Abstract

Entomopathogenic nematodes (EPNs) of families Heterorhabditidae and Steinernematidae are known to be effective against a variety of pests. In the present work, different EPNs that are isolated from the Egyptian environment were tested against the onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), under field conditions. The Egyptian EPNs were tested at different concentrations and against different onion thrips stages (adult and nymph). When used as a foliage spray, the tested EPN isolates were efficient against both adult and nymph stages. Differences in pathogenicity were observed within the same EPN species as in Heterorhabditis indica (EGAZ3) that caused higher reduction in population of T. tabaci (adult and nymph) after 24 and 48 h at a concentration of 10,000 infective juveniles (IJs)/ml compared to H. indica (EGAZ2) after 24 h post treatment at a concentration of 15,000 IJs/ml. The same pattern was observed with Heterorhabditis bacteriophora (HP88), where a higher reduction percent was recorded after 24 h at a concentration of 20,000 IJs/ml. On the other hand, Steinernema carpocapsae (All), S. carpocapsae (EGAZ9), and S. carpocapsae (BA2) isolates were less effective in controlling onion thrips (adult and nymph) population. In general, controlling T. tabaci at the nymphal stage was more efficient than at the adult stage (12–73% reduction at the nymph stage compared to 6–65% at the adult stage). It was also found that increasing inoculation concentration above 15,000 IJs/ml had no significant difference in controlling onion thrips populations.

Highlights

  • Onion, Allium cepa L. (Amaryllidaceae (Alliaceae), is an important cash crop in Egypt for local consumption and exportation

  • Onion plants are infested with different insect pests throughout their growing season (Mahmoud, 2008 and Diaz-Montano et al, 2011)

  • One of the major destructive pests of onion is onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), which feeds on onion plants during their vegetative growth and fruit filling (Mahmoud, 2008)

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Summary

Introduction

Allium cepa L. (Amaryllidaceae (Alliaceae), is an important cash crop in Egypt for local consumption and exportation. The efficiency of foliar application of several Egyptian EPN isolates was tested against the onion thrips under field conditions.

Results
Conclusion
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