Abstract
The present study has documented, for the first time in Egypt, the natural occurrence of four entomopathogenic protozoans (EPP) among five of the most abundant and damaging insect pests of stored grains or their products. These insect pests (Laemophloeus (Cryptolestes) turcicus (Grouvelle), Rhyzopertha dominica (Fabricius), Sitophilus zeamais (Motschulsky), Tribolium castaneum (Herbst), and Plodia interpunctella (Hobner) were infesting lots of crushed-maize grains, wheat grains, and wheat flour, brought, in 2015, from El-Behera Governorate, Egypt. The morphological characteristics, including spore size, of the entomopathogen infective units, spores, of the isolated entomopathogenic protozoans, were closely fit with the description to the following genera: Mattesia, Farinocystis, Adelina, and Nosema. The prevalence of these entomopathogens ranged between 9 and 89%. This study seems to be the first report of Mattesia sp. on S. zeamais; Adelina sp. on L. turcicus or R. dominica, and the second report of Nosema sp. on R. dominica. The rate of natural infection by the neogregarine, Mattesia sp. (tentatively, M. dispora), was the highest in L. turcicus beetles (89%) followed by that in P. interpunctella moths (48%), larvae (40%), and pupae (32%) and then in S. zeamais weevils (42%) and R. dominica beetles with a low rate of infection (9%). The microsporidian entomopathogen, Nosema sp., (tentatively, N. whitei) was naturally occurred in 11% of the examined adult cadavers of R. dominica. The coccidian entomopathogen, Adelina sp., was found, respectively, in 60% and 27% of larval and adult cadavers of T.castaneum, while the Adelina-natural infection rates in R. dominica and L. turcicus adult cadavers were 34% and 14%, respectively. A high rate of natural infection with another neogregarine, Farinocystis sp. (tentatively, F. tribolii), has also been recorded in T. castaneum adult (50%) or larval cadavers (36%).
Highlights
Stored products as a unique habitat, present a prime opportunity to use entomopathogenic protozoans (EPP) by distributing infective quantities of the entomopathogen
The coccidian entomopathogen, Adelina sp. (Fig. 4), was found, respectively, in 60% and 27% of larval and adult cadavers of T. castaneum, while the Adelina-natural infection rates in R. dominica and L. turcicus adult cadavers were 34 and 14%, respectively (Table 1)
This study provides a clear evidence that the isolated Mattesia sp. has a relatively broad host range that crosses two orders, Coleoptera and Lepidoptera, which include many damaging storedgrain insects (Lord 2003, 2006)
Summary
Stored products as a unique habitat, present a prime opportunity to use entomopathogenic protozoans (EPP) by distributing infective quantities of the entomopathogen. Controlling stored-product insect pests may be most beneficial in long-term storage since such EPP produce slow-acting chronic infection. They may cause a reduction in host vitality, feeding, fecundity, longevity, and survivorship (McLaughlin 1971; Khan and Selman 1989; Flinn and Schöller 2012; Ramanujam et al 2014). Weiser et al (1976) recorded promising examples for certain entomopathogenic protozoans that cause reductions in storage insect pests. Attempts to use entomopathogenic protozoans for microbial control of stored product insect pests are few. Insect pests of stored grains and their products are among
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