Parasite diversity and ecology in a model species, the guppy (Poecilia reticulata) in Trinidad.

The guppy (Poecilia reticulata) is a model species in ecology and evolution. Many studies have examined effects of predators on guppy behaviour, reproduction, survival strategies, feeding and other life-history traits, but few have studied variation in their parasite diversity. We surveyed parasites of 18 Trinidadian populations of guppy, to provide insight on the geographical mosaic of parasite variability, which may act as a source of natural selection acting on guppies. We found 21 parasite species, including five new records for Trinidad. Spatial variation in parasite diversity was significantly higher than that of piscine predators, and significant variation in parasite richness among individuals and populations was correlated with: (i) host size, (ii) snail species richness, and (iii) the distance between populations. Differences in parasite species richness are likely to play an important, yet underestimated role in the biology of this model species of vertebrate ecology and evolution.

Raccoon social networks and the potential for disease transmission.

Raccoons are an important vector of rabies and other pathogens. The degree to which these pathogens can spread through a raccoon population should be closely linked to association rates between individual raccoons. Most studies of raccoon sociality have found patterns consistent with low levels of social connectivity within populations, thus the likelihood of direct pathogen transmission between raccoons is theoretically low. We used proximity detecting collars and social network metrics to calculate the degree of social connectivity in an urban raccoon population for purposes of estimating potential pathogen spread. In contrast to previous assumptions, raccoon social association networks were highly connected, and all individuals were connected to one large social network during 15 out of 18 months of study. However, these metrics may overestimate the potential for a pathogen to spread through a population, as many of the social connections were based on relatively short contact periods. To more closely reflect varying probabilities of pathogen spread, we censored the raccoon social networks based on the total amount of time spent in close proximity between two individuals per month. As this time criteria for censoring the social networks increased from one to thirty minutes, corresponding measures of network connectivity declined. These findings demonstrate that raccoon populations are much more tightly connected than would have been predicted based on previous studies, but also point out that additional research is needed to calculate more precise transmission probabilities by infected individuals, and determine how disease infection changes normal social behaviors.

Bollgard cotton and resistance of tobacco budworm (Lepidoptera: Noctuidae) to conventional insecticides in southern Tamaulipas, Mexico.

Insecticide susceptibility in tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae), was determined for 8 yr (1991-2001) with larvae sampled from cotton in southern Tamaulipas, Mexico. Before 1996, when Bollgard cotton expressing the Cry1A(c) delta-endotoxin was introduced into the region, two important patterns were documented. The first was economically significant increases in resistance to certain insecticide groups. The second was occurrence of virtually complete control failures in the field during 1994 and 1995. The largest resistance changes were recorded for the type II pyrethroids cypermethrin and deltamethrin. These products are the most widely used products in the region. Resistance ratios for these products increased up to > 100-fold from 1991 to 1995. After 1996, the resistance levels declined. These findings did not occur with other products of scant use (e.g., permethrin, profenofos, and endosulfan) or low tobacco budworm efficacy coupled to a high use pattern (e.g., methyl parathion). This clear trend toward reversal of resistance to type II pyrethroids can be understood, in part, with respect to two factors: 1) the high adoption rate of transgenic cotton in the region, from 31.2% in the beginning (1996) to approximately 90% in 1998; this has considerably curbed the use of synthetic insecticides, with the attending loss of selection pressure on this pest; and 2) the potential immigration to the region of susceptible tobacco budworms from cultivated and wild suitable hosts as well as from transgenic cotton might have influenced the pest population as a whole. The influence of transgenic cotton on southern Tamaulipas can be more clearly seen by the drastic reduction of insecticide use to control this important pest. Now tobacco budworms in this region are susceptible to type II pyrethroids. Two effective and fundamentally different pest management tools are now available to cotton growers in southern Tamaulipas: transgenic cotton, coupled with careful use of pyrethroids, offers the possibility of sustainable and profitable cotton production.

The uses of pollen and its implication for Entomology / Os usos do pólen e suas implicações na Entomologia

Palinologia é o estudo dos grãos de pólen produzidos por plantas sementeiras (angiospermas e gimnospermas) e esporos (pteridófitas, briófitas, algas e fungos). O pólen representa a flora terrestre e pode ser útil em muitas disciplinas: é único, não deteriora facilmente e é um marcador natural. O pólen pode ser usado para determinar os mecanismos de polinização, os recursos de forrageamento, as rotas de migração e locais fontes de insetos e outros polinizadores. O pólen fornece meios para análises paleoambientais de rochas terrestres sendo de interesse de geólogos. Também auxilia a explicar as correlações de ambientes terrestres com as sucessões marítimas e é usado para determinar trocas ecológicas e ambientais. Recentemente, a palinologia tem sido utilizada nos meios forenses. Esse artigo introduz a idéia do uso do pólen em várias disciplinas e, em particular, na entomologia.

Palynology is the study of pollen grains produced by seed plants (angiosperms and gymnosperms) and spores (pteridophytes, bryophytes, algae and fungi). It represents the land flora and can be use in many different disciplines. Pollen is distinctive, does not easily decay and is a natural marker. Pollen can be used to determine pollination mechanisms, foraging resources, migration routes and source zones of insects and other pollinators. It provides a means for paleoenvironmental analyses of terrestrial rocks and is of interest to geologists. Pollen also aids in the correlation of terrestrial with marine successions and is used to determine environmental and ecological changes. Recently, palynology is used in forensics. This manuscript introduces the ideas of using pollen in a variety of disciplines, in particular in entomology.