Bt eggplant (Solanum melongena L.) in Bangladesh: Fruit production and control of eggplant fruit and shoot borer (Leucinodes orbonalis Guenee), effects on non-target arthropods and economic returns.

Eggplant or brinjal (Solanum melongena) is a popular vegetable grown throughout Asia where it is attacked by brinjal fruit and shoot borer (BFSB) (Leucinodes orbonalis). Yield losses in Bangladesh have been reported up to 86% and farmers rely primarily on frequent insecticide applications to reduce injury. Bangladesh has developed and released four brinjal varieties producing Cry1Ac (Bt brinjal) and is the first country to do so. We report on the first replicated field trials comparing four Bt brinjal varieties to their non-Bt isolines, with and without standard insecticide spray regimes. Results of the two-year study (2016-17) indicated Bt varieties had increased fruit production and minimal BFSB fruit infestation compared with their respective non-Bt isolines. Fruit infestation for Bt varieties varied from 0-2.27% in 2016, 0% in 2017, and was not significantly affected by the spray regime in either year. In contrast, fruit infestation in non-Bt lines reached 36.70% in 2016 and 45.51% in 2017, even with weekly spraying. An economic analysis revealed that all Bt lines had higher gross returns than their non-Bt isolines. The non-sprayed non-Bt isolines resulted in negative returns in most cases. Maximum fruit yield was obtained from sprayed plots compared to non-sprayed plots, indicating that other insects such as whiteflies, thrips and mites can reduce plant vigor and subsequent fruit weight. Statistically similar densities of non-target arthropods, including beneficial arthropods, were generally observed in both Bt and non-Bt varieties. An additional trial that focused on a single Bt variety and its isoline provided similar results on infestation levels, with and without sprays, and similarly demonstrated higher gross returns and no significant effects on non-target arthropods. Together, these studies indicate that the four Bt brinjal lines are extremely effective at controlling BFSB in Bangladesh without affecting other arthropods, and provide greater economic returns than their non-Bt isolines.

Synergism of co-digestion of food wastes with municipal wastewater treatment biosolids.

Five semi-continuous flow anaerobic digesters treating a mixture of food waste (FW) and municipal biosolids (primary sludge and thickened wasted activated sludge) at an solids retention time (SRT) of 20 days and different blend ratios i.e. 0, 10%, 20%, 40% by volume with the fifth digester treating only biosolids at the same COD/N ratio as the 40% FW digester were operated to investigate co-digestion performance. Sixty days of steady-state operation at organic loading rates (OLR) of 2.2-3.85kgCOD/m3/d showed that COD removals were higher for the three co-digesters than for the two municipal biosolids digesters i.e. 61-69% versus 47-52%. Specific methane production per influent CODs were 1.3-1.8 folds higher in co-digestion than mono-digestion. The first-order COD degradation kinetic constants for co-digestion were more than double the mono-digestion. Additional methane production through synergism accounted for a minimum of 18-20% of the overall methane production. The estimated non-biodegradable fraction of the FW particulate COD was 7.3%. However, the co-digesters discharged 1.23-1.64 times higher soluble nitrogen than the control.

Characterization of typical household food wastes from disposers: fractionation of constituents and implications for resource recovery at wastewater treatment.

Food wastes with typical US food composition were analyzed to characterize different constituents in both particulate and soluble phases i.e., solids, chemical oxygen demand (COD), 5-day biochemical oxygen demand (BOD), nitrogen (N), phosphorus (P). Relationships between various pollutants were also investigated using 50 samples. One gram of dry food waste generated 1.21 g COD, 0.58 g BOD5, 0.36 g Total SS, 0.025 g Total N, and 0.013 g Total P. Distribution of constituents between particulate and aqueous phases indicated that 40% of COD and 30% of nitrogen were present in soluble form. Relative mass ratios of COD and nitrogen to solids were three to five times higher in particulates than in aqueous phase. However, COD/N ratios were higher in aqueous form than particulates at 63:1 versus 42:1. Detailed relationships between parameters showed that COD, nitrogen, and phosphorus in particulates are 200%, 3.6%, and 3.5% of the volatile suspended solids.