Antibody-Based Methods Reveal the Protein Expression Properties of Glucosinolate Sulfatase 1 and 2 in Plutella xylostella.

The glucosinolates (GLs) and myrosinase defensive systems in cruciferous plants were circumvented by Plutella xylostella using glucosinolate sulfatases (PxGSSs) during pest-plant interaction. Despite identifying three duplicated GSS-encoding genes in P. xylostella, limited information regarding their spatiotemporal and induced expression is available. Here, we investigated the tissue- and stage-specific expression and induction in response to GLs of PxGSS1 and PxGSS2 (PxGSS1/2) at the protein level, which shares a high degree of similarity in protein sequences. Western blotting (WB) analysis showed that PxGSS1/2 exhibited a higher protein level in mature larvae, their guts, and gut content. A significantly high protein and transcript levels of PxGSS1/2 were also detected in the salivary glands using WB and qRT-PCR. The immunofluorescence (IF) and immunohistochemistry (IHC) results confirmed that PxGSS1/2 is widely expressed in the larval body. The IHC was more appropriate than IF when autofluorescence interference was present in collected samples. Furthermore, the content of PxGSS1/2 did not change significantly under treatments of GL mixture from Arabidopsis thaliana ecotype Col-0, or commercial ally (sinigrin), 4-(methylsulfinyl)butyl, 3-(methylsulfinyl)propyl, and indol-3-ylmethyl GLs indicating that the major GLs from leaves of A. thaliana Col-0 failed to induce the expression of proteins for both PxGSS1 and PxGSS2. Our study systemically characterized the expression properties of PxGSS1/2 at the protein level, which improves our understanding of PxGSS1/2-center adaptation in P. xylostella during long-term insect-plant interaction.

Using essential oils from Citrus paradisi as a fumigant for Solenopsis invicta workers and evaluating the oils' effect on worker behavior.

The red imported fire ant is one of the world's most devastating invasive species, adversely affecting humans, wildlife, crops, and livestock. To control infestations, chemical pesticides are deployed extensively around the world. However, their extensive use has led to negative effects on the environment and human health. Essential oils, which are safe and ecofriendly, can potentially be used as alternatives to chemical pesticides. In this study, grapefruit essential oils were used as fumigant agents to control red imported fire ants. The crude grapefruit oil (GO1) contained 28 compounds, and the concentrated grapefruit oil (GO2), which was refined from GO1 by vacuum distillation, contained 20 compounds. D-Limonene was the dominant constituent in both GO1 (70.1%) and GO2 (73.96%), and other important constituents included ß-pinene, α-pinene, ß-phellandrene, octanal, d-carvone, α-terpineol, and linalool. Both the essential oils and their individual constituents (α-pinene, α-terpineol, ß-phellandrene, octanal, and d-carvone) showed strong lethal fumigant effects against workers. Workers were more susceptible to GO2 than GO1, and octanal was more toxic to workers as compared with the other four constituents. When antennas of workers were treated with the two oils or the five constituents, their walking and gripping abilities were significantly suppressed, and there was an obvious bending or breaking phenomenon on the sensilla of the antennas. Fumigant activity by grapefruit essential oils and their main compounds were associated with their effects on the walking and gripping behavior of workers, and this confirmed that grapefruit essential oil is a promising, ecofriendly, and safe fumigant for the control of red imported fire ants.