This project investigated the impact of bird predation on insect pest populations within two cornfields of Southwestern Quebec. Birds were excluded from portions of these fields through the use of bird-proof netting. Rhopalosiphum maidis, Ostrinia nubilalis, Agrotis spp. and Sphenophorus spp. were all found at greater densities in plots where birds were excluded as compared with the non covered plots. Only the adult Diabrotica longicornis population was not reduced by birds. Results significantly suggest that birds can reduce insect pest populations. Bird visits in cornfields with respect to distance from field edge, type of edge habitat and corn phenology were also studied. Red-winged Blackbird, Song and Chipping Sparrows and American Robin were the most frequently observed bird species inside cornfields. Early in the summer, birds tended to stay closer to the field edge, especially when composed of mature coniferous trees. Different bird species visited the cornfields at specific periods during corn development.

Soybean (Glycine max (L.) Merr.) is one the major crops produced worldwide. However, soybean is susceptible to many diseases. Sclerotinia stem rot (SSR) disease caused by Sclerotinia sclerotiorum (Lib.) de Bary is considered one of the most important fungal diseases of soybean. It can be controlled by chemicals (e.g. fungicides), by breeding cultivars with disease resistance and by cultural control (e.g. increasing the width between rows, reducing plant populations). A promising and complementary method of controlling SSR disease in the field is the application of biological control agents. Biological control agents introduced in a soil environment will interact with other soil food web organisms, as do the pathogenic organism and infected plants, which may change the genetic and functional diversity in soil microbial communities. Profiling these changes may lead to an improved understanding of the interactions between these players (biological control agents, pathogens, soil biota and plants) in the biological control phenomenom, permiting us to exploit naturally-occurring ecological relationships and develop more sustainable approaches to control soybean diseases. Fatty acid biomarkers analysis was used to profile microbial communities in soils. Two laboratory studies were conducted to evaluate the methods used for extraction and profiling the fatty acid biomarkers from soil samples with a range of soil properties (clay content, organic matter content), The first study investigated the best solvent mixture for recovering fatty acid biomarkers from soil using an automated pressurized solvent extraction (PSE) system. Solvent mixtures containing chloroform and methanol were more efficient at extracting fatty acids from agricultural soils than hexane:2-propanol and acetone. The second study presented an exploratory pyrolysis-mass spectrometry technique to rapidly fingerprint soil lipids extracted from different agroecosystems. Pyrolysis-mass spectrometry discriminated among soils and crop production systems in the same way as the fatty acid profiling. I also report on the efficicacy of biological control agents to control Sclerotinia stem rot disease in soybean. A two-year study was conducted in soybean fields under conventional or no tillage to determine whether Trichoderma virens (SoilGard(TM)) and arbuscular mycorrhizal fungi (a mixture of Glomus intraradices and G. mosseae ), used alone or in combination, could reduce sclerotinia stem rot (SSR) disease incidence. Generally, SSR disease indicators, as well as the soybean yield, were not affected significantly by the biological control treatments. I then studied whether changes in microbial community composition were related to the inoculation of the biological control agents and the disease incidence in soybean fields. Inoculation of biological control agents changes the expression of many soil fatty acids during both years of the trial. Also, in the plots with severely diseased plants, fatty acids biomarkers of gram positive and actinomycetes bacteria were significantly greater than in plots with healthy plants. I conclude that further improvement in laboratory techniques and procedures will permit researchers to efficiently extract and characterize soil lipids, providing new insight into soil organic matter dynamics and soil microbial ecology. Further study will be needed to verify the efficacy and optimize the application method, dose and timing of biocontrol agents to provide protection against SSR disease in soybean fields.

No description available.

Orientador: Jaime Maia dos Santos / Banca: Nilza Maria Martinelli / Banca: Bruno Flávio Figueiredo Barbosa / Resumo: Em razão das elevadas perdas que os nematoides causam a agricultura e das limitações e impactos causados pelos defensivos químicos, assim como do cultivo sucessivo de plantas hospedeiras que propiciam o aumento das populações dessas pragas, esse trabalho teve como objetivo, isolar, identificar fungos nematófagos e avaliar o potencial como agentes de controle biológico das principais espécies de fitonematoides no Brasil. Os fungos foram isolados de amostras de solo coletadas em regiões dos estados do MS, MG e SP, de cisto e de nematoides naturalmente parasitados. Para testar a patogenicidade dos isolados fúngicos parasitas de ovos e cisto de Heterodera glycines pelos fungos Pochonia chlamydosporia, Fusarium solani e Trichoderma sp., dois experimentos in vitro foram conduzidos, compostos pela combinação das espécies de nematoides com cada isolado parasita e a testemunha: 1) capacidade de parasitismo de ovos de Meloidogyne javanica e H. glycines, e 2) capacidade de parasitismo de ovos de H. glycines dentro do cisto, totalizando 10 e 4 tratamentos, respectivamente e 3 repetições cada. Para o fungo endoparasita Catenaria sp. foram usados ovos e formas ativas de Pratylenchus brachyurus, 3 tratamentos e 3 repetições. Os ovos e cistos parasitados foram avaliados e fotomicrografados. O isolado de P. chlamydosporia se destacou, tendo parasitado mais de 80% dos ovos de H. glycines. O fungo endoparasita Catenaria sp. parasitou 89% das formas ativas de P. brachyurus, além de parasitar ovos dessa mesma espécie / Abstract: Given the high losses that nematodes cause agriculture and the limitations and impacts of agrochemicals, as well as the continuous cultivation of host plants that provide increased populations of these pests, this study aimed to isolate, identify and fungi nematophagous evaluate the potential as biological control agents of the main species of plant-parasitic nematodes in Brazil. The fungi were isolated from soil samples collected in regions of the states of MS, MG and SP, cyst and naturally infected nematodes. To test the pathogenicity of the isolated fungal parasite eggs and cysts of Heterodera glycines by fungi Pochonia chlamydosporia, Fusarium solani and Trichoderma sp, two in vitro experiments were conducted, composed by the combination of species of nematodes with every single parasite and the witness: 1 ) parasitism capacity of Meloidogyne javanica eggs and H. glycines, and 2) parasitism capacity of H. glycines eggs within the cyst, totaling 10 and 4 treatments, respectively, and 3 repetitions each. For fungus endoparasite Catenaria sp. they were used eggs and active forms Pratylenchus brachyurus, three treatments and three replications. Eggs and infected cysts were evaluated and photomicrographed. The isolate of P. chlamydosporia stood, infested with more than 80% of the eggs of H. glycines. The fungus endoparasite Catenaria sp. parasitized 89% of active forms of P. brachyurus, and parasite eggs of the same species / Mestre

Water lettuce, Pistia stratiotes Lamarck (Araceae) is a South American plant that has the potential to be a very damaging and important aquatic weed in many tropical countries, including South Africa. It has the potential to rapidly multiply vegetatively and completely cover watercourses in a very short space of time outside of its natural range under ideal conditions and without its natural enemies. In such instances, the weed may cause hindrances to water transport and fishing, increasing chances of malaria, as well as affecting the natural ecology of the system. Water lettuce can also set seed, which may lay dormant for long periods, germinating when conditions are favourable. It is therefore very necessary to adopt control methods against the weed where it is a problem. However, water lettuce has also been effectively and completely controlled in many countries by the leaf-feeding weevil, Neohydronomus affinis Hustache. High nutrient levels in the form of nitrates and phosphates have been shown to have largely negative effects on biological control in several studies, with control being incomplete or taking longer than in similar areas with lower nutrient levels. The effectiveness of N. affinis on the biological control of water lettuce was investigated in a laboratory study, growing P. stratiotes plants with and without insects at different nutrient concentrations. In these studies biological control of water lettuce with N. affinis was found to be complete under eutrophic nutrient conditions, although control took longer when higher nutrient levels were tested. A field site study was conducted at a sewage settlement pond in Cape Recife Nature Reserve near Port Elizabeth, South Africa. This highly eutrophic system was used as a field example for the effectiveness of biocontrol of P. stratiotes by N. affinis under eutrophic conditions. The weevils at Cape Recife caused a massive and rapid crash in the percentage coverage of the weed, from 100% in May 2003, to approximately 0.5 % in September 2003. Plant growth parameters were also found to decrease considerably in size correspondingly with this crash from May 2003 until spring 2003. Plant size only again started to increase gradually but steadily through spring 2003 and into summer. In the laboratory studies, the fecundity of weevils was shown to be much higher on plants grown under higher nutrient concentrations than on plants grown in lower nutrient concentrations. The results from the wing-muscle analysis under different nutrient concentrations were not easy to interpret, and there were few differences in wing muscle state between most of the concentrations. From these findings it is suggested that nutrient concentration, particularly high levels of nitrates and phosphates is not a limiting factor in terms of effective biological control of P. stratiotes with N. affinis, but that under high nutrient conditions biological control might take longer.

False codling moth (FCM), Thaumatotibia (=Cryptophlebia) leucotreta (Meyr) (Lepidoptera: Tortricidae), is one of the most important pests on citrus. The Cryptophlebia leucotreta granulovirus (CrleGV) has been developed into a successful biological control agent, registered under the name Cryptogran, and is currently the preferred product for the control of FCM on citrus in South Africa. A prerequisite to the continued success of Cryptogran as a means of controlling false codling moth is to understand the factors affecting field persistence of the virus, and to find ways to improve it. The aim of this study was to gain a clearer understanding of the product and the abiotic and biotic factors affecting its persistence in the field, and to investigate methods to improve this persistence. The effect of UV-irradiation on the virus was determined, and various products were tested as UV protectants in laboratory bioassays. Lignin was the most effective additive, and was tested in several field trials, where it also enhanced the efficacy of Cryptogran. Laboratory trials indicated that Cryptogran is rainfast. Cryptogran applications early in the season had a longer period of residual activity than sprays applied closer to harvest. Daytime applications were less effective that evening sprays. Sprays applied coinciding with peaks in pheromone moth trap catches were more effective than those applied between peaks. Biotic factors influencing persistence were investigated. Residual efficacy was longer when treatments were applied to blocks than as single tree treatments. Attempts were made to quantify the effect of the navel end of a navel orange on the field persistence of Cryptogran. Cryptogran was shown to be compatible with many agricultural chemicals used on citrus. Economic thresholds and various cost-benefit analyses are discussed. A list of practical recommendations to growers was drawn up, and possibilities for future research are presented.

Inbreeding was thought to be responsible for the loss in the second filial generation (F₂) of Amalafrida leithella Dyar, Cactoblastis mundelli Heinrich, Nanaia sp. Heinrich, Sigelgaita sp. Heinrich and Sigelgaita transilis Heinrich in the laboratory. This pre-empted the investigation of the effects of inbreeding on another cactophagous moth, Mimorista pulchellalis Dyar, an established biological control agent of jointed cactus in South Africa. Initially three populations were set up. A randomly-mating control (OUT 1) population, and a sibmating experimental (IN 1) population, consisted of laboratory-reared stock . A second experimental population (KR 1) comprised a small number of field-collected randomly-mating individuals which recreated the conditions under which the five abovementioned species were lost. The inbreeding depression of fifteen fitness components was assessed. The mean values of each component in each generation of treatments IN 1 and KR 1 were compared with those of OUT 1. In addition the mean values of IN 1 were regressed against the coefficients of inbreeding since inbreeding depression is linear with respect to the probability of two genes at any locus being homozygous through ancestry. The component egg viability was important because a reduction in OUT 1, IN 1 and KR 1 in the F₂ resulted from mated females producing no viable eggs. Duplicate treatments OUT 2, IN 2 and KR 2 were set up to confirm whether this was a general F₂ phenomenon. Assessment of the fitness components prevented a direct evaluation of the numbers of offspring produced. However a hypothetical estimate of population size and growth rate was made using the percentage survival calculated from life-table analysis. Although not statistically demonstrable in the component analysis, life table analysis indicated that egg viability suffered an inbreeding depression and affected population fitness. It was also evident that treatments OUT 1 and 2 were fitter than treatments IN 1 and 2 and KR 1 and 2 with respect to population fitness. Thus, inbreeding, resulting from sibmating and introduction of a small number of individuals to a laboratorYJ caused a decrease in numbers of offspring produced and population growth rate. This is important in relation to the demise of the cactophagous Lepidoptera and to future biological control programmes.

The diamondback moth, Plutella xylostella (L.), is a pest on crucifer crops worldwide, damaging the leaves, florets and seed pods of many crucifers including cabbage, cauliflower, broccoli and canola. It has been controlled using broad-spectrum insecticides, but this has led to a rapid build-up of insecticide resistance. In the Grahamstown area of the Eastern Cape Province, South Africa, diamondback moth showed resistance to cypermethrin (a pyrethroid) on commercially grown cabbages. Therefore it is imperative that other methods of control be adopted, including both cultural control and biological control using parasitoids, and that these are incorporated into an Integrated Pest Management (IPM) programme. The diamondback moth and its parasitoids were monitored weekly from April 1997 to November 1999 at three sites near Grahamstown. One site was a commercial farm with an active insecticide spraying program; the others were unsprayed. Infestation levels were highest during spring (September to November) and autumn (March to May). Nine species of parasitoids were associated with the diamondback moth, with abundances being highest over spring and early summer (September to December). Cotesia plutellae (Kurdjumov) dominated the sprayed site, while the unsprayed sites yielded a complex of parasitoids, including C. plutellae, Diadegma mollipla (Holmgren), Diadromus collaris Gravenhorst and Oomyzus sokolowsldi (Kurdjumov). Parasitism levels ranged between 10 and 90%. There was a large amount of site-to-site and year-to-year variation. Parasitoids were an effective mortality factor against the diamondback moth. The effects of temperature on development and mortality, and of field size and non-crop plants on the distribution of diamondback moth and its parasitoids, were investigated. The results show that high temperatures can depress pest populations, and that the size and surroundings of fields can be manipulated to improve cultural control of the diamondback moth. Suggestions for effective rPM in the Eastern Cape Province include a reduction in insecticide applications, the use of bioinsecticides, for example Bacillus thuringiensis Berliner (Bt) and the encouragement of indigenous parasitoids by planting suitable nectar sources. Cultural control methods are also important and involve removal of cabbage refuse after harvest, management of wild crucifers around cabbage fields, scouting and monitoring the moth population and determining the optimal field size to assist with control by parasitoids.

The study examined the larval parasitoids of Cryptophlebia leucotreta (Meyrick) on citrus in South Africa and aimed to improve the existing rearing techniques of C. leucotreta with a view to mass rearing of biological control agents. The biological characteristics of Agathis bishopi Nixon (Hymenoptera: Braconidae) were studied, with an emphasis on parasitism rates in the field, host stage preference, developmental rate, life span and offspring sex ratios. Two larval parasitoids, A. bishopi and Apophua leucotretae (Wilkinson) (Hymenoptera: Ichneumonidae), and an egg parasitoid, Trichogrammatoidea cryptophlebiae Nagaraja (Hymenoptera: Trichogrammatidae), were recorded on C. leucotreta on citrus. A. bishopi was the more abundant of the larval parasitoids and exhibited density dependent parasitism. The highest parasitism rates were observed in December with up to 38% in Sundays River Valley and 34% in Gamtoos River Valley, at a time when the highest false codling moth infestations were observed. Agathis bishopi was recorded only in the Eastern Cape Province. The sex ratio of A. bishopi was biased towards females throughout the study (77% in Gamtoos River Valley and 72% in Sundays River Valley). Agathis bishopi is a solitary, koinobiont, larval-pupal endoparasitoid. The species showed a preference for 1st and 2"d instar hosts. Females regulate the sex of their progeny according to the size and larval stage of the host, ovipositing unfertilised eggs in younger, smaller larvae (1st instars) and fertilised eggs in older, larger larvae (2nd instars). The developmental rate of A. bishopi is in synchrony with that of the moth and adults emerge when adult moths that have escaped parasitism emerge. Agathis bishopi and T. cryptophlebiae compliment each other because they have different niches and strategies of attack. Integrating A. bishopi and T. cryptophlebiae into the management of citrus orchards has potential to suppress false codling moth. Larger rearing containers seemed ideal for large-scale rearing of false codling moth. A higher percentage of adults was obtained from larvae reared in larger containers than in smaller ones. The width of the sponges used as stoppers prevented escape of the larvae. Media prepared in larger containers are easier and simpler to prepare than in smaller ones, thus eliminating many precautions otherwise necessary to prevent contamination. Moth production was greatly reduced by the high concentration of Sporekill used for egg decontamination.

Orientador: Sergio Antonio de Bortoli / Coorientador: Alessandra Marieli Vacari / Banca: Ana Carolina Pires Veiga / Banca: Raphael de Campos Castilho / Resumo: O parasitoide Cotesia flavipes (Hymenoptera: Braconidae), quando liberado em cana-de-açúcar, depende de sua capacidade de dispersão e forrageamento para o efetivo controle de Diatraea saccharalis (Lepidoptera: Crambidae). Nesse sentido, o objetivo do trabalho foi analisar a influência da temperatura nos aspectos biológicos dos insetos produzidos em dez biofábricas brasileiras: I) Santa Ernestina-SP, II) Américo Brasiliense-SP, III) Ribeirão Preto-SP, IV) Pradópolis-SP, V) Sertãozinho-SP, VI) Promissão-SP, VII) Bandeirantes-PR, VIII) Quirinópolis-GO, IX) Campo Novo do Parecis-MT e X) Coruripe-AL, bem como analisar a influência das temperaturas 22, 24, 26, 28, 30, 32 e 34 ± 1°C na performance do parasitoide. Para tanto, foram avaliados: atividade de voo, sobrevivência, capacidade de parasitismo, descendentes viáveis e razão sexual dos insetos produzidos. Os parasitoides da Biofábrica IX foram aqueles que apresentaram a maior porcentagem de insetos voadores (43,4%) a 25°C; independente da temperatura, a maioria das populações apresentaram maiores porcentagens de insetos caminhadores. As fêmeas da biofábrica I apresentaram maior sobrevivência média (56 horas). A temperatura influenciou a sobrevivência dos parasitoides, sendo maior a 22°C para todas as populações. Apenas as biofábricas III) Riberirão Preto-SP e VII) Bandeirantes-PR apresentaram menor produção de descendentes. No geral, as temperaturas de 28 e 30°C favoreceram a produção de descendentes de C. flavipes, sendo que a ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The parasitoid Cotesia flavipes (Hymenoptera: Braconidae), when released in sugarcane, depends on its dispersal and foraging capacity for the effective control of Diatraea saccharalis (Lepidoptera: Crambidae). In this sense, the objective of the work was to analyze the influence of temperature in some biological aspects of the insects produced in ten Brazilian biofactories: I) Santa Ernestina-SP, II) Américo Brasiliense-SP, III) Ribeirão Preto-SP, IV) Pradópolis-SP, V) Sertãozinho, VI) Promissão-SP, VII) Bandeirantes-PR, VIII) Quirinópolis-GO, IX) Campo Novo do Parecis-MT and X) Coruripe-AL, as well to analyze the influence of temperatures 22, 24, 26, 28, 30, 32 and 34 ± 1°C in the parasitoid performance. For that, the following biological parameters were evaluated: flight activity, survival, parasitism capacity, viable offspring and sex ratio of insects produced. The parasitoids of biofactory IX were those that presented the highest percentage of flying adults (43.4%) at 25°C. Independent of temperature, most of the populations had higher percentages of walkers insects. The females of biofactory I presented highest survival average (56 hours). The temperature influenced the parasitoids survival, being higher at 22°C for all populations. Only biofactories III) Ribeirão Preto-SP and VII) Bandeirantes-PR showed lower production of offspring. In general, temperatures of 28 and 30°C favored the production of C. flavipes offspring, and the sex ratio was not influenced by temperature. / Mestre