The sterile insect technique (SIT) is widely used as part of an integrated approach to reduce field populations of the Mediterranean fruit fly (Ceratitis capitata, Diptera: Tephritidae). Aromatherapy based on exposure to ginger root oil (GRO) volatiles is known as a method to significantly improve the sexual performance of sterile medfly males, and is being used in many mass‐rearing facilities around the world. However, the optimum dose of GRO is not well defined. This work evaluated in laboratory cages four different doses of GRO and a control (0, 0.1, 0.25, 0.5 and 0.75 ml/m3), and two different methods to hold flies prior to release (paper bags and plastic cages). The objective was to find the lowest dose that provides optimal improvement in mating performance of sterile males when competing with wild males for wild females and optimal reduction in fertility of wild females. Egg hatch, copula duration, the Relative Sterility Index (RSI), and a Competitiveness (C) value (based on RSI) were calculated for each treatment to assess male sexual performance and induction of sterility. The method used to hold flies did not influence the aromatherapy effect. The mean time spent by wild females in copula with wild males was significantly longer than with sterile males for all treatments, except when sterile males were treated with 0.1 ml of GRO/m3. Amongst all doses studied, it is recommended to apply the lowest dose, 0.1 ml of GRO/m3, since at this dose both the RSI and induced sterility reached the highest levels, and were not statistically different from the 0.25 and 0.5 GRO/m3 doses. Indeed, this dose showed a very significant improvement in the mating competitiveness of sterile males aromatically treated with GRO.

2016-11-03T14:11:40

No abstract

Florida is a major fresh-market cabbage (Brassica oleracea L. var. capitata) producing state in the United States. The current cabbage production system relies on bare ground and subirrigation that requires a large volume of water to irrigate the crop. The bare ground system facilitates a maximum of 48,438 plant/ha, while there is a potential to increase plant population per area using plasticulture and drip irrigation. The objectives of this study were to determine the optimum cabbage plant population and plant arrangement that maximizes marketable yield per area for a high cabbage population plasticulture system. Cabbage was grown on 1.2-m-wide raised beds with black plastic mulch and drip irrigation. Plants were grown in either three or four rows with in-row plant spacings ranging from 15 to 35 cm and plant populations ranging from 41,518 to 129,167 plants/ha. Cabbage marketable yield increased as in-row spacing increased. Yields ranged from 19.7 to 69.7 Mg·ha−1. Marketable yield was not different between 3 and 4 rows for in-row spacings above 25 cm. The 15 and 20 cm in-row spacing produced significantly lower yields in the 4-row configuration as compared with the 3-row configuration in Fall and Winter 2011. Wider in-row spacings produced a greater percentage of heads of marketable size while reducing the percentage of small heads when compared with narrower in-row spacings. Mean head weight increased as in-row spacing increased and a 3- or 4-row configuration with an in-row spacing between 25 and 30 cm had consistently high yields in all three seasons compared with narrower in-row plant spacings. These results indicated that with a high population plasticulture system variable plant populations could be selected. In-row plant spacings between 30 and 35 cm may be beneficial for early plantings while a 25-cm spacing could be more productive for later plantings, especially when weather conditions are favorable.

Seepage is characterized as an inefficient irrigation method with regard to water and nutrient use. There is a need for an economically viable irrigation alternative to seepage, which increases crop productivity and profitability in Florida. The use of plastic mulch and drip irrigation for cabbage (Brassica oleracea var. capitata) production increases plant population per area and reduces the irrigation water requirement. However, plasticulture has a high capital investment and operating cost. The objectives of this study were to compare the profitability of plasticulture cabbage production and traditional seepage bare ground irrigation systems for Florida cabbage production, and to determine the breakeven point for cabbage grown under plasticulture given a range of market prices. The preharvest cost per acre for the plasticulture system was significantly higher than the cost for the seepage system ($4726 and $3035 per acre, respectively). However, for all planting dates considered in this study, the plasticulture system resulted in a significant increase in marketable yields when compared with the seepage system. The resulting increase in potential revenue offset the increase in preharvest costs and assured a positive net return on investment over the whole range market prices. It was also observed that low air temperatures combined with reduced solar radiation can prevent optimum plant development for cabbage transplanted between November and mid-December. Therefore, the return on investment may be reduced during less favorable climatic conditions for cabbage growth, making the plasticulture system less economically desirable for certain planting dates.