The ever-changing global environment currently includes an increasing ambient temperature that can be a devastating stress for organisms. Plants, being sessile, are adversely affected by heat stress in their physiology, development, growth, and ultimately yield. Since little is known about the response of biochemical traits to high-temperature ambiance, we evaluated eight parental lines (five lines and three testers) and their 15 F1 hybrids under normal and high-temperature stress to assess the impact of these conditions over 2 consecutive years. The research was performed under a triplicate randomized complete block design including a split-plot arrangement. Data were recorded for agronomic, biochemical, and fiber quality traits. Mean values of agronomic traits were significantly reduced under heat stress conditions, while hydrogen peroxide, peroxidase, total soluble protein, superoxide dismutase, catalase (CAT), carotenoids, and fiber strength displayed higher mean values under heat stress conditions. Under both conditions, high genetic advance and high heritability were observed for seed cotton yield (SCY), CAT, micronaire value, plant height, and chlorophyll-a and b content, indicating that an additive type of gene action controls these traits under both the conditions. For more insights into variation, Pearson correlation analysis and principal component analysis (PCA) were performed. Significant positive associations were observed among agronomic, biochemical, and fiber quality-related traits. The multivariate analyses involving hierarchical clustering and PCA classified the 23 experimental genotypes into four groups under normal and high-temperature stress conditions. Under both conditions, the F1 hybrid genotype FB-SHAHEEN × JSQ WHITE GOLD followed by Ghuari-1, CCRI-24, Eagle-2 × FB-Falcon, Ghuari-1 × JSQ White Gold, and Eagle-2 exhibited better performance in response to high-temperature stress regarding the agronomic and fiber quality-related traits. The mentioned genotypes could be utilized in future cotton breeding programs to enhance heat tolerance and improve cotton yield and productivity through resistance to environmental stressors.

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Dietary exposure studies are initial steps in environmental risk assessments of genetically engineered plants on non-target organisms. These studies are conducted in the laboratory where surrogate species are exposed to purified and biologically active insecticidal compounds at higher concentrations than those expected to occur in transgenic crops foliage. Thus, dietary exposure (early tier) tests provide robust data needed to make general conclusions about the susceptibility of the surrogate species to the test substance. For this, we developed suitable artificial diet and used it to establish a dietary exposure test for assessing the toxicity of midgut-active insecticidal compounds to the larvae of the Asian ladybird beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae). Using boric acid as a model compound, we validated the bioassay established for H. axyridis larvae. An artificial diet containing boric acid which negatively affected survival, development and adult weights was offered to larvae and indicated that the bioassay was able to detect toxic effects of insecticidal substances incorporated in diets. Using this dietary exposure test, environmental risk assessment of Cry1Ac, Cry2Ab, Cry1Ca, Cry1F and the non-Cry protein Vip3Aa was evaluated by analysing pupation rates, adult emergence rates, 7-day larval weights, and freshly emerged male and female weights among the toxin treatments and a pure artificial diet. These life-table parameters did not vary among artificial diets containing 200 lg/g Bt proteins or pure artificial diet. In contrast, boric acid adversely affected all life-table parameters. Thus on these bases, we concluded H. axyridis larvae are not sensitive to these Bt proteins expressed in genetically engineered crops.

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Biosafety of a genetically modified crop is required to be assessed prior to its commercialization. For this, a suitable artificial diet was developed and used to establish a dietary exposure test for assessing the toxicity of midgut-active Bt insecticidal proteins on Chrysopa pallens (Rambur). Subsequently, this dietary exposure test was used to evaluate the toxicity of the proteins Cry1Ab, Cry1Ac, Cry1Ah, Cry1Ca, Cry1F, Cry2Aa, Cry2Ab, and Vip3Aa on C. pallens larvae. Temporal stability, bioactivity, and the intake of the insecticidal proteins were confirmed by enzyme-linked immunosorbent assay and a sensitive-insect bioassay. The life history characteristics, such as survival, pupation, adult emergence, 7-day larval weight, larval developmental time, and emerged male and female fresh weights remained unaffected, when C. pallens were fed the pure artificial diet (negative control) and the artificial diets containing 200 μg/g of each purified protein: Cry1Ab, Cry1Ac, Cry1Ah, Cry1Ca, Cry1F, Cry2Aa, Cry2Ab, or Vip3Aa. On the contrary, all of the life history characteristics of C. pallens larvae were adversely affected when fed artificial diet containing boric acid (positive control). The results demonstrate that diets containing the tested concentrations of Cry1Ab, Cry1Ac, Cry1Ah, Cry1Ca, Cry1F, Cry2Aa, Cry2Ab, and Vip3Aa have null effects on C. pallens larvae. The outcome indicates that genetically modified crops expressing the tested Bt proteins are safe for the lacewing, C. pallens.

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