Efficiency of certain insecticides and their histological effects against sugar beet beetle Cassida vittata (Coleoptera: Chrysomelidae)‎ in sugar beet field

الملخص EN

Sugar beet beetle Cassida vittata (Vill.) (Coleoptera: Chrysomelidae) is a serious pest on sugar beet causes losses in root yield and sugar content in Egypt.

The present work dealt with the efficiency of four compounds representing different classes of insecticides against sugar beet beetle C.

vittata larvae under field conditions at Dakahlia and Behira Governorates in 2015 season.

The tested compounds were imatrade (35% SC) (Imidacloprid), flagtra (25% WP) (Thiamethoxam), agriflex (18.6% SC) (Thiamethoxam + Abamectin) and dora (48% EC) (Chloropyrefos).

In each field, the results revealed that, all treatments were able to suppress the larval population comparison to the untreated control.

The suppression varied according to the tested compound, dora caused 93.51% reduction after ten days post spray in the larval population followed by flagtra (87.15%).

Generally, the highest reduction was recorded in dora treatment at two regions.

The mean Reduction percentage were 89.64 and 91.09 % in Dakahlia and Behira Governorates, respectively.

The histological examination of mid gut of 3rd instar larvae of C.

vittata showed that all tested insecticide lead to several damages occurred in all the cells layers in the mid gut as separation of the basement membrane.

In addition, imatrade (35% SC) possessed many mid gut cells with a weakly stained cytoplasm as well as a nucleus with decondensed chromatin and evident nucleoli.

Agriflex (18.6% SC) due to increase proliferation of columnar cell.

While, dora (48% EC) caused increase most of columnar cell lining mid gut were necrosis.

Also, flagtra (25% WP) lead to increase in number of goblet cell, most of columnar suffer from necrosis.