Molecular Entomology 2024, Vol.15, No.1, 32-42 http://emtoscipublisher.com/index.php/me 34 Figure 1 Evaluation of resistance of 1,520 accessions of Oryza sativa to three brown planthopper (BPH) biotypes (Adopted from Zhou et al., 2021) Image caption: (A)Typical images showing the appearance of adult BPH female after feeding on various rice accessions for 48 h. The values below the images indicate weight gain rate (WG) of each insect. (B) Representative photographs of rice plants with variable resistance levels in the bulk seedling test. The values below the images show the associated plant resistance score, which can be negatively related to the WG values in (A). Note that the accessions in (A) are not identical to those shown in (B). (C) Distribution of WG for BPH biotype I on all 1,520 accessions. (D, E) Distribution of WG for BPH biotypes II and III, respectively. (F) Percentage of the 1,520 rice accessions with resistant (R; WG < 0.3), moderately resistant (MR; 0.3 < WG < 0.6), moderately susceptible (MS; 0.6 < WG < 0.9), and susceptible (S; WG > 0.9). (G) Boxplots of WG for the three BPH biotypes in 1,520 rice accessions. Significant differences between biotypes are indicated by different lowercase letters (P < 0.05, least significant difference test) (Adopted from Zhou et al., 2021) 2 Breeding Approaches for Enhancing Resistance 2.1 Conventional breeding Conventional breeding methods have been instrumental in developing rice varieties resistant to insect pests. These methods typically involve selecting and crossbreeding plants that exhibit desirable traits, such as resistance to specific pests. For instance, traditional breeding has successfully incorporated resistance to leaf folder and other leaf-feeding insects, which are significant due to their ability to defoliate rice plants and reduce yield (Dash, 2020). However, the effectiveness of conventional breeding is often limited by the genetic diversity of the cultivated rice
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