Combination of <i>Bacillus thuringiensis</i> and <i>Habrobracon hebetor</i> for the biological control of <i>Plodia interpunctella</i>

  • R. O. Akinkurolere Laboratory of Food Storage Technology, Biology Department, Federal University of Technology, P. M. B. 704, Akure, Nigeria.
  • H. Zhang Institute of Urban Pests, and Hubei Key Laboratory of Insect Resource Application and Sustainable Pest Control, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, Hubei, P. R. China. Email: hongyu.zhang@mail.hzau.edu.

Abstract

In this paper, we review our work on biological control of Plodia interpunctella (Hubner) (Zhang et al., 1995) in our laboratory over the years. We isolated, screened and evaluated Bacillus thuringiensis strains collected from warehouses against P. interpunctella and determined the lethal concentration for 50% of the population (LC50) of highly toxic isolates and compositions of crystal proteins and the genotypes of these isolates; evaluated the role of host-instar and refuge on the parasitization behavior of Habrobracon hebetor Say (Hymenoptera: Braconidae); investigated the effect of combining B. thuringiensis with H. hebetor for management of P. interpunctella infestation and assessed the influence of B. thuringiensis on H. hebetor during this combination treatment. The results showed that three strains of B. thuringiensis (IMM130, IMM368 and IMM408) were highly toxic to P. interpunctella among 122 B. thuringiensis isolates obtained from 413 field samples (Zhang et al., 2000a); Isolate IMM408 with LC50 1.24 μg/g diet, was most potent
(Akinkurolere et al., 2007). It belongs to H7 serotype and contains ~135kDa crystal proteins and cry1Ab9, cry1Ca1, cry1Da1 and cry2 genotypes (Zhang et al., 2000b). It was observed that H. hebetor could parasitize all larval stages of P. interpunctella, but significantly fewer first and second instars were parasitized under choice and no-choice conditions (Akinkurolere et al., 2009a). Parasitized fourth instars were more profitable to H. hebetor irrespective of refuge or choice factors, as significantly more adult parasitoids emerged from host instars. Therefore, H. hebetor females consistently showed high preference for late instars of P. interpunctella when they were offered a choice between early and late host instars. Refuge significantly hindered H. hebetor from locating the early instars, but not the late instars (Akinkurolere et al., 2009a). Bacillus thuringiensis-parasitoid combination treatment significantly evoked more P. interpunctella mortality than either treatments (B. thuringiensis or parasitoid) when used singly (Akinkurolere et al., 2009b). Bacillus thuringiensis or H. hebetor alone caused 42% and 35% P. interpunctella larval mortality, respectively. The B. thuringiensis-parasitoid combination treatment significantly evoked more P. interpunctella mortality (86%) than other single treatments. Progeny development of parasitoid wasp was dependent upon its susceptibility to B. thuringiensis contaminated hosts. H. hebetor was able to successfully complete its development on the hosts although, fewer wasps emerged from B. thuringiensis-parasitoid combined treatment than in none B. thuringiensis treatments (Akinkurolere et al., 2009b). H. hebetor showed positive response to acetone and hexane extracts from frass and larvae of P. interpunctella, and the active compounds are mostly hydrocarbons (unpublished data).

Keywords: Bacillus thuringiensis, Habrobracon hebetor, Plodia interpunctella, Pest management, Parasitoid.
Veröffentlicht
2010-09-02