More than 2,000 plant species with insecticidal activity have already been identified (Jacobson 1989), some plants have evolved a wide range of physical conditions and chemical defenses against a variety of insects through substances such as (phenols and polyphenols, terpenoids, alkaloids) that can be isolated using various extraction methods (Dubey 2010).
The experiences of Pranati et al. (2018) have shown the larvicidal and pupicidal effect of extracts of Clerodendrum philippinum leaves against Aedes aegypti and Anopheles stephensi with considerable mortality rates. In addition the study realized by Kaura et al. (2019) reveals the larvicidal and pupicidal effect of the essential oil of Eucalyptus globulus which acts quickly on the larvae and pupae of Aedes aegypti and Aedes albopictus with LC 50 of 93.3 and 144.5ppm and LC90 was found to be 707.9 and 741.3 ppm respectively.
The results of the present study reveal a considerable and variable sensitivity translated by rates of low to very high mortality which correlates with the extension of time from one concentration to the other.
The same observation made by Aksorn and Mayura (2018) on the larvae and nymphs of Aedes aegypti, which showed that the mortality is correlated with the doses used is all the more increased as the exposure of larvae and nymphs to insecticides is extended over time.
This activity can be expressed by the diversification of the bioactive molecules which compose this essential oil being able to carry out a singular action of one of the major components, of which it is dominated by Davanone (48.8%), or a synergistic effect between several compounds towards the larvae and the nymphs of mosquitos which are exposed to it.
The oil yield recorded in the present study was relatively higher to those extracted from the same species collected in the region of Spain with 0,8% (Salido et al. 2001) and Tunisia 0,7% (Haouari and Ferchichi 2009). While it equal to those extracted in Tunisia per Zouari et al. (2010) and by Boutemak et al. (2009) in Algeria. Also it is lower at the one extracted in Morocco 3,3% by Paolini et al. (2010)
This difference in yield can be explained by the impact of several factors such as the nature of the species, the effect of the vegetative stage of the plant and the edaphic conditions of the region (Ghanmi et al. 2010).
Regarding the chemical composition of this oil a variability of volatile constituents was observed in many country from previous studies As such in Moroco [Camphor (40–70%), α-or β-Thujone (32–82% and 43–93%, respectively), Chrysanthenone (51.4%), Chrysanthenyl acetate (32–71%), or Davanone (20–70%)] were the major components from that of Paolini et al (2010)(Paolini et al. 2010), Whereas [Davanone (0.5 − 39.1%), 1,8-Cineole (0.8 − 25.8%), Chrysanthenone (0.1 − 36.4%), Cis-Chrysanthenol (0.2 − 27.8%), Cis-Chrysanthenyl acetate (0.2 − 18.4%), p-Cymene (0.6 − 20.6%), α-Pinene(0.2 − 17.2%)] were reported as dominant in Spain(Salido et al. 2002), also in Tunisia the major components were [Cineole (1.5 − 26.99%), Thujones (1 − 64.67%), Chrysanthenone (1 − 17.37%), Camphor (0.56 − 16.73%), Borneol (0.72 − 10.75%), Chrysanthenyl acetate (0.52–7.37%), Sabinyl acetate (0.53 − 22.46%), Davana ethers (0.65 − 6.23%) and Davanone (2.37 − 20.14%)] as referred by Haouari and Ferchichi (2009).
In the other hand, with the exception to Davanone which is the main compound of the present work, it was not detected in the study of Abu-Darwish et al. (2015) in Jordan [β-Thujones (25.1%), α-Thujones (22.9%), Eucalyptol (20.1%) and Camphre (10%)] neither in that of Abou El-Hamd et al(2010) in Egypt [1,8-Cineole (50%), Thujone (27%), Terpinen-4-ol (3.3%), Camphor (3%) and Borneol (3%)], as well in Iran Sharifianet al. (2012) reported the [β-Thujone (35.66%), Camphor 34.94%), 1,8-Cineole (7.42%), α-Thujone (4.12%)] as the main components.
In addition, even within Algeria, different chemical compositions of the essential oil of Artemisia herba alba have been recorded for example in the region of Djelfa Touil and Benrebiha (2014) found [ Davanone (62,20%), Carvacrol (4,88%), Davana ether (3,62%), Camphor (3,48%) ] as major components.
In Msila region the main components announced by Dob and Benabdelkader (2006) were the Camphor (19%), trans-pinocarveol (17%), chrysanthenone (16%), b-thujone (15%), b-Thujone (32–41%), camphor (16–25%), cineol (0.1– 10%)
However, Boutekedjiret et al. (1992), bring out that there is a variation of the volatile component of Artemisia herba alba under the seasonal change factor, within the same region.
Overall this wide chemical variability may be a result of the genetic characteristics of the plant combined with the influences of geographical locations and climatic conditions as well as the difference of the developmental stages of the plant and method used to obtain the essential oil (Belhattab et al. 2014; Lakehal and A 2016).
Indeed, several previous studies have revealed the different bioactivities of the components of Artemisia herba alba extracts against many pests such as an insecticidal activity against tobacco whitefly Bemisia tabaci (Gennadius), cotton aphid Aphis gossypii (Glover), thrips of tobacco and onion Thrips tabaci (Lindman) (Soliman 2007), another study of Tani et al. (2008) on bean leaf beetle Acanthoscelides obtectus(Say) and of Hifnawy et al. (2001) on Cotton Worm Spodoptera littoralis (Boisduval) revealed also the toxic effect against insects. Moreover an acaricidal activity was been reported against carmine spider mite Tetranychus cinnabarinus (Boisduval) per Azaizeh et al. (2007). Further Hifnawy et al. (2001) proved the ability of this essential oil to control white mice Mus musculus (Linnaeus) by provoking a rodenticidal activity.
The mechanism of action of the essential oil on insects is mainly due to neurotoxic effects involving several modes of action, including acetylcholinesterase (AChE) inhibition (Mills et al. 2004), disruption of gamma-aminobutyric acid (GABA) receptor functionality (Priestley et al. 2003) and agonist of the octopamine system (Enan 2005).
According Pavela (2016) the most important neurotoxic mode of action symptoms are hyperactivity followed by hyperarousal leading to rapid reversal and immobilization as well as the insects' mouthparts become paralyzed and stop feeding and starve.
In addition Rattan (2010) confirms that essential oils and their constituents affect biochemical processes, which specifically disturb the endocrinological balance of insects. They can be neurotoxic or act as insect growth regulators, disrupting the normal process of morphogenesis, in insects, the result of this nerve poisoning can be immediate death or several days of paralysis before death.
In the same context Jun-Hyung and Murray B. Isman (2015) note that insecticidal activity is the result of a series of complex actions and contractions between a toxic tissue and an insect tissue. This mechanism of toxicity can be expressed in three steps: penetration, activation (target site interaction) and detoxification. Plant extracts act in two possible ways; a larvicidal action that can cause an appreciable mortality of larvae in 1 to 12 days, or a juvenile hormone mimetic action, with an extension of the larval life span that can inhibit pupation (Rageau and Delaveau 1979).
Taking into account the toxic effect of these essential oils, a study was carried out to ensure the therapeutic safety therefore Boukhennoufa et al. (2021) confirmed the indemnity of the toxic effect of the essential oil of Artemisia herba alba on the proper functioning and survival of the organism after a cutaneous exposure