The visual capabilities employed by B. tabaci during the search for host plant locations were confirmed in this study, indicating that the B. tabaci visitation is influenced by chili pepper species. The visitation to C. annuum was lower compared to that to C. chinense and C. frutescens. C. annuum exhibited higher chlorophyll content than C. chinense and C. frutescens, resulting in a darker green leaf color. This suggests that C. annuum exhibits stronger antixenosis than C. chinense and C. frutescens, as indicated by the fewer visits. These findings support several previous studies that have reported B. tabaci prefers plants with lighter leaves over those with darker leaves22. Plant attributes can influence B. tabaci activity in visual and olfactory aspects, as well as the content of secondary metabolites in leaves, commonly referred to as passive resistance. Although this study did not report on olfactory aspects, the findings support the mechanisms of passive resistance that have been extensively documented in previous research23; Daryanto et a.l, 2025;24,25. The antixenosis mechanisms of plants can disrupt insect behaviour during the host plant selection phase. Leaf color can serve as an indicator for selection in breeding programs aimed at developing chili pepper varieties resistant to B. tabaci, as this research relates to the antixenosis mechanism. Furthermore, this study reaffirms the role of B. tabaci as the primary vector in the transmission of yellow viruses for chili pepper plants, a finding widely reported in the literature1,3,12.
The progression of yellow curl disease exhibits significant variation among species. The highest disease incidence was observed in C. chinense (58.3%), followed by C. frutescens (50.0%) and C. annuum (16.7%). Furthermore, the progression of the disease in C. annuum was slower during the first four weeks compared to C. chinense and C. frutescens, suggesting the presence of resistance mechanisms that may be functioning in this species. The rate of disease development also varied among species, indicating the potential for more effective early resistance mechanisms in C. annuum that inhibit viral replication and spread from the initial phase of infection. Additionally, lower B. tabaci visitation rates on C. annuum are suspected to reduce the likelihood of yellow virus transmission. The results of this study demonstrate a relationship between the frequency of B. tabacivisits and the incidence of yellow curl disease. As the frequency of vector visits increases, so does the level of infection. These findings emphasize that vector preference for hosts significantly influences disease spread. Leybourne and Aradottir26, stated that B. tabaci is a sap-feeding insect that can cause physical damage to host plants during probing and feeding, and can alaso indirectly transmit pathogens and viruses to them.
Visual symptoms observed in infected plants have been confirmed through molecular analysis. The visually observable symptoms of infected plants have been confirmed at the molecular level. The research findings indicate that two primers can be used to detect viral genomes in chili pepper plants. The results demonstrate that the presence of the virus in C. annuum is lower compared to C. chinense and C. frutescens. Koeda et al.27, found that the recessive gene of pepy-1 resistance plays a role in C. annuum’s resistance to the bipartite begomovirus that causes curly leaves in Indonesia in general and the virus that causes chili pepper leaf curls in Aceh. Similarly, Pohan et al.5, showed that C. annuum homozygous for the pepy-1 gene has higher resistance than heterozygous. This discrepancy may be attributed to C. annuum’s superior strategy for responding to viral presence in plant tissues, as it appears to suppress viral development more rapidly than C. chinense and C. frutescens. However, in detail, the capacity of C. annuum to inhibit viral replication warrants further investigation. These findings suggest a specific interaction between the virus and its host, which could serve as a foundation for future research on viral evolution and adaptation.
Yellow curl virus infection significantly disrupted vegetative growth in all three chili pepper species, as indicated by reduced plant height and canopy size. This disruption indicates the inhibition of key physiological processes, including photosynthesis, energy metabolism, and growth hormone regulation28. The virus is known to reduce chlorophyll activity, inhibit photosynthate translocation, and interfere with hormones such as auxin, cytokinin, and gibberellin, disrupting cell elongation and new tissue formation29. This impact was most pronounced in C. frutescens and C. annuum, indicating significant disruptions in carbon distribution and shoot meristem activity. Yellow curl virus infection not only inhibits morphological growth but also fundamentally disrupts the physiological mechanisms underlying chili plant growth performance.
Yellow virus infection triggers morphological responses that vary across species, depending on the complex interactions between the virus and host physiological regulation. Leaf enlargement in C. annuum may be caused by hormonal imbalances that trigger cell hypertrophy or by energy allocation focused on fewer leaves formed as a form of photosynthetic compensation30. Interestingly, C. chinense shows an increase in leaf number. This can be viewed as a physiological compensatory mechanism, namely an increase in leaf number to maintain photosynthetic capacity when leaf quality decreases31. This difference is likely due to changes in host gene expression induced by viral infection, which affect physiological processes such as photosynthesis and hormone regulation. Viruses can modulate hormone pathways and cross-react between hormones through small RNA (sRNA) systems32. In C. frutescens, leaves were smaller and fewer, suggesting impaired cell division associated with reduced cytokinin levels and low meristem activity33. Chili species exhibit different physiological strategies for adapting to metabolic disturbances caused by viral infections.
The development of virus-symptomatic chili pepper plants also decline. The findings indicate a reduction in the number of flowers that develop into fruits, a decrease in production components such as the number of fruits per plant and fruit weight, and a decreace in overall yield. Among all observed parameters of plant development in this study, C. annuum exhibited a greater tendency for resistance compared to C. chinense and C. frutescens. These findings provide important insights into agricultural practices, particularly in the context of selecting chili pepper varieties that are more resistant to disease. Previous research has shown that variations in plant resistance can be influenced by genetic and physiological factors, which are focal points for developing new varieties more resistant to viral attacks34. This discovery also indicates the compensatory mechanisms of particular species that may contribute to their resistance to viral infection. Additionally, the number of leaves in C. chinense increased by 19% despite the plants exhibiting disease symptoms, indicating a complex physiological adaptation.
Overall, the decline in plant growth and development due to the virus in C. annuum is slower than in C. chinense and C. frutescens. This is associated with lower visits from B. tabaci, lower incidence and intensity, the undetected presence of viral genomes at the molecular level, uninterrupted chlorophyll formation, and a lesser reduction in yield components and production in C. annuum compared to C. chinense and C. frutescens. There is still limited scientific evidence explicitly stating that C. annuum is more resistant than C. chinense and C. frutescens. However, several previous studies have implicitly indicated this; Andarwening et al., (2022) reported that C. annuum has higer resistance level than to C. frutescens, although C. chinensewas not tested. Siddique et al.35, reported the discovery of QTLs for resistance to PepYLCV in C. annuum, which may be associated with resistance levels compared to other species. Meanwhile, Pohan et al.5, successfully identified recessive genes in C. annuum that are effective against Begomovirus, which were not found in C. frutescens.
The biochemical adaptations may function as defense mechanisms. In this study, phenol and vitamin C levels did not differ between infected and healthy plants of the three species. The response of plants to viral infection can be detected through changes in flavonoid and chlorophyll levels. An increase in flavonoids occurred in plants infected with C. frutescens. Flavonoid content is known to increase with increasing disease severity36. Yang37, reported that flavonoids mediate the tri-trophic interactions between plants, herbivorous insects, and natural enemies. Meanwhile, chlorophyll content exhibits varying trends, with an increase observed in C. annuum. The results of this study indicate that biochemical responses to viral infection can vary among species and that the plant defense mechanisms may operate differently in response to infection. The increase in chlorophyll in infected C. annuum is likely related to the green island phenomenon, where local tissues remain photosynthetically active despite systemic infection38,39.
Analysis of yield components indicates that viral infection significantly reduces the number of fruits per plant and the weight of each fruit. The most pronounced decrease in the number of fruits per plant due to flower-to-fruit failure occurs in C. frutescens at 74.8%. In comparison, C. annuum at 35.5% and C. chinense at 40.6% do not show significant differences. The reduction in fruit weight per plant ranges from 24.9% in C. annuum, 83.5% in C. chinense, to 68.5% in C. frutescens. These findings underscore the importance of understanding the economic impact of yellow curl disease, which can lead to significant losses for farmers and the agricultural industry as a whole. The economic repercussions of yellow virus disease, as reported in previous studies based on survey results, have been extensively documented10,11. This research complements the existing literature by presenting primary data on yield loss.
This study makes a significant contribution to expanding the understanding of the complex interactions between host plants, insect vectors, and pathogenic viruses. One of the most prominent aspects of novelty is the methodological approach employed. For the first time, a comprehensive comparison of three chili pepper species—C. annuum, C. chinense, and C. frutescens—was conducted under natural field infection, integrating data from molecular, physiological, and biochemical analyses. This holistic approach enables a more comprehensive understanding of the relationships between vector behavior, disease development, and plant physiological responses. Furthermore, this research provides new biological insights into species compensation mechanisms and variations in biochemical responses, revealing differences in adaptive capacity in response to viral infection pressure.
Specifically, C. annuum demonstrates a more effective defense response, characterized by a slower progression of disease and the undetectability of viral genomes by molecular testing, suggesting the presence of potential resistance mechanisms. The research results show that C. annuumresistance is likely a combination of antixenosis against the vector and antiviral (physiological) resistance that suppresses replication. The research results align with those of Siddique et al.35. These findings are crucial for developing superior varieties. The research results suggest that efforts to mitigate chili pepper production losses due to yellow virus should begin by controlling B. tabaci populations by reducing their visitation rates to chili pepper plants. The high visitation rates of B. tabaci to chili pepper plants indicate a trend of increasing incidence and intensity of yellow virus symptoms, ultimately impacting the quantity and weight of fruits produced and increasing yield loss rates. Reducing vector insect visitation can be achieved by cultivating varieties with high antixenosis levels. Apart from antixenosis, further research is needed to identify and regulate genes related to virus resistance in C. annuum.
Identifying resistance traits in C. annuum and clarifying yield-loss components provides a foundation for targeted breeding and environmentally friendly disease management. Priority research includes exploring genetic mechanisms of resistance, such as genes and pathways that suppress viral replication, and examining secondary metabolites, such as flavonoids and chlorophyll, that contribute to antiviral and antifeedant defenses. Studies on the genetic factors underlying susceptibility to diverse virus strains are also crucial, given the high viral diversity that affects long‑term resistance. A deeper understanding of plant–virus interactions will enable breeding programs to produce chili varieties with broad resistance. Such insights strengthen disease management strategies and support sustainable agricultural practices.
