Factors affecting the natural occurrence of some insect biocontrol agents in cultivated soil in Ismailia Governorate.
El-Adawy A. M., El-Barogy E. S., Naiem M. H. S., Essa M. A. A., El-Hamawi M. H., El-Sharkawy T. A.
Author Affiliation: Plant Protection Research Institute, Agricultural Research Centre, Dokki, Giza, Egypt.
Egyptian Journal of Agricultural Research 79 : 419-430
Abstract : The occurrence of biological control agents in soil samples collected from fields in Egypt (Ismailia, Fayed, El-Tall El-Keeber, Quantra East, and Quantra West) cultivated with vegetable (okra, cabbage, tomato, pepper [Capsicum annuum], cucumber, and strawberry), field crops (maize, groundnut, cotton, sesame, wheat, and berseem [Trifolium alexandrinum]), and fruit trees (mango, citrus, and olive) was studied in 1999. The biological control agents were detected in 24.07% of soil samples collected at a depth of 5.0 cm, 53.8% of which was collected under fruit trees (mainly mango), 30.8% under field crops, and 15.45% under vegetables. Entomopathogenic fungi occurred at 19.12% and entomoparasitic nematodes at 69.78%. Beauveria bassiana occurred in all districts except El-Tall El-Keeber at a frequency of 8.4%. Metarhizium anisopliae, which occurred at a frequency of 10.8%, was absent in Ismailia and Fayed samples. The entomoparasitic Heterorhabditis spp. infected with Fusarium spp. were found in all districts at 59.7%. The reduction in the growth of B. bassiana was 92.2-96.5% due to sethoxydim, thiophanate-methyl, diniconazole, profenofos, pirimifos-methyl, and fenamiphos, and 72.2-83.3% due to penconazole, metalaxyl, haloxyfop, metribuzin, fentin acetate, and carbofuran. The least inhibition was recorded for sulfur (55.6%) and robigan (42.7%). Thiophanate-methyl, fentin acetate, metribuzin, and carbofuran showed the greatest inhibition (91.1-94.4%); penconazole, haloxyfop, fenamiphos, diniconazole, and profenofos lesser inhibition (72.2-77.7%); and pirimiphos-methyl, robigan, and sethoxydim the least inhibition (34.2-66.0%) of M. anisopliae. Profenofos and pirimiphos-methyl inhibited the nematodes by 90.3-94.6%. The population of B. bassiana was high in soil rich in organic matter. M. anisopliae was most frequent in clay soil. Nematodes were less frequent in clay soil.