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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 11  |  Issue : 2  |  Page : 102-107  

Utilization of the castor seed cake (biowaste) for mosquito vector control


1 National Institute of Malaria Research, New Delhi, India
2 Institute of Pesticide Formulation and Technology (IPFT), Gurugram, Haryana, India
3 SOS, Indira Gandhi National Open University (IGNOU), New Delhi, India
4 WHO SEARO, World Health House, Indraprastha Estate, Mahatma Gandhi Marg, New Delhi, India

Date of Submission06-Aug-2019
Date of Decision12-Nov-2020
Date of Acceptance09-Apr-2021
Date of Web Publication20-Oct-2021

Correspondence Address:
B N Nagpal
WHO SEARO, World Health House, Indraprastha Estate, Mahatma Gandhi Marg, New Delhi-110 002
India
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DOI: 10.4103/tp.TP_36_19

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   Abstract 


The present work is related to the utilization of castor (Ricinus communis) seed cake, biowaste produced during the oil extraction of castor seeds, as efficient mosquitocidal composition against Aedes aegypti and Anopheles culicifacies. The efficacy of coil formulations was evaluated in the Peet Grady chamber and resulted in 90% and 100% knocked down and mortality against A. aegypti and A. Culicifacies, respectively. Further heavy metals' (Cr, Pb, Co, As, Cd, Cu, Mn, and Zn) analysis of the coil was performed using Inductively Coupled Plasma mass spectrometry and was compared with commercially available mosquito repellent coil. Heavy metal analysis revealed that commercial repellent coil had a higher content of heavy metals than the castor seed cake coil. Finding of the present research study indicates that castor seed cake coil has the potential to be used in mosquito vector control. Castor seed cake coil formulation will also open up avenues in future for sustainable utilization of the biowaste.

Keywords: Biowaste, biopesticide, castor seed cake, coil, heavy metals, knocked down


How to cite this article:
Sogan N, Kala S, Kapoor N, Patanjali P K, Nagpal B N. Utilization of the castor seed cake (biowaste) for mosquito vector control. Trop Parasitol 2021;11:102-7

How to cite this URL:
Sogan N, Kala S, Kapoor N, Patanjali P K, Nagpal B N. Utilization of the castor seed cake (biowaste) for mosquito vector control. Trop Parasitol [serial online] 2021 [cited 2021 Dec 8];11:102-7. Available from: https://www.tropicalparasitology.org/text.asp?2021/11/2/102/328691




   Introduction Top


Mosquitoes, belonging to phylum Arthropoda and class Insecta, act as vectors of an extremely wide number of pathogens and parasites, which potentially led to the transmission of various diseases including malaria, dengue, Chikungunya, Zika, Japanese Encephalitis and lymphatic filariasis, which is a public health concern.[1],[2],[3] For malaria, drug prophylaxis and vector control are the only options available, but in case of dengue, there is no specific treatment available; hence, prevention by vector control strategies remains only cure available.[4] Numerous products are available in the market to control the vector population at the community level. These products either act as a repellent or as adulticide (Coil, Vaporizer, and aerosol sprays). Coils generally act as a good repellent, because of continuous emission of smoke along with the active ingredient from the coil which wards off the mosquitoes and thus help in mitigating the vector-borne diseases.[5] Pyrethroid-based coils available in the market may pose a threat to human health as there are reports of pyrethroid causing behavioral and developmental neurotoxicity, especially in infants and children.[6] Long-term exposure to pyrethroid-based mosquito repellents may lead to chronic neurotoxicity such as dysfunction of blood–brain barrier permeability, oxidative damage to the brain, and cholinergic dysfunction, leading to learning and memory deficiencies.[7],[8],[9] Besides that pyrethroids are reported to be endocrine disruptors and carcinogenic.[10],[11] Negative health issues associated with synthetic pyrethroid coils have prompted us to formulate a botanical formulation, which is biodegradable, user, and environmental friendly and free from residues.

The extraction of oil from castor seeds results in the production of tons of the castor seed cake as a waste [Figure 1] and [Figure 2]. According to the estimation of Food and Agriculture Organization Corporate Statistical Database (FAOSTAT) 2016, the annual production of the castor seed cake in India is 1,554,000 tonnes.[12] Although castor seed cake is rich in proteins and fiber, it can neither be used as animal feed nor in agricultural farming because of high toxicity, due to the presence of ricin, ricinine, agglutinin, and allergen CB-1A.[13] The ricinine, agglutinin, and allergen CB-1A are present in lower concentrations, and toxic effects are negligible. While ricin is known to render the most toxic effects to castor seed cake.[14],[15] The concentration of ricin ranges from 0.1 mg to 5.6 mg/g of mature seed.[16] While in the castor seed cake, ricin makes up to 1.5% of the castor seed cake.[17] Managing a high amount of castor seed cakes is a huge environmental concern as the presence of nonedible seed cakes, in an open atmosphere, would lead to the generation of various gases such as CH4, N2O, H2S, NH3, and CO2 and volatile organic compounds due to self-decomposition of biomass over the action of various microorganisms.[18] In the present study, we have sustainably utilized the castor seed cake biomass, as an active ingredient in pesticidal coil formulation (patent has been filed, through an application number 20171102819[19] and evaluated its efficacy against mosquitoes).
Figure 1: Castor seeds

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Figure 2: Castor seed cake

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   Materials and Methods Top


Materials

Castor (Ricinus communis) bean cake was procured from Centre for Rural Development and Technology, Indian Institute of Technology, Delhi. Sawdust (Wood dust), jigat (Machilus macrantha), sodium benzoate, KNO3, and guar gum (Litsea glutinosa) were purchased from Burari, New Delhi.

Preparation of the mosquito repellent coil

Mosquito coils were prepared according to Pant et al.[20] Using the ingredients in different compositions, i.e. sawdust as organic filler, jigat, and guar gum as binding materials, sodium benzoate as a preservative, and KNO3 as burning material along with castor seed cake as the active ingredient [Table 1]. In case of blank coil, no active ingredient was used. All the individual ingredients were minced in a mixer into a fine powder (50 mm) and finally extruded through a coil machine to get the final product, i.e. mosquito coil with desired shape and size.
Table 1: Mosquito coils with different proportions of active ingredients and inert materials

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Mosquitoes rearing

Larvae of Aedes aegypti and Anopheles culicifacies were maintained in the National Institute of Malaria Research, Dwarka, Sector-8, Delhi, India, following method of Govindarajan et al.[21] They were colonized and maintained at 27°C ± 2°C and 75%–85% RH under a photoperiod of 14:10 h (light/dark) continuously in the laboratory, free of exposure to pathogens, insecticides, or repellents. Larvae were fed on finely ground dog biscuit and yeast extract in the ratio of 3:1. The adult mosquitoes were reared in respective glass/plastic cages (30 cm × 30 cm × 30 cm), and the adult colony was provided with 10% glucose solution, and it was periodically blood-fed on restrained rabbits to maintain the generation.

Test of bio-efficacy of the coil against mosquitoes

The bioassay was conducted in a Peet-Grady chamber measuring 120 cm × 120 cm × 120 cm following the method of Chadwick.[22] Mosquitoes in the polyethylene cup and coils both were introduced into the chamber through a 30 cm × 30 cm sliding window at the mid-bottom on one side of the chamber. The mosquito coil was kept on a stand in the middle of the chamber and allowed to burn for 2 min before 100 glucose-fed mosquitoes were released into the chamber. Knocked-down mosquitoes (i.e., those that no longer maintained normal posture and were unable to fly or were on their backs) were recorded at l0 min interval up to 6 h or until total knock-down (KD) was achieved. Knocked-down mosquitoes were placed in a clean container containing cotton wool soaked with 10% glucose solution, and the mortality of the mosquitoes was observed after 24 h. The above procedures were carried out in three replications for each coil formulation. Control was performed by exposing the mosquitoes to the smoke of a blank coil. KD times (KD50 and KD90, as the minutes needed to KD 50% and 90% of mosquitoes, respectively) were determined by the probit analysis.[23]

Heavy metal analysis of the mosquito repellent coil

A method adapted from EPA 2003[24] was used to prepare the sample of mosquito coils for heavy metal analysis using an Agilent 7500 Inductively Coupled Plasma mass spectrometry (ICP-MS). After the samples were ground into a fine powder, 0.25 g of coil was added to a 100 mL beaker along with 5 mL of nitric acid and 2.5 mL of hydrochloric acid. Followed by heating for approximately 3 h and then allowed to cool to room temperature. Then, 5 mL of hydrogen peroxide was added, and the samples were left at room temperature for approximately 2 h. The samples were heated a second time for approximately 3 h. Finally, samples were diluted to 50 mL using Milli Q water and centrifuged before analysis. Blank samples were prepared as explained above, without adding coil sample, to ensure there was no contamination during the digestion process.

Statistical analysis

The data collected were represented as mean ± standard deviation. KD times (KD50 and KD90, as the minutes needed to KD 50% and 90% of mosquitoes, respectively) were determined by the probit analysis.[23]


   Results Top


The tests of bio-efficacy of the coil were performed in Peet Grady chamber. Castor seed cake coil resulted in 9%–100% KD and mortality of the mosquitoes. The knocked down mosquitoes did not recover during 24 h recovery period. Of all the concentrations tested, mortality value was found to be higher in coil containing 20% of castor seed cake as active ingredient. A linear relationship was observed between concentration of active ingredient and percentage mortality as shown in [Table 2]. With increase in the concentration of active ingredient, percentage mortality increased in A. aegypti and A. culicifacies. While reciprocal relationship was found between the KD time and concentration of the active ingredient, with increase in the concentration of the active ingredient, KD time decreases. KD50 values of 20% castor seed cake coil were 43.75 and 45.11 min for A culicifacies and A. Aegypti, respectively, and were compared with commercial coil with a KD50 value of 16.17 min. No KD was observed in the control groups, i.e. when a blank coil or no coil was used. This indicated clearly that the smoke from blank coil and condition in the chamber without coil had no toxic effect on the mosquitoes. The mortality effects are attributed the active ingredient, i.e. castor seed cake used in the study.
Table 2: Percent knocked down and mortality in Aedes aegypti and Anopheles culicifacies on exposure to coils

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Heavy metal analysis of the coils was performed using ICPMS and was compared with commercially available mosquito repellent coil. Based on the elemental analysis of the coils tested, the concentrations of heavy metals were Cr (6.2, 9.8 μg/g), Pb (0.06, 1.8μg/g), Co (0.35, 0.67 μg/g), As (0.1, 0.26 ug/g), Cd (0.04, 0.18 μg/g), Cu (8.0, 9.4 μg/g), Mn (41.1, 78.0 μg/g), and Zn (1.7, 4.14 μg/g) in castor seed cake coil and commercial coil, respectively [Table 3]. It was observed that the concentration of heavy metals such as As, Cu, Zn, Co, Mn, Pb, and Cr was higher in commercial mosquito repellent coil as compared with the castor seed cake coil. The castor seed cake coil has shown good efficacy, although the KD time is higher, it is more eco-friendly as it has less heavy metal content and does not leave any residues.
Table 3: Comparative analysis of heavy metal content of the coils

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   Discussion Top


Botanical insecticides can provide an eco-friendly option to control vector population in a sustainable way. The nonedible castor seed cake of R. communis can be exploited to function as bio-pesticides. The bio-efficacy result of coil containing 2.5%–20% active has shown 9%–100% mortality. Although synthetic coils have less KD50 values, they pose threat to terrestrial and aquatic invertebrates and even exhibit low toxicity toward fish.[25],[26],[27] Therefore, improper usage of the mosquito coils for outdoor purposes can pose risks to both terrestrial and aquatic organisms. In the present scenario, coil formulation containing botanical derivatives can provide a sustainable and economical way of controlling mosquito vectors.[28],[29] Castor seed cake coil formulation efficiently utilizes the waste of oil extraction for vector control, which otherwise creates an ecological problem for its disposal. Efficacy of the castor seed cake coil against mosquitoes may be due to synergistic activity of the various phytochemicals such as ricin, ricinine present in the castor seed cake. The finding of the present research study is corroborated by a previous report on insecticidal activity of castor seed cake against termite.[30]

The elemental analysis of the castor seed cake has shown high nitrogen content; thus, castor seed cake coil will produce low emission of CO and CO2 (that contributes to greenhouse effect and may lead to global warming), but it has high NO and NO2 emission because of high nitrogen content.[31] The major component of the synthetic coils is sawdust and wood pellet, so it will produce more greenhouse gases as compared to the castor seed cake coil. Mosquito coils prepared using botanical ingredients are reported to be less toxic, user, and environmental friendly and more sustainable option as compared with synthetic coils.[20] Thus, on account of its biodegradability and natural ingredients, castor seed cake coil would have minimum impact on nontarget organism, making it compatible with Integrated Pest Management module. Issues of pesticide resistance and pest resurgence would also be minimal because of an array of complex constituents present in them.

When a coil is burnt, it releases particulate matter[32],[33],[34],[35],[36],[37] and heavy metals.[33],[38],[39] Based on the heavy metal analysis of the coils, the concentration of heavy metals such as Cr, Pb, Co, As, Cd, Cu, Mn, and Zn in castor seed cake was 6.20 μg/g, 0.06 μg/g, 0.35 μg/g, 0.1 μg/g, 0.04 μg/g, 8 μg/g, 41.1 μg/g, and 1.7 μg/g, and in commercial repellent coil concentrations were 9.8 μg/g, 1.8 μg/g, 0.67 μg/g, 0.26 μg/g, 0.18 μg/g, 9.4 μg/g, 78 μg/g, and 4.14 μg/g, respectively. Kasumba et al.[39] have done the heavy metal analysis of the mosquito repellent coil and reported the concentrations of heavy metals in the following range (in μg/g): Cr: 2.9–9.4, Co: 0.1–1.2, Cu: 0.7–16.1, Se: 0.10–0.4, Ni: 2.1–5.8, As: 0.10–2.2, Cd: 0.10–0.2, and Pb: 1.1–3.6. The present research study is in the confirmation of the findings of Kasumba et al.,[39] regarding the concentration of Cr, Co, Cu, and As in castor seed cake coil, but concentrations of Cd and Pb were not in agreement to findings of Kasumba et al.[39] It was observed that heavy metal content of As, Cu, Pb, Zn, Co, Mn, and Cr in castor seed cake coil was less as compared with the commercial mosquito repellent coil. The higher concentration of heavy metals in the commercial coil may result in higher risk as long-term exposure to heavy metals may lead to diseases such as multiple sclerosis, Parkinson's disease, Alzheimer's disease, and muscular dystrophy.[40] From the findings of the present research study, it can be deduced that castor seed cake coil is comparatively safer, user, and environment friendly than commercial mosquito coil and efficiently addresses the disposal-related issues of biowaste in a sustainable way.


   Conclusion Top


Castor seed cake-based coil can be used for vector control at the community level in the rural and urban area. Using castor seed cake with other ingredients, a sustainable and economically feasible green product, i.e. mosquito coil is developed. The product can be commercialized and is a boon for the rural communities and can be used to generate employment and also for the vector control.

Submission declaration

This manuscript is not under consideration for publication elsewhere; it is approved by all authors, if accepted, it will not be published elsewhere in the same form, in English or in any other language, including electronically without the written consent of the copyright holder.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Tables

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