Evaluation of the sublethal effect of tetrachlorantraniliprole on Spodoptera exigua and its potential toxicity to two non-target organisms

Abstract

Tetrachlorantraniliprole (TCAP) is a novel anthranilic diamide insecticide that specifically targets the ryanodine receptors of lepidopteran insect species with excellent insecticidal activity. Previous studies have reported the sublethal effects of multiple diamides on several lepidopteran species, whereas the sublethal and non-target effects of TCAP remain largely unknown. We assessed the sublethal effects of TCAP on Spodoptera exigua. We also investigated the effects of TCAP on non-target Harmonia axyridis and Eisenia fetida, S. exigua was more sensitive to TCAP than to chlorantraniliprole, as the LC50 (10.371 μg L-1 at 72 h) of TCAP was relatively lower. Compared with those of the control, sublethal concentrations of TCAP (LC10 and LC30) not only prolonged the duration of the larval and pupal stages as well as the mean generation time but also reduced certain population parameters. On the other hand, TCAP exposure, even at the highest concentration, did not induce toxic effects in H. axyridis ladybugs (1st instar larvae and adults) or E. fetida earthworms. Taken together, our results suggest that TCAP can be used as a novel and promising component of the integrated pest management (IPM) program against S. exigua due to its robust target effects and negligible non-target risks.

Fig 1. Toxicity of TCAP to S. exigua.

A, LC₁₀, LC₃₀, and LC₅₀ of the 1^st and 3^rd instar larvae of S. exigua; and B, The larval and pupal mortalities of S. exigua treated with TCAP. The bars labeled with different letters are significantly different (via Fisher’s protected least significant difference (LSD), P < 0.05).

Fig 2. Age-stage specific survival rate (S_xj) curves of S. exigua treated with sublethal concentrations of TCAP.

A, control; B, LC₁₀ group; and C, LC₃₀ group.

Fig 3. Effects of sublethal TCAP on the age-specific survival rate and population fecundity.

A, age-specific survival rate curve (l_x); B, age-specific curve of the fecundity of the total population (m_x); and C, age-specific maternity curve (l_xm_x) for S. exigua.

Fig 4. The age-stage reproduction curves (V_xj) of S. exigua.

A, the V_xj curves of the larvae in the control group; B, the V_xj curves of the pupae and adult females in the control group; C, the V_xj curves of the larvae in the LC₁₀ group; D, the V_xj curves of the pupae and adult females in the LC₁₀ group; E, the V_xj of the larvae in the LC₃₀ group; and F, the V_xj of the pupae and adult females in the LC₃₀ group.