Browsing by Subject "pheromone"
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Item Honey bee gene regulation and transcriptional effects of a pheromone and a parasite(2009-05-15) Butler, Lara ElizabethThe European honey bee, Apis mellifera, is a primarily beneficial insect for mankind. It has been utilized by humans for thousands of years for the products and services it provides. Crop pollination and honey production are two of the most economically beneficial activities of the honey bee. Though they have been important for many centuries and immeasurable amounts of effort have been expended investigating the methods and means to harness their natural abilities, a far lesser amount of attention has been directed towards exploring their molecular makeup. These experiments involve identifying modification of gene transcription as a result of exposure to a pheromone or a parasite. This data will provide information on the general types of transcripts involved in the biochemical response of the honey bee to the two stimuli and will also provide specific candidates for further investigation of their potential role in downstream behavioral events.Item Male-female interaction among different geographic strains of the Gulf Coast tick Amblyomma maculatum Koch(Texas A&M University, 2006-08-16) Sleeba, Sarah BethThe overall goal of this research was to examine the interactions of adult Amblyomma maculatum Koch, the Gulf Coast tick, with respect to their utilization of hosts and to male-female cross strain interaction. Historical data along with two Petri dish experiments were used to understand male-female interaction in the field, and to determine if the aggregation attachment pheromone (AAP) produced by fed males of varying strains is attractive to geographic specific strains of unfed female ticks. It was hypothesized that questing female Gulf Coast ticks are attracted to fed males and can discriminate between grazing cattle with fed males and those without. Archival control data from ear tag studies conducted in 1985, 1987, and 1991 were analyzed to better understand female Gulf Coast tick behavior in the field relative to fed male tick presence. Females were found primarily on hosts with an abundance of male ticks, leading one to conclude that female ticks are attracted to hosts infested with male ticks. It was also discovered that females were more likely to be found on a host as the number of males on a host increased. A female??s ability to detect hosts parasitized by males likely allows them to feed and mate on-host in a fairly limited period of time. A Petri dish bioassay was used to evaluate female preference to varying geographic strains of fed males. One experiment was designed to determine if a female preferred fed males from her geographically specific strain over other males. A second experiment evaluated female response to a non-specific male in the absence of her geographically specific male. While female responses to fed males regardless of strain were higher than to unfed male control ticks, no statistical differences in female response could be determined. The Petri dish bioassay was determined to be inadequate to test female preference over several populations of pheromone producing males, and a more intensive procedure was proposed.Item Mating behaviour, epibiotic growth, and the effect of salinity on grooming activity in the hermaphroditic shrimp Lysmata wurdemanni(Texas A&M University, 2004-09-30) Giri, TuhinMany species of caridean shrimp are protandrous hermaphrodites, maturing initially as males but developing into females as they age and grow. A unique sexual system was recently discovered in the peppermint shrimp, Lysmata wurdemanni. In this species, individuals are initially male, but become simultaneous functional hermaphrodites over time. As in most caridean shrimp, L. wurdemanni can mate as a male during the intermoult period, but can reproduce through female function for only a short period after moulting. Ecdysis does not occur en masse in this species, and thus the operational sex ratio found in populations of L. wurdemanni is extremely male-biased. Sexual selection theory suggests that these conditions will result in increased competition for access to mates. Evolutionary pressures should therefore have selected for mechanisms that permit individuals to quickly identify and locate potential mating partners. L. wurdemanni were exposed to chemical stimuli collected from recently moulted conspecifics of varying reproductive condition. Test animals were able to distinguish among the different conditions, and physically manipulated only the plastic nozzle used to pump solutions collected from shrimp with ovaries filled with vitellogenic oocytes. It was subsequently hypothesized that methyl farnesoate, a hormone associated with ovarian maturation in crustaceans, might be a key component of sex pheromones used by L. wurdemanni. However, a series of methyl farnesoate concentrations did not elicit responses, indicating this species does not use this hormone alone when determining reproductive condition. Reproductive behaviour in L. wurdemanni was observed to differ both before and after copulation, as well as with increasing population density. Intermoult individuals were more likely to approach, follow and remain in the vicinity of a near-moult shrimp before mating could occur, and under high density conditions. The near-moult shrimp approached conspecifics only under low density conditions, and performed rapid escape behaviours only after copulation had occurred. The unusual occurrence of epibiota upon L. wurdemanni was described, and the location, size and age of barnacles quantified. The effect of salinity upon grooming activities was tested. Results indicated that carapace grooming was depressed at low salinities, and could account for the considerable epibiota found in this region.Item Molecular and Pheromone Studies of Pecan Nut Casebearer, Acrobasis nuxvorella Neunzig (Lepidoptera: Pyralidae)(2011-02-22) Hartfield, Emilie AnneThe pecan nut casebearer, Acrobasis nuxvorella Neunzig (Lepidoptera: Pyralidae) is the most damaging insect pest of pecan, Carya illinoinensis (Wang) K. Koch (Fagales: Juglandaceae). Two sex pheromones have been identified for this species and are currently being used to assist pecan growers in the timing of insecticide applications. The discovery that there are two pheromone types produced by A. nuxvorella has led to complications in the implementation of pheromone monitoring programs. One pheromone (referred to as standard) is attractive to moths in the southern US, but not in Mexico. The other pheromone (referred to as Mexican) is attractive to moths in the southern US and in Mexico. Because most male lepidopterans respond only to a specific pheromone, it was suspected that there were two pheromone strains of A. nuxvorella, one exclusively present in the northern distribution of A. nuxvorella (US strain) and the other widely distributed from Sonora, Chihuahua, and Durango in Northern Mexico to Texas, Georgia, and Oklahoma in the US (Mexican strain). In order to confirm the existence of the two alleged pheromone strains, AFLP markers were obtained and analyzed, male response to pheromones was observed and phenological differences were assessed. Additionally, the relative abundance of each of the two pherotypes was evaluated and the population structure of this pest across its geographic distribution was determined. Results of genetic analysis show that the genetic differentiation between these insects is not explained by pheromone type. This information is further supported by a pheromone assay in which a large proportion of US collected A. nuxvorella males and Mexican collected A. nuxvorella males chose both pheromones when tested multiple times. Furthermore, no phenological differences were detected between the two pherotypes in the US, although significantly more male A. nuxvorella in the US are attracted to field-deployed pheromone traps baited with the standard pheromone than the Mexican pheromone. Finally, population genetic analyses indicate a high degree of genetic structure in A. nuxvorella across its geographic distribution, with the genetically distinct populations occurring in areas where A. nuxvorella is not native, but has been introduced.