Morphological alterations in salivary glands of Rhipicephalus sanguineus ticks (Acari: Ixodidae) exposed to neem seed oil with known azadirachtin concentration

Abstract

Neem (Azadirachta indica) has attracted the attention of researchers worldwide due to its repellent properties and recognized effects on the morphology and physiology of arthropods, including ticks. Therefore, this study aimed to demonstrate the effects of neem seed oil enriched with azadirachtin on salivary glands of Rhipicephalus sanguineus ticks, targets of great veterinary interest because of their ability to transmit pathogens to dogs. For this, R. sanguineus semi-engorged females were subjected to treatment with neem seed oil, with known azadirachtin concentrations (200, 400 and 600ppm). After dissection, salivary glands were collected and evaluated through morphological techniques in light microscopy, confocal scanning laser microscopy and transmission electron microscopy, so that the possible relation between neem action and further impairment in these ectoparasites feed performance could be established. Neem oil demonstrated a clear dose-dependent effect in the analyzed samples. The agranular (type I) and granular acini (types II and III) showed, particularly in individuals treated with the highest concentrations of the product, cells with irregular shape, intense cytoplasmic disorganization and vacuolation, dilation of rough endoplasmic reticulum lumen, besides alterations in mitochondrial intermembrane space. These morphological damages may indicate modifications in salivary glands physiology, demonstrating the harmful effects of compounds present in neem oil on ticks. These results reinforce the potential of neem as an alternative method for controlling R. sanguineus ticks, instead of synthetic acaricides.

The effects of neem oil (Azadirachta indica A. JUSS) enriched with different concentrations of azadirachtin on the integument of semi‐engorged Rhipicephalus sanguineus sensu lato (Acari: Ixodidae) females

“…female ticks. The responses were dose‐dependent; i.e., as the azadirachtin concentrations increased, the damages were more aggressive, corroborating Denardi et al () and Remedio et al ().…”

“…With specific regard to the species Rhipicephalus sanguineus , it was demonstrated that the damages caused in the female reproductive system would be lethal, preventing the ovaries to produce viable germ cells (able to reach mature stages), and, consequently, produce new individuals (Denardi et al, ). Some authors also performed bioassays exposing the synganglion, salivary glands and the integument of Rhipicephalus sanguineus to different neem formulations (Remedio, Nunes, & Anholeto, ; Remedio et al, ).…”

“…Some authors also performed bioassays exposing the synganglion, salivary glands and the integument of Rhipicephalus sanguineus to different neem formulations (Remedio, Nunes, & Anholeto, 2014b;Remedio et al, 2016).…”

In vitro efficacy of essential oils with different concentrations of 1,8-cineole against Rhipicephalus (Boophilus) microplus

“…When crossing the integument of the tick, the substances can reach the haemolymph and act on the internal organs (REMEDIO et al, 2015). Certain substances may affect the salivary glands, consequently impairing the process of concentrating ingested blood and thus hindering the effective absorption of nutrients by the ticks (REMEDIO et al, 2016). There is an important correlation between the tick's digestive and reproductive system and, thus, digestive problems can damage their reproductive capacity (REMEDIO et al, 2016).…”

The prevalence of <i>Gasterophilus intestinalis</i> (Diptera: Oestridae) in donkeys (<i>Equus asinus</i>) in Egypt with special reference to larvicidal effects of neem seed oil extract (<i>Azadirachta indica</i>) on third stage larvae

“…Alcoholic concentrate of neem seeds has an antifilarial action against Setaria cervi (Tahir et al, 1998;Mishra et al, 2005). Remedio et al (2016) studied the effects of neem seed oil had azadirachtin against Rhipicephalus sanguineus ticks with demonstration the effects of this plant extract on salivary glands of the ticks, with results that; the cells were distorted, cytoplasmic disorganization, and some endoplasmic changes of its lumen, besides several alteration in mitochondrial membrane. Neem had been utilized as antiparasitic in a few types of ectoparasites and some pests because of its quick action.…”