To effectively control mosquitoes and reduce the incidence of diseases they carry, strategic, sustainable and environmentally friendly alternatives to chemical pesticides are needed. We evaluated seed meals from certain Brassicaceae (family Brassica) as a source of plant-derived isothiocyanates produced by enzymatic hydrolysis of biologically inactive glucosinolates for use in the control of Egyptian Aedes (L., 1762). Five-defatted seed meal (Brassica juncea (L) Czern., 1859, Lepidium sativum L., 1753, Sinapis alba L., 1753, Thlaspi arvense L., 1753 and Thlaspi arvense – three main types of thermal inactivation and enzymatic degradation Chemical products To determine toxicity (LC50) of allyl isothiocyanate, benzyl isothiocyanate and 4-hydroxybenzylisothiocyanate to Aedes aegypti larvae at 24-hour exposure = 0.04 g/120 ml dH2O). LC50 values for mustard, white mustard and horsetail. seed meal was 0.05, 0.08 and 0.05 respectively compared to allyl isothiocyanate (LC50 = 19.35 ppm) and 4. -Hydroxybenzylisothiocyanate (LC50 = 55.41 ppm) was more toxic to larvae via 24 hours after treatment than 0.1 g/120 ml dH2O respectively. These results are consistent with the production of alfalfa seed meal. The higher efficiency of benzyl esters corresponds to the calculated LC50 values. Using seed meal can provide an effective method of mosquito control. the effectiveness of cruciferous seed powder and its main chemical components against mosquito larvae and shows how the natural compounds in cruciferous seed powder can serve as a promising environmentally friendly larvicide for mosquito control.
Vector-borne diseases caused by Aedes mosquitoes remain a major global public health problem. The incidence of mosquito-borne diseases spreads geographically1,2,3 and re-emerges, leading to outbreaks of severe disease4,5,6,7. The spread of diseases among humans and animals (eg, chikungunya, dengue, Rift Valley fever, yellow fever and Zika virus) is unprecedented. Dengue fever alone puts approximately 3.6 billion people at risk of infection in the tropics, with an estimated 390 million infections occurring annually, resulting in 6,100–24,300 deaths per year8. The reappearance and outbreak of the Zika virus in South America has attracted worldwide attention due to the brain damage it causes in children born to infected women2. Kremer et al 3 predict that the geographic range of Aedes mosquitoes will continue to expand and that by 2050, half of the world’s population will be at risk of infection by mosquito-borne arboviruses.
With the exception of the recently developed vaccines against dengue and yellow fever, vaccines against most mosquito-borne diseases have not yet been developed9,10,11. Vaccines are still available in limited quantities and are only used in clinical trials. Control of mosquito vectors using synthetic insecticides has been a key strategy to control the spread of mosquito-borne diseases12,13. Although synthetic pesticides are effective in killing mosquitoes, the continued use of synthetic pesticides negatively affects non-target organisms and pollutes the environment14,15,16. Even more alarming is the trend of increasing mosquito resistance to chemical insecticides17,18,19. These problems associated with pesticides have accelerated the search for effective and environmentally friendly alternatives to control disease vectors.
Various plants have been developed as sources of phytopesticides for pest control20,21. Plant substances are generally environmentally friendly because they are biodegradable and have low or negligible toxicity to non-target organisms such as mammals, fish and amphibians20,22. Herbal preparations are known to produce a variety of bioactive compounds with different mechanisms of action to effectively control different life stages of mosquitoes23,24,25,26. Plant-derived compounds such as essential oils and other active plant ingredients have gained attention and paved the way for innovative tools to control mosquito vectors. Essential oils, monoterpenes and sesquiterpenes act as repellents, feeding deterrents and ovicides27,28,29,30,31,32,33. Many vegetable oils cause the death of mosquito larvae, pupae and adults34,35,36, affecting the nervous, respiratory, endocrine and other important systems of insects37.
Recent studies have provided insight into the potential use of mustard plants and their seeds as a source of bioactive compounds. Mustard seed meal has been tested as a biofumigant38,39,40,41 and used as a soil amendment for weed suppression42,43,44 and control of soil-borne plant pathogens45,46,47,48,49,50, plant nutrition. nematodes 41,51, 52, 53, 54 and pests 55, 56, 57, 58, 59, 60. The fungicidal activity of these seed powders is attributed to plant protective compounds called isothiocyanates38,42,60. In plants, these protective compounds are stored in plant cells in the form of non-bioactive glucosinolates. However, when plants are damaged by insect feeding or pathogen infection, glucosinolates are hydrolyzed by myrosinase into bioactive isothiocyanates55,61. Isothiocyanates are volatile compounds known to have broad-spectrum antimicrobial and insecticidal activity, and their structure, biological activity and content vary widely among Brassicaceae species42,59,62,63.
Although isothiocyanates derived from mustard seed meal are known to have insecticidal activity, data on biological activity against medically important arthropod vectors are lacking. Our study examined the larvicidal activity of four defatted seed powders against Aedes mosquitoes. Larvae of Aedes aegypti. The aim of the study was to evaluate their potential use as environmentally friendly biopesticides for mosquito control. Three major chemical components of the seed meal, allyl isothiocyanate (AITC), benzyl isothiocyanate (BITC), and 4-hydroxybenzylisothiocyanate (4-HBITC) were also tested to test the biological activity of these chemical components on mosquito larvae. This is the first report to evaluate the effectiveness of four cabbage seed powders and their main chemical components against mosquito larvae.
Laboratory colonies of Aedes aegypti (Rockefeller strain) were maintained at 26°C, 70% relative humidity (RH) and 10:14 h (L:D photoperiod). Mated females were housed in plastic cages (height 11 cm and diameter 9.5 cm) and fed via a bottle feeding system using citrated bovine blood (HemoStat Laboratories Inc., Dixon, CA, USA). Blood feeding was carried out as usual using a membrane multi-glass feeder (Chemglass, Life Sciences LLC, Vineland, NJ, USA) connected to a circulating water bath tube (HAAKE S7, Thermo-Scientific, Waltham, MA, USA) with temperature control 37 °C. Stretch a film of Parafilm M onto the bottom of each glass feed chamber (area 154 mm2). Each feeder was then placed on the top grid covering the cage containing the mating female. Approximately 350–400 μl of bovine blood was added to a glass feeder funnel using a Pasteur pipette (Fisherbrand, Fisher Scientific, Waltham, MA, USA) and the adult worms were allowed to drain for at least one hour. Pregnant females were then given a 10% sucrose solution and allowed to lay eggs on moist filter paper lined in individual ultra-clear soufflé cups (1.25 fl oz size, Dart Container Corp., Mason, MI, USA). cage with water. Place filter paper containing eggs in a sealed bag (SC Johnsons, Racine, WI) and store at 26°C. The eggs were hatched and approximately 200–250 larvae were raised in plastic trays containing a mixture of rabbit chow (ZuPreem, Premium Natural Products, Inc., Mission, KS, USA) and liver powder (MP Biomedicals, LLC, Solon, OH, USA). and fish fillet (TetraMin, Tetra GMPH, Meer, Germany) in a ratio of 2:1:1. Late third instar larvae were used in our bioassays.
Plant seed material used in this study was obtained from the following commercial and government sources: Brassica juncea (brown mustard-Pacific Gold) and Brassica juncea (white mustard-Ida Gold) from the Pacific Northwest Farmers’ Cooperative, Washington State, USA; (Garden Cress) from Kelly Seed and Hardware Co., Peoria, IL, USA and Thlaspi arvense (Field Pennycress-Elisabeth) from USDA-ARS, Peoria, IL, USA; None of the seeds used in the study were treated with pesticides. All seed material was processed and used in this study in accordance with local and national regulations and in compliance with all relevant local state and national regulations. This study did not examine transgenic plant varieties.
Brassica juncea (PG), Alfalfa (Ls), White mustard (IG), Thlaspi arvense (DFP) seeds were ground to a fine powder using a Retsch ZM200 ultracentrifugal mill (Retsch, Haan, Germany) equipped with a 0.75 mm mesh and Stainless steel rotor, 12 teeth, 10,000 rpm (Table 1). The ground seed powder was transferred to a paper thimble and defatted with hexane in a Soxhlet apparatus for 24 h. A subsample of defatted field mustard was heat treated at 100 °C for 1 h to denature myrosinase and prevent hydrolysis of glucosinolates to form biologically active isothiocyanates. Heat-treated horsetail seed powder (DFP-HT) was used as a negative control by denaturing myrosinase.
Glucosinolate content of defatted seed meal was determined in triplicate using high‐performance liquid chromatography (HPLC) according to a previously published protocol 64 . Briefly, 3 mL of methanol was added to a 250 mg sample of defatted seed powder. Each sample was sonicated in a water bath for 30 minutes and left in the dark at 23°C for 16 hours. A 1 mL aliquot of the organic layer was then filtered through a 0.45 μm filter into an autosampler. Running on a Shimadzu HPLC system (two LC 20AD pumps; SIL 20A autosampler; DGU 20As degasser; SPD-20A UV-VIS detector for monitoring at 237 nm; and CBM-20A communication bus module), the glucosinolate content of seed meal was determined in triplicate . using Shimadzu LC Solution software version 1.25 (Shimadzu Corporation, Columbia, MD, USA). The column was a C18 Inertsil reverse phase column (250 mm × 4.6 mm; RP C-18, ODS-3, 5u; GL Sciences, Torrance, CA, USA). Initial mobile phase conditions were set at 12% methanol/88% 0.01 M tetrabutylammonium hydroxide in water (TBAH; Sigma-Aldrich, St. Louis, MO, USA) with a flow rate of 1 mL/min. After injection of 15 μl of sample, the initial conditions were maintained for 20 minutes, and then the solvent ratio was adjusted to 100% methanol, with a total sample analysis time of 65 minutes. A standard curve (nM/mAb based) was generated by serial dilutions of freshly prepared sinapine, glucosinolate and myrosin standards (Sigma-Aldrich, St. Louis, MO, USA) to estimate the sulfur content of defatted seed meal. glucosinolates. Glucosinolate concentrations in the samples were tested on an Agilent 1100 HPLC (Agilent, Santa Clara, CA, USA) using the OpenLAB CDS ChemStation version (C.01.07 SR2 [255]) equipped with the same column and using a previously described method. Glucosinolate concentrations were determined; be comparable between HPLC systems.
Allyl isothiocyanate (94%, stable) and benzyl isothiocyanate (98%) were purchased from Fisher Scientific (Thermo Fisher Scientific, Waltham, MA, USA). 4-Hydroxybenzylisothiocyanate was purchased from ChemCruz (Santa Cruz Biotechnology, CA, USA). When enzymatically hydrolyzed by myrosinase, glucosinolates, glucosinolates, and glucosinolates form allyl isothiocyanate, benzyl isothiocyanate, and 4-hydroxybenzylisothiocyanate, respectively.
Laboratory bioassays were performed according to the method of Muturi et al. 32 with modifications. Five low-fat seed feeds were used in the study: DFP, DFP-HT, IG, PG and Ls. Twenty larvae were placed in a 400 mL disposable three-way beaker (VWR International, LLC, Radnor, PA, USA) containing 120 mL deionized water (dH2O). Seven seed meal concentrations were tested for mosquito larval toxicity: 0.01, 0.02, 0.04, 0.06, 0.08, 0.1 and 0.12 g seed meal/120 ml dH2O for DFP seed meal , DFP-HT, IG and PG. Preliminary bioassays indicate that defatted Ls seed flour is more toxic than four other seed flours tested. Therefore, we adjusted the seven treatment concentrations of Ls seed meal to the following concentrations: 0.015, 0.025, 0.035, 0.045, 0.055, 0.065, and 0.075 g/120 mL dH2O.
An untreated control group (dH20, no seed meal supplement) was included to assess normal insect mortality under assay conditions. Toxicological bioassays for each seed meal included three replicate three-slope beakers (20 late third instar larvae per beaker), for a total of 108 vials. Treated containers were stored at room temperature (20-21°C) and larval mortality was recorded during 24 and 72 hours of continuous exposure to treatment concentrations. If the mosquito’s body and appendages do not move when pierced or touched with a thin stainless steel spatula, the mosquito larvae are considered dead. Dead larvae usually remain motionless in a dorsal or ventral position at the bottom of the container or on the surface of the water. The experiment was repeated three times on different days using different groups of larvae, for a total of 180 larvae exposed to each treatment concentration.
The toxicity of AITC, BITC, and 4-HBITC to mosquito larvae was assessed using the same bioassay procedure but with different treatments. Prepare 100,000 ppm stock solutions for each chemical by adding 100 µL of the chemical to 900 µL of absolute ethanol in a 2-mL centrifuge tube and shaking for 30 seconds to mix thoroughly. Treatment concentrations were determined based on our preliminary bioassays, which found BITC to be much more toxic than AITC and 4-HBITC. To determine toxicity, 5 concentrations of BITC (1, 3, 6, 9 and 12 ppm), 7 concentrations of AITC (5, 10, 15, 20, 25, 30 and 35 ppm) and 6 concentrations of 4-HBITC (15, 15, 20, 25, 30 and 35 ppm). 30, 45, 60, 75 and 90 ppm). The control treatment was injected with 108 μL of absolute ethanol, which is equivalent to the maximum volume of the chemical treatment. Bioassays were repeated as above, exposing a total of 180 larvae per treatment concentration. Larval mortality was recorded for each concentration of AITC, BITC, and 4-HBITC after 24 h of continuous exposure.
Probit analysis of 65 dose-related mortality data was performed using Polo software (Polo Plus, LeOra Software, version 1.0) to calculate 50% lethal concentration (LC50), 90% lethal concentration (LC90), slope, lethal dose coefficient, and 95 % lethal concentration. based on confidence intervals for lethal dose ratios for log-transformed concentration and dose-mortality curves. Mortality data are based on combined replicate data of 180 larvae exposed to each treatment concentration. Probabilistic analyzes were performed separately for each seed meal and each chemical component. Based on the 95% confidence interval of the lethal dose ratio, the toxicity of seed meal and chemical constituents to mosquito larvae was considered to be significantly different, so a confidence interval containing a value of 1 was not significantly different, P = 0.0566.
The HPLC results for the determination of the major glucosinolates in defatted seed flours DFP, IG, PG and Ls are listed in Table 1. The major glucosinolates in the seed flours tested varied with the exception of DFP and PG, which both contained myrosinase glucosinolates. The myrosinin content in PG was higher than in DFP, 33.3 ± 1.5 and 26.5 ± 0.9 mg/g, respectively. Ls seed powder contained 36.6 ± 1.2 mg/g glucoglycone, whereas IG seed powder contained 38.0 ± 0.5 mg/g sinapine.
Larvae of Ae. Aedes aegypti mosquitoes were killed when treated with defatted seed meal, although the effectiveness of the treatment varied depending on the plant species. Only DFP-NT was not toxic to mosquito larvae after 24 and 72 h of exposure (Table 2). The toxicity of the active seed powder increased with increasing concentration (Fig. 1A, B). The toxicity of seed meal to mosquito larvae varied significantly based on the 95% CI of the lethal dose ratio of LC50 values at 24-hour and 72-hour assessments (Table 3). After 24 hours, the toxic effect of Ls seed meal was greater than other seed meal treatments, with the highest activity and maximum toxicity to larvae (LC50 = 0.04 g/120 ml dH2O). Larvae were less sensitive to DFP at 24 hours compared to IG, Ls and PG seed powder treatments, with LC50 values of 0.115, 0.04 and 0.08 g/120 ml dH2O respectively, which were statistically higher than the LC50 value. 0.211 g/120 ml dH2O (Table 3). The LC90 values of DFP, IG, PG and Ls were 0.376, 0.275, 0.137 and 0.074 g/120 ml dH2O, respectively (Table 2). The highest concentration of DPP was 0.12 g/120 ml dH2O. After 24 hours of assessment, the average larval mortality was only 12%, while the average mortality of IG and PG larvae reached 51% and 82%, respectively. After 24 hours of evaluation, the average larval mortality for the highest concentration of Ls seed meal treatment (0.075 g/120 ml dH2O) was 99% (Fig. 1A).
Mortality curves were estimated from the dose response (Probit) of Ae. Egyptian larvae (3rd instar larvae) to seed meal concentration 24 hours (A) and 72 hours (B) after treatment. The dotted line represents the LC50 of the seed meal treatment. DFP Thlaspi arvense, DFP-HT Heat inactivated Thlaspi arvense, IG Sinapsis alba (Ida Gold), PG Brassica juncea (Pacific Gold), Ls Lepidium sativum.
At 72-hour evaluation, the LC50 values of DFP, IG and PG seed meal were 0.111, 0.085 and 0.051 g/120 ml dH2O, respectively. Almost all larvae exposed to Ls seed meal died after 72 h of exposure, so mortality data were inconsistent with Probit analysis. Compared to other seed meal, larvae were less sensitive to DFP seed meal treatment and had statistically higher LC50 values (Tables 2 and 3). After 72 hours, the LC50 values for DFP, IG and PG seed meal treatments were estimated to be 0.111, 0.085 and 0.05 g/120 ml dH2O, respectively. After 72 hours of evaluation, the LC90 values of DFP, IG and PG seed powders were 0.215, 0.254 and 0.138 g/120 ml dH2O, respectively. After 72 hours of evaluation, the average larval mortality for the DFP, IG and PG seed meal treatments at a maximum concentration of 0.12 g/120 ml dH2O was 58%, 66% and 96%, respectively (Fig. 1B). After 72-hour evaluation, PG seed meal was found to be more toxic than IG and DFP seed meal.
Synthetic isothiocyanates, allyl isothiocyanate (AITC), benzyl isothiocyanate (BITC) and 4-hydroxybenzylisothiocyanate (4-HBITC) can effectively kill mosquito larvae. At 24 hours post-treatment, BITC was more toxic to larvae with an LC50 value of 5.29 ppm compared to 19.35 ppm for AITC and 55.41 ppm for 4-HBITC (Table 4). Compared to AITC and BITC, 4-HBITC has lower toxicity and a higher LC50 value. There are significant differences in the mosquito larval toxicity of the two major isothiocyanates (Ls and PG) in the most potent seed meal. Toxicity based on the lethal dose ratio of LC50 values between AITC, BITC, and 4-HBITC showed a statistical difference such that the 95% CI of the LC50 lethal dose ratio did not include a value of 1 (P = 0.05, Table 4). The highest concentrations of both BITC and AITC were estimated to kill 100% of the larvae tested (Figure 2).
Mortality curves were estimated from the dose response (Probit) of Ae. 24 hours after treatment, Egyptian larvae (3rd instar larvae) reached synthetic isothiocyanate concentrations. The dotted line represents the LC50 for isothiocyanate treatment. Benzyl isothiocyanate BITC, allyl isothiocyanate AITC and 4-HBITC.
The use of plant biopesticides as mosquito vector control agents has long been studied. Many plants produce natural chemicals that have insecticidal activity37. Their bioactive compounds provide an attractive alternative to synthetic insecticides with great potential in controlling pests, including mosquitoes.
Mustard plants are grown as a crop for their seeds, used as a spice and a source of oil. When mustard oil is extracted from the seeds or when mustard is extracted for use as biofuel, 69 the by-product is defatted seed meal. This seed meal retains many of its natural biochemical components and hydrolytic enzymes. The toxicity of this seed meal is attributed to the production of isothiocyanates55,60,61. Isothiocyanates are formed by the hydrolysis of glucosinolates by the enzyme myrosinase during hydration of seed meal38,55,70 and are known to have fungicidal, bactericidal, nematicidal and insecticidal effects, as well as other properties including chemical sensory effects and chemotherapeutic properties61,62,70. Several studies have shown that mustard plants and seed meal act effectively as fumigants against soil and stored food pests57,59,71,72. In this study, we assessed the toxicity of four-seed meal and its three bioactive products AITC, BITC, and 4-HBITC to Aedes mosquito larvae. Aedes aegypti. Adding seed meal directly to water containing mosquito larvae is expected to activate enzymatic processes that produce isothiocyanates that are toxic to mosquito larvae. This biotransformation was demonstrated in part by the observed larvicidal activity of the seed meal and loss of insecticidal activity when dwarf mustard seed meal was heat treated before use. Heat treatment is expected to destroy the hydrolytic enzymes that activate glucosinolates, thereby preventing the formation of bioactive isothiocyanates. This is the first study to confirm the insecticidal properties of cabbage seed powder against mosquitoes in an aquatic environment.
Among the seed powders tested, watercress seed powder (Ls) was the most toxic, causing high mortality of Aedes albopictus. Aedes aegypti larvae were processed continuously for 24 hours. The remaining three seed powders (PG, IG and DFP) had slower activity and still caused significant mortality after 72 hours of continuous treatment. Only Ls seed meal contained significant amounts of glucosinolates, whereas PG and DFP contained myrosinase and IG contained glucosinolate as the major glucosinolate (Table 1). Glucotropaeolin is hydrolyzed to BITC and sinalbine is hydrolyzed to 4-HBITC61,62. Our bioassay results indicate that both Ls seed meal and synthetic BITC are highly toxic to mosquito larvae. The main component of PG and DFP seed meal is myrosinase glucosinolate, which is hydrolyzed to AITC. AITC is effective in killing mosquito larvae with an LC50 value of 19.35 ppm. Compared to AITC and BITC, 4-HBITC isothiocyanate is the least toxic to larvae. Although AITC is less toxic than BITC, their LC50 values are lower than many essential oils tested on mosquito larvae32,73,74,75.
Our cruciferous seed powder for use against mosquito larvae contains one major glucosinolate, accounting for over 98-99% of the total glucosinolates as determined by HPLC. Trace amounts of other glucosinolates were detected, but their levels were less than 0.3% of the total glucosinolates. Watercress (L. sativum) seed powder contains secondary glucosinolates (sinigrin), but their proportion is 1% of the total glucosinolates, and their content is still insignificant (about 0.4 mg/g seed powder). Although PG and DFP contain the same main glucosinolate (myrosin), the larvicidal activity of their seed meals differs significantly due to their LC50 values. Varies in toxicity to powdery mildew. The emergence of Aedes aegypti larvae may be due to differences in myrosinase activity or stability between the two seed feeds. Myrosinase activity plays an important role in the bioavailability of hydrolysis products such as isothiocyanates in Brassicaceae plants76. Previous reports by Pocock et al.77 and Wilkinson et al.78 have shown that changes in myrosinase activity and stability may also be associated with genetic and environmental factors.
Expected bioactive isothiocyanate content was calculated based on the LC50 values of each seed meal at 24 and 72 hours (Table 5) for comparison with corresponding chemical applications. After 24 hours, the isothiocyanates in the seed meal were more toxic than the pure compounds. LC50 values calculated based on parts per million (ppm) of isothiocyanate seed treatments were lower than LC50 values for BITC, AITC, and 4-HBITC applications. We observed larvae consuming seed meal pellets (Figure 3A). Consequently, larvae may receive more concentrated exposure to toxic isothiocyanates by ingesting seed meal pellets. This was most evident in the IG and PG seed meal treatments at 24-h exposure, where LC50 concentrations were 75% and 72% lower than pure AITC and 4-HBITC treatments, respectively. Ls and DFP treatments were more toxic than pure isothiocyanate, with LC50 values 24% and 41% lower, respectively. Larvae in the control treatment successfully pupated (Fig. 3B), while most larvae in the seed meal treatment did not pupate and larval development was significantly delayed (Fig. 3B,D). In Spodopteralitura, isothiocyanates are associated with growth retardation and developmental delay79.
Larvae of Ae. Aedes aegypti mosquitoes were continuously exposed to Brassica seed powder for 24–72 hours. (A) Dead larvae with particles of seed meal in the mouthparts (circled); (B) Control treatment (dH20 without added seed meal) shows that larvae grow normally and begin to pupate after 72 hours (C, D) Larvae treated with seed meal; the seed meal showed differences in development and did not pupate.
We have not studied the mechanism of toxic effects of isothiocyanates on mosquito larvae. However, previous studies in red fire ants (Solenopsis invicta) have shown that inhibition of glutathione S-transferase (GST) and esterase (EST) is the main mechanism of isothiocyanate bioactivity, and AITC, even at low activity, can also inhibit GST activity. red imported fire ants in low concentrations. The dose is 0.5 µg/ml80. In contrast, AITC inhibits acetylcholinesterase in adult corn weevils (Sitophilus zeamais)81. Similar studies must be carried out to elucidate the mechanism of isothiocyanate activity in mosquito larvae.
We use heat-inactivated DFP treatment to support the proposal that hydrolysis of plant glucosinolates to form reactive isothiocyanates serves as a mechanism for mosquito larval control by mustard seed meal. DFP-HT seed meal was not toxic at the application rates tested. Lafarga et al. 82 reported that glucosinolates are sensitive to degradation at high temperatures. Heat treatment is also expected to denature the myrosinase enzyme in seed meal and prevent the hydrolysis of glucosinolates to form reactive isothiocyanates. This was also confirmed by Okunade et al. 75 showed that myrosinase is temperature sensitive, showing that myrosinase activity was completely inactivated when mustard, black mustard, and bloodroot seeds were exposed to temperatures above 80°. C. These mechanisms may result in loss of insecticidal activity of heat-treated DFP seed meal.
Thus, mustard seed meal and its three major isothiocyanates are toxic to mosquito larvae. Given these differences between seed meal and chemical treatments, the use of seed meal may be an effective method of mosquito control. There is a need to identify suitable formulations and effective delivery systems to improve the efficacy and stability of the use of seed powders. Our results indicate the potential use of mustard seed meal as an alternative to synthetic pesticides. This technology could become an innovative tool for controlling mosquito vectors. Because mosquito larvae thrive in aquatic environments and seed meal glucosinolates are enzymatically converted to active isothiocyanates upon hydration, the use of mustard seed meal in mosquito-infested water offers significant control potential. Although the larvicidal activity of isothiocyanates varies (BITC > AITC > 4-HBITC), more research is needed to determine whether combining seed meal with multiple glucosinolates synergistically increases toxicity. This is the first study to demonstrate the insecticidal effects of defatted cruciferous seed meal and three bioactive isothiocyanates on mosquitoes. The results of this study break new ground by showing that defatted cabbage seed meal, a byproduct of oil extraction from the seeds, may serve as a promising larvicidal agent for mosquito control. This information can help further the discovery of plant biocontrol agents and their development as cheap, practical, and environmentally friendly biopesticides.
The datasets generated for this study and the resulting analyzes are available from the corresponding author on reasonable request. At the end of the study, all materials used in the study (insects and seed meal) were destroyed.
Post time: Jul-29-2024