The effect of sublethal concentrations of deltamethrin and alphacypermethrin on the fecundity and development of Ixodes ricinus (Acari: Ixodidae) eggs and larvae

Abstract

Two pyrethroids, deltamethrin (D) and alphacypermethrin (AC), have been used as commercial products for tick control worldwide. However, the effects of sublethal doses of these compounds on various tick species and their developmental stages have not been fully explored yet, although such knowledge could contribute to a more effective application of both pyrethroids and simultaneous reduction of their costs and undesirable side effects, including the harmful impact on other organisms and environmental contamination. This study investigates the effect of sublethal concentrations of D and AC applied to engorged females on the fecundity, development of eggs and larvae, and the number of offspring in the Ixodes ricinus (L.) tick, which is the most important vector of tick-borne diseases of humans in Europe. After detachment from rabbit's skin, fully engorged I. ricinus females were treated with 20 μl of pyrethroid solutions at five concentrations from 0.01562 to 0.25% and kept at 28 °C and 75% relative humidity. The impact of the pyrethroids on maturation and development of eggs as well as development of larvae was assessed based on parameters of the preoviposition and oviposition periods and the course of embryogenesis and egg hatch. The investigations have shown that both tested acaricides reduce the reproductive rate in I. ricinus females by inhibition of egg development and disturb embryonic development and larval hatch. Females did not lay eggs at concentrations higher than 0.0625% AC and 0.125% D. The lower concentrations of both pyrethroids disturbed or inhibited the embryogenesis and egg hatch in I. ricinus.

A seven-legged tick – anomalous <i>Ixodes ricinus</i> female (Acari: Ixodidae) from Poland

“…The causes of morphological abnormalities in natural populations of ticks are diverse and may be related to both internal (germinal mutations, somatic mutations, abnormalities during embryonic development, e.g. fusion of eggs, incorrect egg divisions) [18,35], and environmental factors (antropopression, heavy metal pollution, mechanical injuries, adverse moulting conditions) [19,35,36]. The influence of the host-related factors and conditions during blood meal are also discussed, such as host resistance [37], feeding of multiple ticks close together, feeding on unusual hosts, and lack of food for a long period [22].…”

Insecticidal effect of deltamethrin, dinotefuran and spiromesifen against the sugarcane whitefly Neomaskellia andropogonis on CP69-1062 sugarcane cultivar

“…Relative toxicity of the tested insecticides on the whitefl y life stages showed that the toxicity of deltamethrin was 9.2 and 9.13 times higher on the pupal than on the egg and nymphal stage, respectively, while it did not diff er between eggs and second instar nymphs, indicating higher biological action on the pupal stage. The high toxicity rate of deltamethrin on sugarcane whitefl y eggs might be due to the eff ect of pyrethroid insecticides on embryonic development and inhibition of larval hatch as indicated by Buczek et al (2019) for deltamethrin and alpha-cypermethrin on Ixodes ricinus (L.) (Acari: Ixodidae) at sublethal concentrations. Both substances disturbed the embryonic development in I. ricinus occurring in hindrance of the earliest stage of embryogenesis, as well as impediment hatch of larvae.…”

The effectiveness of acaricidic drugs based on herbal raw material

“…Thus, M. Tabari and co-authors reported about the better effect of carvacrol and thymol against I. ricinus maggots than permethrin (100% mortality in 24 hours) (Tabari et al, 2017). It is known that pesticides of the metrin group affect the reproductive system, in particular the ability of females of I. ricinus to lay eggs (Buczek et al, 2019). Also, these pesticides are considered to be neurotoxicants (Pereira et al, 2017), which are also able to change the behavior of ticks during feeding, which affects the duration of this process (Buczek et al, 2015).…”