Palatability of glyphosate in ants: a field experiment reveals broad acceptance of highly polluted solutions in a Mediterranean ant.

Glyphosate is a systemic herbicide still used in many countries, though there are several known detrimental effects on animals. Previous studies concerning its effects on social insects are available, but they are primarily focused on honeybees; little is known about the interactions of this compound with ants. Here, we assessed whether different concentrations of glyphosate can be perceived by ant workers and to what extent. As a model species, we used the Mediterranean ant Crematogaster scutellaris, commonly found in agroecosystems. We performed 3000 individual tests of acceptance using ten different solutions of various concentrations of the herbicide. Half of the solutions contained added sucrose in order to test the possible masking effect of the sugar taste on glyphosate. We used comparable glyphosate concentrations to those previously used in other studies on social insects or suggested by the producer. We found that the acceptance of the solutions decreased as the concentration of the herbicide increased. However, a significant percentage of ants drank the solutions with concentrations up to dozens of times higher than those inducing toxic effects in bees. In light of these results, we urge further assessment of the effects of glyphosate on ants, particularly because the food ingested by workers is transferred to the brood and queens, posing a potential threat to the health of the entire colony. Surprisingly, we did not record any difference in acceptance between solutions with and without sugar; this point is discussed regarding drought stress.

The antibiotic jinggangmycin increases brown planthopper (BPH) fecundity by enhancing rice plant sugar concentrations and BPH insulin-like signaling.

The brown planthopper (BPH), Nilaparvata lugens, is a resurgent pest with an unexpected response to jinggangmycin (JGM), a broadly applied antibiotic used to control rice sheath blight disease. JGM stimulates BPH fecundity, but the underlining molecular mechanisms remain unclear. Here we report that JGM sprays led to increased glucose concentrations, photosynthesis and gene expression, specifically Rubsico, sucrose phosphate synthase, invertase 2 (INV2) and INV3 in rice plants. JGM sprays led to high-glucose rice plants. Feeding BPH on these plants led to increased insulin-like signaling and vitellogenin synthesis. Treating BPH with metformin, a gluconeogenesis inhibitor, reversed the influence of feeding on high-glucose rice, which was rescued by glucose injections. Silencing insulin-like peptide 2 using per os dsRNA led to reduction in juvenile hormone (JH) III titers and other fecundity parameters, which were reversed by topical applications of the JH analog, methoprene. We infer that JGM acts via two broad mechanisms, one through increasing rice plant sugar concentrations and a second by upregulating BPH insulin-like signaling.

Protein abundance changes of Zygosaccharomyces rouxii in different sugar concentrations.

Zygosaccharomyces rouxii is a yeast which can cause spoilage in the concentrated juice industries. It exhibits resistance to high sugar concentrations but genome- and proteome-wide studies on Z. rouxii in response to high sugar concentrations have been poorly investigated. Herein, by using a 2-D electrophoresis based workflow, the proteome of a wild strain of Z. rouxii under different sugar concentrations has been analyzed. Proteins were extracted, quantified, and subjected to 2-DE analysis in the pH range 4-7. Differences in growth (lag phase), protein content (13.97-19.23mg/g cell dry weight) and number of resolved spots (196-296) were found between sugar concentrations. ANOVA test showed that 168 spots were different, and 47 spots, corresponding to 40 unique gene products have been identified. These protein species are involved in carbohydrate and energy metabolism, amino acid metabolism, response to stimulus, protein transport and vesicle organization, cell morphogenesis regulation, transcription and translation, nucleotide metabolism, amino-sugar nucleotide-sugar pathways, oxidoreductases balancing, and ribosome biogenesis. The present study provides important information about how Z. rouxii acts to cope with high sugar concentration at molecular levels, which might enhance our global understanding of Z. rouxii's high sugar-tolerance trait.