Susceptibility of immature stages of the locustsSchistocerca gregariaandLocusta migratoria migratorioidesto the microsporidiumJohenrea locustaeand effects of infection on feeding and fertility in the laboratory

Abstract

Ouna (2008) Susceptibility of immature stages of the locusts Schistocerca gregaria and Locusta migratoria migratorioides to the microsporidium Johenrea locustae and effects of infection on feeding and fertility in the laboratory, Biocontrol Science and Technology, 18:9, 913-920, Second instar nymphs of African migratory locust, Locusta migratoria migratorioides, and desert locust, Schistocerca gregaria, were tested for their susceptibility to the microsporidium pathogen Johenrea locustae (Lange et al. 1996, Journal of Invertebrate Pathology, 68, 28) in the laboratory. Spores of J. locustae were produced from live L.m. migratorioides, a conspecific to L. migratoria capito. Locusta m. migratorioides and S. gregaria were exposed to wheat seedlings sprayed with 20 mL of three concentrations (10 6 , 10 7 and 10 8 spores mL (1 ). Both second-instar nymphs of L.m. migratorioides and S. gregaria were susceptible to J. locustae infection at the three concentrations. There was no effect of concentration of the microsporidium on mortalities of S. gregaria (92Á98%) 19 days postinfection. Adjusted mortality in L.m. migratorioides at 19 days postexposure was 24, 43 and 80% at the corresponding treatment concentrations. The effect of infection on fecundity was tested on both L.m. migratorioides and S. gregaria. Spinach leaf discs were treated with different concentrations (0, 10 4 , 10 5 and 10 6 spores mL (1 ) of J. locustae and presented to female insects for 24 h. Female L.m. migratorioides surviving infection as nymphs laid significantly fewer egg pods than untreated controls at all levels of exposure. The number of eggs per female was also significantly lower in treated lots than in the controls. Higher spore concentrations also adversely affected egg hatching rate. The effect of J. locustae infection on feeding was tested on S. gregaria. There was a significant decrease in food intake among S. gregaria nymphs treated only at the high concentration (10 6 spores mL (1 ).

Safety of frozen and dried formulations from migratory locust (Locusta migratoria) as a Novel food pursuant to Regulation (EU) 2015/2283

“…During farming, L. migratoria can be infected by pathogens, including bacteria, viruses, entomopathogenic fungi, microsporidia and protists (Eilenberg et al., 2015). Pathogens that may affect L. migratoria include the virus Cricket iridovirus (CrIV) (Kleespies et al., 1999), the fungus Metarhizium acridum (Eilenberg et al., 2015) and a microsporidium named Paranosema locustae (Maniania et al., 2008). Literature review conducted by the applicant highlighted that these pathogens are specific at species or family level, and non‐pathogenic for humans or other vertebrates.…”

Diseases in insects produced for food and feed

“…A common clade of Microsporidia includes the genera Nosema and Vairimorpha. Paranosema locusta is a well-known pathogen of L. migratoria mostly present as a chronic disease but also resulting in mortality of the host or resulting in lower fitness upon experimental infections (Maniania et al, 2008). P. locusta has proven an interesting interaction with fungi: at the phase of spore maturation of P. locusta in locusts, the insects became more susceptible to infections by the fungus M. acridium (Tokarev et al, 2011).…”