Histological Studies on Heteracris littoralis (Rambur) Treated with Silica Nano-particles / Challenger Formulation

Aim: Local diatomaceous earth (Silica nano-particles) and commercial pesticide (Challenger 36% SC) formulation was tested against alfalfa grasshopper, Heteracris littoralis (Rambur, 1838) (Orthopetra: Acrididae) under laboratory conditions.

Study Design: Histological study for alimentary tract using light microscope.

Place and Duration of Study: Department of Pests and Plant Protection, National Research Centre, Egypt- 2016-2017.

Methodology: Fourth instar nymphs of H. littoralis were taken from laboratory culture reared on semi-artificial diet [1] for the experiments. The nymphs were fed on diet mixed with 1% concentration of Silica nano-particles/Challenger formulation. The tissue specimens of the alimentary canal were dissected in 0.9% NaCl solution and fixed in Bouin's solution for 24 hours [2] then dehydrated in ascending alcoholic series and cleared in Xylen for few seconds, and then specimens were infiltrated in three changes of paraffin wax each lasted 20 minutes. With Ehrlich's acid haematoxylin and alcoholic eosin. The stained sections were dehydrated, cleared and mounted using D.P.X. For microscope examination.

Results: The Silica nano-particles induced great irregularity or deformity in the alimentary tract, that leading finally to death. All parts of the alimentary tract were affected by silica treatment (fore-gut, mid-gut and associated gastric caeca and hind-gut).

Conclusion: Histological changes were observed as a result of Silica effect on the enzymes and the physiology of the treated insect. So, it could be concluded that Silica nano-particles may be used through the integrated pest management programme against H. littoralis by spray on the plants or as a food bait traps.