Insecticidal impact of Kalonji (Nigella Sativa) as Bio-pesticide against Stored Grain Insect Pests especially on Lesser Grain Borer (Rhyzopertha dominica)
Author: Awais Rasool, Zeeshan Ali, Urooj Mazhar, Samra Shakoor, Aqsa Yaseen
National Agriculture Research Center (NARC), Islamabad
Introduction
Rhyzopertha dominica (Fabricius, 1792) lesser grain borer belongs to the Bostrichidae, commonly referred to as bostrichids beetles, comprise of about 550 species in 99 genera of which 77 species in 26 genera occur in North America (Ivie 2002a, Ivie 2002b, Marske and Ivie 2003). Most of which are wood boring insects. Adult borers have very powerful mandibles and destructive feeders. Lesser grain borer is most common and destructive in tropical, sub-tropical and temperate climates but can spread to any area in transported grain. It is a problem of grain only rather than cereal products and is also considered one of the most destructive pests of stored grains in Pakistan. The lesser grain borer attacks a wide variety of stored foods including cereals, seeds and dried fruit; almost all grains, particularly wheat, barley, sorghum and rice, commodities such as seeds, drugs, cork, timber and paper products (Canadian Grain Commission 2009). Adult R. dominica are long lived and can fly to disperse and initiate new grain infestations. The adult beetles are 2-3 mm long and have cylindrical, dark brown or brown bodies. Eggs are laid singly and in small clusters between grains or in crevices in the store-house and up to 500 eggs may be laid in total. After hatching, the larvae molt 2-5 times before pupation, this takes place inside the grain. Young larvae are not cannibalistic, but free living and as they mature.
Bio-pesticides which are more effective than pesticides;
Bio–pesticides are certain type of pesticides derived from such natural materials as animal, plants, bacteria, and certain materials. Synthetic pesticides are used to control stored grain pests which are harmful for human health as well as for plant and food materials. With heightened concern for environmental problems and human health, the search for readily biodegradable and environmentally friendly insecticides is more interest among scientists (Shaaya et al., 1997; Isman, 2000). In the present study, the chemical constituents of essential oils from N. sativa seeds was determined, and the insecticidal activity of the essential oil was tested against the adult stages of the stored– products pests, Rhyzopertha dominica.
Comparison Between Bio-pesticides and pesticides
| Bio-pesticides | Pesticides |
| · Friendly to non-target species | · Harmful to non-target species |
| · Do not cause pollution | · Serious pollution to environment |
| · Relatively cheaper | · Relatively expensive |
| · Pests never develop resistance | · Pests eventually become resistant |
| · Growing market preference | · Diminishing market |
Nigella sativa
Black cumin (Nigella sativa L., Family: Ranunculaceae) is an annual herb possessing wide range of medicinal uses apart from its commercial significance as a spice yielding plant. Black cumin seeds are used in herbal medicine all over the world for the treatment and prevention of a number of diseases. Prophet Mohammad (SAWW) said: “Use this black seed; it has a cure for every disease except death” (Sahih Bukhari). About Mohammad (SAWW) Almighty Allah says in the Holy Quran, “He does not speak anything of his own desire…” (Surah An-Najm 53:3). Black cumin seeds have been used to successfully keep people super healthy for over 3,300 years. It is one of the earliest cultivated plants in human history. Black seed is remedy for colds, headache, respiratory, digestive disorders, toothaches, infections, inflammatory disorders and allergies.
- sativa Seed
Materials
- sativa Seed
- Ethanol acid
- Cotton plug
- Filter paper
- Conical Flasks
- Petri dishes
- Beakers
- Pipette
- Jar
- Weight balance
- Rotary Evaporator. It consists of the following parts:
- Water bath
- Vacuum chamber
- Inlet pipe
- Outlet pipe
- Solvent condenser
- Rotatory flask
- Water flask
- sativa seed has water content of 7.8% and oil content of 49.58%. Prior to use, the N. sativa seeds are repeatedly washed to remove the dirt and other impurities material, and subsequently dried in oven at 50ºC until it reached constant moisture content. These materials are grinded and required material is taken in flask.
- The Process of Extraction of Oil from sativa Seed involve following steps;
- Grinding of seeds
- Defatting of seeds
- Isolation of sativa oil
- Storage of final product
Oil extraction by solvent extraction procedure, using a solvent i.e., Ethanol acid
- At temperature 30ºC is carried out by taking sativa seed powder and solvent in a ratio of 1:5 in a flask.
- The extraction is continued for about 3 to 4 days and three times shake in a day.
- Then the solvent is filtered with the help of filter paper.
- It is heated and evaporated at 70ºC to obtain solvent free sativa oil with the help of Rotary evaporator. Further solvent traces are removed by putting the oil in a round bottom flask and placed on a water bath for 12 hours at 60ºC-70ºC.
- Then the oil is weighed and its percentage is calculated. The pure oil is stored in a refrigerator. The flask is heated at 60ºC with the use of an electric mantle.
- The solvent is vaporized and condensed into the evaporator. The obtained mixture (Solvent and oil) is moved directly into round bottom flask.
- The process continues for the specified time. This process is repeated 6 times. Oil is recovered by distillation process using the same apparatus. The obtained oil is stored in a bottle for further processes.
Purifying Solvent in Flask after filtration and N. sativa Extract
Method
- After sieving the wheat, the insect (Rhyzopertha dominica) is collected. Then, 200g wheat (galaxy-variety) is placed in sterilizer for 24 hours at 60◦. After sterilization, 30g wheat is weighted for 12 petri dishes (N. sativa extract) and 50g wheat for 4 petri dishes (in acetone).
- First of all, 10% stock solution is prepared by diluting 1ml sativa extract with 9ml acetone. All remaining stock solution (4%, 2%, 1%) is prepared similarly.
- With the help of pipette, applied 3ml of solution on wheat in that way every petri dish (30g) treated with following concentrations. Mixed (treated wheat) in such a way that solution should apply uniformly. 5ml acetone on 50 g wheat was applied and mixed uniformly for control purpose. 30 g wheat into 3 petri dishes was divided equally for replication purpose and divided 50 g wheat into 5 petri dishes.
- Every petri dish was labelled according to its replications and concentrations. Now every treatments having 4 replications (3 treated, 1 control). 20 insects (Rhyzopertha dominica) were released in every replication. The treated wheat was allowed to dry for 60 minutes and then 20 adults (1 week old) were released in every petri dishes.
- Following this method, 3 petri dishes 10%, 4%, 2%, 1% concentration of sativa solution (in acetone) were observed for 24 hours, 48 hours, 72 hours and 1 week respectively.
- At least, 4th petri dish of each concentration of Acetone were observed for 24 hours, 48 hours, 72 hours and 1 week. All these petri dishes put into growth chamber.
- Data collected at constant 28+2ºC and relative humidity 70+5%. Took data of mortality after 24 hours, 48 hours, 72 hours and one week by using sieving utensils. Removed dead insects and noted data on paper.
Mortality was corrected according to Abbott’s Formula (1925);
Corrected% = (1- n in T after treatment / n in Co after treatment) *100
Conclusion
- sativa had toxic effect against Rhyzopertha dominica at different concentrations were applied to check the insecticidal effect of N. sativa against R. dominica at different exposure periods. Highest mortality is observed nearly 44% in 10% concentration followed by after one week. According to results, N. sativa has some insecticidal properties but should be further tested for its use as safe grain protectant.
