Pour des raisons patrimoniales autant que pour les services qu'elle rend à l'humanité, il apparaît nécessaire de soutenir la diversité des organismes vivants et, pour cela, de connaître leur utilisation des milieux dans les paysages ruraux. En particulier, des travaux récents soutiennent un modèle de colonisation cyclique qui énonce qu'une partie des espèces circulant dans les milieux cultivés en été trouvent un abri propice à l'hivernation dans les milieux semi-naturels. Notre but était ici de mettre au jour les facteurs locaux et paysagers déterminant la répartition spatiale et la structure des assemblages de Carabidae dans un paysage rural des coteaux de Gascogne. Les patrons de répartition des Carabidae, obtenus à deux échelles spatiales différentes, celle du paysage et celle de la parcelle, et à deux moments clés de la vie de ces insectes, la période durant laquelle ils sont actifs (circulants) et la période d'hivernation, ont été interprétés en termes de processus écologiques grâce à la prise en compte des traits biologiques et écologiques des espèces de Carabidae. Les résultats montrent que le type de milieu a un effet structurant majeur sur les assemblages de Carabidae circulants comme hivernants, comparable aux effets des conditions environnementales locales et paysagères réunies. Par ailleurs, les effets de lisière sur les Carabidae circulants, au niveau des interfaces entre les bois et les cultures, sont limités à quelques mètres ou quelques dizaines de mètres. Concernant les Carabidae hivernants, nous avons noté de manière surprenante que leur densité était de deux à six fois plus élevée dans les marges (cultivées) des cultures que dans les milieux semi-naturels. De plus, nous n'avons noté aucun contraste de répartition spatiale entre les Carabidae hivernants et les Carabidae circulants, quels que soient les espèces ou les groupes fonctionnels considérés. Ceci indique donc que les marges des cultures sont des milieux d’hivernation très importants dans le contexte considéré et que si un mouvement de colonisation cyclique existe pour les Carabidae des cultures, il doit se dérouler entre leur zone intérieure et leur marge. L'ensemble de nos résultats soutient l'idée que si l'agencement spatial des milieux seminaturels dans le paysage est important pour promouvoir les populations de Carabidae auxiliaires dans les cultures, la gestion des cultures elles-mêmes, et notamment de leurs marges, est également de première importance. / Supporting biodiversity is an ethical as well as a practical issue since it provides numerous ecosystem services. In that purpose, it is necessary to determine how organisms use the different habitats in rural landscapes. In this view, recent studies suggest that a number of arthropods cyclically colonise cultures, where they feed and reproduce, and semi-natural areas, where they overwinter. We aimed to determine the local and landscape determinants of spatial distribution and structure of ground beetle (Coleoptera: Carabidae) assemblages in a rural landscape of south-western France. We studied spatial distribution patterns of ground beetles at landscape and habitat scales, and at two key periods of their life, that when they are active, and winter. We then considered biological and ecological traits to deduce from these spatial patterns ecological processes affecting ground beetles. Our results show that habitat type has a major effect on species assemblages of active (circulating) as well as overwintering ground beetles, equivalent to that of local conditions and landscape context combined. Edge effects on circulating ground beetles at the woodlot-filed interface were limited to a few meters or a few dozen of meters in both habitats. Amazingly, we found that the density of overwintering ground beetles was two-to six-fold higher in crop margins than in semi-natural habitats. Moreover, we failed to show any difference between the spatial distribution of overwintering ground beetles and circulating ground beetles, whatever the species or functional group considered. Crop margins are thus major overwintering sites in the context studied and cyclic colonisation of ground beetles in crops, if real, may take place between the inner zone and the margins of crops. These results suggest that, in addition to spatial arrangement of semi-natural habitats, crop management, and in particular management of crop margins, is important to promote ground beetles and their beneficial effects on crop protection in agro-forested landscapes.

No description available.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / From december 2006 to april 2008 was conducted a experiment at Universidade Federal de Santa Maria, Santa Maria, RS, Brasil, with objective to verify spatial and temporal distribution of soybean stink bug, with georeferenced surveying. The samplings was accomplished in area of 6,64 hectares of soybean (Glycine max (L.) Merrill), it was divided in a sample grid of the 105 points, spaced in 25 x 25 m. Colonization of the field occurred on soybean s vegetative period, from its adjacent borders to the fields of early soybean and sunflower, by the adults entry from these crops to the experimental area, because later sowing. From the beginning seed until the pod filling of the soybean, the tendency of stink bug population increase by the borders was kept. In the crop 2007/08, due to the sowing have been carried through at that recommended period, the spatial distribution of stink bugs started simultaneously in several points in the field and it did not present clear influence of the adults entry from other areas. In both the crops the populations increase occurred from beginning pod and beginning seed and to species abundance and its population s peaks varied of a crop for another. During overwintering it verified presence of stink bug in the area, feeding itself in the straw on the soil and living on grains fallen into the harvest, or in alternative host plants as Raphanus sp. With objective to study nymphs and adults of Piezodorus guildinii (Westwood, 1837) (Hemiptera: Pentatomidae) behavior on day time on soybean, was conducted a experiment at Universidade Federal de Santa Maria, from april to may 2007. The experimental design employed was a factorial of order fourth, in randomized complete block design (24x3x3x3) (day time x distribution x location x behavior), with five blocks. The stink bugs were observed hourly, during 24 times. The stink bugs plant distribution (top, middle and botton), their location in plant organs (pod, leaf ou HRPR stem, branch, stick or raceme) and their behavior (resting, locomotion, feeding ativity) was registered. During the first and second instars, the nymphs had presented gregarious habit, and a small percentage in movement around of the posture. The nymphs started the feeding activity on second instar, and the locomotion was just around of the posture and the same organ where they were. From the third instar nymphs became more active, with bigger ditribution on plant and feeding more frequently. Locomotion times were near and precedents to feeding times and precedent the dusk, indicating the search for preferential locations for feeding or shelter. Nimphs and adults P. guildinii located preferentially in pod, them whats are associated to repose and feeding activity behaviors. In the nocturnal period, with air temperature lower than in the diurnal period, P. guildinii s nymphs had remained in stems circled by pods, because of the search by sheltered locations. Percentage P. guildinii in feeding activity increased of 7,37% of second-fourth instar for 16,92% in the fifth instar, and 34,77% adult phase. P. guildinii remained, preferentially, in middle plants stracta along the day time, not presenting a clear behavior of distribution in superior plants stracta in defined chedules. Thus, should not be indicated groups ideal schedule's for insecticides application for your control. / De dezembro de 2006 a abril de 2008 foi conduzido um experimento na Universidade Federal de Santa Maria, Santa Maria, RS, Brasil, com o objetivo de verificar a distribuição espacial e temporal de percevejos da soja, através de levantamento georreferenciado. As amostragens foram realizadas em uma área de 6,64 hectares de soja (Glycine max (L.) Merrill) dividida em uma grade amostral com 105 pontos, espaçados em 25 x 25 m. A colonização da lavoura ocorreu no período vegetativo da soja, a partir das bordas adjacentes a lavouras de soja precoce e girassol, pela entrada de percevejos adultos destes cultivos do entorno para a área georreferenciada, em função da semeadura tardia. Desde o início do enchimento de grãos até o enchimento pleno de grãos, a tendência de aumento populacional de percevejos pelas bordas foi mantida. Na safra 2007/08, devido a semeadura ter sido realizada na época recomendada, a distribuição espacial dos percevejos começou simultaneamente em vários pontos na lavoura e não apresentou clara influência da entrada de adultos de outras áreas. Em ambas as safras o aumento das populações ocorreu a partir da formação de legumes e do início do enchimento de grãos e a abundância de espécies e seus picos populacionais variaram de uma safra para outra. Durante todo o período de entressafra, verificou-se a presença de percevejos na área, abrigados na palhada sobre o solo e alimentando-se de grãos caídos na colheita, ou em plantas hospedeiras alternativas como Raphanus sp. Com o objetivo de estudar o comportamento de ninfas e adultos de Piezodorus guildinii (Westwood, 1837) (Hemiptera: Pentatomidae) ao longo do dia em soja, foi conduzido um experimento na Universidade Federal de Santa Maria, de abril a maio de 2007. O delineamento experimental foi um fatorial de quarta ordem em blocos ao acaso (24x3x3x3) (horários x distribuição x localização x comportamentos), com cinco repetições. Os percevejos foram observados de hora em hora, por 24 horas. Registrou-se a sua distribuição nas plantas (terço superior, médio e inferior), a sua localização nos órgãos (legumes, folhas e HRPR haste, ramo, pecíolo ou racemo) e o seu comportamento (repouso, movimento e atividade alimentar). Durante o primeiro e segundo ínstares, as ninfas apresentaram hábito gregário, e uma pequena percentagem de ninfas em movimento em torno da postura. As ninfas começaram a alimentar-se no segundo ínstar, e tornaram-se mais ativas a partir do terceiro ínstar, movimentando-se não só a pequenas distâncias entre órgãos próximos, mas distribuindo-se pelos terços da planta, e alimentando-se mais regularmente. Os horários de movimento foram próximos e antecedentes aos horários de atividade alimentar, e do anoitecer, indicando a procura por locais para alimentação ou abrigo. Ninfas e adultos de P. guildinii localizaram-se preferencialmente em legumes, os quais estão associados aos comportamentos de repouso e atividade alimentar. No período noturno, com a temperatura do ar mais baixa que no período diurno, ninfas de P. guildinii se localizaram em hastes circundadas por legumes, em função da busca por locais abrigados. A percentagem de P. guildinii em atividade alimentar aumentou de 7,37% do segundo ao quarto ínstar para 16,92% no quinto ínstar, e 34,77% na fase adulta. P. guildinii permaneceu, preferencialmente, no terço médio das plantas ao longo do dia, não apresentando um comportamento claro de distribuição no terço superior das plantas em intervalos de horários definidos. Desta forma, não devem ser indicadas faixas de horário ideais para a aplicação de inseticidas para seu controle.

<p>Urban areas are warmer than surrounding rural areas. During the cold of winter, warming increases surrounding host temperature and may improve the overwintering survival of marginally hardy insects like evergreen bagworms. Similarly, during the summer, it has the potential to increase the fecundity and abundance of sap feeding insect pests such as scale insects in ways that change the capacity of their natural enemies to regulate their populations. </p> <p>Although in parts of Indiana winters can be cold enough to kill bagworm eggs, they thrive in cities. I conducted field experiments to determine the extent to which impervious surface near an infestation could keep temperatures warm enough to affect bagworm survival during cold of winter. My results suggest that the percentage of live eggs inside overwintering pupae decreased as ambient temperature drops. This response was moderated by the presence of impervious surface around an infested plant. Eggs found in bagworms collected from host trees surrounded by more impervious surface had a higher chance of survival than those collected from trees with low levels of hardscape. However, impervious surface has its limit such that egg mortality was not buffered by impervious surfaces at temperatures at or below -21.67°C. Similarly, I also conducted field experiments with sap feeding insects on honeylocust trees, a commonly planted tree in cities. Hot sites had a mean daily temperature more than 1.5 °C warmer than cool sites and scale insects were more abundant and fecund on trees in the hottest part of Indianapolis compared to cooler areas. No differences were observed in rates of parasitism on the scale insect. However, I found strong density dependence relation between parasitoids and scales abundance at scale density at or below the levels present in cool sites. The top-down regulation was prevalent at or below a critical density of scale hosts. Conversely, bottom-up regulation was prevalent above this host density as pests benefit from bottom-up factors. This suggests that urban habitats helped the scales to escape biological control by resident natural enemies above critical density of scale hosts. </p> <p>My findings can be useful to landscape designers to design landscapes that are less prone to insect pests. My finding adds to a growing body of evidence that suggests that planting urban trees with lesser amount of impervious surface can help reducing the urban warming effect and increase the regulation from natural enemies. </p>

From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / The importance of pine forest as a timber and water producing area has led to intensive management, including protection from wildfire. This has resulted in dense stand growth with increased destructive fire potential and transpirational water loss. In Arizona, as in many areas, prescribed forest burning has been used to effectively reduce these fuel hazards. Some question has arisen about the possible side effects of such treatments, particularly air pollution and reduction of infiltration and water yield. In an effort to determine the effects on infiltration, plots receiving various treatments (control, light burn, heavy burn) were fitted with fusion pyrometers before burning, to measure soil surface temperatures during burning. After burning, infiltrometers were installed. Surface temperatures did not exceed 200 degrees f. For the light burns, and ranged over 350-500 degrees f. During heavy burns. Both heavy and light burns produced highly significant decreases in infiltration capacities after burning and the surface 2 inches showed increases in soil pH, carbon and total nitrogen percentages. Infiltration capacities returned to normal after overwintering and were attributed to frost action on soil texture and porosity. The soil chemical changes decreased slowly over 2 years. Soil water repellency also increased and the significance of this is discussed.

No description available.