Four to six separate inundative releases of ~30,000 to 50,000 T. ostriniae per 0.02 ha significantly reduced damage by O. nubilalis in bell pepper. Egg parasitization averaged 48.7% in T. ostriniae release plots, which was significantly higher than non-release plots (1.9%). Also, cumulative green pepper fruit damage averaged 8.7% in release plots, which was significantly less than non-release plots (27.3%). Pesticides tested against T. ostriniae were spinosad and methoxyfenozide. Spinosad adversely affected adult T. ostriniae producing 100% mortality at the field rate of 498 mg [AI]/L for both the preimaginal and adult toxicity tests. Use of T. ostriniae can provide effective control of O. nubilalis in pepper compared to conventional and organic spray regimes (Spinosad and methoxyfenozide respectively). Augmentative releases of T. ostriniae integrated with methoxyfenozide with its limited toxicity to both preimaginal and adult stages indicate that it is a superior candidate for control O. nubilalis. To determine the behavioral differences of T. ostriniae and its response to O. nubilalis in green bell peppers, experiments were carried out to classify likely areas of O. nubilalis oviposition within the green pepper plant canopy. A total of 426 O. nubilalis egg masses were found on pepper plants during our study. Over 92% of egg masses were found on the lower surface of the leaf compared with the upper surface indicating a significant ovipositional preference for the undersides of leaves in 2002 ( x2 = 9.68; df = 1; P < 0.05) followed by similar results in 2004 (x2 = 4.34; df = 1; P < 0.05). No significant differences were found in the observed spatial distribution of egg masses among the three vertical strata in either 2002 or 2004 (x2 = 1.75; df = 2; P < 0.05 and x2 = 5.69; df = 2; P < 0.05 respectively). Field release rates of 17.0 foraging T. ostriniae females can achieve 80.0% parasitism of O. nubilalis egg masses distributed throughout the pepper plant canopy found primarily on the undersides of leaves. These data demonstrate that T. ostriniae has potential as a biocontrol agent for O. nubilalis in solanaceous crops. / Ph. D.

Master of Science

Master of Science

Thesis (M.S.)--Mississippi State University. Department of Plant and Soil Sciences. / Title from title screen. Includes bibliographical references.

No description available.

Call number: LD2668 .T4 1985 M444 / Master of Science

The aim of this work was to compare the infestation of Diatraea saccharalis (Fabricius), D. flavipennella (Box), Mahanarva fimbriolata (Stal), M. posticata (Stal) e Castnia licus Drury in eight RB varieties of sugar cane. The varieties evaluated were RB72454, RB931003, RB867515, RB92579, RB971755, RB863129, RB951541 and RB93509. The experiment was set up in the first fortnight of September 2005. The evaluations started from March 2006 and the subsequent evaluations on a basis of approximately 30 days. The results showed when compared the complex borer/rottenness, for occasion of the harvest, the varieties RB92579, RB867515, RB93509 and RB863129 showed higher tolerance to the attack of the borers, while the variety RB971755 was significantly more susceptible. The variety RB867515 was more infested by M. fimbriolata. In relation to infestation by M. posticata, statistical differences were not verified between the studied varieties. The varieties RB951541, RB92579, RB971755 and RB93509 were significantly less damaged by C. licus than the variety RB72454. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O objetivo deste trabalho foi comparar a infestação de Diatraea saccharalis (Fabricius), D. flavipennella (Box), Mahanarva fimbriolata (Stal), M. posticata (Stal) e Castnia licus Drury em oito variedades RB de cana-de-açúcar: RB72454, RB931003, RB867515, RB92579, RB971755, RB863129, RB951541 e RB93509. O experimento foi instalado na primeira quinzena do mês de setembro de 2005. As avaliações foram realizadas a partir do mês de março de 2006 e as subseqüentes a intervalos de aproximadamente 30 dias. O último levantamento aconteceu por ocasião da colheita, o que possibilitou avaliar o complexo broca/podridão de Diatraea spp. e infestação de Castnia licus. Os resultados mostraram quando comparadas com base no complexo broca/podridão, por ocasião da colheita, as variedades RB92579, RB867515, RB93509 e RB863129 apresentaram maior tolerância ao ataque de Diatraea spp., enquanto que a variedade RB971755 se revelou significativamente mais susceptível. A variedade RB867515 foi a mais infestada por M. fimbriolata (Stal). Quanto às infestações de M. posticata (Stal) não se constataram diferenças estatísticas entre as variedades estudadas. As variedades RB951541, RB92579, RB971755 e RB93509 foram significativamente menos danificadas por C. licus do que a variedade RB72454.

No description available.

Thesis (PhD(Agric))--Stellenbosch University, 2012. / The sugarcane borer, Eldana saccharina Walker (Lepidoptera: Pyralidae) is the most limiting factor in the South African sugar industry with losses to this insect pest estimated to be at least ZAR60 million per annum. Because of its cryptic nature as well as the fact that E. saccharina is both indigenous to Africa and occurs on several host plants, attempts to control or eradicate it using several available methods have not been very successful. However, the sterile insect technique (SIT) is one of the newer control methods that can be incorporated into an area-wide integrated pest management (AW-IPM) programme to achieve better control or eradication. The implementation of the SIT program needs to go through a series of well-researched phases in order to be successful. In the first of this multi-phase project, it was determined that E. saccharina is susceptible to ionizing radiation, and is thus a suitable candidate for the SIT development against it and that a sub-sterilizing dose of 200 Gy is sufficient to induce F1(inherited) sterility in male and complete sterility in female moths respectively. The results presented here are discussed in the context of further development of the SIT as an addition to the arsenal of tactics in an AW-IPM programme against E. saccharina. Based on these initial findings, the study examined the lek and mating behavior of male moths subjected to three radiation doses (150, 200, 250 Gy) against normal non-irradiated/fertile moths. Both mass-rearing and irradiation of E. saccharina led to a quantitative departure of male mating behavior away from that exhibited by their wild counterparts. However, treated males are still able to form leks and mate with wild females. Male E. saccharina irradiated at all three doses tested were found to be as active and competitive as wild males, but in some of the traits measured, performance diminished significantly with an increase in the radiation dosage. In general, the performance of moths treated at 200 Gy did not differ significantly from that of moths treated at 150 Gy and therefore the former dose is ideal for SIT development since it results in a lower residual F1 fertility than the latter. The level of mating competitiveness and compatibility was assessed under both laboratory and semi-field conditions in pairwise comparisons consisting of laboratory reared vs. wild (L-W), 200 Gy irradiated vs. wild (S-W) and laboratory reared vs. irradiated moths (L-S). Based on the results from the more robust field cage assays, the mating indices generated indicated that the mass-reared E. saccharina strain produced in South Africa has not yet evolved sexual behaviours suggestive of incipient pre-mating isolation barriers with local wild strains. Wild moths did not discriminate against either the partially sterile or laboratory reared moths and most importantly, the irradiated males mated significantly more than their wild counterparts regardless of the type of female. The irradiated insects could therefore achieve the purpose for which they are intended upon release into the field. Third, the critical thermal limits (CTLs) to activity at high and low temperatures (i.e. critical thermal maxima “CTmax” and minima “CTmin”) of different E. saccharina strains/treatments were investigated under standard experimental conditions. The effect of laboratory rearing and increasing radiation dosage on thermal tolerance of the adult stage of E. saccharina was explored. There were highly significant differences between the laboratory-reared and wild strain and also between non-irradiated and irradiated strains in both CTmax and CTmin. Laboratory reared E. saccharina moths were more heat tolerant compared to wild moths for both genders while in the case of CTmin, the reverse was true. Irradiation had a negative effect on both CTmax and CTmin. Moths treated at the lowest radiation dose were more cold and heat tolerant than those treated at higher dosages thereby reinforcing the importance of lower dosages rather than those that induce full sterility against E. saccharina. In general, gender effects on the CTLs were non-significant. Pilot sterile male releases in shade house trials to measure the impact of sustained releases of partially sterile adult males at an over-flooding moth ratio of 10T: 1U (treated to untreated),were conducted to measure their efficacy to stop E. saccharina incursions and suppress populations prior to testing in pilot studies under true season-long and area wide conditions. Results from the current study demonstrated that releasing partially irradiated (200 Gy) adult male moths at the afore mentioned release rate significantly reduced sugarcane stalk damage as well as lowered the number of fertile progeny from F1to succeeding generations in a stable E. saccharina population initiated in a cage house. There were more damaged internodes per stalk in the control than in the sugarcane receiving regular releases of partially sterile male moths. Overall, there were significantly more undamaged stalks in the treated sugarcane than the untreated control. Furthermore, there were significantly more larvae per stalk retrieved from the control compared to the treated sugarcane suggesting that the sustained release of steriles was efficacious in reducing emergence of fertile larvae in the succeeding generations. The results of this study indicate that there is considerable scope for the SIT against E. saccharina.

An increment borer is the primary tool used to collect samples for dendrochronological analyses. These are precision instruments and users should be trained in their proper use, care, and maintenance. In this paper, I describe the various parts of an increment borer and how to keep these in working condition. I provide details on how to sharpen an increment borer, properly core a tree, check for core compression ("jamming"), extract the core, and store the core for transport. I provide tips on how to clear a jammed borer and remove a borer stuck in a tree. An important topic concerns the effects of boring on trees. The majority of studies indicate that conifers are minimally affected by both fungal decay and discoloration, whereas certain hardwood species can sustain major internal damage. Plugging the holes created by coring is unnecessary.