1. Maternal effects and performance of Delia platura (Diptera: Anthomyiidae) in a native and an introduced crop
Patricia C. Guerra Bustios1, Clifford Keil2, Phillip Stevenson1, Diego Mina3, Servio Samaniego3, Nelson Mazon3, Eduardo Peralta3 & Tim Chancellor1
1. University of Greenwich, 2. Pontifical Catholic University of Ecuador, 3. Instituto Nacional de Investigaciones Agropecuerias

2. Important insect pest in the highlands of Ecuador
Introduction
Seedcorn maggot, Delia platura (Meigen) (Diptera: Anthomyiidae)
Host location
Olfaction
Generalist
volatiles
- Seeds - seedlings
Cosmopolitan
- Decaying plant material
More than 50 hosts
Important insect pest in the highlands of Ecuador

3. Lupinus mutabilis Sweet (chocho) in Ecuador
Cultivated mainly in the Provinces of: Cotopaxi, Chimborazo and Cañar

4. Proteins
Fats

5. -Losses of 70-100% of crop at initial stages of growing (no control).
Damage:
-Losses of % of crop at initial stages of growing (no control).
-25% of crop lost with chemical control)
Cotopaxi, San Ramón

6. Brassica oleracea (broccoli) – Delia platura – Lupinus mutabilis relationship

7. It is not known whether D
It is not known whether D. platura females are preferentially attracted to L. mutabilis emerging seeds or B. oleracea residues or how D. platura larvae adapt to these two different hosts

8. ? OVIPOSITING FEMALE HOST CHOICE D. platura oviposition KNOWN HOST
(PREVIOUSLY EXPOSED) ?
D. platura oviposition
SUITABLE HOST
(BETTER DEVELOPMENT AND SURVIVAL)
MEDIATED BY VOLATILE SIGNALS

9. Quinolizidine alkaloids
LARVAE DEVELOPMENT IN HOSTS
(Chemical traits)
Glucosinolates
Quinolizidine alkaloids
M. Wink
Metabolism of sulfur containing compounds could be similar to those used by other insect pests (Burow and Wittstock 2008, Hopkins et al. 2009).
(1- 4% of dry weight)

10. Objectives
Evaluate the performance of Delia platura larvae on broccoli residues and germinating seeds of Lupinus mutabilis.
Evaluate the ovipositional preference of Delia platura for Brassica oleracea residues and Lupinus mutabilis germinated seeds, when exposed simultaneously to both stimuli under laboratory conditions.

12. Materials and Methods
INSECTS: Expt. Station Santa Catalina (INIAP) Quito, Ecuador
10 – 24°C and 12L:12D light regimen

13. Performance test Total life cycle Duration larva-pupa
10 repetitions
Total life cycle
Duration larva-pupa
Duration pupa-adult
Number of larvae
Number of pupae
Mean Pupal weight
Mean Pupal area 20
Eggs (diet)
B. oleracea (stems)
10 repetitions 20
Seeds L. mutabilis var
450 Andino

14. All these variables were tested for significance using a Student’s t-test for independent samples

15. Preference test - Olfactometer
Variable: Number of flies in each capture jar after 60 minutes
Fluxometer
Stimulus
Arena
Capture jar

16. Olfactometer Experiment
Preference test
Olfactometer Experiment
Larval host
Number adult flies
Repet.
Stimuli
Control
Total tested (N)
Chocho
germinating seeds 12 6
Chocho (germinating seeds)
Broccoli (residue)
Soil
Empty 72
Broccoli
Residue
Diet (Harris et al., 1966)

17. Statistical test
Simple multi-trial, chi-square analysis, using a null hypothesis of 1: 1: 1: 1 expected ratio of flies at each of the four ports. Each experiment was analyzed separately and then the aggregate data were analyzed against the null hypothesis using a heterogeneity G test based on the chi-square distribution.

18. Results

19. Performance Test Developmental time Survival Measures Broccoli Chocho
Total life cycle duration (days) 37.3 ± 6.8 a ± 3.2 b
Duration larva – pupa (days) ± 0.9a ± 0.9 b
Duration pupa-adult (days) ± 1.6 a ± 1.5 b
Number of larvae ± 4.6 a ± 2 b
Number of pupae ± 6.0 a ± 2.53 b
Number of adults ± 3.9 a 1.8 ± 1.6 b
Pupal weight (mg) ± a ± b
Pupal area (cm2) ± 0.01a ± a
Developmental time
Survival

20. Preference Test Larval host: Brassica oleracea
% of D. platura attracted by each of four stimuli
X2 (3, N = 72) = 28.86, p < 0.05

21. Larval host: Lupinus mutabilis Larval host: Diet
% of D. platura attracted by each of four stimuli
% of D. platura attracted by each of four stimuli
Not significant by X2 Heterogeneity analysis, p>0.05

22. Discussion

23. Performance: Pupal weight (mg) - Developmental time life cycle (days),
larva – pupa (days)
pupa-adult (days)
- Immature survival
Number of larvae
Number of pupae
Number of adults
Pupal weight (mg)

24. Mechanical barrier for recent hatched larvae
M. Wink (1992) : alkaloids are feeding deterrents for generalist insects
Hough-Goldstein: Microorganism pre-digested vegetable tissue making them more nutritious for larvae
Fiber content: 10% L. mutabilis seeds
Mechanical barrier for recent hatched larvae

25. Preference – Olfactometer Test
Delia platura fertilized females reared on broccoli were more attracted by broccoli residues than germinating chocho seeds.

26. SOIL MICROORGANISMS – PLANT DECOMPOSITION
PATTERNS OF OVIPOSITION OF THE SEEDCORN MAGGOT Delia platura
SOIL MICROORGANISMS – PLANT DECOMPOSITION
Seedborne organisms stimulate seedcorn maggot egg-laying (Eckenrode 1975)

27. MICROORGANISMS CAN BE IMPORTANT IN HOST LOCATION FOR OVIPOSTION IN THE ONION FLY, Delia antiqua (DIPTERA: ANTHOMYIIDAE)

28. CONCLUSIONS
Delia platura larvae had a higher survival and shorter development time in broccoli residue in comparison with germinating seeds of chocho. This could be attributed to the presence of alkaloids in seeds that deter larvae from feeding.
Fertilized female Delia platura reared on broccoli were more attracted to broccoli residue than germinating chocho seeds. Volatiles released during broccoli decomposition by soil microorganisms may be used as chemical cues for host finding.

29. Acknowledgments,
Francisco Baez, Patricio Gallegos, Jose Pinzon and Javier Silva
This work has been funded by the McKnight Foundation through the project “Apoyo a la seguridad alimentaria en comunidades de las provincias de Cotopaxi, Chimborazo y Cañar en Ecuador; a través de los cultivos de quinua, chocho y amaranto”.