Yield Losses of Potato Tubers due to Infestation with Gryllotalpa gryllotalpa (Gryllotalpidae: Orthoptera) and Penitodon bispinosus (Scarabaeidae: Coleopteran) Based on Insecticide Treatment at Nubaria Region, Egypt

Emad, M. El- Adawy, Osman, A. Zaghloul, Ahmed, M. Kordy, Mohamed, M.El-Shazly and Magda,M. Khtab

The present investigation has been conducted in the two successive summer seasons of 2014 followed by the winter one of 2015, for the purpose of appraising yield losses to potato tubers caused by the two key subterranean insect pests: Gryllotalpa gryllotalpa(L), Penitodon bispinosus Kust

Potato plants were treated with two recommended doses of seven insecticidal baits at 70 and 85 days from sowing. These poisonous baits were Fipronil, Chloropyrifos methyl, Fentrothion, Dimethoate, Azadirachtin, Bacillus thuringiensis and Beauveria bassiana.

In the summer season of 2014, the obtained data revealed that loss percentages were 7.86, 9.13, 11.62, 12.5, 25, 25.01, 25.63 and 50 for tubers treated with Fipronil, Chloropyrifos methyl, Fentrothion, Dimethoate, Azadirachtin, B.T, B. bassiana and control, respectively.

 Correspondingly 2015 as a winter season for the crop, these percentages were 3.76, 6.24, 12.5, 12.51, 25, 28.12 and 40.62% for the control successively.

 It is worth mentioning, that loss percentages are considered as a prerequisite step for the determination of seven economic injury levels for each insect pest. The computed economic injury levels (EILs) values pertaining to G. gryllotalpa were 0.1, 0.11, .011, 0.31, 0.10, .014, 0.17, insect/100 tubers as a result of using Fipronil, Chloropyrifos methyl, Fentrothion, Dimethoate, Azadirachtin, B.T and P. bispinosus, respectively. Whereas in case of the B. coriacea, the economic injury levels (EILs) values were 0.41, 0.65, 1.44, 0.64, 1.81, 0.52 and 1.23 insect /100 tubers were also due to the application of the same poisonous baits, respectively, for P. bispinosus, G. gryllotalpa plantation of 2014.

In the season 2015, the EILs values due to infestation by G. gryllotalba were 0.54, 0.25, 0.18, 1.43, 0.36, 2.8 and 0.25 insects/100 tubers for Fipronil, Chloropyrifos methyl, Fentrothion, Dimethoate, Azadirachtin, B.T and Beauveria bassiana baits,  in respect. Corrispondingly,  EILs  the  P. bispinosus were 0.1, 0.1, 0.1, 3.8, 0.41, 0.22 and 0.31 insect/100 potato tubers for the some applied baits, in respect.   

Keywords: Potato soil insect - Insecticidal control-Yield loss assessment - Economic injury levels.