A Review of the Use of Black Soldier Fly Larvae, Hermetia illucens (Diptera: Stratiomyidae), to Compost Organic Waste in Tropical Regions.

Hermetia illucens (L., 1758) is a fly of the family Stratiomyidae frequently found in tropical zones. Adult flies are not considered pathogens as they are incapable of biting and feeding thus not transmitting sicknesses to humans. The larval stage feeds off organic matter and offer a rich protein source naturally consumed by animals. The use of black soldier fly (BSF) larvae to treat organic waste is growing around the world. This is especially true for tropical low- and middle-income countries as their favourable climate conditions mean that the BSF technology has significant potential to solve existing problems associated with a poorly developed sanitation infrastructure. In this study, we evaluate the feasibility, benefits and limitations of implementing BSF projects in tropical regions using Belem, in Brazil, as a case study. Black soldier fly prepupae, arising from the waste reduction process, can be used as animal feed. It therefore offers potential to promote regional development, create jobs and dispose of organic waste locally. Legal requirements as outlined in the Brazilian National Policy on Waste offer further incentives. However, more studies are needed to compare BSF waste reduction efficiency and prepupae yield to other technologies such as traditional composting and vermiculture, which can inform the decision-making for implementation of organic waste treatment facilities.

Evidence for dual effects of nitric oxide in the forced swimming test and in the tail suspension test in mice.

L-Arginine (L-Arg), a substrate for nitric oxide synthase (NOS) at a dose of 250-500 mg/kg, i.p., significantly reduced the duration of immobility both in the forced swimming test (FST) and in the tail suspension test (TST), two models of depression in mice, without changing locomotion in an open field. Paradoxically, a similar effect was observed with the administration of N(G)-nitro-L-arginine (L-NNA) (0.3-10 mg/kg, i.p.), an inhibitor of NOS. However, higher doses of L-Arg (750-1000 mg/kg) and L-NNA (30 mg/kg) did not produce any anti-immobility effect in FST and TST. The inactive isomers D-Arg (100-1000 mg/kg, i.p.) and D-NNA (0.3-30 mg/kg, i.p.) did not affect immobility duration in either the FST and TST. Preadministration of L-NNA (30 mg/kg, i.p.), but not of D-NNA completely blocked the anti-immobility effect of L-Arg (500 mg/kg, i.p.) in the FST. Similarly, L-Arg (750 mg/kg, i.p.), but not D-Arg blocked the anti-immobility effect of L-NNA (3 mg/kg, i.p.) in the FST. The results indicate that either the synthesis of NO or the inhibition of its synthesis may produce antidepressant-like effects when assessed in the FST and TST. The physiological meaning of this finding is still obscure, but it could indicate that NO has a dual role in the modulation of depression.