The invasive fall armyworm S. frugiperda is considered nowadays
the most important dangerous insect pest on the main crops especially in
Egypt as it caused many losses to the Egyptian felid crops, this pest needs
more alternative control methods to avoid chemical control harms, in this
study, we have to estimate the virulence of two entomopathogenic
nematodes on larval and pupal stages of S. frugiperda under laboratory
conditions. Results indicated that mortality percentages of S. frugiperda
were very satisfied with using the two entomopathogenic nematodes
Steinernema carpocapsae and Heterorhabditis bacteriophora in controlling
FAW larvae and pupae. As S. carpocapsae and H. bacteriophora caused
high mortality percentages against the 4 larval instars of FAW, results
indicate that mortality percentages reached 100% after (48-120 h) posttreatment with five concentrations of S. carpocapsae (500, 1000, 1500, 2000
and 2500 IJs) against small larval instars (3rd and 4th) and after (72-120 h)
against older instars (5th and 6th) exposed to the same five concentrations.
Also, results indicated that S. carpocapsae caused faster mortality than H.
bacteriophora under laboratory conditions. After calculation of LC50 of the
two entomopathogenic nematodes against FAW larval instars; 3rd, 4th, 5th
and 6th after 72 h, LC50 were; 454.183, 546.029, 600.777 and 908.079 for S.
carpocapsae against the 4 larval instars, respectively, and 474.456, 552.126,
753.022 and 976.908 for the H. bacteriophora against the same four instars,
this results cleared that the statistical analysis showed that there were slight
or non-significant differences between the efficiency of the two EPNs in
combating the fall armyworm larvae under laboratory conditions. Also, both
EPNs were highly efficient in combating FAW pupae under laboratory
conditions. |
