Comparative Effect of Dichlorvos and Ginger (Zingiber officinale L.) On the Indian Meal Moth (Plodia interpunctella hübner) Feeding on Zea mays Grains
Publié en ligne: 11 déc. 2023
Pages: 159 - 168
Reçu: 01 mars 2023
Accepté: 01 sept. 2023
DOI: https://doi.org/10.2478/johr-2023-0023
Mots clés
© 2023 Folasade K. Olufemi-Salami et al., published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 International License.
The Indian meal moth
Despite the proliferation of insecticides, the battle to control stored grain losses due to insect infestation appears to be unending. Although synthetic insecticides elated the hope of farmers in the control of the insects, nevertheless, the resistance and residual effects on the ecosystem, especially on nontarget organisms, pose a severe challenge to environmentalists (Varma & Dubey 1999; Jeyasankar & Jesudasan 2005; Ahmad & Arif 2010). The United States Environmental Protection Agency (USEPA 2017) reported a budget of over $100 billion (annually) to manage the side effects of these pesticides on man and the environment (Kataria & Kumar 2012; Abdullha 2016). Therefore, support for botanical insecticides is growing day by day as many scientists have identified plant material that can be used to control insects (Isman 2006; Begum et al. 2013). Some botanicals, such as
The way insecticides work depends on many factors (Gianessi 2009); therefore, this research aims to compare the effects of the organophosphate insecticide – dichlorvos, commonly called DDVP, and ginger rhizome extract oil on the mortality, adult emergence inhibition, neurotransmitters, and digestive enzymes of Indian meal moth adults and larvae.
Indian meal moth used to establish cultures obtained from naturally infested maize grains at the Storage Entomology Laboratory, Department of Biology, Federal University of Technology, Akure, Ondo State, Nigeria. The moth larvae were reared in a 1-liter Kilner jar containing 300 g of disinfested, crunched maize grains, covered with a muslin cloth. The cultures were maintained under laboratory conditions of 28 ± 2 °C and 75 ± 5% relative humidity. The crunched maize grains used for culturing were regularly replaced to prevent contamination. TZESR-20 maize from the Agricultural Development Program Centre in Akure, Nigeria, was used for the study and was disinfested in a freezer at −2 °C for 72 h. It was then allowed to equilibrate in the laboratory.
The ginger rhizomes were obtained from the Oba market in Akure, Ondo State, Nigeria. The rhizomes were air-dried and pulverized to a fine powder using a Binatone electric blender (model 373). The powdered rhizomes were sieved through a 1 mm2 sieve and stored in airtight plastic containers for subsequent use. 80 g of the powdered rhizomes were weighed on a thimble and the oil was extracted with ethanol in a Soxhlet apparatus. The extracted oil was exposed to air to facilitate evaporation of any residual volatile extracting solvent. The extracted oil was then preserved in a plastic container for the subsequent experiments.
Five different concentrations of 0.1, 0.2, 0.3, 0.4, and 0.5% were prepared by adding 0.1, 0.2, 0.3, 0.4, and 0.5 mL of oil or DDVP to 99.9, 99.8, 99.7, 99.6, and 99.5 mL of solvent. Ethanol and water were used as solvents for oil and DDVP, respectively. These concentrations were then used as a treatment for maize grains. Maize grains were treated by soaking them in the concentrate for 1 min and then allowed to air dry before introducing thirty freshly laid eggs (0–24-h-old) per 20 g of treated maize grains. Treated maize and eggs were kept in plastic containers (8 cm in diameter and 4 cm in depth) covered with muslin cloth. A control (20 g of untreated maize grain with eggs of Indian meal moth) was set up under the same environmental conditions as other treatments. All treatments and control were replicated three times. Daily observations were made with a dissecting microscope to determine the number of hatched eggs. After forty days, the rate of adults was determined.
Whatman 1 filter paper was cut into four equal parts. One part was soaked in each concentration (0.1, 0.2, 0.3, 0.4, and 0.5%). The soaked filter paper was packed in muslin cloth and suspended by thread in plastic containers covered with muslin cloth containing 20 g of untreated maize grains and thirty freshly laid eggs. Daily observations were made with a dissecting microscope to determine the percentage of eggs that hatched and larvae that emerged. After forty days, the percentage of adults that emerged was determined.
Ten third-instar larvae were introduced separately into each treatment and control experiment. Dead larvae were counted at 24, 48, 72, and 96 h of post-treatment. The same procedure was repeated for the fumigant effect.
Ten pairs of freshly emerged 0–24-hour-old adult Indian meal moth males and females from the stock culture were introduced into the 20 g treated maize. Adult mortality was counted at 24, 48, 72, and 96 h posttreatment. Control experiments were also set up with water and ethanol as the treatments. All treatments and the control experiment were replicated three times. The same procedure was repeated for the fumigant effect.
Crude enzymes from ten living adults and ten Indian meal moth larvae were prepared by separately homogenizing the insects in 0.1 M phosphate buffer at pH 7.0 using a mortar and pestle. The homogenate was centrifuged at 10 000 × g for 10 min. The supernatants were decanted into sample bottles and stored in the freezer until needed for enzyme assays.
Protease activity was determined by Anson's method (1938). 1 mL of 1.5% casein solution at pH 7.0 was placed at 37 °C, and then 1 mL of appropriately diluted enzyme sample was added. The reaction was incubated for 10 min, then 2 mL of 0.4 M trichloroacetic acid was added. The solution with the precipitate was filtered and 2.5 mL of 0.4 M Na2CO3 and 0.5 mL of Folin's reagent were added to 0.5 mL of the clear filtrate. After 10 min of incubation, the obtained color density was determined at 660 nm. The amount of tyrosine liberated during the reaction was determined from the standard tyrosine curve and used to calculate enzyme activity. One unit was defined as 1 micromole of tyrosine released per minute by 1 milliliter of the enzyme under the assay condition.
Lipolytic activity was determined by a colori-metric method based on the activity in cleavage of p-nitrophenylpalmitate (p-NPP) at pH 8.0 (Lotrakul & Dharmsthiti 1997). The reaction mixture contained 180 μL of solution A (0 : 062 g of p-NPP in 10 mL of 2-propanol, sonicated for 2 min before use), 1620 μL of solution B (0.4% triton X-100, and 0.1% gum Arabic in 50 mM Tris-HCl, pH 8.0) and 200 μL of properly diluted enzyme sample. The product was detected at 410 nm wavelength after incubation for 15 min at 37 °C. Under this condition, the molar extinction coefficient (410 nm) of p-nitrophenol (p-NP) released from p-NPP was 15000 M−1. One unit of lipase activity was defined as 1 micromole of p-nitrophenol (p-NP) released per minute by 1 milliliter of the enzyme.
Amylase activity was determined by adding 1 ml of 1% starch solution at pH 7.0 to 1 ml of diluted enzyme and incubated in test tubes for 3 min at room temperature. 1 ml of dinitrosalicylic acid color reagent was added. After incubation, the mixture was boiled in a water bath for 5 min, cooled to room temperature, and 10 ml of distilled water was added. The mixture was mixed thoroughly, and the absorbance was read at 540 nm against the reagent blank (Bernfeld 1955). One unit of amylase activity was defined as the enzyme needed to catalyze one micromole of the substrate to product under assay conditions.
Acetylcholinesterase activity was determined spec-trophotometrically using acetylcholine iodide AChI as a substrate. To measure acetylcholinesterase (AChE) activity, 300 μL of TRIS buffer (0.1 mol·L−1, pH 8.0), 20 μL of 5,5′-dithiobis-(2-nitrobenzoic acid) (DTNB, 0.01 mol·L−1), and 10 μL of enzyme suspension were added successively. Acetylcholine iodide (10 μL, 0.1 mol·L−1) was added before the enzymatic reaction was started, and absorbance was monitored using a UV-visible spectrophotometer at 410 mm. Enzyme activity was calculated as micromole CDNB conjugate formed per minute per milligram of protein using a molar extinction coefficient of 1.36 × 106·M−1·cm−1 at 410 nm.
Data were presented as mean ± standard deviation. Significant differences in means were determined by one-way analysis of variance, and means were separated using Duncan's new multiple range test. Statistical significance was considered P ≤ 0.05. Statistical analyses were performed using the Statistics Package for Social Sciences (SPSS), version 21. Bar charts were plotted in MS Excel.
Ginger rhizome extract oil and DDVP inhibited egg hatching and adult emergence at all concentrations used and in both types of application – contact and fumigation. After 72 h, no larval mortality was observed in all contact treatments. However, after 96 h, DDVP concentrations of 0.2, 0.3, 0.4, and 0.5% caused 11.67, 16.67, 21.67, and 16.67% mortality, respectively, but these values did not differ significantly. The ginger rhizome extract oil achieved 5.00, 6.67, and 6.67% larvae mortality at 96 h post contact treatment with 0.3, 0.4, and 0.5%, respectively (Table 1).
Contact effect of DDVP and ginger rhizome extract oil on the mortality of newly emerged adults Indian meal moth
| % conc. (v/v) | DDVP | ginger rhizome extract oil | ||||||
|---|---|---|---|---|---|---|---|---|
| 24 h | 48 h | 72 h | 96 h | 24 h | 48 h | 72 h | 96 h | |
| control | 0.00 ± 0.00a | 0.00 ± 0.00a | 0.00 ± 0.00a | 0.00 ± 0.00a | 0.00 ± 0.00a | 0.00 ± 0.00a | 0.00 ± 0.00a | 0.00 ± 0.00a |
| 0.1 | 86.67 ± 6.67b | 100.0 ± 0.00b | 100.0 ± 0.00b | 100.0 ± 0.00b | 8.33 ± 4.40b | 26.67 ± 4.41b | 48.33 ± 7.26b | 65.00 ± 0.00b |
| 0.2 | 100.0 ± 0.00c | 100.0 ± 0.00b | 100.0 ± 0.00b | 100.0 ± 0.00b | 18.33 ± 7.27b | 36.67 ± 3.33b | 47.00 ± 5.77b | 70.00 ± 0.00b |
| 0.3 | 100.0 ± 0.00c | 100.0 ± 0.00b | 100.0 ± 0.00b | 100.0 ± 0.00b | 20.00 ± 2.88bc | 28.33 ± 7.27b | 60.00 ± 5.77b | 70.00 ± 0.00b |
| 0.4 | 100.0 ± 0.00c | 100.0 ± 0.00b | 100.0 ± 0.00b | 100.0 ± 0.00b | 36.67 ± 4.41c | 55.00 ± 2.89c | 61.67 ± 7.27b | 82.00 ± 0.00b |
| 0.5 | 100.0 ± 0.00c | 100.0 ± 0.00b | 100.0 ± 0.00b | 100.0 ± 0.00b | 33.33 ± 4.41cd | 58.33 ± 10.93c | 56.67 ± 12.02b | 90.00 ± 0.00b |
Note: Each value is the mean ± standard error of three replicates; values followed by the same letter in the same column are not significantly different at P = 0.05 using Duncan's new multiple range test
Fumigation with DDVP and the extract oil was not detrimental to larvae at all concentrations. 0.1% DDVO contact treatment killed 86.67% of freshly emerged adults after 24 h, while at higher concentrations of DDVP, all freshly emerged adults died within the same treatment period. Contact treatment with ginger extract oil was less effective than the equal DDVP concentrations: after 24 h, mortality of newly emerged adults ranges from 8.33% to 33.33%. Mortality increased with time, and after 96 h, depending on concentration, 65% to 90% of newly emerged adults died (Table 1). Fumigation of newly emerged adults with DDVP caused 100% mortality except for 0.1% concentration, where after 24 and 48 h, 81.67% and 96.67% of the adult insects were killed, respectively. Fumigation with ginger rhizome extract oil killed 50% to 100% of newly emerged adults within 24 h, and mortality increased with time and concentration up to 100% after 96 h (Table 2).
Fumigant effect of DDVP and ginger rhizome extract oil on the mortality of newly emerged adults Indian meal moth
| % conc. (v/v) | DDVP | ginger rhizome extract oil | ||||||
|---|---|---|---|---|---|---|---|---|
| 24 h | 48 h | 72 h | 96 h | 24 h | 48 h | 72 h | 96 h | |
| control | 0.00 ± 0.00a | 0.00 ± 0.00 a | 0.00 ± 0.00 a | 0.00 ± 0.00 a | 0.00 ± 0.00 a | 0.00 ± 0.00 a | 0.00 ± 0.00 a | 0.00 ± 0.00 a |
| 0.1 | 81.67 ± 7.26b | 96.67 ± 3.33 b | 100.0 ± 0.00 b | 100.0 ± 0.00 b | 50.00 ± 8.67 b | 53.33 ± 10.13 b | 56.67 ± 8.82 b | 100.00 ± 0.00 b |
| 0.2 | 100.0 ± 0.00c | 100.0 ± 0.00 b | 100.0 ± 0.00 b | 100.0 ± 0.00 b | 55.00 ± 13.23 b | 56.67 ± 13.64 b | 61.67 ± 14.53 b | 100.00 ± 0.00 b |
| 0.3 | 100.0 ± 0.00 c | 100.0 ± 0.00 b | 100.0 ± 0.00 b | 100.0 ± 0.00 b | 70.00 ± 2.89 b | 75.00 ± 2.89 bc | 88.33 ± 4.41 c | 100.00 ± 0.00 b |
| 0.4 | 100.0 ± 0.00 c | 100.0 ± 0.00 b | 100.0 ± 0.00 b | 100.0 ± 0.00 b | 71.67 ± 6.01 b | 80.00 ± 2.89 cd | 98.33 ± 1.67 c | 100.00 ± 0.00 b |
| 0.5 | 100.0 ± 0.00 c | 100.0 ± 0.00 b | 100.0 ± 0.00 b | 100.0 ± 0.00 b | 100.0 ± 0.00 c | 100.0 ± 2.89 cd | 100.0 ± 0.00 c | 100.00 ± 0.00 b |
Note: See Table 1
The highest amylase activity in adults and larvae was observed in control samples. It decreased with the concentration of DDVP and ginger extract oil (Fig. 1). Usually, significantly higher amylase activity values at all concentrations were recorded in adults. The most increased amylase activity (29.19 mmol·min−1) was observed in the larvae fed on maize grains treated with 0.3% DDVP, whereas 0.2% concentration of the extract oil caused the highest enzyme activities of 27.50 mmol·min−1 in the larvae of Indian meal moth (Fig. 1).
Figure 1.
Amylase activity in adults and larvae of Indian meal moth exposed to DDVP and ginger extract oil The line above the bar is the standard error; the means of the same color and letters are not significantly different at P = 0.05
The protease activity in control samples was higher in adults than larvae (Fig. 2). The highest protease activity was recorded in adults at a concentration of 0.2% under treatment with DDVP and extract oil. At concentrations of 0.3% and higher, protease activity in Indian meal moth was lower, especially in those fed on DDVP-treated maize corns.
Figure 2.
Protease activity in adults and larvae of Indian meal moth exposed to DDVP and ginger extract oil
Note: see Figure 1
At all the concentrations of DDVP and ginger rhizome extract oil, lipase activities were higher in the Indian meal moth exposed to DDVP than those exposed to ginger rhizome extract oil used as a treatment for maize grains (Fig. 3). Moreover, the value of lipase activities decreases with an increase in the concentration of DDVP and ginger rhizome extract oil. Nevertheless, DDVP incites more lipase activities than ginger rhizome extract oil at all the percentage concentrations used.
Figure 3.
Lipase activity in adults and larvae of Indian meal moth exposed to DDVP and ginger extract oil
Note: see Figure 1
At all the concentrations of DDVP and ginger rhizome extract oil, lipase activities were higher in the Indian meal moth exposed to DDVP than those exposed to ginger rhizome extract oil used as a treatment for maize grains (Fig. 3). Moreover, the value of lipase activities decreases with an increase in the concentration of DDVP and ginger rhizome extract oil. Nevertheless, DDVP incites more lipase activities than ginger rhizome extract oil at all the percentage concentrations used.
Acetylcholinesterase activities in adults of Indian meal moth were very low in adult insects exposed to grains treated with ginger rhizome extract oil at all concentrations when compared with the acetylcholinesterase activities in adult insects exposed to DDVP-treated grains at the same concentration. The same pattern was recorded in larvae (Fig. 4). The highest acetylcholinesterase activities were recorded in those exposed to grains treated with DDVP.
Figure 4.
Acetylcholinesterase activity in adults and larvae of Indian meal moth exposed to DDVP and ginger extract oil
Note: see Figure 1
Oils from ginger rhizome extract have proven effective as an insecticide against the Indian meal moth. This experiment confirms the data reported by Salvadores et al. (2007), Asawalam et al. (2012), Abdullha (2016), and Abdulhay and Yonius (2019), who reported the effectiveness of ginger in the control of weevils and moths. The well-known synthetic insecticide dichlorvos used in the experiment proved to be effective in controlling the Indian meal moth, which is similar to the reports of Zhang et al. (2021) and Bedford and Robinson (1972).
A high percentage mortality of adults of Indian meal moth was achieved by both DDVP and ginger within 96 h of the application when used as a contact and as a fumigant insecticide. On the contrary, it was observed that Indian meal moth larvae showed resistance to DDVP and ginger, even at the highest concentrations used in the experiment. Larval resistance may be the result of a protective sheath, smaller spiracles, an abundance of detoxifying enzymes, the ability to feed, and the possession of additional genes not present in the adult Indian meal moth. These observations are similar to those of Jiang et al. (2021), who reported that insect larvae possess genes capable of enhancing resistance. Rajamohan et al. (1996) and Feyereisen (1999) also reported mutations that prevent insecticides from binding effectively to their target site in the larvae of insects. Marcombe et al. (2018) and Benade (2022) identified secreted outer cuticles as a protective barrier to insecticide penetration. Moreover, most insect pests at the larva stage escape formulated insecticides because most manufacturers tested preparations on adult insects, neglecting the larvae stage, which is even more destructive to plants (Saleem et al. 2016).
Both DDVP and ginger applied in contact and fumigation inhibited egg hatchability and adult emergence of Indian meal moth. This result is similar to those reported by Ojianwuna and Surveyor (2017), who noted that ginger extract oil was toxic to emerging larvae of Indian meal moth.
Both DDVP and ginger extract oil affect the enzymatic activities of Indian meal moth, which concurs with the report that most insecticides affect enzymatic reactions in insects (Brito et al. 2001; Bown et al. 2004; Macedo et al. 2011). The digestive and neurotransmitting enzymes were unevenly affected by DDVP and ginger. DDVP favored lipase but not protease secretion. This favor might be a result of the composition and inorganic nature of DDVP. The protease activity was highly favored in the larvae of Indian meal moth exposed to the extract oil. This may be due to its feeding ability, which promotes rapid development, which is not found in adult insects, and the organic nature of botanical insecticides. This observation is similar to those by Truman and Riddiford (1999) and Silva et al. (2006), who reported that during the larva stage, the insect undergoes rapid growth and development, processes involving high protein intake to support tissue formation and energy requirement.
Acetylcholinesterase activity in adult and larval Indian meal moth was more induced by DDVP than by ginger extract oil. This may be due to the synthetic, polar nature of DDVP and its ability to quickly interfere with neurotransmitter metabolism. This report concurs with Wang et al. (2004) and Dwivedi et al. (2010), who reported that DDVP has the ability to interfere with neurotransmitter mechanisms and cause their malfunction.
Comparative effects of dichlorvos and ginger extract oil showed that both were effective in controlling the adult Indian meal moth. Nevertheless, the insect larvae were resistant to ginger oil and dichlorvos at the same concentration that is lethal to adult insects. The effectiveness of the oil shows that it can be an alternative to dichlorvos as an ecological insecticide against the Indian meal moth. Finally, the integrated use of oil and dichlorvos could effectively control the Indian meal moth larvae.