Effects of glyphosate on the growth, development, and physiological functions of silkworm, Bombyx mori

Abstract

Glyphosate is an herbicide widely used worldwide, but whether it is safe to nontarget organisms is controversial. In this study, the lepidopteran model insect silkworm was used to investigate the effects of glyphosate residues. The LC 50 (72 h) of glyphosate on silkworm was determined to be 14875.98 mg/L, and after exposure to glyphosate at 2975.20 mg/L (a concentration comparable to that used for weed control in mulberry fields), silkworm growth was inhibited by 9.00%, total cocoon weight was lowered by 10.53%, feed digestibility was decreased by 7.56%, and the activities of alpha-amylase and trypsin were reduced by 10.41% and 21.32%, respectively. Pathological analysis revealed that glyphosate exposure led to significantly damaged midgut, along with thinner basal layer, shedding microvilli, blurred cytoplasmic membrane, and appearance of vacuoles. Exposure to glyphosate also led to accumulation of peroxides in the intestinal tissue; the messenger RNA transcription of SOD, Cu/Zn-SOD, and Mn-SOD was all significantly upregulated by glyphosate treatment for 24 h, while CAT transcription was increased at 24, 48, and 72 h.The activity of SOD was increased significantly at 24 h, while significant activity changes were observed for CAT at

The effects of glyphosate exposure on gene transcription and immune function of the silkworm, Bombyx mori

“…Our previous study has shown that glyphosate exposure can inhibit silkworm growth and development, reduce total cocoon weight and digestive enzymes, and induce the histopathological changes in the midgut and oxidative stress (Feng et al, 2022). In this study, we used the silkworm, Bombyx mori , as the research subject, and performed RNA‐Seq to analyze the transcriptome profile of silkworm midgut after exposed to glyphosate at 2975.20 mg/L (a concentration commonly used at mulberry fields).…”

“…Redox imbalance is considered as an important mechanism of glyphosate toxicity on nontarget organisms. Studies have shown that glyphosate exposure causes accumulation of H 2 O 2 and O 2− in silkworm midgut (Feng et al, 2022), and Cat can quickly decompose H 2 O 2 (Scandalios, 2005). This study found that the transcription level of Cat in silkworm midgut after glyphosate exposure was 1.93‐fold of the control group, which is consistent with our results; however, the transcript level of Jafrac1 , which encodes thiol peroxiredoxin, was downregulated (0.71‐fold of the control group).…”

“…The activity of digestive enzymes in animals directly reflects their ability to digest, absorb and utilize nutrients, thus determining their growth and health status (Xu et al, 2011). It has been shown that after 48 h of glyphosate exposure, the activity of digestive enzymes (α‐amylase and trypsin) were significantly reduced (Feng et al, 2022). In this study, we found that the genes related to protein digestion and absorption were downregulated.…”

“…In addition, the gene encoding lipase 1, LOC101735952 , was transcriptionally upregulated, which was 1.76‐fold of the control group. Studies have shown that the lipase activity in silkworm was significantly increased after 24 h of glyphosate exposure, and then significantly decreased after 48 h (Feng et al, 2022); moreover, it has been shown that acetamiprid exposure led to a transient increase in lipase activity in silkworm, which might be related to inflammation (Wang et al, 2019). These results were similar to our results in this study.…”

“…Glyphosate is used for weeding in mulberry fields. Although feeding silkworms with polluted mulberry leaves does not cause acute poisoning and death, it can affect the digestion and cocoon formation of silkworms (Feng et al, 2022), whereas the underlying mechanisms are still unclear. At present, RNA sequencing (RNA‐Seq) has been widely used to explore the molecular mechanism of various physiological activities of silkworms (Jiang et al, 2022; Li et al, 2012; Lu et al, 2021; Zhang et al, 2021).…”