Dolycoris baccarum (L.) (Hemiptera: Pentatomidae) Infestation Induced Differential Changes in Plant Physiology: Preference and Damaging Nature to Different Sesame (Sesamum indicum L.) Varieties

Dolycoris baccarum (Hemiptera: Pentatomidae) is a cosmopolitan stink bug that causes substantial damage to several leguminous crops, including sesame. Herbivorous insect feeding can alter key physiological processes in plants, particularly photosynthesis and chlorophyll fluorescence, thereby affecting plant growth and productivity. This study investigated the effects of D. baccarum feeding on photosynthetic traits, including carbon assimilation rate (A) and stomatal conductance to water vapor (gsw), as well as chlorophyll fluorescence signal in different sesame varieties using a photosynthesis system and a portable gas exchange and fluorescence analyzer. Preference of D. baccarum among sesame varieties was evaluated through a choice test using seed pods, and feeding damage was quantified using the acid fuchsin test. Feeding by D. baccarum significantly reduced photosynthetic performance and chlorophyll fluorescence signal in sesame plants. The insect exhibited clear varietal preferences, and feeding damage differed significantly among sesame varieties. A positive association was observed between feeding activity and damage intensity, whereas photosynthetic parameters (A and gsw, and chlorophyll fluorescence signal) showed negative associations with yield following insect infestation. These findings indicate that D. baccarum feeding adversely affects both the physiological performance and productivity of sesame and highlight the potential for identifying resistant or tolerant sesame varieties for breeding programs. Further studies should examine the physical characteristics and nutrient composition of sesame seed pods and seeds to better understand the host selection behavior of D. baccarum and support the development of sesame varieties with improved resistance or tolerance to stink bug infestation.