belle Glade (n=2)
Spermathecae
Totals
85
A. albopictus 0
161.0(60.0)
1
71
72
aegypti
67.5(2.5)
82
3
85
albopictus
411.5(170.5)
1
61
62
169
135
304
Totals
A.aegypti
85
Ex: Tripet et al. (2011) Am. J. Trop. Med. Hyg.
Sperm extracted from field-collected females and DNA amplified
Hypothesis: Male accessory gland (MAG) products of A. albopictus asymmetrically sterilize A. aegypti
Science 156: 1499-1501 (1967)
Experiment: 1. Inject MAG homogenates from conspecific or heterospecific males into unmated females of both species. 2. Allow post-injection females access to conspecific males in cages. 3. Assess insemination rates by spermathecal dissections
Results (Tripet et al. [2011] AJTMH 85) confirmed that the sterilizing effects of MAG extracts are asymmetric in their interspecific effects
Reproductive Character Displacement
= phenotypic evolution in a population caused by cross-species mating and which results in enhanced prezygotic reproductive isolation between sympatric species. (Grether et al. 2009, Biol. Rev. 84)
Hypothesis: Aedes aegypti which remain in sympatry with A. albopictus will evolve a mechanism(s) to avoid wasteful interspecific matings
Experiment: compare frequencies of interspecific matings in cages of allopatric vs. sympatric populations of the two species from the USA
Cage Trials of Interspecifc Matings between Populations 100
Mean (± SE) percentage of females inseminated
90 80 70 60 50
Females: A. aegypti Allopatric females
source χ2(1) female origin 25.3*** male origin 0.1ns female X male 0.1ns block(2) 30.9***
Sympatric females
Females: A. albopictus Allopatric females
source χ2(1) female origin 47.7*** male origin 3.0ns female X male 4.4* block(2) 1.3ns
Males: A. aegypti Ex Bargielowski et. al. (2013) PNAS
Percentage (± s.e.) of females inseminated
70 60
Allopatric populations of
50 40 30
KW
A. aegypti females exposed
KW control
to A. albopictus males evolve
20 10 0
resistance to interspecific mating in a few generations 70 60 50 40
Miami
30 20
Miami control
10 0
Bargielowski & Lounibos (2013) Evol Ecol
Factors contributing to competitive displacement and segregation of Aedes aegypti by Aedes albopictus
U N F A V O R A B L E
LARVAL COMPETITION
rural
SATYRIZ ATION
+
albopictus (invader)
C L I M A T E
HABITAT SEGREGATION
aegypti
albopictus & aegypti
(resident)
suburban
-
30° Ν
urban 1985
ARRIVAL & ESTABLISHMENT
L A T I T U D E
25° Ν
Natural History & Ecology of Life Stages in Florida • Eggs:
A. albopictus
A. aeg ypti
Desiccation-resistance of aedine eggs influences what habitats may be colonized. All species shown (3 included as ‘forest’) belong to the subgenus Stegomyia. Numbers refer to different geographic strains. (ex: Sota & Mogi 1992. Oecologia 90:353-358)
Aedes eggs, laid on tongue depressors
Depressors with eggs of each species in a screened vase
1.0
2001
A. aegypti A. albopictus
% Hatch (SE)
0.8
0.6
2006
***
***
0.4
*** **
0.2
0.0 2 weeks.
4 weeks.
2 weeks
4 weeks
Weeks of Exposure Lounibos et al. 2010 An. Entomol. Soc. Am.
