Malick Ba 1, Baoua I., Amadou L., Kabore A., Ndiaye M., Karimoune L., Sarr I., Dabire L.C., Muniappan R. ICRISAT-Niger,

Transcription

1 Biological control of insect pests by augmentative release of parasitoids: case study of the millet head miner and the parasitoid wasps Habrobracon hebetor in West Africa Malick Ba 1, Baoua I., Amadou L., Kabore A., Ndiaye M., Karimoune L., Sarr I., Dabire L.C., Muniappan R. 1 ICRISAT-Niger, b.malick@cgiar.org

2 The pest: the millet head miner Heliocheilus albipunctella is a univoltine species Female laid eggs on the spikelet and floral peduncles of newly exerted pearl millet heads Developing larvae feed on the spike They chew between the rachis and flowers and cut floral peduncles,

3 The pest: the millet head miner As the larvae developed, they lift the destroyed flowers or developing grains, leaving a characteristic spiral pattern on the millet head. Damage to the crop is due to larvae that feed on the panicle and prevent grain formation. Typical yield losses range from 40 to 85% Almost every year, the MHM causes significant damage to pearl millet in the Sahel region

4 Why biological control of the Millet head miner? Other control means are either not applicable or inefficient Effective biocontrol agents are available The braconidae parasitoid wasp Habrobracon (=Bracon) hebetor Say naturally inflicted significant mortality to MHM. H. hebetor can be easily mass reared

5 The biocontrol agent: Habrobracon hebetor It is a minute parasitic wasp of the Braconidae family H. hebetor is a larval ectoparasitoid of several species of pyralids Stored product insects: Plodia interpunctella, Cadra cautella, Ephestia kuehniella; Corcyra cephalonica; Sitotroga cerealella Olivier, Galleria mellonella. Field insect pests: Helicoverpa armigera; Spodoptera species; Earias vittella; Maruca vitrata; Diatraea saccharalis; Cydia leucostoma; Pempelia morosalis; Opisina arenosella, Ectomyelois ceratoniae, Palpita unionalis, Heliocheilus albipunctella

6 H. hebetor against MHM : mass rearing of parasitoids Colony of H. hebetor are established and maintained in the laboratory on an alternate host, the rice moth Corcyra cephalonica C. cephalonica is reared on a mixture of millet flour and millet grains and the parasitoids were reared on third and fourth instar C. cephalonica larvae The subsequent generation of H. hebetor emerged 7 14 days after confinement of female parents with C. cephalonica larvae.

7 H. hebetor against MHM : Releases of parasitoids The parasitoids are released from small jute bags containing a mixture of millet grains and flour together with 25 larvae of C. cephalonica, and 2 mated H. hebetor females. The 2 females then parasitize the 25 C. cephalonica host larvae, and emerging progeny escape through the jute mesh and disperse to parasitize MHM larvae in millet fields.

8 H. hebetor against MHM : Releases of parasitoids The jute bags are suspended to the ceiling of traditional straw granaries or directly attached to trees within pearl millet fields. A number of 15 parasitoid bags are used for coverage of a 5 km 2 area of pearl millet.

9 H. hebetor against MHM : Releases of parasitoids Daily emergence of parasitoid from jute bags: Initial population 30 Total: 70 parasitoïds No emerging parasitoids Days after bags are placed Ba et al. (2014): Biocontrol 59,

10 H. hebetor against MHM : Releases of parasitoids Projected numbers of parasitoid produced from Initial population 1600 Burkina Faso Niger No H. hebetor females ('000) No days after parasitoid bags are placed

11 H. hebetor against Millet head miner

12 H. hebetor against MHM : Effectiveness H. hebetor releases villages Control (no releases) % Parasitized head miner larvae Burkina Faso Mali Niger Burkina Faso Mali Niger Ba et al., 2013: Phytoparasitica 41,

13 H. hebetor against MHM : Effectiveness A Parasitoid H. hebetor bags releases directly villages placed within millet crop Control (no parasitoid released) A % parasitized head miner larvae B Years B Ba et al., 2014: Biocontrol 59,

14 H. hebetor against MHM : Effect of 2 successive releases Kabore et al., 2017: Biological control 108, 64-69

15 H. hebetor against MHM: Persistance of parasitoids No. MHM larvae parasitized per spike Release Control Year Kabore et al., 2017: Biological control 108, 64-69

16 H. hebetor against MHM: Parasitoids dispersal % head miner larvae parasitized by H. hebetor No days after parasitoid bags are placed Baoua et al., 2017:to be submitted

17 H. hebetor against MHM: Yield gain 30% yield gain Damaged spike Saved spike Baoua et al 2013: Journal Applied Entomology 138,

18 H. hebetor against FAW: Is it feasible? L. Amadou L. Amadou L. Amadou

19 Conclusion H. hebetor has a rapid development time H. hebetor has a high rate of population growth H. hebetor mass rearing is easy and quit cheap Effective releases techniques for H. hebetor are available

20 Thank You