**3. Results**

#### *3.1. E*ff*ect of My-It on Mosquito Survival*

The larvicidal activity of My-It with its discriminating dosage (1 × 102, 1 × 104, 1 × 106, and 1 × 10<sup>8</sup> conidia/mL) against the second instar larvae displayed that the maximum mortality rate of 96% was obtained at the maximum dosage of 1 × 10<sup>8</sup> conidia/mL and it was more significant than that of the other treatments—1 × 10<sup>6</sup> (86.32%-F4,20 = 16.66, *p* ≤ 0.001), 1 × 10<sup>4</sup> (63.21%-F4,20 = 16.66, *p* ≤ 0.001), 1 × 10<sup>2</sup> (35.45%-F4,20 = 16.66, *p* ≤ 0.001) conidia/mL—and the control (5.140%-F4,20 = 16.66, *p* ≤ 0.001) (Figure 1).

**Figure 1.** Percentage mortality of second, third and fourth instar larvae of *Ae. aegypti* after treatment with *Isaria tenuipes* conidial spores (My-It). Means (±SE) followed by the same letters above bars indicate no significant difference (*p* ≤ 0.05) using Probit analysis. The different letters (a–e) indicate significant differences between the control and treatments.

Similarly, the larval toxicity of My-It against the third instar larvae was also uplifted in a dose dependent manner. At the maximum dosage (1 × 10<sup>8</sup> conidia/mL), the larval mortality increased significantly to 94.44% (F4,20 = 18.22, *p* ≤ 0.001) when compared to those of the other treatments (further total mosquito survival significantly declined when compared with that of the control) (Figure 2).

**Figure 2.** Survival rate of *Ae. aegypti* after treatment with My-It (1 × 103) conidial spores and the control. Survivorship curves differ at the α = 0.05 confidence interval according to log-rank statistics.

Likewise, the larvicidal activity of My-It against the fourth instar larvae was increased to 90.67% at the prominent dosage of 1 × 10<sup>8</sup> conidia/mL and it was significant at 1 × 10<sup>6</sup> (80.41%-F4,20 = 12.33, *p* ≤ 0.001), 1 × 10<sup>4</sup> (50.18%-F4,20 = 12.33, *p* ≤ 0.001), 1 × 10<sup>2</sup> (28.45%-F4,20 = 12.33, *p* ≤ 0.001) conidia/mL and with the control (5.110%-F4,20 = 12.33, *p* ≤ 0.001) (Figure 1). The lethal concentrations (LC50 and LC90) of My-It were 2.27 and 2.93 log ppm, respectively (Figure 3).

**Figure 3.** Lethal concentrations (LC50 and LC90) of My-It conidial spores against fourth instars of *Ae. Aegypti*, obtained using Probit analysis. Dot represents the lethal concentration of *My-It* conidial spores against fourth instar larvae of *Ae. aegypti*.

#### *3.2. Oviposition Deterrence Index*

The sub-lethal dosage of My-It statistically reduced the oviposition deterrence index of the dengue mosquito at 1 × 10<sup>4</sup> conidia/mL with maximum deterrence index of 83.4% (F4,20 = 25.88, *p* ≤ 0.001) and it is more significant than those of the other treatments—1 × 10<sup>4</sup> (57.6%-F4,20 = 25.88, *p* ≤ 0.001), 1 × 10<sup>3</sup> (57.6%-F4,20 = 25.88, *p* ≤ 0.001), 1 × 10<sup>2</sup> (28.45%-F4,20 = 25.88, *p* ≤ 0.001), 1 × 10<sup>1</sup> (10.2%-F4,20 = 25.88, *p* ≤ 0.001)—as well as the control (7.50%-F*4,20* = 25.88, *p* ≤ 0.001) (Figure 4).
