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Research topics in:
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Entomology |
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Chiri, Ben, "An investigation of the relationship between Theope virgilius (Lepidoptera: Riodinidae) and attendant ants in a Costa Rican mangrove." Adv. Eric Olson. Grinnell College. 1997. 15pp. Many larvae of the lepidopteran families Lycaenidae and Riodinidae form symbiotic relationships with ants (myrmecophily). This study offers a basic description of the relationship between larvae of Theope virgilius (Riodinidae) and Azteca ants found in a mangrove of southern Costa Rica. Observations are offered concerning microhabitat preferences of larvae and ants, larval development of T. virgilius, and daily interactions of caterpillars and ants. An ant-exclusion experiment suggests that attendant ants are not protecting caterpillars from predation at this site. The implications of this observation and others are discussed with regard to the evolution of myrmecophily in T. virgilius. Dona, Amy, "Plant-Insect Herbivore-Insect Parasitoid Studies in the Río Sierpe Mangrove Forest, Osa Peninsula, Puntarenas, Costa Rica." Adv. Paul Hanson. Grinnell. 1996. 16pp. I studied several aspects of herbivorous insects and parasitoid ecology in the mangrove forest of the Río Sierpe on the Osa Peninsula of Puntarenas, Costa Rica. I collected and reared caterpillars found feeding on mangrove species and reared parasitoids out of the catepillars collected. In total I found 36 species of herbivores, of which 26 were reared succesfully, and obtained at least 16 species of parasitoids, possibly more. Approximately 35 percent of all herbivores collected were parasitized. To further understand the impact of the insect herbivore population on the mangrove forest, leaf damage was collected for four mangroves species, Rhizophora mangle, Rhizophora racemosa, Avicennia germinas, and Laguncularia racemosa. I compared herbivory between habitat type and between species in Sierpe and to results of a published study on herbivory in Belize for Rhizophora mangle and Avicennia germinas. Herbivory in the Sierpe mangroves was found to be significantly less than herbivory in the Belize mangroves. Enough Rothschildia lebeau larvae and cocoons were collected to compare wasp parasitism of Rothschildia lebeau to wasp parasitism in a tropical dry forest. The parasitism was found to be significantly less in the Sierpe mangroves than in the tropical dry forest. Heuser, Laura, "Foraging Behavior of Bombus ephippiatus on Rubus sp. and Pernettia coriacea" Adv. Carlos Valerio. Lawrence. 1992. 17pp. The purpose of this study was to learn about the pollination behavior of Bombus ephippiatus. This bumblebee species, in Cerro de la Muerte, has an extreme dimorphism between the queens as distinguished from workers and drones. B. ephippiatus activity at two Rubus sp. and Pernettia coriacea was recorded for 118.5 hours. Queens visited Rubus sp. 4.4 percent of the time as compared to the P. coriacea, which they visited 25 percent of the time. Both queens and workers visited between 5.8 to 8.9 blossoms on average for both flower species. A species list of other flowering plants pollinated by Bombus ephippiatus was also compiled. LaRock, Jenna, "Evaluation and Patterns of Termite (Nasutitermes nigriceps) Damage in Avocado (Persea americana) in Two Lowland Regions of Costa Rica." Advs. Paul Hanson and Ruth León. St. Olaf College. 1997. 24pp. To initiate research on insect pests of avocado, I studied termites, Nasutitermes nigriceps, one of the insect pests causing Costa Rican farmers most problems. My main objective was to collect data on patterns of termite damage in order to provide information on prevention. The month of March was spent in Las Juntas de Abangares, Guanacaste, and the month of April in Paquera, Puntarenas. I measured trees for the dependent variables of age, presence of the root disease Phytophtora cinnamomi, and tree density. To compare to each of the dependent variables, I recorded whether the tree had termites or not. From these comparisons I obtained preliminary information on the relationships between the three dependent variables and the presence of termites. I also compared the percent damages between farms that were well managed and farms that were poorly managed. My research will provide farmers with recomendations that will help with termite prevention and with avocado cultivation in general. Leverence, Nathan, “Ant-epiphytic mutualisms and the density richness of the invertebrate community of the inner and outer canopy.” Adv. Dora Ingrid Rivera. Lawrence. 1999. 25pp. The two aspects of this investigation consisted of qualitatively analyzing ant-epiphytic mutualisms in a private cloud forest reserve-Sky Trek/Walk, and quantitatively comparing the density and richness of invertebrates within the inner and outer canopy-Monteverde Cloud Forest Reserve, Costa Rica. The analysis of the ant-epiphytic relationships yielded no existing interactions, although ants do occupy the canopy community. The second study, of the invertebrate community, showed that inner and outer canopy exhibited no differentiation (p>0.57), though it seems that the number of individuals were influenced through time (p<0.0063). The Pit-Fall trap effectiveness appears to be an issue between the four and eight day replacement interval. The numerically dominant order was Coleoptera with the family Scolytidae the outstanding individual. |
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Lundgren, Christopher N., "An Introductory Study on the Damage Present in Coffee, as Regards the Hypothesis that Natural Biological Control is Working in the Coffee Farms of San Vito de Coto Brus." Adv. Paul Hanson. The College of the University of Chicago. 1996. 37pp. This study concerning coffee pests and their wasp parasites originally hypothesized that natural biological control in coffee farms in Costa Rica is working. Since the actual pests were not found in large enough numbers to study, three indirect methods were developed to study the problem. Leaf samples were taken from seven farms. Size, damage amount, and type of damage was recorded. Damage was put into one of three categories, mineral deficiency, fungus, and insect damage, and the amounts were compared. Results show that, as expected by the original hypothesis, insect damage is low in comparison to the other two types. Additionally, a survey of chemical use was taken for each farm. It was found that the use of control chemicals doesn´t neccesarily result in lower levels of the related type of damage. The second method was yello-pan trapping. This was carried out in order tosurvey the populations of parasitic wasps in the farms. Two farms were sampled. Results indicate that there are greater numbers of wasps in the farm with less chemical use, as expected by the original hypothesis. However, there was also an extensive polyculture on this farm, which may also explain at least some of the increased numbers. The third method consisted of studying the only pest found in significant numbers to do so. This pest, the serpentine leaf miner, is an unknown species of fly. In order to get some preliminary information on its life-history, its spatial distribution in the farms was surveyed. Results show that it is more likely to be encountered near the edges of coffee plots. An unsuccessful attempt at rearing the miner to an adult was also made. Marks, Melissa, “Natural history and diversity of caterpillars (order Lepidoptera) feeding on Quercus costaricencis and Weinmannia pinnata in Villa Mills, Costa Rica.” Adv. Paul Hanson. Grinnell. 1999. 15pp. In this study I examined the species diversity of Lepidoptera (moths and butterflies) larvae feeding on two Montane Rain Forest plant species: Quercus costaricencis (black oak, encino) and Weinmannia pinnata. According to the species-area hypotheses based on island biogeography, Q. costaricencis should host more diversity of phytophagous insects than W. pinnata. During March and April, 1999 I collected and reared 196 caterpillars, 113 from Q. costaricencis and 93 from W. pinnata in Villa Mills, Cartago, Costa Rica. I found that Q. costaricencis hosts a significantly more diverse community (F=8.13; Df=1, 102; p=0.0053) and a greater abundance (F=4.85; Df=1, 192; p=0.0053) of caterpillars than W. pinnata. In addition, I obtained detailed natural history descriptions for 12 species of Q. costaricencis caterpillars and 9 species of W. pinnata caterpillars. Peterson, Snow Brook, “Differences in flower characteristics and insect visitor composition for two species of Ageratina (Asteraceae) on Cerro de la Muerte, Costa Rica.” Adv. Paul Hanson. Grinnell. 2000. 18 pp. This study investigated differences in insect visitor rates and flower characteristics between two superficially similar species of the genus Ageratina (Asteraceae) -- A. ixiocladon and A. reticulifera. The study was conducted during March and April of 2000 between the towns of Jaular and Villa Mills, Costa Rica, in a tropical montane rainforest life-zone. I made a series of observations of different individuals of each plant species and found that A. ixiocladon was more frequently visited by bumblebees than A. reticulifera, while A. reticulifera was more frequently visited by tachinid flies. Both types were visited by equal numbers of total visitors and syrphid flies. The corolla tubes of A. ixiocladon are significantly longer than those of A. reticulifera, and their flower heads also average a higher number of florets. The differences in visitor composition, which may be correlated to the differences in flower characteristics, contradict the theory of similar looking Asteraceae acting as generalists in the insects they attract (i.e. the insects do not distinguish between species). Prescott, Kristina, “Oak islands: an application of island biogeography theory to populations of gall making wasps (Family: Cynipidae) parasitizing Quercus copeyensis (white oak).” Adv. Paul Hanson. Grinnell. 1999. 28pp. My study involved distribution and colonization of gall making wasps (Hymenoptera: Cynipidae) specializing on Quercus copeyensis (white oak, roble) during March and April near Tres de Junio in Cerro de la Muerte, Costa Rica. I applied MacArthur and Wilson’s Island Biogeography theory to a comparison of populations of cynipid wasps on oaks in continuous forest to populations on isolated patches of oak. Identifying wasp species by their leaf and stem galls, I calculated species richness and diversity for five isolated patches of one to three trees, and five groups of near by forest trees. Species diversity and richness per branch were both significantly higher in forest trees than in isolated trees, indicating that MacArthur and Wilson’s predictions for lower species diversity and richness on islands are appropriate for gall wasps on isolated oaks. Using a contingency table of total galls of each species collected from these two groups of trees, I was able to associate some wasp species with a particular habitat and to identify possible differences in colonization ability. I also constructed an expanded table of gall descriptions to include species I discovered during the study. In addition to providing descriptive data on cynipid wasp species, my research provides valuable information about their ability to colonize distant habitats; an ability which may be increasingly important as deforestation continues in the Cerro de la Muerte region. Rebar, Bryan, "Herbivory by the Citrus Leafminer (Phyllocnistis citrella) and the Future of Citrus in Costa Rica." Adv. Paul Hansen and Ruth León. Grinnell. 1996.28pp. This study includes two major sections: first, a scientific evaluation of the citrus leafminer (Phyllocnistis citrella) infestation and damage at la Estación Experimental Enrique Jiménez Nuñez near Cañas, Guanacaste, considering three variables and, second, a description of the citrus industry largely based on interviews and observations. The evaluation showed that infestation was more significant among orange (Citrus sinensis) than lime (Citrus latifolia) species by an average 0.09 mines per leaf but damage was more significant among lime than orange species by an average of 1.1% per leaf. The infestation and damage to lime trees distant from woodlands was greater than those close to woodlands (by 0.03 mines per leaf and 0.6% damage per leaf), but not significant at 95% confidence. Finally, infestation and damage was significantly lower where insecticides were used (by an average 0.08 mines per leaf and 1.6% damage per leaf). Inquiries about leafminer damage and how it is treated in different regions of Costa Rica served as the basis for a description of how the citrus industry works and recommendations for how it might improve. At present, the government is promoting the rapid expansion of citrus at all levels of production. Using the leafminer problem as an example, it is evident that more cooperation and communication is necessary between the various groups of people involved in the citrus industry. The philosophy of sustainable development espoused by the Costa Rican government, apparent in both the objectives of the National Program of Citrus and the Integrated Pest Management, provides a good vision of the future, but lacks specific guidelines for its implementation. Recommendations regard farming practices as well as organizational suggestions. |
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Ridley, Caroline, “Cecidomyiid galls on Peperomia species in a tropical montane cloud forest on Cerro de la Muerte, Costa Rica.” Adv. Paul Hanson. Grinnell. 2000. 16pp. During the months of March and April 2000, I investigated a little known gall type induced by members of the family Cecidomyiidae, also known as the gall midges, on plants of the genus Peperomia on Cerro de la Muerte, Costa Rica. This study was a preliminary examination of the morphology of these galls, as well as a general characterization of the Peperomia plants which are used as hosts. Results indicate that one species of cecidomyiid is responsible for inducing morphologically similar galls on three of eleven species of Peperomia found within the study site. Variation in gall color seems to be due to differences in gall age while variation in gall size appears to be attributable to multiple factors including host species, age, and the number of larvae within the gall. Swanson, Stacey, "Parasitic Insects of the Sarapiquí Region." Advisor: Paul Hanson. Ripon. 2005. 9pp. It has been concluded from past studies that seed parasitism, for the most part, has a negative effect on seed mortality, but to what extent that effect is, no one is certain. My study of seed parasites in the Sarapiquí region will, hopefully, make a foundation to better understand the effects of seed mortality and give way to experiments with related topics. For the study of parasitic insects in the Sarapiquí region, 15 types of seeds were randomly collected from different plant species. Of those 15 types of seeds, four seeds produced parasitic insects: Siparuna (Siparunaceae), Miconia impetiolaris (Melastomataceae), Miconia cf longifolia (Melastomataceae), Neea (Nyctaginaceae). The interesting thing about the results of the parasitic insects that were collected is that all of the insects were Cecidomyiidae. The other insects that were produced were three different parasitic wasps that parasitize the Cecidomyiidae. There was really no differentiation in the groups of insects that were produced among the plants, and there were no other parasitic insects produced that are also usually related to seed parasitism. This is unusual and can be concluded as a matter of chance, but also raises interesting questions that could be answered by further studies of this topic. Thompson, Chris, "Territorial and reproductive behavior of Sympetrum illotum and Aeshna jalapensis (Odonata) in Cerro de la Muerte, Costa Rica, and a study of dragonfly diversity in relation to altitude." Adv. Carlos Valerio. Grinnell. 1996. 22pp. Two species of dragonflies were studied in Cerro de la Muerte: Sympetrum illotum (Odonata: Libelulidae) and Aeshna jalapensis (Odonata: Aeshnidae). Observations of the two species revealed typical territorial and reproductive behavioral patterns. Individuals were captured, marked, released, and recaptured to estimate local populations, however not enough were recaptured to make the necessary calculations. Of the S. illotum males captured alone and mating, the reproductively successful males were larger on average. These results agree with contemporary studies of sexual selection in other insects. In contrast, the size of males winning territorial contests was smaller on average. In addition, a study of dragonfly species diversity in terms of elevation was conducted. The results showed a typical pattern in biology: greater diversity in lower altitudes. |
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