Obligatory and facultative diapause responses in Rhagoletis cerasi and associated costs

Transcription

1 Obligatory and facultative diapause responses in Rhagoletis cerasi and associated costs Nikos Papadopoulos, Cleopatra Moraiti and Stela Papanastasiou Laboratory of Entomology and Agricultural Zoology University of Thessaly, Greece

2 Synopsis Biology and ecology of the European cherry fruit fly Geographic distribution Life cycle Dormancy, diapause and prolonged dormancy Variability in diapause and prolonged dormancy Cost of prolonged dormancy Morphological traits of cherry fly pupae and prolonged dormancy Conclusions

3 Terms Dormancy. A generic term covering any state of suppressed development (developmental arrest) or suspended activity. May include both diapause and quiescence Diapause. Endogenously- and centrally-mediated interruption of ontogeny that routes the developmental programme away from morphogenesis or sexual maturation into an alternative diapause programme. Obligate facultative Quiescence. Immediate response (without central regulation) to a decline of any limiting environmental factor below the physiological thresholds with immediate resumption of the processes if the factor rises above them. Bed hedging. Life history patterns that reduce variance in fitness. The proverb "Don't put all eggs in one basket" describes a bed-hedging strategy Prolonged dormancy. Longer than typical dormant period

4 Rhagoletis cerasi So far the most important pest of cherries and sour cherries in Europe and elsewhere Stenophagous species Direct effects of larvae feeding coupled with fungi and bacterial infections At early stages of infestation hard to separated infested fruits.

5 Geographic distribution

6 Response of cherry fly to adverse field condition Long dormancy diapause and quiescence Adaptive and plastic responses Dispersion immigration Adult flight

7 Scope Adaptive and plastic components of R. cerasi dormancy Focus on prolonged dormancy and determine possible associated costs Morphological stages of dormant pupae

8 Avg adults per trap ± SE Adult population trends Yellow sticky Rebell 4 24/3 3/4 3/5 23/5 2/6 Dates 26 2/7 22/7 /8

9 Variation in diapause termination Adaptation in diapause responses Highland Highland

10 Prolonged dormancy

11 Proportion of pupae,8,6,4,8,6,4,8,6,4,8,6,4.8,8.6,6.4,4.2 Dossenheim Dafni K. Nera o C 45 o C o C o C,8,6, o C ,8.6,6.4, Diapause termination Αποτελέσµατα περάτωσης διάπαυσης,8,6,4,8,6,4,8,6,4 o C o C,8,8,6,6,4, o C o 5 C ,8,8,6,6,4, o C 8 o C ,8,8,6,6,4, o C o C ,8,8,6,6,4, o C 2 o C ,8,8.6,6,6.4,4, Chilling period (months) Adult Alive pupae Dead pupae Delay in diapause termination Peak of adult yielding 4-5 months for K. Nera 5 6 months for Dafni and Dossenheim: High proporton of diapause termination only in K. Nera No diapause termination

12 Proportion of overlaying pupae during cold storage at 5 o C

13 Description of Rhagoletis cerasi pupal developmental stages; Indications of prolonged diapause Stella Papanastasiou and Nikos Papadopoulos

14 Progress of pupae development Pupae maintained at 25oC for 3 mo. at 3oC for 7 mo. and back at 25oC Pupae dissected under a stereomicroscope

15 Proportion of pupae at a transitional stage of development

16 Scenarios of Rhagoletis cerasi pupae development

17 Next question What is the role and the characteristics of adults emerging form pupae following a prolonged life cycle?

18

19 Methods = + Ceresin (Dome 8 mm) Common garden experiments 25 ± o C, RH 65 ± 5 %, 4: (L:D) We recorded Egg laying Age at death and adult size 33-5 επαναλήψεις

20 Adult size A Thorax length (mm ± SE) Thorax width (mm ± SE),6.6,5.5,4.4.3,3 Males,8.8,7.7,6.6,5.5,2,4 Adults obtained from,4.4 Mikra Kernitsa,5.5 Mikra,3.3,2.2 B Females prolonged dormancy are,4.4 larger,3.3 than Kernitsa.,.2,2 counterparts emerging from,, year Mikra cycle Kernitsa Mikra Kernitsa,5.5.6,6 Head width (mm ± SE),4.4,3.3.2,2, Macedonia Mikra Peloponnesus Kernitsa.5,5.4,4.3,3,2 Macedonia Mikra Peloponnesus Kernitsa

21 Average longevity Population/ Type of dormancy Ν Males Longevity (days ± SE) Females Macedonia annual ± ± 3. prolonged ± ± 4.2 Peloponnesus annual ± ± 2.7 prolonged ± ± 3.6

22 A 6 annual B6 annual Age specific and average rates eggs / female prolonged Age (days) Population/ Type of dormancy eggs / female prolonged Age (days) Reproductive rates (eggs per female) Average Gross!!! Macedonia annual ± prolonged 9.9 ± Peloponnesus annual 32.2 ± prolonged 9.5 ± !!!!

23 Conclusions There is variability in diapause intensity among geographically isolated R. cerasi populations Both low and high temperatures seem to inhibit diapause termination, inducing higher mortality rates and promoting prolonged dormancy. Temperature and chilling period affect the proportion of pupae following prolonged dormancy Dormancy is associated with pupae stage I and it seems pupae can follow two radically opposite developmental directions. Prolonged pupae dormancy in R. cerasi is associated with larger body size of adults, and conveys significant fitness costs to specific aspects of adult life.

24 Acknowledgements Christos Nakas, University of Thessaly Alex Diamanditis, University of Thessaly Kostas Bourtzis, University of Patras, IAEA Antonis Augoustinos, University of Patras, IAEA Penelope Mavragani, Aristotle University of Thessaloniki Eleni Drosopoulou, Aristotle University of Thessaloniki Heidrun Vogt, Julius Kühn-Institut (JKI) Kirsten Koppler, Referentin für Pflanzenschutz im Obstbau Funds provide by European Community University of Thessaly Greek Ministry of Education and Religious Affairs IKYDA