Please read the abstract in the section 00front of this document / Thesis (PhD (Entomology))--University of Pretoria, 2005. / Zoology and Entomology / unrestricted

A North American biotype of the old house borer, Hylotrupes bajulus (L.) was established from field and laboratory data. This biotype is based on differences in size and longevity of the life stages and on adult fecundity. N. A. females were observed to oviposit a mean of 165.1 ± 15.5 eggs in comparison to 119.4 (South African) and 105.2 (European). Oviposition period was 5.2 ± 0.5 days for the N. A. biotype and 3.9 and 12 days for the South African and European, respectively. Eggs of the N. A. biotype were smaller than those of the South African and incubation period (8.5 ± 0.3) shorter than both South African (14.0) and European (9-12). Development and comparisons of the pupal and larval stages are presented and discussed. Comparisons of the N. A. and European biotypes under similar temperature, humidity and nutritional conditions found no significant differences between biotypes. These results indicate that the biotypes have undergone little genetic change since their separation over 200 years ago. The old house borer is quite responsive to environmental conditions and the biological variation noted in field populations is attributed to non-genetic modifications of the phenotype. The high degree of biological flexibility noted in this species allows the OHB to inhabit marginal habitats and explains its present world-wide distribution. The OHB was successfully reared from egg to adult in 9-11 months on an artificial diet. An oligidic diet was developed and was composed of ground host tissue (southern yellow pine, Pinus spp.), purified cellulose, agar, and basic nutrients. This diet provided an adequate physical and nutritional environment as noted in the reduction in larval mortality and developmental period when compared to conventional rearing methods. Comparative nutritional, physiological and behavioral studies are now possible between larvae feeding on artificial diets and conventional wooden blocks. Observations of the adult mating behavior, fecundity, oviposition period and egg viability were reported under two mating regimes: single and multiple. Fecundity and egg viability were not significantly different between regimes. However, the number of egg batches, length of oviposition period and the longevity of adult females were significantly different. Adult behavior between regimes was not noticeably different. Males actively compete for females when other males are present and aggressive interactions are common. The practical and evolutionary significance of single and multiple matings is discussed. Consumption, growth, utilization and respiration by three weight classes of old house borer larvae, under 5 constant temperatures and relative humidity were studied. Wood consumption in all larval weight classes was greatest in the temperature range of 20° to 30°C and significantly reduced below and above these temperatures. Growth rates for small larvae were not significantly different among temperatures. Medium and large larvae recorded negative growth rates at 15° and 35°C. Wood utilization was greatest at temperatures of 20° and 25°C. Respiration rates were highest for small larvae. Small larvae were apparently more efficient at converting wood ingested to biomass at all temperatures. / Ph. D.

Marine bioeroders, borers, and burrowers can have drastic effects to marine habitats and facilities. By physically altering the structure of marine habitats, these organisms may elicit ecosystem-level effects that cascade through the community. While borer damage is typically restricted to a few substratum types, burrowing isopods in the genus Sphaeroma attack a diversity of substrata in tropical and temperate systems. My dissertation examined how boring sphaeromatid isopods affect coastal habitats (saltmarshes, mangroves) and other estuarine substrata as well as marine structures. I used a combination of lab and mensurative field experiments to quantify the effects of boring by isopods and examine how select factors affect the colonization, hence burrowing damage by isopods. I explored these questions primarily using the temperate boring sphaeromatid, Sphaeroma quoianum, as a model organism. My initial lab experiments quantified the per capita erosion rates of S. quoianum in four commonly attacked estuarine substrata. I found marsh banks and Styrofoam substrata were the most affected per capita. I supplemented this lab experiment with a year-long mensurative field experiment examining how erosion rates differ between marshes infested and uninfested by boring isopods. Marshes infested with isopods eroded 300% faster than uninfested marshes. I further examined the boring effects on Styrofoam floats. I compiled surveys and observations and conducted a short experiment to describe how isopods affect Styrofoam floats used in floating docks. I observed dense colonies of isopods attacking floats and expelling millions of plastic particles in the ocean. The boring effects to simulated Styrofoam floats were also affected by seawater temperature. Burrowing effects in Styrofoam floats exhibited a curvilinear relationship with temperature and peaked around 18°C. These results suggest a 1-2°C increase in water temperature could increase boring effects 5-17% of populations of isopods in Oregon and California bays. To examine the small-scale factors that mediate colonization and boring, I conducted a series of binary choice experiments. I found the presence of conspecifics, biofilm, and shade were important factors influencing colonization. These small scale factors likely explain why isopod attack is focused in some substrata. Finally, to examine the boring effects of tropical isopods in mangroves, I examined the associations between burrowing by S. terebrans and mangrove performance and fecundity. I found negative relationships between boring effects and performance and fecundity in two mangrove species in a restored mangrove stand in Taiwan. Together, these studies elucidate the effects of bioerosive isopods on saltmarshes, mangroves, and marine structures. However, the similar mechanisms involved in bioerosion in other boring species suggest that these results can be used to infer similar effects of other borers. In addition, since many species of sphaeromatid isopods have been introduced, this research shows how the effects of a non-native bioeroder can damage marine facilities and degrade and alter marine habitats. Through biological erosion and thus changing the physical structure of a marine habitat these non-native species can have ecosystem-level effects that cascade throughout the local community.

Thesis (M.S.)--Oregon State University, 2003. / Typescript (photocopy). Includes bibliographical references (leaves 85-92). Also available online.

The maize stem borers, Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) are economically important pests of maize in South Africa. Genetically modified Bt maize (MON810) expressing Cry1Ab protein is used to control these pests on approximately 425 000 hectares in South Africa. Before this study no information was available on the diversity of Lepidoptera on maize in South Africa or the potential impact of Bt maize on non-target Lepidoptera species under field conditions. There was also no information on the susceptibility to Bt maize of another stem borer species, Sesamia calamistis (Hampson) (Lepidoptera: Noctuidae), which is not a target species of Bt maize. The aims of this study were to determine which Lepidoptera species occur and feed on maize and could be directly exposed to Bt toxin as well as to assess the levels of infestation of target stem borer species and non-target Lepidoptera species on Bt- and non-Bt maize fields. Field collections of Lepidoptera that were directly exposed to Bt toxin through feeding on Bt maize plants were done between January 2004 and May 2006. Surveys were conducted in the North-West, Free State, Gauteng and Limpopo provinces. In order to quantify infestation levels and incidence of larvae on plants, sampling was done by inspecting between 300 – 900 plants per field. Studies were also done to compare the incidence of damaged plants and larvae on plants between Bt- and adjacent non-Bt maize fields. The susceptibility of S. calamistis to several Bt maize hybrids was evaluated under laboratory and greenhouse conditions. Fifteen species of Lepidoptera were recorded on maize plants. The following six species were recorded to feed on Bt maize and were reared on Bt maize until the adult stage: Acantholeucania loreyi (Noctuidae), Agrotis segetum (Noctuidae), B. fusca (Noctuidae), Helicoverpa armigera (Noctuidae), Eublemma gayneri (Noctuidae) and Nola phaeocraspis (Nolidae). Although Bt maize was damaged by several species of leaf, stem and ear feeding Lepidoptera in this study, the incidence of damage was always significantly lower on Bt maize fields than susceptible fields. This study provided base line data on Lepidoptera that feed on Bt maize in South Africa. Non-target Lepidoptera species that are directly exposed to Bt toxin was identified. An ecological model wasused to develop a preliminary risk assessment for Bt maize through which priority species for research and monitoring was identified as well as species that are at risk of resistance development. / Thesis (M. Environmental Science (Plant Protection))--North-West University, Potchefstroom Campus, 2007.

The maize stem borers, Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) are economically important pests of maize in South Africa. Genetically modified Bt maize (MON810) expressing Cry1Ab protein is used to control these pests on approximately 425 000 hectares in South Africa. Before this study no information was available on the diversity of Lepidoptera on maize in South Africa or the potential impact of Bt maize on non-target Lepidoptera species under field conditions. There was also no information on the susceptibility to Bt maize of another stem borer species, Sesamia calamistis (Hampson) (Lepidoptera: Noctuidae), which is not a target species of Bt maize. The aims of this study were to determine which Lepidoptera species occur and feed on maize and could be directly exposed to Bt toxin as well as to assess the levels of infestation of target stem borer species and non-target Lepidoptera species on Bt- and non-Bt maize fields. Field collections of Lepidoptera that were directly exposed to Bt toxin through feeding on Bt maize plants were done between January 2004 and May 2006. Surveys were conducted in the North-West, Free State, Gauteng and Limpopo provinces. In order to quantify infestation levels and incidence of larvae on plants, sampling was done by inspecting between 300 – 900 plants per field. Studies were also done to compare the incidence of damaged plants and larvae on plants between Bt- and adjacent non-Bt maize fields. The susceptibility of S. calamistis to several Bt maize hybrids was evaluated under laboratory and greenhouse conditions. Fifteen species of Lepidoptera were recorded on maize plants. The following six species were recorded to feed on Bt maize and were reared on Bt maize until the adult stage: Acantholeucania loreyi (Noctuidae), Agrotis segetum (Noctuidae), B. fusca (Noctuidae), Helicoverpa armigera (Noctuidae), Eublemma gayneri (Noctuidae) and Nola phaeocraspis (Nolidae). Although Bt maize was damaged by several species of leaf, stem and ear feeding Lepidoptera in this study, the incidence of damage was always significantly lower on Bt maize fields than susceptible fields. This study provided base line data on Lepidoptera that feed on Bt maize in South Africa. Non-target Lepidoptera species that are directly exposed to Bt toxin was identified. An ecological model wasused to develop a preliminary risk assessment for Bt maize through which priority species for research and monitoring was identified as well as species that are at risk of resistance development. / Thesis (M. Environmental Science (Plant Protection))--North-West University, Potchefstroom Campus, 2007.

Made available in DSpace on 2016-03-07T19:20:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-10-22. Added 1 bitstream(s) on 2016-03-07T19:24:05Z : No. of bitstreams: 1 000858012.pdf: 1284178 bytes, checksum: cfce2de78690541ace8955e96d438bab (MD5) / Avaliou-se a atratividade de fêmeas colonizadoras da broca-docafé por voláteis de frutos de café em diferentes estádios de maturação (verde, cereja e seco) e condições (frutos infestados por broca, danificados mecanicamente e sadios) de Coffea arabica cultivar Catuaí Vermelho IAC-144, em condições de laboratório. A atratividade da broca-do-café por voláteis de frutos foi determinada utilizando-se um olfatômetro de quatro braços em testes comportamentais. A brocado- café apresentou preferência por voláteis de frutos cereja em comparação a frutos verdes, e por frutos secos em comparação a frutos verdes; não houve diferença significativa quanto à preferência entre os estádios cereja e seco. A broca preferiu voláteis de frutos cereja infestados por broca (dust/frass de coloração preta e todos os estádios de vida do inseto presentes) em comparação aos provenientes de frutos cereja sadios, e por frutos infestados em comparação a frutos danificados mecanicamente; não houve diferença significativa entre frutos sadios e frutos danificados mecanicamente. A preferência de H. hampei por frutos de café cereja infestados indica que, além dos voláteis produzidos pelo fruto de café, provavelmente estão presentes outros semioquímicos envolvidos no processo de localização da planta de café com frutos por essa espécie, muito provavelmente associados aos resíduos alimentares e fecais produzidos pelo inseto (dust/frass). Os resultados foram discutidos em termos da importância de voláteis liberados por frutos cereja, secos, infestados por broca e dust/frass / It was evaluated the attractiveness of colonizing females of the coffee berry borer (CBB) by coffee berries volatiles at different stages of ripeness (green, ripe and dry) and conditions (infested by CBB, mechanically damaged and healthy berry) of Coffea arabica Catuaí Vermelho IAC-144, under laboratory conditions. The attractiveness of CBB females by berries volatiles was determined using a four-arm olfactometer in behavioral bioassays. The CBB showed preference by ripe berries volatiles compared to the green ones, and by dry berries compared to green ones; there was no significant difference in preference between ripe and dry stages. The CBB preferred volatiles of ripe infested berries (black dust/frass and all life stages of the insect present) compared to those from healthy ripe berries, and by infested berries compared to mechanically damaged berries; there was no significant difference between healthy and mechanically damaged berries. The preference of CBB by infested ripe coffee berries indicates that in addition to volatiles produced by the ripe berry probably are present other semiochemicals involved in the process of host selection for this species, most likely associated to dust/frass. The results were discussed in terms of the importance of volatiles released by ripe, dry, infested coffee berries and dust/frass

Orientador: Antonio Carlos Busoli / Banca: Nilza Maria Martinelli / Banca: José Maurício Simões Bento / Resumo: Avaliou-se a atratividade de fêmeas colonizadoras da broca-docafé por voláteis de frutos de café em diferentes estádios de maturação (verde, cereja e seco) e condições (frutos infestados por broca, danificados mecanicamente e sadios) de Coffea arabica cultivar Catuaí Vermelho IAC-144, em condições de laboratório. A atratividade da broca-do-café por voláteis de frutos foi determinada utilizando-se um olfatômetro de quatro braços em testes comportamentais. A brocado- café apresentou preferência por voláteis de frutos cereja em comparação a frutos verdes, e por frutos secos em comparação a frutos verdes; não houve diferença significativa quanto à preferência entre os estádios cereja e seco. A broca preferiu voláteis de frutos cereja infestados por broca ("dust/frass" de coloração preta e todos os estádios de vida do inseto presentes) em comparação aos provenientes de frutos cereja sadios, e por frutos infestados em comparação a frutos danificados mecanicamente; não houve diferença significativa entre frutos sadios e frutos danificados mecanicamente. A preferência de H. hampei por frutos de café cereja infestados indica que, além dos voláteis produzidos pelo fruto de café, provavelmente estão presentes outros semioquímicos envolvidos no processo de localização da planta de café com frutos por essa espécie, muito provavelmente associados aos resíduos alimentares e fecais produzidos pelo inseto ("dust/frass"). Os resultados foram discutidos em termos da importância de voláteis liberados por frutos cereja, secos, infestados por broca e "dust/frass" / Abstract: It was evaluated the attractiveness of colonizing females of the coffee berry borer (CBB) by coffee berries volatiles at different stages of ripeness (green, ripe and dry) and conditions (infested by CBB, mechanically damaged and healthy berry) of Coffea arabica Catuaí Vermelho IAC-144, under laboratory conditions. The attractiveness of CBB females by berries volatiles was determined using a four-arm olfactometer in behavioral bioassays. The CBB showed preference by ripe berries volatiles compared to the green ones, and by dry berries compared to green ones; there was no significant difference in preference between ripe and dry stages. The CBB preferred volatiles of ripe infested berries (black dust/frass and all life stages of the insect present) compared to those from healthy ripe berries, and by infested berries compared to mechanically damaged berries; there was no significant difference between healthy and mechanically damaged berries. The preference of CBB by infested ripe coffee berries indicates that in addition to volatiles produced by the ripe berry probably are present other semiochemicals involved in the process of host selection for this species, most likely associated to dust/frass. The results were discussed in terms of the importance of volatiles released by ripe, dry, infested coffee berries and dust/frass / Mestre

Maize contributes substantially to food security in the Eastern Cape province of South Africa. It is a staple food to many of the province’s rural and urban inhabitants. Insect pests are one of the factors that hamper its productivity and as a result, deprive farmers of good yields. The adverse effects of insecticides and the high cost associated with them and the cost of transgenic seeds are some of the challenges faced by small-scale farmers in rural areas. Alternative control methods which include the use of indigenous techniques to control pests are now sought. A study to identify and document ethnobiological means used by rural farmers to manage insect pests of maize was conducted in the rural areas of the Eastern Cape Province. A total of 217 participants were interviewed on the matter, using semi-structured but detailed questionnaires. Rural farmers due to their linkage to agriculture activities and the fact that they are considered as custodians of agricultural indigenous knowledge were selected as respondents. Only maize producing and IsiXhosa speaking people were chosen to contribute. Main focus was on the demography of respondents, crop production activities and insect pest control. Pretesting of the questionnaire in order to assess the appropriateness of questions and comprehension by both farmers and enumerators was done. Data was analysed using descriptive statistics. Fifty five percent (55 %) of the respondents were females and the highest number of participants was from the Chris Hani District Municipality. Majority of the people were unemployed or pensioners. Most had only attended primary school and the mean age was 59 years. Apart from maize, respondents were cultivating other crops such as cabbage, Swiss chard, potatoes etc. Stalk borers followed by cutworms were the main pests of maize in these areas. Respondents used mainly insecticides, followed by alternative substances, which also included cultural control methods such as planting date manipulation. Few respondents used plants as control agents for insect pests. Some people did not control pests even though they were a problem in their fields. The most used plant was Chenopodium ambrosiodes L, while the most used substance was Madubula (a detergent). The most used insecticide was carbaryl from the carbamite family. Respondents listed different preparation techniques for all the control methods mentioned. These techniques revealed different times of preparation, quantities of ingredients, amounts applied on plants, modes of application and intervals of application. Rural farmers in the study areas used different atypical methods which may play a significant role in pest management today. Some of the products may have a positive influence on agriculture, while some are dangerous to humans and environmental health. Further research which will investigate their potential use in pest control needs to be done.

Chez les insectes phytophages, la sélection de la plante-hôte qui constitue un site de ponte et d'alimentation est cruciale pour la survie et le bon développement de la descendance. Les sens chimiques – olfaction et gustation - sont déterminants pour un insecte lors du choix de sa plante hôte. Ainsi, une expérience olfacto-gustative des signaux chimiques d'une plante permet aux insectes d'optimiser la période de recherche et d'identification de celle-ci. Dans ce travail, nous avons testé l'effet d'une expérience pré-imaginale et imaginale pour un nouveau substrat de développement (enrichi en vanilline) sur l'induction de préférence olfactive et alimentaire à ce substrat chez trois espèces de lépidoptères foreurs de graminées ayant des spectres alimentaires différents, Sesamia nonagrioides (polyphage), Busseola fusca (oligophage) et Busseola nairobica (monophage). Il s'est avéré que la préférence olfactive des femelles pour les odeurs de ce substrat peut être induite par une expérience préalable pré-imaginale et imaginale pour ce nouveau substrat et que cette induction est transmise de façon transgénérationnelle. Elle n'est cependant pas liée à une augmentation de la sensitivité des antennes des femelles à la vanilline. De plus, elle dépend de l'espèce étudiée. Elle se manifeste plus rapidement chez l'espèce la plus polyphage (au bout de deux générations), plus tardivement chez l'espèce monophage (au bout de cinq générations) et est, par contre, absente chez l'espèce oligophage. Même si plusieurs mécanismes peuvent être impliqués dans cette induction, nos résultats valident à la fois la théorie d'Hopkins, le principe néo-Hopkins et l'héritage chimique chez les espèces qui ont présenté cette induction. Concernant les larves, nous avons pu montrer que celles-ci suivent, en général, la préférence olfactive des femelles pour les odeurs d'un nouveau substrat mais que cette préférence n'est pas corrélée avec leurs préférences alimentaires. / Among herbivorous insects, the selection of the host plant as an egg laying site and food is crucial for the survival and development of the offspring. The chemical senses - olfaction and gustation – of an insect are crucial in host plant selection. An olfactory-gustatory experience of plant chemical signals allows insects to optimize their search period and host identification. In this study, we tested the effect of pre-imaginal and imaginal experience for a new artificial diet (enriched in vanillin) on the induction of olfactory and food preference for this diet in three species of lepidopteran stem borers with different food spectra, namely Sesamia nonagrioides (polyphagous), Busseola fusca (oligophagous) and Busseola nairobica (monophagous). It was shown that the olfactory preference of females for the odor of the new diet could be induced by pre-imaginal and imaginal experience for this new diet and that this induction was transmitted transgenerationally. It was however not linked to an increase in the sensitivity of the female antennae to vanillin. In addition, it depended on the species studied. It occurred after two generations only in the polyphagous species, after five generations in the monophagous species, and it was absent in the oligophagous species. Although several mechanisms may be involved in this induction, our results validate both the theory of Hopkins, neo-Hopkins principle and the chemical legacy in the species in which the induction occurred. The larvae exhibited generally the same olfactory preference than the adult females for the odors of the new diet but this preference was not correlated with their food preferences, indicating in larvae a discrepancy between olfaction and gustation.