Republic of the PhilippinesNEGROS ORIENTAL STATE UNIVERSITYMain Campus I, Dumaguete CityCollege of Education

Republic of the PhilippinesNEGROS ORIENTAL STATE UNIVERSITYMain Campus I, Dumaguete CityCollege of EducationCHAPTER IThe Problem and Its ScopeRationaleSpiders are among the most abundant predators of insects of terrestrial ecosystem and thus play a significant role serving as natural biological agents against insect pest that destroy plants. Mostly, these little creatures are disliked by many people yet these animals are of great importance to us. Aside from their capacity of suppressing undesirable and unwanted insect pest pests, they also help stabilize the equilibrium in an ecosystem. Since these animals exhibit abundance in our environment, many researchers already invested their time and effort in conducting several to numerous numbers of researches about the spiders. In relevance, the study that we are to conduct is based on the idea that we can actually control insect pest which infest plants and crops without completely relying on the use of chemicals such as herbicides, fungicides or pesticides which can be detrimental and hazardous to our health and also to our environment. According to recent studies, pesticides have linked to a wide range of human health hazards ranging from short-term impacts such as headaches and nausea to chronic impacts like cancer. On the other hand, pesticides have damaging effects to our environment such as water and air pollution and depletion of organic matters in soil. In order to maximize the effectiveness of using of spiders as pest controller, our study seeks to determine their ability to feed on this insect pest as well as their predatory potential as biological control agents. As we can observe in our present time, the use of pesticide is widespread, not only in Philippines, but nationwide. The constant use of these chemicals results to health and environmental problems. The after effects of these chemicals give rise to our interest to conduct an experimental study on the use of biological agents, specifically spiders to minimize the like hood of using pesticides.Statement of the ProblemThe focal point of this study was to determine the role of selected species of spiders as natural biological agents in controlling insect pest population in plants.Specifically, this study sought to find the answers to the following questions:1. Does the use of spiders as biological agents displays effectiveness towards suppression of the number of insect pest in plants?2. Is there a significant difference on the number of spider species used and the number of insect pest being killed or eaten?3. What is the average insect feeding capacity of each selected spiders and the type of insect pest that they favorably feed on?4. What genera of spiders have the highest capacity of feeding on the pest in order to decrease its number?Hypotheses This study is premised on the following hypothesis:Ho: There is no significant difference on the number of spider species used and the number of insect pest being killed or eaten. Ha: There is a significant difference on the number of spider species used and the number of insect pest being killed or eaten.Assumptions In the course of the study, the researchers assume and presume that: 1. Spiders of different species would result to varying feeding rate and choice of preference of insect pest to feed upon.2. Spiders would give various feeding-responses on the type of prey being administered during the duration of the study.3. There will be a change in the predation behavior of the spiders when used in the course of experimental study.4. Spiders would feed on the preys being administered.The Significance of the StudyRecent trends towards reduced pesticide use and ecological sustainability have led to increased interest in spiders as potential biological agents. Indeed, their predatory potential is not only beneficial to our environment, but also to us, individuals.The results that will be obtained from this study will benefit the following groups of people:Farmers. The farmers, which are the ones who till and cultivate the land and take care of the crops in his farm, are very important manpower in our society. Due to the emergence of several pests of crops being infested, they resort on using pesticide as solution. But over the years, this develops resistance to pesticides. To help them counteract this pest,they can use natural way of controlling pest using the spiders. Our study on spiders detailed in this research is designed to address the problems faced by these farmers.Agricultural Sector. One of the many problems of our agricultural sector in the present time is the insect pest. Crop infested with this insect pest may loss its essentiality and in the long run, lowers crop harvest. The use of pesticide may help to the suppression of insect pest but these have been proven to be extremely toxic and may have led to a number of side effects. To help solve this problem, agricultural sector may adapt the sample technology of using spiders as biological control agents against pest. It has been already proven to be great success in countries like China and Japan (Vijayalakshmi). As a result, crop yields and productivity then increases without the like hood of the effects of chemicals.The Society. Insecticides are the number one thing that comes on every household when taking about pests that lurks from the close area of the house. Many have greatly neglected and even forgotten the role of spiders as natural pest controllers. What people are not so aware of this is that even small creatures commonly found in their own homes can play an important role in controlling domestic pests. The crab spider (locally called Kaka) for instance is one such example of a beneficial house guest. People may use spider and let go of the use of harmful insecticides which is detrimental to their health.Educational Community. Many people fear spiders. Others may either be repulsed by or ignored the sight of such animal with which they should not deserve such response. Most spiders are harmless, beneficial, colorful predatory creatures. Awareness on nature and ecology of spiders among educational community may help them understand that most spiders in our locality are not fatal to human beings and are in fact very efficient predators of insect pest. Their awareness will allow them to willingly accept spiders as an organism which they can live in harmony.Health Department. As we all know, insecticides have negative side effects having an impact on public health, toxic residues in food and disturbance of local ecosystem. The avoidance of the use of pesticide and resorting to the use of bio control agents such as spiders may decrease the like hood of incidence where people were able to manifest the side effects of pesticide intoxication such as nausea, vomiting, etc. due to ingestion of food sprayed with insecticides.Researchers. The results of the study may be used by other local researchers interested in studying the predatory capacity of spiders present in our locality and making use of them as biological control agent in their garden or farm crops. This study will serve as a supplemental reference to support new researchers to come up with better experimental method on predicting spiders ability to minimize insect pest in plants.Scope and Limitations of the StudyThe study aimed only to find out the different level of predatory and feeding potential of spiders which are abundant in our locality. Artificial habitat was used to collect data and make observation.The study was limited discussion on the average insect feeding capacity of each selected spiders and the type of insect pest that they favorably feed on. It will also be included in this study whether the use of spiders as biological agents would displays effectiveness towards suppression of the number of insect pest in plants.Research Methodology`A. Research DesignThe study used the true-experiment research design. The design for this study use random assignment of selected species that were gathered on different conditions of the treatment variable in order to assess the feeding behavior and predatory capacity of these selected species of spiders to prey on different insect pest. In realizing the research, we are going to evaluate the feeding potential of spiders by observation and quantitative analysis. The species of spiders used were: A (Argiope sp.), B (Gasteracantha sp.), C (Neoscona sp.) and D (Heteropoda sp.). Insect pest were nymphs and adults of aphids, short horned grasshoppers, leaf worms and mealy bugs. Spiders of the same genera were placed in a clear terrarium container (made from aquarium) supplied with definite number of prey and allowed them to feed. The additions of prey is made at such frequency that the prey density remained constant throughout the trial. Preys killed and consumed by the spider were counted up to 24 hours at an interval of 6 hours.

Figure 1 Spider species collected includes (from top-left to bottom right) a. Argiope sp. b. Gasteracantha sp. c. Neoscona sp. d. Heteropoda sp.B. Research EnvironmentSpiders and insect pest were collected in the different sites within Dumaguete City, Negros Oriental. It includes the barangay of Batinguel, Cadawinonan, Cantil-e and Junob. Spiders and insects were separately placed in different containers. The study was done at the orchard of Ragays residence at Northern Junob, Dumaguete City, Negros Oriental. Performing the experiment in such environment would enable the researchers to monitor, observe and gather data in 24 hour basis having a monitoring time interval of 6 hours since spiders do not feed every hour. The method in carrying the experiment is by placing the spiders in plants enclosed in a square net in order to avoid them from escaping and in order to monitor their feeding potential in such circumstances.

Figure 2 Locator map of Dumaguete City where the research was done. The encircled portion is the area where the study was conducted and the portion with yellow arrow indicates the area where the spiders and insect pest were collected.C. Research InstrumentsThe things used in the course of the study include: fine wire mesh nylon constructed into20 inch 15 inches rectangular net cage used to enclose the potted plant inside. Three set up A, B and C of 20 15 inches net cage were used which has plant inside. An aquarium was transformed into a 128 inches. This was used to contain the crab spider species. Plants were place inside the terrarium to project the natural environment for crab spiders. Each cage has two spiders which were also fed with the same number (15) of different kinds of insects which includes three (3) leaf worms, five (5) short horned grasshoppers, four (4) aphids and four (4) mealy bugs. Water were placed in plastic tubes plugged with cotton.D. Statistical Treatment of the DataTo establish solutions and give clarity to the problem, numerical presentation and analysis of the data gathered for this study, the following statistical tools were used:1. Frequency and Percentage DistributionIn order to determine the mortality rate of insect pest, a simple percentage was used by applying this formula:

Where:P- Percentage of insect mortality per cagef- FrequencyN- Number of insects per cage2. MeanMean was used to determine the average insect feeding capacity of each selected spiders and also the average insect mortality rate by applying the formula:

Where:x- is the mean/average n- is the number of insects (preferably the live ones)- is the sum of all dead insects3.T-testThe t-test compares the actual difference between two means in relation to the variation in the data (expressed as the standard deviation of the difference between the means). For data analysis, we used Microsoft Office Professional Plus 2010 sp2VL RTL (Excel) and the obtained result was tabulated and was interpreted.Data Gathering Procedure

Collection of Spiders and Insect PestSpiders and insect pest were collected in the different site within the locality of Dumaguete City, Negros Oriental in a grassy and bushy ecosystem of barangay Batinguel, Cadawinonan, Cantil-e and Junob through manual hand picking and by using nets. Spiders and insects were separately placed in different containers.

Figure 3 Collection of spiders and insects used during the course of the study.

Figure 4 Manual hand picking method was used in the collection process.Spiders and insects in a separate container.

Figure 5 Spider were hunted under the leaves and along the ground were they are suspected to be found.

Figure 6 Hunting of spiders and insects in a grassy and bushy ecosystem.Preparation and Construction of Cage Set UpFine wire mesh nylon was used to construct a 20 inch 15 inches rectangular net cage used to enclose the potted plant inside. The materials used were the following: twelve 25 inches bamboo sticks which was used as the foundation for the rectangular cage obtained from young bamboo; white fine wire mesh nylon which was used to in covering the skeleton made cage, thumbtacks used for keeping the nylon mesh attached to the bamboo skeleton; and the plants which will be placed inside each set up. In the construction of the cage, the bamboo sticks were molded into a rectangular shape to attain the desired cage. After that, the molded bamboo cage was covered with the nylon mesh all around the cage except the opposite side openings of each. This was done in order to leave a space for opening and closing the cage. It was then mounted on the ground by stoning the cage on the soil surface approximately 5 inches deep to keep the cage attached to the ground. The plants were then placed inside each cage. One plant was assigned for each cage. Three cage set up was made in order to cater the different species of spiders that will be used in the study. On the other hand, the terrarium was constructed using an unused aquarium which measures 14 7 8 inches in length, width and height. The aquarium was washed thoroughly in a running water to remove dirt. It was then air dried and was added with pebbles as the first layer, then sand as the second layer. Then, small plants that can fit inside the terrarium were placed in order to finish the cage terrarium. A wire mesh was used to cover the opening the terrarium to avoid the spiders from escaping.

Figure 7 Collection of bamboo twigs which will be used as framework for cage set up where the spiders will be kept for further investigation on their predatory behavior.

Figure 8 Construction of cage set-up were the spiders was placed inside to keep them from escaping outside.

Figure 9The plants were placed inside the finished cage together with the spiders and the insect pests.

Figure 10 The finished glass terrarium where the crab spiders were placed in being covered by a cloth mesh. Arrow indicates the crab spider carrying her egg sac.Observation and Data CollectionData that was presented, analyzed and interpreted was collected by observing the feeding capacity of the selected species of spiders in a 24 hour basis and by 6 hours interval (therefore, we will have four observation time per day: 3am, 9am, 3pm and 9pm) and a total observation of 5 days. Insect which was eaten or trapped in its web where counted manually and then, was tallied in a data sheet for further use. The data collection was done equally for each treatment group/cage set up group.Review of Related LiteratureSpiders are among the most abundant predators of insects of terrestrial ecosystem (Jackson, 1977; Benz 1987;Greenstone, 1999;Nyffeler, 2000; Hoefler et. al, 2006). They are the most diverse arthropod orders, with over 30,000 species and exhibit a great variety of foraging strategies (Nyffeler, 2000;Ghavani, 2008). Of the 30,000 described species all over the world, the checklist of Philippine spiders is just 1.47%, consisting of 517 species, 225 genera belonging to 38 families grouped into two infraorders (Mygalomorphae and Araneomorphae) of the order Opisthothelae. The Philippine species record is the highest in the entire Asian tropical rice fields (Barrion, 2001). Under favorable conditions they can reach maximal densities of up to 1000 individuals/m approximately. The relative seasonal abundance of spiders is highest in August and September; moderately high in December and July and lowest in November (Barrion, 1999). It has therefore been supposed for sometimes that spiders may play an important role as stabilizing agents and/or regulators of insect populations in agro ecosystems, forest ecosystems, and other terrestrial ecosystems (Benz, 1987). Spiders, on the other hand are economically significant arthropod predators, their most important use is in agriculture and forestry where they serve as natural biological control agents against insect pests (Barrion, 2001). Most spiders are polyphagous predators that prey predominantly on insects and to a lesser extent on other spider (Nyeffeler, 2001). Spiders are considered to be predators of live, moving prey. However, recent studies have modified this view when evidence was found that spiders utilize a much broader range of foraging strategies, including feeding on arthropod eggs (oophagy), dead animals (scavenging), plant pollen, and even artificial diets. Stealing of prey from other spiders (kleptoparasitism) plays an important role as an alternative foraging strategy of various web spinners. Spiders have been reported feeding on a wide range of different animal groups including some unusual prey such as small mice, bats, birds, fish, crayfish, crabs, frogs, lizards, snakes, and scorpions; however, in general they predominantly tend to concentrate on small insect prey relative to their own size and to a lesser degree on other spiders (Nyeffeler, 1994; 2000; 2003). Like any other animals, spiders too have their own foes. As cited by Barrion of 2001 in his research on spiders as natural biological control agents in Philippine rice fields, among the natural enemies of spiders are parasitoid wasps, pathogen and nematodes. On the other hand, predators of spiders are bull frogs, toads, birds, ants and wasps. Natural enemies and predators are strong limiting factor in the effective utilization of spiders in natural biological of insect pests.Many studies have demonstrated that spiders can significantly reduce prey densities. Lang et al. (1999) found that spiders in a maize crop depressed populations of leafhoppers (Cicadellidae), thrips (Thysanoptera), and aphids (Aphididae). In another study conducted, it showed that insect populations significantly increase when released from predation by spiders. Riechert and Lawrence (1997) reported that plots in an old field from which spiders had been removed had significantly higher herbivorous insect numbers than in those plots that contained spiders. Several studies have shown that assemblages of many predator species may be more effective at controlling agricultural pests than single species augmentation since its performance will be influenced by site fidelity, prey detection capabilities, sit-and-wait versus active foraging, potential for learning ecological compatibility and culturability. (Maloney, 2003;Hoefler, 2006). However, some evidence suggests that single spider species can be more effective than an assemblage in reducing pests, because spiders also prey upon one another. (Hoefler, 2006). Example on the use of spiders for biological pest control is reported from South Africa. There, spiders were settled in houses. Steyn (1959) recorded a reduction of they fly population by 99% within 2 months ans at the same time, a pronounced decreased of intestinal infection of men in that region, because the vectors of disease were destroyed (Benz&Nyffeler,1987).Spider's preference to their prey is a matter of discussion. Bilsing (1920) stated that there is no evidence that any species of spider has a particular preference to the prey. Savory (1928) stated that spiders show no trace of discrimination for prey. Turnbull (1966) pointed out that the spiders will tolerate a wide range of species of prey and the preferred species will vary from time to time and from place to place depending on the particular time and place.Furthermore, spiders can lower insect densities, as well as stabilize populations, by virtue of their top-down effects, microhabitat use, prey selection, polyphagy, functional responses, numerical responses, and obligate predatory feeding strategies. Nevertheless, as biological control agents, spiders must be present in crop fields and prey upon specific agricultural pests. Spiders may be important mortality agents of crop pests such as aphids, leaf hoppers, plant hoppers, flea hoppers, and lepidopteran larvae. However, the same species of spider that feeds mostly on pests in one location may feed mostly on beneficial insects in another (Nyeffeler, 1999).In relation, experiments involving artificial habitat manipulations have provided evidence that spider communities quickly react to these variations in vegetation structure. As a rule, spiders are highly sensitive to habitat structure. Therefore, variations in spider communities can give an index of zoological changes associated with natural or anthropogenic (human) changes in vegetation structure (Hore, 2009).Definition of TermsThe following terms have been operationally defined in order to achieve clarity and understanding of the present study.Biological Agents. This refers to the organisms that are capable of suppressing or decreasing the number of insect pest by predation involving eating or killing the prey.Biological Control. This refers to the use of living organisms for suppressing pest in order to counteract the damaging effects of uncontrolled insect pests infesting the plants.Insect Pest. These includes insect family that are capable of destroying farm crops and plants through chewing or burrowing on their leaves, fruits, flowers, roots or stem.Predators. These are the organisms that hunt or feed on other organism for consumption. They are potential organism (especially spiders) for the reduction or suppression of certain opportunistic pest.Predatory Potential. This refers to the feeding capacity/ability of an organism prey on another pest organism that is potentially destructive agent in plant crops.Prey. This refers to the organism being hunted by the predators; in this case the insects are the prey being hunted by spiders.Theoretical Framework of the StudyThis research is primarily focused on the potential capacity of spiders as bio control agent for the suppression of unwanted insect pest. Incline to this are the theories, concepts and models that will further explain the predatory potential of spiders. One of the theories related to the study is the Optimal foraging theory strategy which offers a generalized and realistic approach to the analysis of hunter-gatherer behaviour. The basic idea behind this theory is that natural selection will favour predators that maximize the efficiency of their capture of prey. The theory provides a cluster of simple models, partially derived from neo-Darwinian postulates, which produce operational hypotheses about foraging behaviours expected in different environmental circumstances. These models focus on patterns expected if foragers behave so as to obtain a high net rate of energy acquisition while foraging. This theory relies on the observation that neo-Darwinian assumptions and simple graphical or algebraic models are often adequate to predict selected aspects of an organism's behaviours.Assumptions and Concepts of Optimal Foraging TheoryAdaptation and OptimizationThe optimization concept derives from the postulates of synthetic evolutionary theory. Pianka (1978:12) states, "Natural selection and competition are inevitable outgrowths of heritable reproduction in a finite environment". Direct and indirect competition for resources gives advantages to organisms that have efficient techniques of acquiring energy and nutrients which can be turned into offspring or used to avoid predators (Pianka 1978). Natural selection might shape decision rules such that animals maximize net energy gain (e.g., gross gain - costs) as a function of time: Energy per prey item - Costs to acquire prey Profitability of Prey = ----------------------------------------------------- Time taken to acquire prey itemForagingForaging refers inclusively to tactics use to obtain non-produced foodstuffs of other resources, those not directly cultivated or husbanded by the human population, although they may in some senses be conserved or managed (Feit, 1973). Foraging may involve hunting, trapping, netting, snaring, gathering, or other techniques. The word hunting implies that the forager is directly and immediately involved in the capturing or killing of animal prey. The focus here on the foraging practices of hunter-gatherers as described here can thus imply the cost s and benefits associated with particular activities in commensurate ecological units (primary calories).Strategy Analysis and Temporal Scales of AssessmentStrategy analysis links a certain kind of explanation to an evolutionary time scale (Pianka 1978:15; Mayr 1976b: 360-63). It looks for the origins of complex behaviors in the effects of selection in patterned environments (Levins, 1968). Despite emphasis on long-term adaptation, strategies are not fixed. Considering a series of intervals in which an organism must make decision s, Schoener (1971:375) states, At the beginning of each, the animal assesses its strategy in the face of alternative future conditions whose probabilities are known (i.e. genetically programmed), but whose exact manifestation is unknown. The assessment includes the organisms immediate physiological state and its evaluation of present and impending environmental conditions. The environment changes as do the requirements of the organism during its life cycle.The strategy concept recognizes that behavior is patterned but that organisms need to evaluate and reach decisions appropriate to changing circumstances. The Marginal Value Theorem and Optimal ForagingAnother concept is the Marginal Value Theorem. The choice about when, where, and how long to settle to feed is another one of the basic decision rules for an organism searching for resources among widely scattered patches. One of the simplest solutions in foraging ecology, the marginal value theorem (Charnov, 1976), is easy to derive from a simple graphical analysis. The marginal value theorem specifies the "giving up time" or when an organism should leave a patch that it is exploiting. As an animal begins to feed, its energy gain gradually begins to slow down when food becomes scarcer in the patch. It takes longer and longer to find the next item of food. The marginal value or amount of energy remaining in the patch declines as the patch is exploited. The curve describing energy gain as a function of the amount of time a predator spends in a patch, starts off with a steep slope that gradually levels off as the prey becomes depleted. Eventually, if the predator stays in the patch long enough, all food is consumed and no more energy can be gained. Two-PreyOne-Predator Population Dynamic ModelIn Krivan (1996) a Two-Prey-One-Predator Population Dynamic Model with optimal predator foraging behavior was considered. This model assumes that predators forage according to optimal foraging theory (Charnov, 1976; Stephens and Krebs, 1986), which predicts that the more profitable prey type is always included in the predator diet while the less profitable (i.e., alternative) prey type is included with probability one only if the density of the more profitable prey type falls below a critical threshold. Therefore, the optimal foraging model does not predict the emergence of partial preferences for the alternative prey type which is either completely included or excluded from predators' diet. The predictions of optimal foraging theory were compared with several experimental and field studies in Stephens and Krebs (1986) (see also Richardson and Verbeeck (1992). These studies support the idea that the diet choice is based on food profitability although the inclusion of the less profitable prey type is more gradual than predicted by optimal foraging theory.Conceptual FrameworkThe study is based on the concept that the use of spiders as bio control agent will be a helpful way in minimizing dangerous pests in plants.In view of this, an experimental study was conducted to determine the predatory potential of spiders whether they are capable of suppressing insect pest or not. The experiment includes preparation and construction of cage set up, collection of spiders and insect pest and data gathering through observation.The data were analyzed and interpreted, and the findings determine the predatory potential of selected species of spiders.

Effectiveness of the Predatory Potential of Spiders

INPUTExperimental Method

PROCESS

Preparation and Construction of Cage Set UpData Gathering through ObservationCollection of spiders and Insect Pest

Analysis and Interpretation of Data Collected

Determination of the Predatory Potential of Selected Species of Spiders

OUTPUT

Figure 11The Schematic diagram of the Conceptual Framework of the Study.

23