Rodent repellents are chemicals which by taste or odour or possibly by both will prevent animal from feeding or gnawing. Such substances may be used in protecting an area from rodent infestation or in protecting packaged food, packing materials, electric cables, and other important vulnerable materials. Mature and healthy house rat,
Rodents have gained the reputation as one of the most persistent and ubiquitous vertebrate pests affecting human populations. They cause economic problems because of the damage they inflict on agricultural systems [
Plants with strong smells act as repellents and can protect the crops nearby [
Among the plant families with promising essential oils used as repellents include
Rodent repellents are chemicals which by taste or odour or possibly by both will prevent animal from feeding or gnawing. Such substances may be used in protecting an area from rodent infestation or in protecting packaged food, packing materials, electric cables, and other important vulnerable materials. Relatively little work has been carried out on plant-derived repellents compared to other aspects of rodent control. No study has yet been made on evaluating the potential of eucalyptus oil as repellent against rodent pests. The present study was hence carried out to evaluate the potential of eucalyptus oil as repellent against
The present work was carried out in Animal House Laboratory, Department of Zoology, Punjab Agricultural University, Ludhiana, India, located at an intersection of 30°55′N parallel of latitude and 75°54′E line of longitude. Commercially available pure eucalyptus oil was used for the present study.
For present studies,
A total of four laboratory pens (each of size 252×100×72 cm) were used for each experiment. Each laboratory pen consisted of three chambers of equal size. One rat was released in each chamber. Each chamber in a laboratory pen, on its opposite facing sides, was connected to two small nest boxes (each of size 20×15×15 cm) by means of holes (each of diameter 6 cm). Each rat had free access to the two nest boxes attached on opposite sides of a chamber. Treatment was carried out in the nest box of one side of a chamber. Oil was sprayed on all the inner sides of the nest box.
Three different concentrations of eucalyptus oil, that is, 5, 10, and 20%, were tested. Different concentrations of the oil were prepared by in isopropyl alcohol. Each concentration was tested on a total of twelve rats (six of each sex) by applying as spray (using a small spray pump of 100 mL capacity). Rats were exposed to each concentration of the oil through three different modes of application, that is, applied daily (from Monday to Thursday), applied once a week (on Monday only), and applied alternatively (on Monday, Tuesday, and Thursday). Weighed (20 g) amount of food, that is, WSO taken in a bowl was placed in both the nest boxes of each chamber.
Repellent effect of the oil was assessed based on the consumption of food by the rat from the food bowls kept in two nest boxes of a chamber in a laboratory pen. Food consumption was recorded daily after every 24 h from both treated and untreated sides for 4 days in a week, that is, from Tuesday to Friday to determine mean daily food consumption (g/100 g body weight (bw)). Based on mean daily food consumption data, percent repellency was determined using the formula given below
Values were determined as mean ± SD. The data on food consumption for two sexes, three concentrations of the oil, three modes of applications, four days of application, and from treatment and untreated sides was collected using factorial experiments in completely randomized design. Analysis was done using general linear model (GLM) in SAS 9.3. All pairwise treatment comparisons were made using Tukeys’ HSD test at 5% level of significance.
Statistical analysis of the data revealed in overall significantly (
Mean daily food consumption by
Mode of application | Days of application | Mean daily food consumption (g/100 g bw) | |||
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Female rats ( |
Male rats ( |
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Treatment side | Untreated side | Treatment side | Untreated side | ||
I | Day 1 | 2.00 ± 3.61a | 12.77 ± 1.40b | 2.04 ± 2.94a | 10.62 ± 3.45b |
Day 2 | 1.41 ± 1.09a | 14.03 ± 3.14b | 2.24 ± 2.03a | 10.18 ± 2.73b | |
Day 3 | 2.00 ± 2.98a | 10.27 ± 5.77b | 3.04 ± 3.72a | 7.01 ± 3.03b | |
Day 4 | 1.28 ± 1.93a | 11.36 ± 2.97b | 1.18 ± 2.06a | 9.17 ± 1.99b | |
Average |
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II | Day 1 | 3.51 ± 2.73a | 9.98 ± 5.98b | 1.82 ± 2.00a | 9.25 ± 2.83b |
Day 2 | 8.18 ± 6.16a | 5.31 ± 4.70b | 3.38 ± 2.74a | 7.82 ± 2.48b | |
Day 3 | 5.51 ± 6.71a | 7.55 ± 5.14b | 2.90 ± 3.02a | 9.46 ± 2.91b | |
Day 4 | 5.75 ± 4.50a | 7.74 ± 4.54b | 5.76 ± 3.88a | 8.05 ± 3.40b | |
Average |
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III | Day 1 | 5.27 ± 1.35a | 10.71 ± 5.05b | 4.75 ± 2.05a | 7.82 ± 3.23b |
Day 2 | 2.21 ± 2.43a | 8.44 ± 5.57b | 3.40 ± 1.89a | 9.37 ± 2.39b | |
Day 3 | 3.88 ± 3.58a | 8.68 ± 5.17b | 4.80 ± 4.01a | 4.68 ± 3.31b | |
Day 4 | 2.75 ± 2.89a | 9.36 ± 4.39b | 2.71 ± 1.55a | 7.76 ± 2.46b | |
Average |
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Values are mean ± SD, I = daily, II = once a week, and III = alternatively.
Values with similar superscripts in a column for four days of application (a or b) and for average values (A, B, or C) at each mode of application indicate no significant difference.
Values with different superscripts in a row for each sex for four days of application (a-b) and for average values (A–C) at each mode of application indicate significant difference at
Mean daily food consumption by
Mode of application | Days of application | Mean daily food consumption (g/100 g bw) | |||
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Female rats ( |
Male rats ( |
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Treatment side | Untreated side | Treatment side | Untreated side | ||
I | Day 1 | 3.64 ± 4.25a | 10.49 ± 3.99b | 1.40 ± 2.83a | 12.74 ± 2.93b |
Day 2 | 0.80 ± 0.91a | 11.45 ± 1.97b | 2.11 ± 2.74a | 9.50 ± 3.10b | |
Day 3 | 4.90 ± 5.32a | 13.37 ± 2.76b | 5.26 ± 5.18a | 10.72 ± 2.99b | |
Day 4 | 4.10 ± 4.49a | 14.18 ± 3.94b | 3.85 ± 5.56a | 11.67 ± 2.60b | |
Average |
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II | Day 1 | 3.47 ± 5.56a | 14.23 ± 4.03b | 2.42 ± 3.82a | 12.07 ± 5.33b |
Day 2 | 2.60 ± 4.22a | 12.67 ± 6.12b | 4.96 ± 5.18a | 11.57 ± 5.78b | |
Day 3 | 4.85 ± 2.89a | 8.99 ± 6.10b | 9.76 ± 6.13a | 3.40 ± 4.28b | |
Day 4 | 9.35 ± 7.46a | 8.85 ± 2.50b | 7.31 ± 4.70a | 3.99 ± 4.88b | |
Average |
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III | Day 1 | 3.76 ± 3.53a | 10.96 ± 5.09b | 1.19 ± 0.92a | 14.48 ± 3.43b |
Day 2 | 4.57 ± 3.10a | 8.71 ± 4.06b | 3.85 ± 5.06a | 9.44 ± 2.62b | |
Day 3 | 7.43 ± 4.93a | 5.81 ± 4.23b | 6.45 ± 2.91a | 4.60 ± 1.80b | |
Day 4 | 12.05 ± 5.41a | 8.58 ± 5.64b | 7.46 ± 5.68a | 9.28 ± 5.80b | |
Average |
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Values are mean ± SD, I = daily, II = once a week, and III = alternatively.
Values with similar superscripts in a column for four days of application (a or b) and for average values (A or B) at each mode of application indicate no significant difference.
Values with different superscripts in a row for each sex for four days of application (a-b) and for average values (A-B) at each mode of application indicate significant difference at
Mean daily food consumption by
Mode of application | Days of application | Mean daily food consumption (g/100 g bw) | |||
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Female rats ( |
Male rats ( |
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Treatment side | Untreated side | Treatment side | Untreated side | ||
I | Day 1 | 2.61 ± 4.22a | 6.62 ± 5.01b | 4.58 ± 4.63a | 10.64 ± 4.01b |
Day 2 | 10.59 ± 5.31a | 14.15 ± 1.02b | 8.37 ± 3.71a | 14.95 ± 2.70b | |
Day 3 | 5.67 ± 3.61a | 11.64 ± 5.70b | 3.42 ± 3.11a | 8.46 ± 4.12b | |
Day 4 | 2.21 ± 1.45a | 8.66 ± 5.14b | 3.04 ± 4.33a | 11.33 ± 2.27b | |
Average |
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II | Day 1 | 1.18 ± 2.01a | 13.49 ± 4.49b | 3.80 ± 4.55a | 10.5 ± 2.16b |
Day 2 | 3.78 ± 4.08a | 11.32 ± 4.82b | 4.68 ± 5.82a | 10.51 ± 3.89b | |
Day 3 | 3.90 ± 3.22a | 6.94 ± 5.48b | 6.15 ± 7.71a | 6.92 ± 2.59b | |
Day 4 | 7.34 ± 4.57a | 5.74 ± 7.23b | 5.54 ± 5.69a | 7.00 ± 5.39b | |
Average |
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III | Day 1 | 2.29 ± 2.99a | 13.24 ± 3.03b | 4.15 ± 2.16a | 13.62 ± 4.82b |
Day 2 | 2.11 ± 2.15a | 10.17 ± 5.63b | 0.8 ± 1.07a | 8.26 ± 3.75b | |
Day 3 | 5.78 ± 5.22a | 11.58 ± 6.47b | 4.17 ± 3.78a | 8.31 ± 4.24b | |
Day 4 | 2.81 ± 3.51a | 9.11 ± 5.97b | 5.84 ± 4.86a | 4.44 ± 3.21b | |
Average |
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Values are mean ± SD, I = daily, II = once a week, and III = alternatively.
Values with similar superscripts in a column for four days of application (a or b) and for average values (A or B) at each mode of application indicate no significant difference.
Values with different superscripts in a row for each sex for four days of application (a-b) and for average values (A-B) at each mode of application indicate significant difference at
No significant difference in average percent repellency of eucalyptus oil in
The average mean daily consumption of food by female rats was significantly (
Average percent repellency with 5% eucalyptus oil applied as spray, was found to be significantly (
Percent repellency with eucalyptus oil applied as spray using three different concentrations against
Mode of application | Days of application | Percent repellency | |||||
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5% | 10% | 20% | |||||
Female rats |
Male rats |
Female rats |
Male rats |
Female rats |
Male rats |
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I | Day 1 | 84.47 ± 28.14a | 82.98 ± 20.55a | 64.79 ± 42.73a | 83.13 ± 37.18a | 62.54 ± 44.80a | 64.39 ± 36.91a |
Day 2 | 88.02 ± 9.91a | 75.36 ± 21.92a | 91.46 ± 9.90a | 76.99 ± 31.96a | 29.10 ± 33.27a | 43.30 ± 29.94a | |
Day 3 | 76.13 ± 37.52a | 54.38 ± 46.45a | 63.96 ± 34.45a | 59.36 ± 33.00a | 54.87 ± 29.31a | 63.68 ± 23.41a | |
Day 4 | 86.12 ± 21.12a | 88.47 ± 26.69a | 71.08 ± 34.40a | 72.26 ± 40.40a | 58.12 ± 32.28a | 74.68 ± 35.68a | |
Average |
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II | Day 1 | 56.48 ± 42.51a | 78.27 ± 26.69a | 76.24 ± 36.25a | 80.07 ± 28.35a | 85.37 ± 25.68a | 64.12 ± 42.80a |
Day 2 | 56.56 ± 37.17a | 54.15 ± 38.84a | 79.05 ± 35.89a | 50.82 ± 36.93ab | 60.10 ± 44.72ab | 60.53 ± 44.73a | |
Day 3 | 60.68 ± 43.23a | 61.35 ± 41.87a | 32.52 ± 42.07ab | 13.15 ± 29.41b | 43.68 ± 43.98bc | 57.84 ± 41.90ab | |
Day 4 | 47.54 ± 41.32a | 38.58 ± 38.89a | 36.24 ± 38.92ab | 30.19 ± 43.04b | 20.50 ± 29.51c | 49.67 ± 39.28a | |
Average |
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III | Day 1 | 42.31 ± 22.28a | 36.58 ± 24.41a | 59.90 ± 38.95a | 92.34 ± 6.16a | 77.54 ± 34.41a | 62.32 ± 34.06a |
Day 2 | 72.80 ± 34.33a | 60.79 ± 21.30a | 46.12 ± 33.78a | 70.08 ± 37.76a | 62.98 ± 45.20a | 85.80 ± 22.19a | |
Day 3 | 57.04 ± 42.37a | 43.07 ± 45.24a | 19.81 ± 20.87ab | 8.10 ± 11.46b | 51.98 ± 45.27a | 50.76 ± 43.24a | |
Day 4 | 70.21 ± 33.99a | 57.77 ± 30.93a | 12.88 ± 20.61a | 45.27 ± 42.73a | 50.24 ± 49.75a | 43.39 ± 44.80a | |
Average |
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Values are mean ± SD, I = daily, II = once a week, and III = alternatively.
Values with similar superscripts in the column for four days (a or b) and for average values (A, B, or C) at each mode of application indicate no significant difference in percent repellency.
Values with different superscripts in a row for four days (a-b) and for average values (A–C) at each mode of application indicate significant difference in percent repellency between the two sexes at
Significant differences in average percent repellency of eucalyptus oil in
When 10% eucalyptus oil was applied as spray, the average mean daily consumption of food was found to be significantly (
In female rats, significant difference in average percent repellency with 10% eucalyptus oil was found among the three modes of application (Figure
However, in male rats, percent repellency on day 3 of treatment was found to be significantly (
The average mean daily food consumption was found to be significantly (
The average percent repellency was not found to differ significantly among the three modes of application in both male and female rats (Figure
In male rats, no significant difference in percent repellency was observed among four days of application at all three modes of application. No significant difference in percent repellency was observed between male and female rats when oil was applied daily and alternatively. Significant (
During the present studies, significant differences were found in mean daily food consumption from treatment and untreated sides at different modes of application and at different concentrations of the oil between male and female rats. This may be due to the sex specific variation in response to
In overall, no significant difference in repellent effects of oil applied as spray was found between the two sexes and among the three concentrations of the oil tested during the present studies. All the three concentrations were equally effective and the repellency was highest when the oil was applied daily. The cost of spraying 5% eucalyptus oil (the minimum effective concentration) per 1 m2 area comes out to be Indian Rs 10 (US $ 0.17), which can be considered cost effective if we keep in view the extent of loss caused by
Since eucalyptus oil possesses a wide spectrum of biological activity and is regarded as safer compounds, there have been attempts to commercialize and market the insecticides/repellent products containing eucalyptus oil as such or based upon them. Quwenling is a eucalyptus-based product that has been successfully marketed as an insect-repellent in China [
The present studies reveal the potential of eucalyptus oil applied as spray in repelling away
No contributing author has a conflict of interests in the publication of this study.
The authors are thankful to Indian Council of Agricultural Research, New Delhi, India, for providing financial assistance and Professor and Head of the Department of Zoology, Punjab Agricultural University, Ludhiana, India, for the facilities provided.