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!