Twelve pumpkin cultivars (Cucurbita maxima D.), cultivated in Iowa, were studied for their seed oil content, fatty acid composition, and tocopherol content. Oil content ranged from 10.9 to 30.9%. Total unsaturated fatty acid content ranged from 73.1 to 80.5%. The predominant fatty acids present were linoleic, oleic, palmitic, and stearic. Significant differences were observed among the cultivars for stearic, oleic, linoleic, and gadoleic acid content of oil. Low linolenic acid levels were observed (<1%). The tocopherol content of the oils ranged from 27.1 to 75.1 μg/g of oil for α-tocopherol, from 74.9 to 492.8 μg/g for γ-tocopherol, and from 35.3 to 1109.7 μg/g for δ-tocopherol. The study showed potential for pumpkin seed oil from all 12 cultivars to have high oxidative stability that would be suitable for food and industrial applications, as well as high unsaturation and tocopherol content that could potentially improve the nutrition of human diets. Keywords: Pumpkin seed oil; pumpkin seed; oilseed; winter squash; Cucurbitaceae; fatty acid; tocopherol

Single and dual choice tests in a flight tunnel revealed that plants damaged by host larvae are the main source of the volatiles that attract females of the parasitoid Cotesia marginiventris (Cresson) to the microhabitat of its hosts. Frass and host larvae, the other two major components of a complete plant‐host complex, were significantly less attractive than the damaged seedlings; frass alone was more attractive than larvae alone. However, a recombination of larvae with the damaged seedlings was significantly more attractive than the damaged leaves alone, or damaged leaves with frass. This was due to the additional feeding damage done by the larvae. The role of plants in the host‐finding behaviour of parasitoids is discussed. Résumé Plantes endommagées par des chenilles: source de synomones volatiles guidant le parasitoïde Cotesia margiventris vers le micro‐habitat de ses hôles L'hyménoptère C. marginiventris Cresson, parasite solitaire, est connu comme étant attiré par les odeurs liées à l'hôte émises par un complexe de chenilles consommant des feuilles. La source exacte de ces substances attractives restait encore à déterminer. Pour cela, des expériences en tunnel de vol ont été réalisées dans lesquelles différents composés du complexe plante et hôte ont été testés individuellement et en combinaisons diverses. Les 3 composés testés ont été: des plantules de maïs endommagées par des chenilles de Spodoptera exigua (BAW); des excréments produits par les chenilles de BAW consommant du maïs; des chenilles de BAW en l'absence de plantes et d'excréments. Les plantes endommagées ont été significativement plus attractives que les excréments ou les chenilles. En expériences de choix, les excréments étaient plus attractifs que les chenilles. Différentes combinaisons de ces 3 composantes principales ont montré que l'attractivité augmentait quand les chenilles étaient associées à des feuilles endommagées. Ajouter des excréments n'augmentait pas significativement l'attractivité. Quand des chenilles étaient associées avec des feuilles endommagées, mais en présence d'écran les empêchant de consommer les feuilles, l'attractivité était celle des feuilles endommagées seules. Des feuilles de maïs n'ayant jamais été exposées aux dégâts des chenilles étaient à peine attractives. On peut en conclure que les feuilles endommagées par les chenilles sont la principale source de substances volatiles qui orientent le parasito'ide C. marginiventris vers le voisinage de ses hôtes. La consommation active par les chenilles augmente probablement la quantité de substances émises par les plantes, ce qui se traduit par une attractivité accrue. Les substances volatiles des plantes jouent un rôle dans la découverte de l'habitat de l'hôte par les parasitoïdes. De plus en plus d'éléments suggèrent qu'une interaction sophistiquée entre hôte, plante et parasitoïde sera éventuellement révélée.

SummaryUndamaged plants emit low levels of green leaf volatiles (GLVs), while caterpillar-damaged and artificially damaged plants emit relatively higher levels of cerrain GLVs. Female braconid parasitoids, Microplitis croceipes, oriented to both damaged plants and to individual GLVs in no-choice tests in a wind tunnel, but seldom oriented to undamaged plants. Female ichneumonid parasitoids, Netelia heroica, also oriented to individual GLVs in a wind tunnel. Males of both wasp species failed to orient to the GLVs. These data show that leaf-feeding caterpillars can cause the release of GLVs, and that parasitic wasps can respond to these odors by flying upwind (chemoanemotactic response), which brings the wasps to their caterpillar hosts. This supports the hypothesis that plants communicate with members of the third trophic level, i.e., plants under herbivore attack emit chemical signals that guide natural enemies of herbivores to sites of plant damage. In this interaction, the GLVs serve as tritrophic plant-to-parasitoid synomones. That parasitoids from two different wasp families oriented to GLVs suggests that the response may be widespread among the Hymenoptera.

Tomato seeds represent a very large waste byproduct from the processing of tomatoes into products such as tomato juice, sauce and paste. One potential use for these seeds is as a source of vegetable oil. This research investigated the oil content of tomato seeds using several extraction techniques as well as an examination of the oil extracts to determine the composition of the minor constituents such as phytosterol and antioxidant composition. The oxygen radical absorbance capacity (ORAC) of the tomato seed oils were also measured and correlated with antioxidant contents. This research demonstrated that tomato seed oil yield was highest using hot ethanol and followed by hot hexane and finally SC-CO 2 . The SC-CO 2 treatment, however, had the highest total phytosterol content as well as highest individual phytosterol content. Sitosterol, cycloartanol, and stigmasterol were the most abundant phytosterols present in the extracts. The highest concentrations of antioxidants were found in the hexane extract. The most abundant antioxidants found in the tomato seed oils were all-trans-lycopene, cis-3-lycopene and b-carotene. ORAC was highest for the hexane extract. Oil yield was inversely proportional to both a-tocopherol and c-tocopherol content and positively correlated with cis-3-lycopene content. ORAC values were positively correlated with only all-trans-lycopene and cis-3-lycopene demonstrating their role as antioxidants in the tomato seed oil.