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The identity and effectiveness of pollinators remain a critical gap that must be filled to improve crop pollination services globally. Observations were made on melons (Cucumis melo L.), a globally significant fruit, to identify floral visitors and their pollinating efficiencies on the plant's quantitative and qualitative yield. The research was carried out between 2019 and 2021 in the Mila region of eastern Algeria. The majority of pollinators on melon flowers were bees (hymenopterans; apoids), specifically Apis mellifera (Linnaeus, 1758), Ceratina cucurbitina (Rossi, 1792), and Megachile pilidens (Alfken, 1924). Compared to other significant pollinators, Megachile pilidens is the most efficient pollinator of melons, with the most pollen seeds deposited on flower stigmas. The results show that all pollinators visit staminate flowers more than pistillate flowers. This is proportional to the amount of nectar secreted by these flowers. We discovered that species abundant in melon flowers prefer staminate flowers over pistillate flowers, which is related to the amount of nectar secreted by the flowers. The quantitative and qualitative yields were calculated immediately after the mature fruits were recovered; the results show that the yield obtained by flowers with free access to insects is higher than that obtained by bagged flowers, implying that insects play an essential role in the pollination of Cucumis melo.
The global threat posed by Culex pipiens is a major concern in many regions. This investigation was carried out to assess the larvicidal properties of Ruta chalepensis extract against Cx. pipiens. Methanolic extract from R. chalepensis was prepared and tested on Cx. pipiens larvae. Results displayed that the methanolic extract of R. chalepensis had larvicidal activity against Cx. pipiens with LC90 and LC95 values of 4.94 and 5.18 µg/mL, respectively, 24 h post application. The total phenolic (TP) and flavonoid (TF) contents of R. chalepensis were 97.70 ± 2.22 µg GAE/mg and 5.64 ± 0.052µg QE/mg, respectively. Histopathological study of treated larvae showed histological alterations in the digestive system, such as collapsed brush border, broken membranes, and cytoplasmic masses. The two major bioactive compounds found in the methanolic extracts were 2-(2-Hydroxyethoxy) phenol (14.8%) and oleic acid (14.7%). Future research is encouraged to evaluate the effectiveness of controlling Cx. pipiens in small-scale field tests using ecologically safe, botanical insecticides.
The red sunflower seed weevil, Smicronyx fulvus LeConte (Coleoptera: Curculionidae), is the most destructive seed-feeding pest of sunflower in North America. The life history of S. fulvus (e.g., univoltine, overwintering within 6 cm of soil surface) suggests several strategies to limit crop damage, but insecticides remain the primary management tool. To facilitate broader management of S. fulvus, a degree-day model for adult emergence was developed and tested. Emergence of adults under controlled conditions produced a lower developmental threshold of 5 °C, ≈ 970 degree-days to first emergence, and ≈ 1160 degree-days to 50% emergence. Soil temperature data showed accumulated degree-days were similar 5 cm below turf and 10 cm beneath bare soil. Observed emergence of weevils in field plots occurred several days earlier than predicted (using 5 cm turf or 10 cm bare soil temperatures) when soil was kept free of vegetation. However, observed emergence was similar to predicted emergence when plots were shaded by spring wheat, which is representative of crops planted after sunflower for much of North America. Though access to soil (rather than ambient) temperature data is needed, this first degree-day model provides a tool to help growers avoid S. fulvus damage using early planting or early-maturing hybrids.
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