Field dispersal of the parasitoid wasp Habrobracon hebetor (Hymenoptera: Braconidae) following augmentative release against the millet head miner Heliocheilus albipunctella (Lepidoptera: Noctuidae) in the Sahel

Abstract

Pearl millet is one of the major staple food crops in Sub-Sahelian Africa, and the millet head miner (MHM) [Heliocheilus albipunctella] is its major pest, causing serious economic damage in the maturity period. We studied the dispersion patterns of the endogenous ectoparasitoid, Habrobracon hebetor (Hymenoptera: Braconidae), after augmentative releases in pearl millet fields for biological control of the MHM, in 2010 and 2011 in Burkina Faso and Niger. The parasitoids were released using 15 jute bags per release site. Parasitoid dispersion was indirectly monitored through weekly assessments of MHM parasitism by H. hebetor at different distances from release points (0, 3 and 5 km) and in control villages (15 km). Our findings indicate that the jute bags released approximately 900-1000 parasitoids per site over a period of three weeks. This initial parasitoid population led to higher parasitism of MHM larvae at the site of dissemination compared to farms at distances of 3 and 5 km. However, usually after five weeks, successive generations of H. hebetor dispersed up to 3 km, causing high levels of MHM larval mortality, which sometimes is similar to those of the release points. Based on these results, we recommend the release of parasitoids at sites spaced 3 km for timely and more efficient control of MHM populations.

Timing of releases of the parasitoid Habrobracon hebetor and numbers needed in augmentative biological control against the millet head miner Heliocheilus albipunctella

“…This is lower than the typical infestation rate observed in the region Amadou et al 2017). As a consequence, the releases of H. hebetor lead to only 35% parasitism of MHM larvae compared with over 70% to 90% parasitism reported in previous studies (Ba et al 2014;Baoua et al 2014Baoua et al , 2018. This could be due to reduced parasitoid searching efficiency caused by low host density, observed in other settings (Sivinski et al 1996;Montoya et al 2000).…”

“…Given the prohibitive cost for producing the parasitoid (Amadou et al 2019) one could recommend the use of 800 parasitoids. As suggested by Baoua et al (2018) the release of 900-1000 parasitoids can disperse over a distance of 3 km from the release point within 2-3 weeks. This could be seen low as compared to numbers involved in augmentative releases of Trichogramma spp.…”

“…Biological control has emerged as the most attractive solution for controlling the MHM and the gregarious parasitoid Habrobracon (= Bracon) hebetor Say (Hymenoptera: Braconidae) is considered a natural enemy with great biocontrol potential (Gahukar et al 1986;Bhatnagar 1987). Recently, augmentative releases of H. hebetor have been successful against the MHM in Niger (Payne et al 2011;Ba et al 2013Ba et al , 2014Baoua et al 2014Baoua et al , 2018. This has led to parasitism of up to 80% of the MHM larvae (Ba et al 2013(Ba et al , 2014, resulting in 34% increase in grain yield .…”

Towards development of a parasitoid cottage industry of the parasitoid wasp Habrobracon hebetor (say): optimum rearing and releases conditions for successful biological control of the millet head miner Heliocheilus albipunctella (De Joannis) in the Sahel

“…Even though H. hebetor mass cultured on C. cephalonica has been successfully used for augmentative releases against the MHM in the Sahel (Kabore et al 2017;Baoua et al 2018), the field fitness of the parasitoid derived from the new proposed rearing method need to be further investigated. As indicated in other settings, rearing conditions can affect field performance of released parasitoids (Collier and Steenwyk 2004;Gandolfi et al 2003;Bloem et al 2004;Joyce et al 2010;Sepúlveda et al 2017).…”

Potencial do ectoparasitoide >i<Habrobracon hebetor>/i< Say, 1857 (Hymenoptera: Braconidae) para controle biológico de treze espécies de lepidópteros-praga

“…Em outros países, liberações do parasitoide H. hebetor, visando ao controle biológico de pragas em campo, foram realizadas com sucesso, como no Irã, para o controle de Helicoverpa armigera (Hübner, 1809) (Lepidoptera: Noctuidae), e na Índia, para o controle de Opisina arenosella (Walker, 1864) (Lepidoptera: Xylorytidae) (MOHANTY et al 2000;DESAI et al 2007). Estudos mais recentes avaliaram a capacidade de H. hebetor em campo para o controle de Heliocheilus albipunctella (de Joannis, 1925) (Lepidoptera: Noctuidae) na região de Sahel, na África, com significativa diminuição da praga (BA et al 2013;KABORE et al 2017;BAOUA et al 2018). No Brasil, H. hebetor tem sido utilizado para controle de Ephestia elutella (Hübner, 1796) (Lepidoptera: Pyralidae) em armazéns de fumo (PARRA, 2014a).…”