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Diapause syndrome on Gratiana boliviana
Rodrigo Diaz, Bill Overholt, Julio Medal, Stephen Hight, Amy Roda, Ana Samayoa, Jorge Rosales, Ben Anuforon, Ken Hibbard
Background on diapause
• Brazilian chrysomelids on Solanum– Report of diapause during dry winter season
in Brazil (23.18oS)– Hidden in the soil under stones, dead stems
and branches– Gratiana spadicea and Gratiana spp.
overwinter as sexually immature adults (28-30oS)
• Florida: G. boliviana– Numbers decrease during winter
Medeiros and Vasconcellos. 1994. Novel aspects of the biology of Chrysomelidae
Noguiera-de-Sa et al. 2004. New developments on the biology of Chrysomelidae
Brazilian chrysomelids on Solanum
Medeiros and Vasconcellos (1994) Novel aspects of the biology of Chrysomelidae
Populations decrease during winter - four months
Gratiana spadicea in S. Brazil
Insect seasonal cycle
Prediapause
Peridod
Diapause
Induction Period
Diapause Maintenance Period
Postdiapause transitional Period
Nondiapause
Period
Tauber and Tauber 1986
Insect seasonal cycle
Prediapause
Peridod
Diapause
Induction Period
Diapause Maintenance Period
Sensitive stage (s)
prediapuse stage(s):neuroendocrine changesincreased feedingaltered growth rateaccumulation of reserves
diapausing stage supression of metabolism supression of growth or reproduction seasonal polyphenism seasonal migration resistance to environmental extremes
Token stimulus
PDP DIP Diapause Maintenance Period Postdiapause Transitional
Period
Nondiapause
Period
Insect seasonal cycle
all symtoms of the diapause syndrome are fully developed
Phase 1-Phase 2 etc. of diapause maintenance by one or more token stimuli
thermal thresholds achieve nondiapuse levels
end of response to token stimuli
Token stimulus for diapause termination
overt manifestation (s) of development development resumes diapause color disappears cold hardiness reducedincreased metabolism
Token stimulus Non-Token factors
Quiescence can intervene
Objectives
• Monitor population dynamics in St. Lucie Co.
• Determine the sensitive stage for diapause induction
• Determine the critical day-length for diapause induction
Population dynamics
Population dynamics
• Methodology– Transect for
demographic parameters
– Random collection of individuals in the hammock for dissections
Population dynamics
Gratiana population decreases during fall, few larvae and pupae
Population status
8/20/2007
9/3/2007
9/17/2007
10/1/2007
10/15/2007
10/29/2007
Col
or
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Per
cent
age
of R
epro
duct
ive
fem
ales
10
20
30
40
50
60
70
80
90
Males Females Percentage
No clear pattern in coloration up to Oct.26
Yellow
Deep green
Pale green
New green
Females
New-pale green
Deep green with yellow linesNote Fat Body
These conditions were associated with reproductively active females
Males
Testis
Accessory glandNew Mature
Winter sampling
Hypothesis: Beetles migrate to organic matter below plant
Trays containing dry TSA
Mark, recapture
Diapause Induction
Diapause Induction-Photoperiod
• Materials & Methods– Eggs, L1, L3, L5, pupae and adults placed in growth
chambers set at 25C, 60% RH– Two conditions: long days 14h and short days 10h
of light– Immatures reared on TSA; one week after adult
emergence, couples were placed on TSA bouquets for 20 days
– Variables measured: oviposition and several internal structures
Diapause Induction-Photoperiod
TSA bouquet
Diapause Induction-Photoperiod
TRT Color Fat BodyDigest system
Hind
wingsMating
Female Male
Weight
mgOocytes
Weight
mgTestis+AG
14:10
L:DFull + + 22.2 17.03
Rounded
10:14
L:DMinimal - - 20.64 17.37
Irregular
Diapause Induction-Photoperiod
0
10
20
30
40
50
60
70
80
Pupae Long Pupae Short Adult Long Adult Short
To
tal
eg
gs
in
30
da
ys
Adults transferred from pupaedid not lay eggs
Adults transferred from adultlaid few eggs at the beginning of the experiment, no eggs were present after 30 days
Digestive System-Diapause
Diapause Induction-Photoperiod
• Preliminary results– Diapause was induced at 25oC and 10 hours
of light– Adult is the sensitive stage for diapause
induction– Recommendation for winter colony
maintenance: keep adults under 14h of light
Interaction of temperature and photoperiod
Temperature X Photoperiod
• Materials and Methods– 15 couples– Photoperiod: 10, 11, 12, 13, 14 hours of light– Temperature: 15, 25, 28, 31, 34oC– Variables measured: % of females in
diapause after 20 days– Estimation of critical day-length
• 50 % of population enters diapause
Temperature X Photoperiod
• Results from 15oC– None of the individuals laid eggs nor presented
diapause symptoms – Temperature was too cold for sexual
maturation or accumulation of fat body– TSA plants showed few signs of damage
• Ongoing experiment 25oC
Estimation of critical day-length
1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1
Month of the year
1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1
Day
-leng
th
10:00
10:30
11:00
11:30
12:00
12:30
13:00
13:30
14:00
Better estimation of Gratiana population dynamics in southeastern USA
Critical day length?
100% reproductive
100% diapause
Conclusions so far
• Population of overwintering adults is critical
• Gratiana overwinters as non-reproductive adult
• Adult is the sensitive stage for diapause induction
• Fourteen light hours will ensure an active colony
Insect seasonal cycle
Prediapause
Peridod
Diapause
Induction Period
Diapause Maintenance Period
Sensitive stage (s)
prediapuse stage(s):neuroendocrine changesincreased feedingaltered growth rateaccumulation of reserves
diapausing stage supression of metabolism supression of growth or reproduction seasonal polyphenism seasonal migration resistance to environmental extremes
Token stimulus
PDP DIP Diapause Maintenance Period Postdiapause Transitional
Period
Nondiapause
Period
Insect seasonal cycle
all symtoms of the diapause syndrome are fully developed
Phase 1-Phase 2 etc. of diapause maintenance by one or more token stimuli
thermal thresholds achieve nondiapuse levels
end of response to token stimuli
Token stimulus for diapause termination
overt manifestation (s) of development development resumes diapause color disappears cold hardiness reducedincreased metabolism
Token stimulus Non-Token factors
Quiescence can intervene
The database is back!!!... whenthe winter starts….
Thanks to all of you for support and beetles!Special thanks to Jackie and Larry Markle for
helping in the project!