Agrotis ipsilon (Lepidoptera: Noctuidae) is a major underground pest that damages many agricultural crops in China and other countries. A diet-incorporation-based bioassay was conducted to evaluate the sublethal effects of the novel anthranilic diamide chlorantraniliprole on the nutritional physiology, enzymatic properties and population parameters of this cutworm. Chlorantraniliprole exhibited signs of active toxicity against third instar larvae of A . ipsilon , and the LC 50 was 0.187 μg.g −1 of artificial diet after treatment for 72 h. The development time of the larval, pupal and adult stages was significantly affected after chlorantraniliprole exposure, compared to the control treatment. Relative to the control treatment, chlorantraniliprole decreased pupal and adult emergence rates, fecundity and fertility and increased the proportions of developmental deformities, the adult preoviposition period (APOP) and the total preoviposition period (TPOP). Furthermore, compared to those treated with the control, A . ipsilon larvae treated with low doses of chlorantraniliprole decreased food utilization and nutrient content (protein, lipid, carbohydrate, trehalose), showed lower pupal weights and growth rates. Compared with the control treatment, chlorantraniliprole significantly reduced digestive enzyme activities and observably increased detoxifying and protective enzyme activities and hormone titers. Importantly, these chlorantraniliprole-induced changes affected life table parameters of the cutworm. These results suggest that chlorantraniliprole at low concentrations can impair A . ipsilon development duration, normal food consumption and digestion process, enzymatic properties, hormone levels, fecundity and population levels. Chlorantraniliprole exhibit the potential to be exploited as a control strategy for this cutworm.

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Diamondback moth, Plutella xylostella (L.; Lepidoptera: Plutellidae), is an important pest of crucifers worldwide. The extensive use of diamide insecticides has led to P. xylostella resistance and this presents a serious threat to vegetable production. We selected chlorantraniliprole (Rf) and flubendiamide (Rh) resistance strains of P. xylostella with resistance ratios of 684.54-fold and 677.25-fold, respectively. The Rf and Rh strains underwent 46 and 36 generations of lab-selection for resistance, respectively. Low cross resistance of Rh to cyantraniliprole was found. Cross resistance to chlorfenapyr, tebufenozid, and indoxacarb was not found in Rf and Rh strains. The P. xylostella ryanodine receptor gene (PxRyR) transcripts level in the Rf and Rh strains was up-regulated. Except for Rf34 and Rh36, PxRyR expression in all generations of Rf and Rh selection gradually increased with increasing resistance. Two resistant populations were field-collected from Guangzhou Baiyun (Rb) and Zengcheng (Rz) and propagated for several generations without exposure to any pesticide had higher PxRyR expression than the susceptible strain (S). In the S strain, PxRyR expression was not related to the resistance ratio. Gene sequencing found that the RyR 4946 gene site was glycine (G) in the S, Rf, and Rh strains, and was glutamate (E) with 70% and 80% frequency in the Rb and Rz populations, respectively. The 4946 gene site was substituted by valine (V) with the frequency of 30% and 20% in Rb and Rz populations, respectively. These results increase the understanding of the mechanisms of diamide insecticide resistance in P. xylostella.

L-Ascorbic acid (AsA) is the most abundant antioxidant and a major redox buffer that regulates plant responses to environmental stresses. AsA is also a precursor of oxalate in plants, while oxalate is associated with aluminum (Al) tolerance in some plant species. To enhance AsA in plants and increase tolerance against oxidative stress and Al toxicity, the yeast D-arabinono-1,4-lactone oxidase (ALO) gene was overexpressed in transgenic tobacco plants. Overexpression of ALO promoted synthesis of AsA and oxalate in leaves, but did not affect oxalate level in roots. Compared to the wild type, transgenic plants maintained higher levels of AsA, glutathione, maximal photochemical efficiency (F v /F m ) and the actual PSII efficiency (Φ PSII ) of photosystem II (PSII), and nonphotochemical quenching (NPQ), and accumulated less H 2 O 2 and malondialdehyde (MDA) in leaves in response to methyl viologen-and high-light-induced oxidative stress. In addition, transgenic plants showed higher AsA level and fresh weight of shoot and roots and lower levels of Al, H 2 O 2 , and MDA in root tips after Al treatment; however, there is no significant difference in organic acid (citrate and oxalate) exudation between the wild-type and transgenic plants in response to Al treatment. The results suggest that AsA and oxalate could be up-regulated by overexpressing ALO. The elevated AsA increased oxidative tolerance due to scavenging of reactive oxygen species (ROS) and induction of NPQ in leaves and enhanced Al tolerance as an antioxidant for avoiding Al-triggered oxidative damages in roots.

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