Oviposition preferences in Grapholita molesta: the relative importance of visual and olfactory cues

Abstract

The oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), is a major pest of fruit trees worldwide. Females oviposit on the young leaves of peach [Prunus persica (L.) Batsch (Rosaceae)] shoots at twilight, when light intensity changes markedly. Previous researches have shown that the oviposition response of this moth is guided particularly by visual and olfactory cues from host plants. However, the relative importance of visual and olfactory cues in their oviposition preference is largely unknown. As a crepuscular moth, how do choices change as light intensity drops rapidly from day to night? In the present study, through two‐choice behavioural experiments, the oviposition responses of G. molesta to visual and olfactory cues (alone or in combination) from peach shoots were tested at four light intensities ranging from daylight to starlight. Grapholita molesta showed similar oviposition responses to plant cues under 1 000, 100, 1 and 0.01 mW m−2 illumination. Olfactory cues from peach shoots attracted significantly more oviposition than the negative control, whereas visual cues alone did not. Furthermore, olfactory cues were more attractive than visual cues, and no significant interaction was observed between the responses to the two cues. Our findings indicate that G. molesta females mainly rely on olfactory cues to recognize oviposition sites, regardless of differences in light intensity. These results do not provide evidence for attraction to visual cues, but the possibility that the brightness of leaves might be used to guide oviposition is discussed.

Identification of Attractants from Three Host Plants and How to Improve Attractiveness of Plant Volatiles for Monochamus saltuarius

“…The selection and location of host plants are crucial for the survival and reproduction of herbivorous insects, which can distinguish nutritional and toxic compounds through their olfactory and gustatory systems [36][37][38]. Adults can detect and distinguish volatile substances from specific plants through VOCs [39][40][41][42], thus helping them search for host plants for oviposition or feeding.…”

Oviposition site selection in the crepuscular moth, Grapholita molesta: does light matter?

“…In this experiment, we presented peach Prunus persica Batsch shoots, which are highly attractive to G. molesta females for oviposition (Yang et al, 2019), to test light vs. dark preference in the presence of host odor. Top peach shoots (cv.…”

“…Top peach shoots (cv. Shenzhou Honey Peach) with 5 ± 1 leaves that served as the odor stimuli were placed individually into plastic cups containing a block of ‘Oasis’ floral foam to maintain shoot freshness (Yang et al, 2019). Plastic cups were pierced with 30 holes (1.5 mm diameter) in their sides, thereby allowing odors to escape.…”

Plant Volatiles Mediate Host Selection of Sitodiplosis mosellana (Diptera: Cecidomyiidae) among Wheat Varieties

“…Selecting and locating host plants are crucial for the survival and reproduction of phytophagous insects. It is widely believed that olfaction plays predominant roles in this process. − Adult females can detect and discriminate volatile semiochemicals from particular plants in a species-specific manner or via specific ratios of ubiquitous compounds − and unitize them to select hosts for oviposition or feeding. Plant semiochemicals mediating host selection of several phytophagous insects among crops or varieties with different resistances have been identified. , It was reported that two sesquiterpene volatile compounds (zingiberence and curcumene), which are present in the wild tomato resistant to the tobacco whitefly Bemisia tabaci, but absent in susceptible cultivated tomato, are strongly repellent to B.…”