The Physical And Chemical Mechanism Of Host Plant Selection Of The Eurpoean Sunflower Moth Homoeosoma Nebulellum

The European sunflower moth,Homoeosoma nebulellum(Lepidopte.ra:Pyralidae)is one of the most serious pests of sunflower head and seed. The relationship between morphological structure and chemical composition of different sunflower cultivars on the resistance to sunflower moth was studied by observation of tubular floret and achene and determination of nutrients and secondary components in laboratory combined with evaluating on the resistance of14different cultivars to sunflower moth on field. Meanwhile, the preference for volatiles from different sunflower cultivars was assayed in laboratory. The results revealed the physical and chemical mechanism in host plant selection of sunflower moth and provide the basis for breeding resistant sunflower cultivars in future.1. The sunflower moth showed significant selection for different sunflower varieties, and preferred the edible sunflower varieties to oil sunflower ones. The pericarps of edible sunflower varieties were more likely in a shape of length or mid-length(≥1.5cm), whereas the pericarps of oil sunflower ones in a shape of short length or extremely short length(<1.5cm). These results suggest that the sunflower varieties with relatively small size of head will be helpful to reduce the damage of sunflower moth to sunflower.2. There were extremely significant differences in morphological structure among different varieties of sunflower with the diameter of head, opening size of tubular floret, thickness of the ovary wall of floret, thickness of the pericarp and density of pericarp pubescence extremely significant positive correlated with percent infestation of seed and infestation index of seed, respectively. Meanwhile, all the criteria of morphological structure had significant positive correlation each other.3. The content of soluble sugar, linoleic acid, aspartic acid, glutamic acid and tyrosine, arginine, proline, and total content of amino acid was extremely significant positively correlated with percent infestation of seed and infestation index of seed, respectively. The content of crude fat, cystine (Cys), and methionine (Met) extremely significant negatively correlated with percent infestation of seed and infestation index of seed, respectively.4. The content of tannin, and flavonoids was extremely significant negatively correlated with percent infestation of seed and infestation index of seed, respectively. The results suggested that cultivars show the higher the contents of tannins, and flavonoids of sunflower seed is, the lighter the damage of sunflower moth to sunflower.5. The female adults of sunflower moth significantly prefered the volatiles from sunflower to air, and show different behavioral responses to volatiles from different sunflower cultivars.