Histological Investigations on Potato Tuber Moths, Phthorimaea operculella Treated with a Botanical Extract of Basil (Ocimum basilicum L), with Particular Attention to the Alterations in the Ultrastructure of the Larval Digestive Tract

Background: Phthorimaea operculella (Zeller), the potato tuber moth (PTM) is one of the most important pests that attacks potato, Solanum tuberosum L. crops worldwide. Adult moths attack tubers in fields as well as in storage. Infested tubers become unsuitable for trade or consumption, the tuber damage increases gradually after several generations of the pest during storage time. Botanicals have been found to be an efficient control method especially when they act as antifeedant or repellent, or even stomach poisons. The estimation of the mortal impact of some extracts against PTM was examined by emphasizing the Ultrastructure changes in the larval digestive tract by using scanning and transmission electron microscope. Results: Structural changes throughout the entire digestive tract (Fore-, Mid- and Hind-gut), induced by Basil extract were detected through both microscope, these changes leading lastly to the death of the treated larvae. Many different ruptures and malformations were detected throughout all the digestive tract assessment. Conclusions: Studies of the occurred changes revealed some histopathological changes through out all the digestive tract (Fore-, Mid- and Hind-gut), the attached muscular layer, tracheal system, and visceral fat bodies of the larvae when fed with tubers treated with Basil extract. From this findings, the use of plant extracts can be recommended for protection of potato tuber against the infestation by the tubers moths.