Veterinary Entomology Degradation of Insecticides in Poultry Manure: Determining the Insecticidal Treatment Interval for Managing House Fly (Diptera: Muscidae) Populations in Poultry Farms Song-Quan Ong, Abdul Hafiz Ab Majid, 1 and Hamdan Ahmad Household & Structural Urban Entomology Laboratory, Vector Control Research Unit, School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia (songguan26@gmail.com; abdhafiz@usm.my; hamdana@usm.my) and 1 Corresponding author, e-mail: abdhafiz@usm.my Received 27 August 2015; Accepted 18 January 2016 Abstract It is crucial to understand the degradation pattern of insecticides when designing a sustainable control program for the house fly, Musca domestica (L.), on poultry farms. The aim of this study was to determine the half-life and degradation rates of cyromazine, chlorpyrifos, and cypermethrin by spiking these insecticides into poultry manure, and then quantitatively analyzing the insecticide residue using ultra-performance liquid chromatog- raphy. The insecticides were later tested in the field in order to study the appropriate insecticidal treatment intervals. Bio-assays on manure samples were later tested at 3, 7, 10, and 15 d for bio-efficacy on susceptible house fly larvae. Degradation analysis demonstrated that cyromazine has the shortest half-life (3.01 d) com- pared with chlorpyrifos (4.36 d) and cypermethrin (3.75 d). Cyromazine also had a significantly greater degrad- ation rate compared with chlorpyrifos and cypermethrin. For the field insecticidal treatment interval study, 10 d was the interval that had been determined for cyromazine due to its significantly lower residue; for ChCy (a mix- ture of chlorpyrifos and cypermethrin), the suggested interval was 7 d. Future work should focus on the effects of insecticide metabolites on targeted pests and the poultry manure environment. Key words: degradation, larvicide, half-life, poultry manure, Musca domestica The major focus of pest management is to ensure the sustainability of the chemical products and methods used. Anastas and Warner (1998) and Hubbard et al. (2014) defined “green chemistry” as sus- tainable chemicals having good characteristics of degradability and low persistence in the environment. However, in pest control, trade- offs in insecticide characteristics have to be balanced between “green chemistry” and sufficient persistence for bio-efficacy. Achieving a good offset between these two aspects is challenging for house fly (Musca domestica L.) control programs in poultry farms (Kunz and Kemp 1994, Watson et al. 2008). This is especially the case for the insecticidal treatment of poultry manure, which is a common practice for controlling this major pest (WHO 1986). Treating manure with insecticides is necessary because manure accu- mulates during the breeding period and as a result, provides a good breeding site for the house fly, an important pest in poultry units (WHO 1986). House flies are attracted to the nutrient-rich manure and usually exist in great abundance in unmanaged poultry units (Ong et al. 2015). When insecticides are applied to manure, it con- tinues to accumulate where quantitative and qualitative changes of the insecticides can occur within the manure (WHO 1991). Studying the degradation and residue profile of insecticides in the poultry manure could assist in understanding the chemistry of these insecti- cides in manure. Currently, there is limited knowledge regarding the degradation of insecticides in manure. Insecticides such as cyromazine, chlorpyri- fos, and cypermenthrin are commonly used in poultry units in Malaysia and are effective in controlling the house fly (Ong et al. 2015). There have been studies conducted on the degradation of cyromazine and chlorpyrifos, but those studies used different matri- ces such as soil, water, and food (Caplan 1981, Zhu et al. 2009). Caplan (1981) investigated the degradation rate of 14 C-labeled cyro- mazine in a 1:1 ratio of soil–manure mixture. However, for a com- plete manure matrix, there is a gap in understanding the insecticide degradation characteristics and therefore, efficacy and green chemis- try characteristics (good degradability and low persistence in the environment). Frequent treatment with insecticides at specific intervals might be required to overcome the changing of quantity and quality of insecticides in accumulated manure (WHO 1991). Usually, recom- mendations for insecticidal treatment intervals can be obtained from V C The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com 952 Journal of Economic Entomology, 109(2), 2016, 952–957 doi: 10.1093/jee/tow014 Advance Access Publication Date: 18 February 2016 Research article Downloaded from https://academic.oup.com/jee/article/109/2/952/2379905 by guest on 14 June 2022