**1. Introduction**

Parasites have been a major threat for millions of humans and animals since ancient times, bringing about chronic debilitating and disabling diseases [1]. Mosquitoes (Diptera: Culicidae) are vectors for serious parasites and pathogens, including malaria, filariasis, and important arboviruses, such as dengue virus, yellow fever, chikungunya, West Nile virus, and Zika virus [2,3]. Aedes spp.is a vector transmitting the previously mentioned arboviruses, whose dispersion is wide-reaching [3,4]. Almost 40% of the global population live under hazard of dengue, and yearly, 24,000 deaths are reported. The incidence of dengue viruses has grown intensely around the world in the current scenario. The actual numbers of dengue cases are underreported and many cases are misclassified [4]. Dengue is considered to be an endemic disease prominent in more than a hundred nations, including the Americas, Africa, the Western Pacific, and, more importantly, Southeast Asian countries [5]. Managing this disease is mainly achieved through decreasing mosquito populations [6,7]. Overuse and misuse of synthetic insecticides led to the development of resistance, environmental contamination, toxicity to non-target organisms, and adverse e ffects on animal and human health; accordingly, there is an urgen<sup>t</sup> need to use eco-smart, bio-rational insecticides including cultural and biological ways which could be integrated into mosquito control strategies [8–11].

Such alternative approaches through biological ways have been widely recognized for decreasing the selective pressure made by chemical pesticide-resistance against arthropods [11,12]. Among them, microbial toxins can target di fferent life-cycle stages of mosquitoes, and, more importantly, they are harmless to non-targets [13]. Entomopathogenic fungi (EPF) are an active substitute for synthetic chemicals due to their degradability [14,15]. Presently, the mode of activity of fungal strains has revealed several avenues for e ffective arthropod managemen<sup>t</sup> [15–17]. EPF are a promising agen<sup>t</sup> for arthropod managemen<sup>t</sup> and the operative fungal strain selection is well established according to its virulence against targeted mosquitoes in the applied settings [18].

*Isaria tenuipes* (formerly *Paecilomyces tenuipes*) is a common fungal species that frequently a ffects major agricultural pests usually belonging to the group lepidopteran [18], and we refer to it as "My-It". Moreover, it has been found that the *Isaria* fungi hold a diversified blend of chemical derivatives delivered chiefly through non-ribosomal peptide synthetase (NRPS), terpenoid synthetase (TS), polyketide synthase (PKS), etc. [18,19]. All of these active metabolites deliver potential anti-viral, anti-bacterial, and anti-cancer agents [20,21]. There is also other previous research on their biological activity against humans and other beings [18]. Active metabolites derived from *I. tenuipes*, such as cephalosporolides B and F, deliver inhibitory activity against the *Panagrellus redivivus* nematode [22]. Despite such benefits, there is no active research on the biological activity of *I. tenuipes* against mosquito vectors of medical importance. Moreover, their mode of action against mosquito reproduction was also unclear.

Thus, the present investigation aimed (i) to determine the e ffective lethal larvicidal dosage of active My-It against the dengue vector *Aedes aegypti;* (ii) to detect the sub-lethal dosage activity of My-It on the reproductive potential in dengue vector; (iii) to detect enzyme regulations in the dengue larvae treated with the sub-lethal dosage of My-It; (iv) to determine the non-target impact of My-It against aquatic mosquito predators sharing the same ecological niche as the dengue vector.
