Experience is well known to affect sensory-guided behaviors in many herbivorous insects. Here, we investigated the effects of natural feeding experiences of Helicoverpa armigera larvae on subsequent preferences of larval approaching and feeding, as well as the effect of host-contacting experiences of mated females on subsequent ovipositional preference. The results show that the extent of experience-induced preference, expressed by statistical analysis, depended on the plant species paired with the experienced host plant. Larval feeding preference was much easier to be induced by natural feeding experience than larval approaching preference. Naïve larvae, reared on artificial diet, exhibited clear host-ranking order as follows: tobacco ≥ cotton > tomato > hot pepper. Feeding experiences on hot pepper and tobacco could always induce positive feeding preference, while those on cotton often induced negative effect, suggesting that the direction of host plant experience-induced preference is not related to innate feeding preference. Inexperienced female adults ranked tobacco as the most preferred ovipositional host plant, and this innate preference could be masked or weakened but could not be reversed by host-contacting experience after emergence.

The cigarette beetle, Lasioderma serricorne (F.) (Coleoptera: Anobiidae) is a destructive pest species of tobacco. Olfactory repellents derived from permitted tobacco flavorants have the advantage of not adversely effecting tobacco flavor. Among 12 test compounds, neral exhibited the strongest repellent effect. Among six binary blends prepared, three blends (neral + ethyl cinnamate, neral + cinnamaldehyde, and neral + methyl cinnamate) evoked the strongest repellent response. The interactions between neral and any one of the cinnamic acid derivatives were additive, and the interactions between neral and the cinnamic acid derivatives were antagonistic. In a 32-d tobacco barn bioassay, neral + cinnamaldehyde (embedded in 0.5% agaropectin) showed the strongest repellent effect with a persistence of at least 30 d. The binary blend of two tobacco additives (neral and cinnamaldehyde) appears promising as a repellent for controlling cigarette beetles in tobacco barns.

Information is lacking regarding the visual cues used by Helicoverpa armigera moths during nectar feeding. Here, we investigated the preference for radial gradient patterns in H. armigera moths. The results indicated that both sexes shared a preference to plain flower models of blue and cyan. The radial gradient pattern (cyan as nectar guide color and blue as petal color) was more attractive than its component plain colors (cyan or blue), especially in male moths. Number of corolla petals did not influence the attractiveness of the cyan-blue pattern. The addition of a tertiary floral attractant to white-blue or cyan-blue radial gradient patterns could dramatically enhance the attractiveness of visual cues in males rather than females, suggesting that males gave a higher weight in olfactory modality than females gave, while females gave a higher weight in vision modality than males gave. All together, we found an optimal combination of floral cues in H. armigera sexes as follows: A tertiary floral attractant (2 μL dose of phenylacetaldehyde, benzyl acetate, and salicylaldehyde mixed in 26:15:2) added to white-blue radial gradient flower model (3 cm in diameter). To our knowledge, this is the first time that rose curve and radial gradient tools were used to simulate floral pattern in the studies of flower-visiting insects. diurnal species give higher weight to visual cues [1]. However, some nocturnal species such as wild Manduca sexta moths did not feed from cloth-bagged fragrant Datura wrightii flowers lacking strong visual contrast, nor did they feed from paper model flowers lacking plant odors, suggesting a synergistic effect between visual and olfactory cues in nectar feeding [2]. Similarly, approaches to odor sources of M. sexta naïve males never resulted in proboscis extension or probing in the absence of a visual target [3]. Further studies demonstrated that