**Target Activity of** *Isaria tenuipes* **(Hypocreales: Clavicipitaceae) Fungal Strains against Dengue Vector** *Aedes aegypti* **(Linn.) and Its Non-Target Activity Against Aquatic Predators**


Received: 17 August 2020; Accepted: 16 September 2020; Published: 29 September 2020

**Abstract:** The present investigation aimed to determine the fungal toxicity of *Isaria tenuipes* (My-It) against the dengue mosquito vector *Aedes aegypti* L. and its non-target impact against the aquatic predator *Toxorhynchites splendens*. Lethal concentrations (LC50 and LC90) of My-It were observed in 2.27 and 2.93 log ppm dosages, respectively. The sub-lethal dosage (My-It-1 × 10<sup>4</sup> conidia/mL) displayed a significant oviposition deterrence index and also blocked the fecundity rate of dengue mosquitos in a dose-dependent manner. The level of major detoxifying enzymes, such as carboxylesterase (α-and β-) and SOD, significantly declined in both third and fourth instar larvae at the maximum dosage of My-It 1 × 10<sup>5</sup> conidia/mL. However, the level of glutathione S-transferase (GST) and cytochrome P-450 (CYP450) declined steadily when the sub-lethal dosage was increased and attained maximum reduction in the enzyme level at the dosage of My-It (1 × 10<sup>5</sup> conidia/mL). Correspondingly, the gut-histology and photomicrography results made evident that My-It (1 × 10<sup>5</sup> conidia/mL) heavily damaged the internal gu<sup>t</sup> cells and external physiology of the dengue larvae compared to the control. Moreover, the non-target toxicity against the beneficial predator revealed that My-It at the maximum dosage (1 × 10<sup>20</sup> conidia/mL) was found to be less toxic with <45% larval toxicity against *Tx. splendens*. Thus, the present toxicological research on *Isaria tenuipes* showed that it is target-specific and a potential agen<sup>t</sup> for managing medically threatening arthropods.

**Keywords:** mycotoxins; entomopathogen; arthropods; CYP450; gut-histology; non-toxicity
