By DENNIS OWUSU BOATENG
polonium90@yahoo.com
+233-(0)240-296835
ABSTRACT
The study investigated the biology and effect of Deltamethrin on Tribolium castaneum (Herbst), a pest of stored cocoa bean. Tribolium castaneum (Herbst) has over the years been a problem on stored cocoa beans. It causes weight loss and contamination to the beans, thereby making it unmarketable. There is therefore a need to control it in stored cocoa beans to forestall its destructive effect. Elementary knowledge on the biology of the insect pest is a necessity in its control.
Synthetic pyrethroids like Deltamethrin are known to be metabolized in mammals, and hence have no tendency to accumulate in tissues and are fairly rapidly degraded in soil and in plants. Deltamethrin a typical example of pyrothoid used by farmers and pest managers was used in this study. Three different concentrations; 2.0 %, 1.5% and 1.0% were prepared. Distilled water was used as a diluent. The efficacy of concentration prepared was checked using the mortality of the insects as an indicator for four exposure times of; 0 day, 1 day, 2 days and 3 days. Mortality increased with increasing concentrations as well as increasing exposure time. It is expected that the results of this study will help ameliorate the many problem posed by Tribolium castaneum to most farmers and pest managers.
CHAPTER ONE
1.0 INTRODUCTION AND LITERATURE REVIEW
1.1 Cocoa Beans
Cocoa belongs to the kingdom-plantae, Subkingdom-Tracheobionta (vascular plants), Super division-spermatophyta (seed plants), Division-Magnoliophyta (Flowering plants), Class-Magnoliopsida (Dicotyledons), Subclass-Dilleniidae, Order-Malvales, Family-Sterculiaceae, Genus-Theobroma and Species-cacao.[Ref: 18]
The cocoa tree “Theobroma cacao” grows only under very special conditions. It needs a climate of humid, warm and preferably constant temperatures between 25oc never over 35°c. Sufficient rainfall is essential. Soil requirements must be humid and rich in nutrients. Its colour depends on variety that is yellow, red or reddish-brown when matured [Ref: 2].
During harvesting, only healthy pod should be harvested for fermentation. Diseased pods are discarded. Frequent harvesting may be dictated by pod disease, but, where it is not, long intervals between harvests should be avoided since this can lead to the collection of pods of varying ripeness. It is preferable to open pods by striking them with a wooden batten rather than a machete which may cut the shell of some beans allowing mould and insect like Tribolium castaneum to enter the beans. The interval between harvesting and opening of the pods has been found to influence fermentation. Flavor can be improved by post harvest storage of pod between 0 and 15 days before the wet beans are removed for fermentation. Post harvest storage of unbroken pods is also impracticable on large scale production of beans because of the amount of extra handling involved and in part of southeast Africa where the cocoa pod borer (CPB) is prevalent [Ref: 11].
Fermentation is normally carried out in heaps or boxes and a crucial stage in the development of chocolate flavor precursors. Many factors increase the process of fermentation. The fermentation process generates considerable heat and temperatures close to 50oc and can be reached within the mass of beans during fermentation. The fermentation of very small quantities of beans will allow heat to dissipate and the fermentation will be unsatisfactory. The duration of fermentation varies according to the variety of cocoa being fermented but is commonly for 3 to 5 days, that is, 72-120 hours. Fermentation is merely the process that set flavor developing reaction in motion. Lack of fermentation or under fermentation will give rise to slat and purple beans with consequent increase in bitterness and astringing fermentation. Fermentation is a basic process which if left alone will look after itself and best kept simple [Ref: 11].
The process is carried out preferably in the sun but alternatively by artificial means. Drying in the sun ideally take 6-10 days and a much longer period may allow mould to develop inside the beans leading to musty or moulds off- flavor. Access to the drying area by animals and domestic fowls should be prevented because they can cause bacterial infections which are harmful. Sun drying gives an opportunity to remove defective beans. Subsequent drying and roasting also improves the flavor. After drying the moisture content is reduced between 6-7 %. Bagging and storage is the next step [Ref: 11].
1.2 Pest of Cocoa Beans
Ghana bags about 700,000 tonnes of cocoa in a year and stores it at warehouses but there are a lot of constraints or losses to its storage. One of the main constraints is insect pest infestation. Insect pest have been with stored product since the dawn of settle agriculture some 10,000 years ago. The establishment of stored products pest research and development at the beginning of the 20th century has evolved many strategies for protection and disinfestations that we see today against plethora of insect pest that confront the grain and food industry [Ref. 12]. Before attempting to apply control measures it is essential to identify the pest concerned and to understand how it is a threat to the safe storage of the commodity. Preventing infestation is always preferable to controlling infestation that has assumed serious proportions. The potential sources of infestation must be known so that the build-up of pests during storage can be controlled more easily and economically [Ref: 10]. Places in which food commodities are store are Traditional cribs, improved cribs, and Silos.
The majority of stored pest insects that attack most stored food commodities come from only two of the roughly 26 orders of the class Insecta; Coleoptera and Lepidoptera. On the other hand, predator and parasitoid of stored insect pest comes from the order Hemiptera, Hymenoptera, and Diptera [Ref. 12]. Stored insect pest are classified by whether they develop and feed inside or outside the bean (kernel) and this is described as either internal or external developer. This is also based on their control. Also the effectiveness of control measures may be greatly increased by applying an elementary knowledge of the biology of pest species. [ref. 10]
1.2.1 Internal Developers
As the most destructive of the stored insect pest, six species from 2 families of the Coleoptera and one family of the Lepidoptera are recognized as internal developers, sometimes referred to as primary invaders. This includes the grain borer, Rhyzopertha domicica (Fabricius), which is one of the most damaging insect and the larger grain weevil (Family, Curculionidae) such as the rice weevil, sitophilus oryae (L). Their control is mostly based on their life cycle [Ref: 10].
1.2.2 External Developers
External developers are sometimes referred to as secondary invaders because they tend to infest broken materials and grain created by primary invaders. They are found in grains but are more common in flour meals and other processed foods. They have also been report in storage, handing equipments and processing facilities. External developers represent six families of coleoptera and one family of Lepidoptera.
The families includes floor beetles, (Family: Tenebronidae), such as the red flour beetle, Tribolium casteneum (Herbat) and the confused flour beetle Tribolium confusum (Jacquelin du Val); and the grain beetle (Families: Laemophoeidae and Silvanidae), which are generally smaller and flatter than other externally developing stored product Coleopterans. The most commonly found species of the family laemphloeidae are the flat grain beetle cryptolestes pusillus [Ref. 12]. Also the most common silvanid is the saw toothed grain beetle, Oryzaephilus surrinamensis (L).
Another important group are the grain-infesting dermestids (Family: Dermestidae), which are generally referred to the several species of Trogoderma. The warehouse beetle, Trogederma variabile [Ref. 12] and khapra beetle Trogoderma granarium are best known. The larvae of these species can diapauses for many months making them partially difficult to control. Of the coleopteran, the anobiid beetle (Family: Anobiidae) are the last main group worth mentioning. These include the cigarette beetle, Lasioderma serricorne (F) and the drugstore beetle, stegobium paniceum. Several moths’ species also infest cereal and stored food commodities which are Epestia cautela and Plodia interpuntella. [Ref: 10]
1.3 THE RED FLOUR BEETLE, Tribolium castaneum (Herbat)
1.3.1 Classification of Red Flour Beetle
Kingdom-Animalia, Phylum-Arthropoda, Class-Insecta, Order-Coleoptera, Suborder- Polyphaga, Family-Tenebrionidae, Species-Tribolium, Genus-castaneum. [Ref: 7]
1.3.2 Life History of Red Flour Beetle
As a major pest of stored grains and grain products, Tribolium castaneum spread around the world with human agriculture. Dead beetles found in ancient Egyptian tombs are indicative of an Old World origin, but beyond that little is known about its place of origin or natural habitat. The strains used by Tribolium geneticists are derived from farms and commercial storages around the world. Their ability to live on dry food alone — metabolic water is the main source for their bodily juices — hints that these beetles evolved in a dry environment, but their original food source is unknown [Ref: 6].
1.3.3 Structure and Identification of Red Flour Beetle
The red flour beetles measure about 0.25-0.32cm inch long and are flat, shiny, reddish-brown, and elongated. Antennae segments of the flour beetle increase in size gradually from the base to the tip to form a club of four segments. The red flour beetle has the antennae abruptly larger than the preceding ones, forming a three-segmented club. When viewed from below, the eyes of the red flour beetle are separated by less than two eye diameters.
They are not usually able to chew through the outer coating of grain unless the moisture content is above 12 percent [Ref: 15]. However, other grain-feeding insects and mechanical harvesting injury provide a source of cracked kernels and dust food for them. The adults have glands on the abdomen and thorax which release a pungent gas when the insects are irritated. This, in turn, may produce a very undesirable odour in the grain. Adults also possess a chewing mouth part. This mouth part points downwards (hypognathous mouth part) to the bean (flour) causing more harm. Contamination also occurs from the accumulation of dead bodies and waste products [Ref: 15].
1.3.4 Life Cycle of Red Flour Beetle
This is a very prolific species. The beetle breeds in damaged grain, grain dust, high-moisture wheat kernels, flour, etc. Female beetles each lay 300 to 400 eggs in flour or other foods during a period of five to eight months (two to three eggs per day). Within 5 to 12 days, these eggs hatch into slender, cylindrical, white larvae tinged with yellow. The length of the larval period varies from 22 to more than 100 days; the pupal period is about 8 days [Ref: 15]. Fully grown larvae transform to naked pupae, and in a week adults emerge. The life cycle (Fig. 1) requires 7 to 12 weeks, with adults living for 3 years or more. Ideally this type of beetle prefers temperatures of 30°C.
The eggs, larvae, and pupae are similar in different species of the beetle. Eggs are whitish or colourless and microscopic in size, with food particles adhering to the sticky surface. Brown-headed larvae are cream to yellow, slender, and wiry, reaching a length of 0.098cm. Larvae have six legs and two-pointed or forked projections that make the body segment. Pupae are white to light brown. The insect undergoes a complete metamorphosis [Ref: 15].
1.4 Control of Stored Cocoa Insect Pest
Literature shows that the development of relatively cheap and very effective methods which matured in the second half of the 20th century, led to pesticides [Ref. 12] and fumigants (Ref. 12) being the most preferred choice in insect management [Ref: 9]. Also admixture of abrasive materials such as fine sand, kaolin or wood-ash, Dissemination of insect pathogens of stored product moths e.g., the bacterium Bacillus thuringiensis, either by direct application onto the stored commodity or by attracting insects to traps containing a source of the disease, Control of pest by natural enemies and the use of genotypes resistant to attack the main post-harvest pests [Ref: 10].
1.4.1 Fumigants
Fumigants generally enter the insect through the respiratory system, and are toxic to all life stages. They defuse through air, permeate products that have little or no residual insecticidal effect [Ref. 12].
Currently several fumigants are used against stored product insect pest. For fumigants with phosphine (PH3), solid metal phosphine are used in grains (Aluminum phosphide) and warehouse (Magnesium phosphide). Phosphine generators mix the metal phosphide with moisture to rapidly produce gaseous phosphine which can be delivered to the site in cylinder and released directly to the commodity or structure [Ref: 10].
Other fumigant includes hydrogen cyanide and ethyl formate. Like suphuryl fluoride, hydrogen cyanide, carbon disulphide, and ethyl formate has been rekindled in recent years to methyl bromide; carbonyl sulphide was patented in 1993 for this purpose [Ref: 10].
1.4.2 Pesticides
Pesticides or protectants generally enter the insects orally or across the cuticle. They are applied either to grains, flour, walls junctions, general surface or crevices in warehouse and food facilities. “Protectants are defined as insecticides that prevent infestation from becoming established in a commodity but are less at managing a well established infestation, and infested commodities and structure are often better treated with fumigants” [Ref 6]. Therefore, insecticides, fungicides, herbicides, etc., are all types of pesticides. Some pesticides must only touch (contact) the pest to be deadly.
1.4.2.1 Contact Insecticides
Insecticides are chemicals used to control insects. Often the word "insecticide" is confused with the word "pesticide." It is, however, just one of many types of pesticides. An insecticide may kill the insect by touching it or it may have to be swallowed to be effective. Some insecticides kill both by touch and by swallowing. Insecticides called Systemic may be absorbed, injected, or fed into the plant or animal to be protected. When the insect feeds on this plant or animal, it ingests the systemic chemical and is killed. Contact pesticides generally control pests as a result of direct contact. Insects are killed when sprayed directly or when they crawl across surfaces treated with residual contact insecticide [Ref: 10].
The most commonly contact compound (insecticide) used are: (1) organophosphates (Malathion, Dichlorvos, fernitriothion, Pirimiophos methyl, Chlorpyrifos methyl, Chlorpyrifos with deltamethrin); (2) Pyrethrins (bioresmethrin, permethrin and deltamethrin); and (3) Synergizer [Ref. 12]. Because pesticides vary in efficacy from species to species, they must be used judiciously. Moreover with fumigants insect resistant is a major issue, which further adds to the complexity of application [Ref. 10]
1.4.2.1.1 Broad Spectrum: Contact Insecticides vary in the numbers of different kinds of insects they kill. Some insecticides kill only a few kinds of insects. Sometimes you can choose these insecticides when you wish to kill only one insect pest and not other beneficial insects in the area. Many insecticides are general purpose or wide range killers. These "broad spectrum" pesticides are used when several different kinds of insects are a problem. One chemical can kill them all. No broad spectrum insecticide kills all insects; each varies as to the kinds of insects it controls [ref 13].
1.4.2.1.2 Narrow Spectrum: While many insecticides are broad spectrum, killing a wide variety of animals by attacking a system common to all, such as the nervous system, a new group of insecticides are much more selective. The chitin inhibitors only affect animals with chitin in their exoskeleton (i.e. insects). Growth regulators are even more specific. They affect certain groups of species that have a particular hormone. Finally, pheromones are the most restrictive because they react with only one species or one sex of a single species [Ref. 13].
1.4.2.2 Deltamethrin
Deltamethrin is a pyrethroid insecticide group that kills insects on contact and through digestion. It is used to control apple and pear suckers, plum fruit moth, caterpillars on brassicas, and tortrix moths (apples). It can be used for the control of aphids, mealy bugs, scale insects, and whitefly on glasshouse cucumbers. It also controls numerous insect pests of field crops. Formulations include emulsifiable concentrates, wettable powders, ULV and flowable formulations and granules [Ref: 1]. Deltamethrin is a synthetic insecticide based structurally on natural pyrethrins, which rapidly paralyze the insect nervous system giving a quick knockdown effect. Deltamethrin has a rapidly disabling effect on feeding insects and for this reason there is hope that it may be useful to control the vectors of "non-persistent" viruses (viruses that can be passed on by the vector within a few minutes of starting to feed on the plant). Deltamethrin's mode of action is thought to be mainly central in action. Death of insects seems to be due to irreversible damage to the nervous system occurring when poisoning lasts more than a few hours. Deltamethrin has very good residual activity for outdoor uses (field crops, cattle dip, and tsetse flies) and for indoor uses (mosquitoes, stable flies, horseflies, fleas, cockroaches, stored product insects). Cases of toxicity have been observed in mammals (cattle), following use of Deltamethrin preparation in external application in tick control. However, over time Deltamethrin is metabolized, with a rapid loss of toxicity, and passed from the body. Deltamethrin has very broad spectrum control. It is considered the most powerful of the synthetic pyrethroids. It is three times more active than some pyrethroids [Ref: 1].
1.4.2.3 Other Contact Insecticides
1.4.2.3.1 Chitin Synthesis Inhibitors:
Chitin Synthesis Inhibitors interferes with the development and molting of immature insects causing their death. Chitin is the primary structural chemical in an insect’s body wall. An immature insect treated with a chitin inhibitor dies the next time it attempts to molt.
1.4.2.3.2 Insect Growth Regulators or IGRs:
It mimics the action of an insect's naturally occurring juvenile hormone. They interfere with certain normal processes and prevent immature insects from completing development into normal reproductive adults. The effects of IGRs on insects include abnormal molting, twisted wings, loss of mating behavior, and sometimes death to embryos in eggs. IGRs attack a growth process found only in insects, thus there is a great margin of safety for humans and other vertebrates. However, one disadvantage is that growth regulators act slowly, since they do not kill the insect until it molts into an adult.
1.4.2.3.3 Pheromones
They are naturally produced chemicals used by animals to communicate to each other. There are three basic types of pheromones. Aggregation pheromones attract many individuals together, for example, a site where food may be plentiful. Sex pheromones are used by one sex of a species to attract a mate. Trail pheromones are deposited by walking insects, such as ants, so that others can follow. Synthetic pheromones produced in laboratories mimic these natural chemicals. They are used to attract pest insects into traps, disrupt mating, and monitor populations of insects. Because they do not kill insects, they are often not considered to be pesticides.
1.4.2.3.4 Repellent
It is a pesticide that makes a site or food unattractive to a target pest. They are registered in the same way other pesticides are and must be used according to the label. Insect repellents are available as aerosols and lotions and can be applied to skin, clothing, or plants to repel biting and nuisance insects. Vertebrate repellents are available as concentrates to be mixed with water, powders, and granules. They can be sprayed or painted on nursery crops, ornamental plantings, orchards, vineyards, vegetables, and seeds. Repelling deer, dogs, birds, raccoons, and others can protect sites from damage. Also, crushed neem seed, neem leaves or neem oil, which has an antifeedant or repellent effect on storage pest, can also be used.
1.5 Pesticide Formulations
When a pesticide active ingredient (a.i) is manufactured, it is not in a usable form. However, it is the active ingredient (AI: also called the active substance) and its concentration that is of most interest from the point of view of efficacy, safety and residue tolerances.
The a.i may not be soluble in water therefore the a.i is mixed with other compounds to improve its effectiveness, safety, handling, and storage. Some of these compounds include solvents, mineral clays, stickers, wetting agents and adjuvants.
The mixture of a.i and inactive ingredients are called pesticide formulation. Some formulations come ready to use while others must be mixed before use [Ref. 9]. Examples are raid and Deltamethrin respectively.
1.6 Adjuvants
Adjuvants are materials added to pesticide formulation to increase its effectiveness or change the properties of the pesticides in the spray mix. Adjuvants may improve the effectiveness of pesticides by:
• Making the spray droplets more uniform to improve coverage
• Wetting the surface so that the spray sticks better
• Increasing absorption into plants
• Increasing or decreasing evaporation so as to prevent the spray from drying too fast or helps it to dry quicker.
Adjuvants which directly improve the efficacy of pesticides are called Activators. These include:
• Surfactants which are used to improve wetting, spreading, dispersion and emulsifying properties of pesticide mixtures.
• Wetting agents which help WP and dry flowables mix with water and sticks on surfaces.
• Ammonium sulphate salts which enhance the uptake of some pesticides in hard water.
• Oil based adjuvants which affect leaf surfaces to allow better contact with the pesticide.
• Stickers which help pesticides resist being washed off by rain.
1.7 STATEMENT OF PROBLEM
Tribolium castaneum has over the years been a major problem to farmers and most pest managers since they destroy one of the most cultivated plant products (Cocoa beans) in the world that brings foreign exchange to most countries, particularly Ghana. Farmers and pest managers have made various attempts to control the harm caused by Tribolium castaneum on cocoa beans. The use of fumigants and other chemicals have been threatening in the control of cocoa destruction. Still the problem persists. This is because, the biology of the insect has not yet been understood very well and in that sense it has become necessary to carry out the project “The Biology and Evaluation of the Effect of Deltamethrin on Tribolium Casteneum on Stored Cocoa Beans”. In this work, the insect will be studied in relation to its biology and also to test the effect of Deltamethrin on the insect pest.
1.8 AIMS AND OBJECTIVES
1. To study the effect of Tribolium castaneum on cocoa beans in storage.
2. To evaluate the effectiveness of Deltamethrin for controlling Tribolium castaneum.
3. To identify the effective concentration of Deltamethrin for the control of Tribolium castaneum.
4. To determine the persistence of Deltamethrin in treated commodity.
1.9 JUSTIFICATION OF STUDY
Even though humans feed predominantly on cocoa and its products, its storage in Ghana is far below our imagination. One of the main contributing factors is the effect of Tribolium castaneum on stored cocoa beans. This pest contributes to the low yield all over the world. Currently, there is very high dependence of the chemical pesticides to destroy the pest. The farmers were prone to high risk of health problem since the use of D.D.T (dichlorodiphenyltrichloroethane), and Methyl bromide chemical used for fogging. These do not affect the farmer alone but general presents environmental hazard to other living organisms. The pest has become resistant to the chemicals stated above. Deltamethrin is considered one of the safer insecticides that have been widely used in pest control and also in spraying mosquitoes. Cases of toxicity have been observed in mammals (cattle), following use of Deltamethrin preparation in external application in tick control. However, over time Deltamethrin is metabolized, with a rapid loss of toxicity, and passed from the body. This work is designed to test the effect of Deltamethrin on Tribolium castaneum which belongs to the Pyrethroid group of insecticides.
CHAPTER THERE
2.0 MATERIALS AND METHOD
2.1 Study Area
The study was carried out in the Research Department of Quality Control Division of COCOBOD, Tema.
2.2 Culturing of insects
The stocked culture of Tribolium castaneum was originally obtained from the Quality Control Division laboratory at Tema for the experiments. Fifty (50) adults of Tribolium castaneum were collected with a horse brush from the stock culture on a tray for the culture. The sub-culture media for the 50 insects used contained crushed cocoa and glycerol (Plate 1) in the ratio of 8:1, which is eight parts cocoa to one part of glycerol in a glass jar. The culture was kept in a Constant Temperature Room (CTR) under the following conditions; temperature of 35-40oc and relative humidity of 89-90%. The feeding behavior and rate of development were studied by direct observation using an electronic magnifying lens during the period of culturing.
When enough adult insects were produced, the insects were then transferred to a Petri dish for temporary holding. The Petri dish was placed on crushed ice cubes in an ice bucket to pre-cool before putting on ice block. Sexing was done by placing the adults in a horizontal line about half way down the plate and separation was done using the small patch of bristles on the inner side of the first pair of legs which is a characteristic feature of the male. The sexes were rechecked while still on the ice block. The sexes were placed separately in Petri dishes. One hundred and twenty (120) adult (50 males and 70 females) insects were collected for the evaluation experiment.
Plate 1-Project student mixing cocoa beans and glycerol for insect culture
2.3 Laboratory bioassay
2.3.1 Topical application
Technical grade of Deltamethrin (2.5% E.C) was provided by the head of the Research Department for the research study. Serial dilutions for three different concentrations were prepared using distilled water as diluent: 2.0%, 1.5% and 1.0%. Three conical flasks were used in preparing the various concentrations (Plate 2). Forty (40) ml of the stock solution was measured and placed in a conical flask using a pipette; Ten (10) mls of distilled water was added using a measuring cylinder to reach the volume mark. The mixture was swirled gently for about 10 seconds to obtain a homogenous mixture. This formulation made 2.0% concentration of Deltamethrin solution. It was labeled with a china marking pencil.
1.5% concentration was prepared by diluting 6mls from the 2.5% formulation already prepared with 4mls of distilled water into another conical flask. 1.0% concentration was also prepared by diluting 4mls from the 2.5% formulation with 6mls of distilled water (Plate 2). Distilled Water was used in place of the insecticide for the control treatment. There were three replicates for each treatment.
Plate 2 Project student preparing solution for experimental work
2.4 Evaluation and Effectiveness Test
A total of forty eight (48) Petri dishes were used for the experiment and these were arranged in three (3) replicates and each was lined with 7cm Whitman’s filter paper. Forty eight (48) open ended glass discs each of seven (7) cm in diameter and 3.5cm in height were placed in each of the Petri dishes over the filter paper. The set-ups were labeled with the appropriate concentration. With the aid of a dropper, the various solutions with the different concentrations prepared were used to moisten the filter papers placed in the Petri dishes at the same time (Plate 3). The experiment was performed under a temperature of 30oc and relative humidity of 43.7%. For each day, twelve (12) Petri dishes were used; three (3) replicates for each concentration and three (3) for control.
For potency test (immediate action), ten (10) adults of Tribolium castaneum (Herbat) were immediately introduced into the set up. The set ups were covered with glass plates having wire gauze in the centre to facilitate aeration and prevent the insects from escaping (bioassay chamber). Percentage mortality counts were made at intervals of two (2) hours until all the insects died.
For persistence test (residual), Ten (10) adults Tribolium castaneum (Herbat) were introduced into each of the various set-ups left after the potency test. The potency for the persistence test was repeated at intervals of one day for a period of 3 days. Specifically adult mortality was also checked and counted at intervals of twenty four (24) hours until all the insects died for 2, 3 and 4 days. The percentage mean mortality of the replicates was calculated for comparison. The entire data collected in the experiment were analyzed at p-value of 0.05 using the Analysis Of Variance, (ANOVA) in Microsoft office Excel 2007. Mean separation was achieved with Tukey Test after ANOVA showed significance.
CHAPTER THREE
3.0 RESULTS
3.1 Developmental Period of Tribolium castaneum
Rearing Temperature (35-40) oC
Rearing Relative Humidity (89-90) %
Table 1 Average Developmental Growth of Tribolium castaneum.
Egg to larval days 6 ± 0.7 s.e
Larvae to pupae days 20 ± 0.8 s.e
Pupae to adults days 5 ± 0.7 s.e
Egg to Adult 31 ± 2 days
During the observational study, twenty (20) eggs of tribolium castaneum from the subculture were placed in a Petri dish each, media was added. This process took place in Controlled Temperature Room (CTR) with the following conditions, temperature of (35-40) oC and relative humidity of (89-91) %. After three (3) days, the eggs were observed for the presence of larvae till enough has been produced. Observed egg took different days during its development to the larval stage. The larval period for each egg was recorded (table 1). The mean developmental period from egg to larvae and standard error was calculated. Also the emergence of larval to pupae was also observed and recorded from the twentieth day. The mean developmental rate was also calculated as well as the standard error. Adult development was also observed and record with their mean and standard error. Due to the mortality of eggs, larvae and nymphs during the experiment, sample size was neither constant nor equal to the number species used. Details of table for the developmental period have been show at appendix 1.
3.2 IMMEDIATE POTENCY TEST RESULTS
For the immediate action of the prepared chemical on the target species, the mortality of the insect was checked at intervals of two (2) hours until the insects were dead as an indicator for potency of the chemical. Each set up had three (3) replicates. The mean of the replicates for each prepared dosage was calculated and this is show in the table 2 below. When results were subject to ANOVA analysis it showed no significances. Results were also subjected to a histogram (Graph 1).
Table 2. Overall mean percentage mortality of Tribolium castaneum at different Concentrations.
DOSAGE OF DELTAMETHRIN MEAN % MORTALITY WITHIN 6HRS
2HRS 4HRS 6HRS
1.0 (%) 100 100 100
1.5 (%) 100 100 100
2.0 (%) 100 100 100
Control (Distilled H20) 0 0 0
At P=0.05, means are not significantly different between the concentrations and exposure time for each two hours.
3.2.1 Graphical Interpretation of Results
Graph 1-Histogram of Tribolium mortality against hours on surface treated with 3 different concentrations of Delatmethrin.
3.3 PERSISTANCE TEST RESULTS
A residual test was also performed to know the persistence of the chemical for a period of three days. The mortality of the insects was checked every 24 hours. Each dosage of chemical use had three replicates. Ten (10) adult were used. Each insect represents (Ten) 10 in terms of percentage. Those insects that did not die were use the next day. The mean of replicates was calculated for each day, it is shown in table 3 below. Results were than subjected to ANOVA analysis with a P value of 0.05 and a histogram (Graph 2). ANOAV table has been shown at appendix 2.
Table 3. Overall mean percentage mortality of Tribolium castaneum at different Concentrations and days.
DOSAGE OF DELTAMETHRIN MEAN % MORTALITY AFTER EACH DAY FOR 3 DAY
1 2 3
1.0 (%) 100 86.67 36.67
1.5 (%) 100 90.00 50
2.0 (%) 100 100 100
Control (H20) 0 0 0
At P=0.05, means are significantly different between the concentrations and exposure time for each day.
3.3.1 Graphical Interpretation of Results
Graph 2- Histogram of Tribolium mortality against days on surface treated with 3 different concentrations of Delatmethrin
CHAPTER FOUR
4.0 DISCUSSION
4.1 Discussion and Analysis of Results
Results show that for immediate test on the insects, there is no significant difference the treatment (concentrations) and exposure time (hours). This shows that all the three concentrations of Deltamethrin are efficacious on target pests, Tribolium castaneum.
The purpose of applying a pesticide is to achieve a biological effect on the target pest. This effect is often described by scientists as a response and it is dose dependent - which usually means that the higher the dose, the more individuals in a population of organisms will be affected (and ultimately killed) [Ref: 10]. The population in question could be the target pests.
In relating the above reference to the persistence test (Residual), there was a significant difference between the treatments (concentration) and exposure time (days) when Analysis of Variance comparison was made. All the formulations proved very efficacious after day 1. There were variations in the potency on the second day between the 1.0% and1.5% and the 2.0% still achieving (100%) when compared to the control during tukey comparison. The mean mortality for 1.0% and 1.5% after the second day were 86.67% and 90 % respectively. The 2.0% proved very effective still after the third day (100% mortality) with variations in the 1.0 % and 1.5%. The P value obtained after the analysis was 0.02. Details of the results have been shown in appendix 2.
CHAPTER FIVE
5.0 CONCLUSION AND RECOMMENDATION
5.1 Conclusion
Tribolium castaneum, a storage pest of cocoa beans which has a high infestation rate on stored cocoa beans has developmental rate of egg to adult to be 31 days under a relative humidity of (89-90) % and temperature of (35-40) oC and can be controlled with 2.0% concentration of Deltamethrin. This is because, this concentration proved very effective and persisted for the period of experiment (evaluation and effectiveness test) and gave a 100% efficacy (indoor use). The other formulations were good for immediate action. The longevity of the chemical will be a further research.
5.2 Recommendation
It is recommended that the most effective concentration (2.0) % should be used by farmers, agriculturalist, stakeholders and pest managers to control the harm caused by this insect in stored cocoa beans. Also the 1.5 and 1.0 % can be used for immediate action control. I also recommend that the application of plant extracts and insecticide (Deltamethrin) mixtures should be studied further in different geographical areas to set a standard to protect stored products. The mode of action of botanical extracts needs to be studied in more detail to promote development of more potent fractions for use as grain protestant. The elementary biology of most insect pest must be studied before applying a control.
REFERENCES CITED
1. Extension Toxicology Network, E X T O X N E T (2006), Pesticide Information Profiles (Deltamethrn), www.google.com/ e x t o x n e t.
2. Http://en.wikipedia.org/wiki/(2005)/Cocoa-cocoa.
3. Irshad, M. and Iqbal, J. (1994). Phosphin resistance in important stored grain insect pests in Pakistan. Pak. J. Zool. 26(4): 347-350. Pak. Entomol. Vol. 28, No.2, 2006.
4. Iurakil, J. M., Sastawa, B. M., Kabir, B. G. K. and Lale, N. E. S. (2007). Susceptibility of Flours Derived From Various Cereal Grains To Infestation By The Rust-Red Flour Beetle (Tribolium Castaneum Herbst) (Coleoptera: Tenebrionidae) In Different Seasons. Journal of Plant Protection Research, Vol. 47, No. 3.
5. Javed, A., Sagheer, M., Ullah, A., Wakil, W. and Hasan, M. (2006). Department of Agri. Entomology, University of Agriculture, Faisalabad. Response of Trogoderma Granarium (Everts) To Different Doses of Haloxylon Recurvum Extract and Deltamethrin, Pak. Entomol. Vol. 28, No.2.
6. Klingler, M. (2004). Tribolium Quick Guide, Current Biology Vol 14 No 17, online.
7. Microsoft student’s Encarta 2009. Redmond, W.A. Version 2008. Microsoft Corporation.
8. Myers, P., Espinosa, R., Parr, C. S., Jones, T., Hammond, G. S. and Dewey, T. A. (2008). The Animal Diversity Web (online). Accessed at http://animaldiversity.org.
9. Registration Requirements for Adjuvant Products. (1993). Pest Management Regulatory Agency, Health Canada Regulatory Directive 93-15.
10. Regnault, B. (2005). ICCO & Cocoa Industry Consultant. Pesticide Use in Cocoa, A Guide for Training, Administrative and Research Staff. 1st Edition, page 14.
11. Subramanyam, B.H., Becket, S. J. and Fields, P. G. (2007). Theory and Practical, Heat treatment for post harvest pest control, CAB International, UK, page 183.
12. Saleem, T. (1996). The Biscuit, Cake, Chocolate and Confectionary Alliance (BCCCA), 4th edition, UK, pages 14-17.
13. US Environmental Protection Agency, "Pesticides and Food: What Does Integrated Pest Management Mean?" http://www.epa.gov/pesticides/food/ipm(2006) .htm
14. Www.agf.gov.bc.ca/pesticedes/ (2007) a_3.htm.
15. Www.ehponline.org/docs/(2006)/114-9/ss.html
16. Www.google.com/Stored Product Pest/Flour beetle (2008).
17. Www.pestcontrolcanada.com , (2009).
18. Www.google.com/Cacao/ (2005)/ United State Department of Agriculture/ Plant database profile.
19. Yang, C. and Yang Z. (2005). Effects of 60Co Irradiation on genetics of adzuki bean weevil, Acta Phytophylacica Sinca. Vol.20, No.4 331-335.
APPENDIX 1
DETAILED DEVELOPMENTAL PERIOD TABLE
Egg to larval days Larvae to pupae days Pupae to adults days
Number of observation
1 4 18 3
2 5 19 4
3 6 20 5
4 7 21 6
5 8 23 7
STATISTICAL ANALYSIS
DATA SET NUMBER MEAN SD SE
Column 1 5 6 1.58 0.71
Column 2 5 20 1.92 0.86
Column 3 5 5 1.58 0.71
APPENDIX 2
PERSISTANCE (RESIDUAL TEST)
DOSAGE OF DELTAMETHRIN MEAN % MORTALITY AFTER A DAY FOR 3 DAY
1 2 3
1.0 (%) 100 86.67 36.67
1.5 (%) 100 90.00 50
2.0 (%) 100 100 100
Control (Distilled H20) 0 0 0
ANOVA ANALYSIS FOR ABOVE DATA
SUMMARY
Groups Count Sum Average Variance
Column 1 3 223.34 74.44667 1114.73
Column 2 3 240 80 700
Column 3 3 300 100 0
Column 4 3 0 0 0
ANOVA
Source of Variation SS df MS F P-value F crit
Between Groups 17269.59 3 5756.53 12.68846 0.002077 4.066181
Within Groups 3629.459 8 453.6824
Total 20899.05 11
At P=0.05, means are significantly different between the concentrations and exposure time for each day.
Means Comparison using Tukey Test
Dataset Mean Difference Significant
Between at 0.05
1.0 74.44667 Means Level
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1.5 80 No
2.0 100 No
Control (Distilled H2O) 0 Yes
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1.5 80
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2.0 100 No
Control (Distilled H2O) 0 Yes
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2.0 100
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Control (Distilled H2O) 0 Yes
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