Impacts on reproduction of Enchytraeus crypticus in fertilized soils with chicken litter treated with synthetic and natural insecticide

Highlights

• Cypermethrin can be toxic for non-target soil organisms.

• Soil texture alters the effects of cypermethrin and cinnamon oil.

• Cypermethrin toxicity is reduced over time.

• Cinnamon oil toxicity is not reduced over time.

Abstract

Poultry litter is used as a fertilizer due to the high concentration of nutrients. However, this material receives application of medicines, whether they are used to treat animals or the litter itself. Thus, the objective was to evaluate if the application in soils of poultry litter doses treated with two insecticides (cypermethrin and cinnamon oil) used to control of the Alphitobius diaperinus, affect the reproduction of Enchytraeus crypticus, and the insecticides effects over time, trough of ecotoxicological tests using soils with different textural classes an Entisol and an Oxisol. In the Oxisol the application of poultry litter stimulated the E. crypticus reproduction regardless of the insecticide and the collection time. In Entisol the poultry litter showed a toxicity at 10 t ha⁻¹ when treated with cypermethrin and at 30 t ha⁻¹ with cinnamon oil. Entisol results show that cypermethrin affects non-target edaphic organisms soon after spraying, but over time has reduced toxicity unlike cinnamon oil.

Introduction

The use of organic sources for soil fertilization has been driven by the need for the destination of waste produced by animal activity and the increased demand from the consumer market for ecofriendly systems. The use of residues from animal production, such as poultry litter, has received high visibility because they are nutrient-rich compounds (Oliveira et al., 2016), produced in large volumes and, for producers, the most common destination. and economically viable to use it for fertilization of agricultural areas and pastures (Rogeri et al., 2015; Mierzwa-Hersztek et al., 2016).

Studies conducted with bioindicator organisms warn of the potential short- and long-term risks of excessive and/or continued use of animal waste in agricultural areas. (Domene et al., 2007; Martin e Stanislav, 2010; Delgado et al., 2012; Segat et al., 2015; Maccari et al., 2016; Mierzwa-Hersztek et al., 2016). However, the use of these organic matrices still needs to be better understood to ensure environmental safety.

Faced with this growing use of poultry litter there is also concern about the inclusion of chemical molecules in sensitive environmental compartments such as soil and water. The poultry litter is subjected to drug application for pest control in the litter itself and treatment of diseases in animals and may contain, for example, insecticide residues such as cypermethrin, used to control weeds that can generate environmental contamination (Nyamasoka et al., 2017).

Alternatively, the use of insecticides has been resorting to the use of herbal compounds capable of controlling diseases and pests, but whose effects on the environment are unknown. Among those used instead of cypermethrin is cinnamon essential oil (Cinnamomun zeylanicum) (Volpato et al., 2016).

An important tool used to understand the effects of possible soil contaminants is terrestrial ecotoxicology which aims to evaluate the effects of stressors (possible contaminants) on edaphic populations, the results of which detect effects on organisms. (Segat et al., 2015; O’Brien, 2017). Due to its high sensitivity to chemical and environmental stress, enchytraeids (Oligochaeta, Annelida) is one of the standard organisms used in ecotoxicological assays (Römbke, 2003), belonging to an important group responsible for the degradation of organic matter and soil nutrient cycling. (Kobeticová et al., 2009).

The objective of this study was to evaluate if the application in natural soils (with different textures - an Entisol and an Oxisol) doses of poultry litter submitted to two treatments (one or two sprays) with two insecticides (cypermethrin and cinnamon essential oil) used in the management of the mealworm (Alphitobius diaperinus) affect the reproduction of Enchytraeus crypticus, also evaluating the remaining effect of insecticides in three poultry litter collection time.