Repellency Mechanism of Natural Guar Gum-Based Film Incorporated with Citral against Brown Planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae)

Abstract

Using of plant essential oil that coevolved as a defense mechanism against agriculture insects is an alternative means of controlling many insect pests. In order to repel brown planthoppers (BPHs), the most notorious rice insect pest, a new film based on guar gum incorporated with citral (GC film) was formulated, which was effective while being environmentally friendly. In this paper, the effect and mechanism of GC film repellency against BPHs were determined. Repellent activity test and olfactory reaction analysis showed that GC film had repellency effect against BPHs, with repellency of 60.00% and 73.93%, respectively. The result of olfactory reaction indicated that GC film repellency against BPHs relied on smell. EPG analysis showed the proportion and mean duration of np waveform were significantly higher than in CK and increased following the treatment concentration, which indicated that GC film affected the recognition of BPHs to rice. Further analysis by RNA sequencing analysis showed a total of 679 genes were significantly upregulated and 284 genes were significantly downregulated in the BPHs fed on the rice sprayed with GC film compared to control. Odorant-binding protein (OBP) gene 797 and gustatory receptor gene (GR)/odorant receptor (OR) gene 13110 showed a significant decrease in differential expression and significant increase in differential expression, respectively. There were 0.66 and 2.55 differential expression multiples between treated BPHs and control, respectively. According to the results described above, we reasoned that GC film repellency against BPHs due to smell, by release of citral, caused the recognition difficulties for BPHs to rice, and OBP gene 797 and GR/OR gene 13110 appeared to be the crucial candidate genes for GC film repellency against BPHs. The present study depicted a clear and consistent repellency effect for GC film against BPHs and preliminarily clarified the mechanism of GC film as a repellent against BPHs, which might offer an alternative approach for control of BPHs in the near future. Our results could also help in the development and improvement of GC films.

Research Progress of a Pesticide Polymer-Controlled Release System Based on Polysaccharides

“…Based on this, we speculated that nano-controlled release pesticide carriers, based on polysaccharides and their derivatives, could be developed simultaneously from the direction of regulating the resistance of plants themselves to pests and directly inhibiting pests (Figure 2). From the direction of regulating the resistance of plants themselves to pests, such as stimulating plant growth [31,[70][71][72][73], triggering an early warning of plant immune mechanism [53,74]. From the direction of direct inhibiting pests, the first development direction is the specific release of pesticides, which is based on the location of pests and diseases and the period of harm, such as targeting specific enzymes' environments in harmful organisms [9,33], or targeting specific pH [9,15,24,27,29,32,[34][35][36][52][53][54][55] or temperature [23,24,27,51,53,56] environments, while protecting other species, such as bees, and earthworms have a poor release capacity in vivo.…”

“…Guar gum and diquat prepared into a gel (Hydrogel) could significantly reduce the drift of off-site herbicides [69]. In addition, guar gum could also be made into a film (GC film) with related repellents, which was both effective and environmentally friendly and could slowly release the brown planthopper repellent citral [70].…”

Drought Stress Response in Guar (Cyamopsis tetragonoloba (L.) Taub): Physiological and Molecular Genetic Aspects

“…Transcriptomics represents another highly efficient approach currently employed for the search of prospective biotechnology-relevant markers to establish new cultivars with high gum contents [107][108][109]. Thus, post-genomic studies combining transcriptomics and metabolomics platforms emerged over the last decade.…”

Homeotic Protein Distal-Less Regulates NlObp8 and NlCsp10 to Impact the Recognition of Linalool in the Brown Planthopper Nilaparvata lugens

“…The transcript of both HoblOBP9 and HoblOBP13 in Holotrichia oblita was significantly increased upon exposure to the attractant ( E )-2-hexenol for 24 h, while the transcript of DcitOBP7 was significantly decreased after Asian citrus psyllid Diaphorina citri was exposed to linalool for 5 h . When the brown planthopper (BPH) Nilaparvata lugens (Stål) were fed on the rice plant sprayed with a natural Guar gum-based film, which was incorporated with citral, an effective repellent for BPHs, RNA sequencing analysis showed that the relative mRNA level of an OBP coding gene named 797 was significantly decreased . Compared with the naive control, the transcriptional level of some OBPs and CSPs of M.…”

“…The transcript of both HoblOBP9 and HoblOBP13 in Holotrichia oblita was significantly increased upon exposure to the attractant (E)-2-hexenol for 24 h, 21 while the transcript of DcitOBP7 was significantly decreased after Asian citrus psyllid Diaphorina citri was exposed to linalool for 5 h. 22 When the brown planthopper (BPH) Nilaparvata lugens (Stal) were fed on the rice plant sprayed with a natural Guar gum-based film, which was incorporated with citral, an effective repellent for BPHs, RNA sequencing analysis showed that the relative mRNA level of an OBP coding gene named 797 was significantly decreased. 23 Compared with the naive control, the transcriptional level of some OBPs and CSPs of M. persicae was downregulated in the aphids continuously treated with EβF, and the aphids were less likely to be repelled by EβF. 24 Furthermore, it has been revealed that there were no significant differences in the populations of both aphids M. persicae and parasitized aphids between genetically modified wheat lines, which can stably produce EβF and untransformed control.…”