Time of spraying effects on insecticidal activity and droplet distribution of certain insecticides controlling Hetracris annulosa and Locusta migratoria (Orthoptera: Acrididae) on Zea mays

Abstract

Field experiments were carried out in an area of about 10 feddans planted with zea mays during season of 2023 on 18th July at Bashiar Elkhaier farm, El-Farafra Oasis, New Valley Governorate. The selected area was split into 10 plots including control plot. Thiamethoxam,  Imidacloprid, Deltamthrin, Alpha-Cypermethrin Acetamiprid, Spinosad, Lambda-Cyhalothrin, Chlorfenapyr, and Emamectin benzoate  were sprayed with recommended rate and one treatment left without spraying as un treated check by using Motorized Knapsack sprayer  (Solo) (52.5 L./Fed.) at 7am and 6 pm. Data indicated that, all tested compounds induce a significant negative influence on Hetracris  annulosa Walker and Locusta migratoria migratorioides (Fairmaire and Reiche) )Orthoptera : Acrididae( nymphs survival. The most  effective compounds are Alpha-Cypermethrin, Deltamthrin E.C. Lambda-Cyhalothrin and Spinosad followed by other compounds at both times of spraying 7 am and 6 pm; where there was no significant difference between the biological efficiency between two times spraying. It could be recommended to use these compounds with LV spraying equipment with a Motorized Knapsack sprayer (Solo) (52.5 L./Fed.). The data showed that spraying at 7 am was a more excellent time than 6 pm for better droplet coverage, distribution, increasing number of droplets per square centimeter and decreasing Volume Mean Diameter these may be due to lower temperature and lower  Relative Humidity %. The rate of performance of a Motorized Knapsack sprayer (Solo) was 15.2 Fed./day.