Effect ofParanosema (Nosema) locustae(Microsporidia) on morphological phase transformation ofLocusta migratoria manilensis(Orthoptera: Acrididae)

Status of the alien pathogenParanosema locustae(Microsporidia) in grasshoppers (Orthoptera: Acridoidea) of the Argentine Pampas

“…It develops slowly (normally 2Á3 weeks before producing significant amounts of propagules, the spores) and causes a debilitative, chronic type of disease in susceptible hosts. Demonstrated effects of P. locustae on hosts include increase of mortality rates, reduction of fecundity and longevity, delay in development, decrease of activity, reduction of food consumption, changes in pigmentation, flying inability or difficulties and disruption of aggregation behaviour and morphological phase transformation (Henry and Oma 1981;Johnson 1997;Shi and Njaqi 2004;Fu, Hunter, and Shi 2010). In 1978Á1982 and 1996, P. locustae was introduced from North America at several grasshopper-affected localities in Argentina.…”

Microsporidia Biological Control Agents and Pathogens of Beneficial Insects

“…P. locustae infection is best characterized as a chronically debilitating disease associated with reduced feeding, development, and fecundity, in addition to increased mortality rates (Canning 1962;Henry & Oma 1974;Ewen & Mukerji 1980;Johnson & Pavlikova 1986). Sublethal infections in locusts were associated with a shift from the gregarious form to the less damaging solitary phase (Fu et al 2010). The pathogen mainly infects adipocytes of fat bodies, disrupting metabolism and energy storage.…”

Effect ofParanosema locustae(Microsporidia) on the behavioural phases ofLocusta migratoria(Orthoptera: Acrididae) in the laboratory

“…In the field, spraying P. locustae on gregarious-phase locusts led to locusts changing their aggregation behaviour within 10 days after treatment (Shi et al, 2000). Further studies showed that when gregarious locusts were treated in the field, females had a substantial increase in the F/C ratio within 10 days, and both sexes had a further increase in the F/C ratio by 16 days such that most of the infected locusts were then in the solitary phase (Fu et al, 2010). It is important to know how the pathogen disrupts the behavioural functions of locust by an analysis of some behavioural changes after infection with the pathogen, which may reveal sub-lethal effects of P. locustae in addition to the direct effects on host mortality.…”

“…Solitary locusts are light in colour and have narrow bodies, while gregarious locusts are darker in colour (during the nymphal stage) and are broader and larger (Byers, 1991). The broader, larger gregarious-phase locusts have a lower F/C ratio (ratio between the length of hind femur and the width of the head), and this F/C ratio has been used for quantitative measurement of the differences between locusts (fourth instar or older) in different phases (Deng et al, 1996;Fu et al, 2010). However, the most labile phase characteristic is behaviour: the solitarious-phase insects are shy and cryptic, occurring at very low densities, and they tend to avoid each other except to mate (Simpson et al, 1999).…”