Role of Parasitoid Species and Insecticides in Controlling Populations of Beet Moth in Sugar Beet Fields

Document Type : Original Article

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Plant Protection Research Institute, Agricultural Research Center, Dokki, Giza, Egypt.

Abstract

During 2020/2021 and 2021/2022 seasons, sugar beet leaves and infested necks with the beet moth, Scrobipalpa ocellatella Boyd. (Lepidoptera: Gelechiidae) were collected from untreated fields with insecticides at Sakha Agricultural Research Station, Kafr El-Sheikh Governorate. Four hymenopterous parasitoids were recorded from larval–pupal stages of this insect in Egypt. These were Agathis sp. (Braconidae); Alysia sp. (Braconidae); Diadegma oranginator Aub. (Ichneumonidae); and for the first time, Eurytoma sp. (Eurytomidae). Parasitism (%) by these parasitoid species was 12.29 ± 0.10, 12.39 ± 0.30, 27.54 ± 2.11 and 24.30 ± 2.01 in the first season and were 11.04 ± 0.22, 9.79 ± 0.31, 21.92 ± 3.21 and 14.31 ± 2.22 in the second season, respectively. Regardless of species, parasitism ranged between 51.78 to 93.38% in the first season and from 56.36 to 84.96% during the second season. In another field, the overall mean of reductions in S. ocellatella larvae populations by three insecticides [Protecto® and Biovar® (biocides) and Robek extra® (conventional)] were 71.39, 76.84 and 85.14% in the first season and were 71.39, 75.99 and 82.53% in the second season. Further, these pesticides reduced parasitoid populations by 33.39, 30.29 and 97.72% in the first season and by 43.22, 41.27 and 97.70% in the second season. Biocides were less harmful to parasitoids than the conventional ones. Finally, the parasitoids' complex of S. ocellatella in addition to biocides seems to be promising tools in the biological control of S. ocellatella in Egypt.

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