In the present study, the infectivity of the four entomopathogenic nematodes,
Steinernema glaseri, Steinernema carpocapsae, Steinernema riobrave and
Steinernema scarptasci on the earwig. Labidura riparia (Nymph and adult) was
studied under laboratory conditions. S. carpocapsae exhibited a high virulence
against the nymphs of L.riparia. On the other hand, S. scarptasci showed a higher
mortality rate to the L.riparia adults. The highest numbers of juveniles emerging from
infected insects (adult and nymphs) by nematode species S. carpocapsae were
38750 Is/adult and 20750 IJs/nymph. Using SDS-polyacrylamide gel electrophoresis
the whole body proteins fractionated into 19, 18, 13, and 15 bands when L.riparia
adult were infected by S.glaseri, S. scarptasci, S. riobrave and S. carpocapsae
,respectively. The most obvious observation was the complete disappearance of the
slow moving protein fractions (fractions number 14-17) in samples infected by S.
riobrave. Also, fractions 16-17 also disappeared in samples infected by S.
carpocapsae. On the other hand, the disappearance of some protein fractions was
accompanied with appearance of new fractions in samples of infected insects, i.e.,
fractions 18 and 19 in S.glaseri- infected insects. Most of these new protein fractions
were among the low molecular weight. The tested samples affected the molecular
weight, band percentage and protein content of the whole body profile protein. These
results suggested the tested four steinernematid species have side effect on the
predacious insect L.riparia (adults and nymphs), penetrates to its haemocoel causing
death 4-days post infection.