Permethrin-induced morphological changes in oocytes of Rhipicephalus sanguineus (Acari: Ixodidae) semi-engorged females

Morphological effects of neem (Azadirachta indica A. Juss) seed oil with known azadirachtin concentrations on the oocytes of semi-engorged Rhipicephalus sanguineus ticks (Acari: Ixodidae)

“…In literature, there are two main assumptions to explain the possible entrance route of the chemical, synthetic, and natural compounds to the interior of the cells: they can directly cross the oocyte wall (Oliveira et al 2009;Vendramini et al 2012) or be transferred into these cells through the pedicel cells (Roma et al 2010a(Roma et al , 2011Denardi et al 2010Denardi et al , 2011. Regarding the neem oil compounds, the way the substances are absorbed is unknown; however, as observed in R. sanguineus ticks exposed to fipronil (Oliveira et al 2009) and andiroba oil (Vendramini et al 2012), the vulnerability of the oocytes in the initial stages of development may indicate that the neem active ingredients have crossed their wall.…”

“…This is particularly noticeable in many studies which aimed to evaluate the morphological effects of substances with acaricide potential on ticks, especially R. sanguineus, considering its great veterinary importance. Synthetic compounds such as fipronil (Oliveira et al 2008(Oliveira et al , 2009 and permethrin (Roma et al 2010a(Roma et al ,b, 2011, and natural ones such as andiroba oil (Vendramini et al 2012;Roma et al 2013a), the esters of ricinoleic acid of castor oil (Arnosti et al 2011;Sampieri et al 2012) and neem leaves extract (Denardi et al 2010(Denardi et al , 2011(Denardi et al , 2012 caused expressive structural alterations in the reproductive system of these ticks, such as irregularity of the oocytes, cytoplasmic vacuolation, alterations in the organelles, nuclear and nucleolar damages, and modifications in the yolk synthesis.…”

Comparative Results of Action of Natural and Synthetic Acaricides in Reproductive and Salivar Systems of Rhipicephalus sanguineus - Searching by a Sustainable Ticks Control

“…Comparative Results of Action of Natural and Synthetic Acaricides in Reproductive and Salivar Systems of Rhipicephalus sanguineus -Searching by a Sustainable Ticks Control 407 Besides these alternative option to control the ticks the BCSTM researcher in Brazil showed the effects of synthetic chemicals acaricides (permethrin and fipronil) in reproductive and salivary systems of R. sanguineus and demonstrate that lower doses and concentrations of acaricides would be used to prevent the ticks reproduction and feed, minimizing the damages to non-target individuals as well as to the environment (Roma et al, 2010). The results presented here have also shown that doses of synthetic acaricides would be still efficient and much smaller and much less harmful to non-target organisms and to the environment being enough to reduce the harm caused by these ticks.…”

“…In this way, the toxicity of a drug is determined by running laboratorial tests on animals and it is expressed as LD 50 (lethal dose fifty) and LC 50 (lethal concentration fifty) values and are the amount or concentration, respectively, of the pesticide's active ingredient that is required to kill 50% of the tested animals under standardized tests conditions (Garcia-Garcia et al, 2005). The first study to described a detailed protocol of laboratorial procedures to determinate de LC 50 of permethrin using semi-engorged females of R. sanguineus ticks was performed by Roma et al (2010) who established the LC 50 =2062 ppm (1.549-2.675). Acaricides currently available in the market have permethrin (chemical substance that cause a nervous impulses disorders and the ticks suffer excitement, indicated by tremors and spasms followed by paralysis and death) as active ingredient in concentration higher than 300.000 ppm and according Roma et al (2010) permethrin in lower concentrations (approximately 100 times less) would be enough to kill R. sanguineus ticks, although this process would be slower.…”

“…The first study to described a detailed protocol of laboratorial procedures to determinate de LC 50 of permethrin using semi-engorged females of R. sanguineus ticks was performed by Roma et al (2010) who established the LC 50 =2062 ppm (1.549-2.675). Acaricides currently available in the market have permethrin (chemical substance that cause a nervous impulses disorders and the ticks suffer excitement, indicated by tremors and spasms followed by paralysis and death) as active ingredient in concentration higher than 300.000 ppm and according Roma et al (2010) permethrin in lower concentrations (approximately 100 times less) would be enough to kill R. sanguineus ticks, although this process would be slower.…”