Pyrrolizidine Alkaloids Negatively Affect A Generalist Herbivore Feeding On The Chemically Protected Legume Crotalaria Pallida

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Plant secondary metabolites can have opposing effects on adapted specialist and non-adapted, generalist herbivores. In this study, we used Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae) as a generalist, non-adapted model herbivore to test the possible effects of Crotalaria pallida (Fabaceae: Papilionoideae) defenses on herbivore performance. Neonate H. virescens larvae were able to consume C. pallida leaves and fruits and grow for a few instars, but none of them survived to pupation. We added isolated pyrrolizidine alkaloids (PAs) to an artificial diet at different concentrations, and PA concentration significantly affected the number of larvae that achieved pupation. Larval survival was not reduced at a PA concentration similar to the concentration on green seeds of C. pallida, but it was significantly reduced at PA concentration 5 and 100 times higher. These results suggest that PAs in isolation are not the defense responsible for the mortality in fresh C. pallida plants, indicating the importance of other possible defenses. The negative effect of PAs on fitness of the non-adapted, generalist herbivore is in agreement with few previous studies, but it is in clear contrast to a previous study on the effects of PAs on the adapted specialist herbivore Utetheisa ornatrix (L.) that were able to sequester PAs with no fitness costs.45252257NSF [DEB 0807418]FAPESP [11/17708-0]CNPq [306103/2013-3]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Pyrrolizidine Alkaloids Negatively Affect A Generalist Herbivore Feeding On The Chemically Protected Legume Crotalaria Pallida

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Plant secondary metabolites can have opposing effects on adapted specialist and non-adapted, generalist herbivores. In this study, we used Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae) as a generalist, non-adapted model herbivore to test the possible effects of Crotalaria pallida (Fabaceae: Papilionoideae) defenses on herbivore performance. Neonate H. virescens larvae were able to consume C. pallida leaves and fruits and grow for a few instars, but none of them survived to pupation. We added isolated pyrrolizidine alkaloids (PAs) to an artificial diet at different concentrations, and PA concentration significantly affected the number of larvae that achieved pupation. Larval survival was not reduced at a PA concentration similar to the concentration on green seeds of C. pallida, but it was significantly reduced at PA concentration 5 and 100 times higher. These results suggest that PAs in isolation are not the defense responsible for the mortality in fresh C. pallida plants, indicating the importance of other possible defenses. The negative effect of PAs on fitness of the non-adapted, generalist herbivore is in agreement with few previous studies, but it is in clear contrast to a previous study on the effects of PAs on the adapted specialist herbivore Utetheisa ornatrix (L.) that were able to sequester PAs with no fitness costs.453252257NSF [DEB 0807418]FAPESP [11/17708-0]CNPq [306103/2013-3]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Mucche in rivolta

La breve graphic novel firmata da Francesca Cogni affronta le tematiche del numero prendendo spunto dal caso di una mandria di mucche fuggita da una allevamento

Complex Coding and Regulatory Polymorphisms in a Restriction Factor Determine the Susceptibility of Drosophila to Viral Infection.

It is common to find that major-effect genes are an important cause of variation in susceptibility to infection. Here we have characterized natural variation in a gene called pastrel that explains over half of the genetic variance in susceptibility to the Drosophila C virus (DCV) in populations of Drosophila melanogaster We found extensive allelic heterogeneity, with a sample of seven alleles of pastrel from around the world conferring four phenotypically distinct levels of resistance. By modifying candidate SNPs in transgenic flies, we show that the largest effect is caused by an amino acid polymorphism that arose when an ancestral threonine was mutated to alanine, greatly increasing resistance to DCV. Overexpression of the ancestral, susceptible allele provides strong protection against DCV; indicating that this mutation acted to improve an existing restriction factor. The pastrel locus also contains complex structural variation and cis-regulatory polymorphisms altering gene expression. We find that higher expression of pastrel is associated with increased survival after DCV infection. To understand why this variation is maintained in populations, we investigated genetic variation surrounding the amino acid variant that is causing flies to be resistant. We found no evidence of natural selection causing either recent changes in allele frequency or geographical variation in frequency, suggesting that this is an old polymorphism that has been maintained at a stable frequency. Overall, our data demonstrate how complex genetic variation at a single locus can control susceptibility to a virulent natural pathogen

Ants nesting on Cecropia purpurascens (Cecropiaceae) in central Amazonia: Influence of tree height, domatia volume and food bodies

Patterns of presence of ant colonies on Cecropia purpurascens CC Berg (Cecropiaceae) were investigated in central Amazonia. All individuals of C. purpurascens along a 14.3 km transect were searched for ants and their height, internode volume, and number of trichilia were recorded. Of the 50 C. purpurascens individuals studied, 32 (64%) were colonized by ants of four species: Azteca alfari Emery (Dolichoderinae) (N = 16), Camponotus balzani Emery (Formicinae) (N = 14), C. abdominalis (Fabricius) (Formicinae) (N = 1) and Crematogaster brasiliensis Mayr (Myrmicinae) (N = 1). Probability of C. purpurascens being colonized by ants increases with tree height, internode volume, and trichilium number. Of the three variables recorded, tree height was the most important in determining the presence of ants. Trees colonized by the two most common ant species (A. alfari and C. balzani) did not differ in height, internode volume, or number of trichilia. The patterns observed, the association between the identity of the ants and plant fitness, as well as the usefulness of this particular system for future studies are discussed.42371972

The genetic architecture of resistance to virus infection in Drosophila.

Variation in susceptibility to infection has a substantial genetic component in natural populations, and it has been argued that selection by pathogens may result in it having a simpler genetic architecture than many other quantitative traits. This is important as models of host-pathogen co-evolution typically assume resistance is controlled by a small number of genes. Using the Drosophila melanogaster multiparent advanced intercross, we investigated the genetic architecture of resistance to two naturally occurring viruses, the sigma virus and DCV (Drosophila C virus). We found extensive genetic variation in resistance to both viruses. For DCV resistance, this variation is largely caused by two major-effect loci. Sigma virus resistance involves more genes - we mapped five loci, and together these explained less than half the genetic variance. Nonetheless, several of these had a large effect on resistance. Models of co-evolution typically assume strong epistatic interactions between polymorphisms controlling resistance, but we were only able to detect one locus that altered the effect of the main effect loci we had mapped. Most of the loci we mapped were probably at an intermediate frequency in natural populations. Overall, our results are consistent with major-effect genes commonly affecting susceptibility to infectious diseases, with DCV resistance being a near-Mendelian trait.European Research Council (Grant ID: DrosophilaInfection 281668), NERC (Grant ID: NE/L004232/1), São Paulo Research Foundation (FAPESP) (Grant IDs: 2015/08307-3, 2013/ 25991-0), Cambridge Commonwealth, European & International Trust, China Scholarship CouncilThis is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1111/mec.1376

Recruitment Behavior During Foraging in the Neotropical Ant Gnamptogenys moelleri (Formicidae: Ponerinae): Does the Type of Food Matter?

Gnamptogenys moelleri nests in bromeliads and feeds on an array of food items, including dead and live animals, and nectar. Field data in Brazilian forests indicate that G. moelleri hunts solitarily, while retrieving is performed both by solitary workers for small items, or by a group of recruited workers for large items. This flexible foraging strategy was investigated in the laboratory through a series of experiments to assess the context in which recruitment is elicited. Three types of food were used: 50% honey solution, large insect prey, and cluster of small insects. For all food types the first encounter by a scout resulted in increased numbers of ants leaving the nest and finding the food in the arena. After finding liquid food or large prey, the forager returns to the nest and transmits information to nestmates about food location on the substrate. The successful scout repeatedly taps the sting on the ground, and recruited ants collectively retrieve the large insect to the nest. On the other hand, there is no transmission of information to nestmates about the location of small clumped prey, although the returning scout induces nestmates to leave the nest and hunt. Because foraging in G. moelleri is restricted mostly to the nest bromeliad, and small worker size (0.5 cm) precludes capturing large prey solitarily, recruitment behavior widens the spectrum of food items consumed by this ant species. Although recruitment behavior in ponerines has already been reported to vary with the type and size of a food source, this study also shows that the transmission of information about food location depends on the type of food found (large prey or liquid food versus cluster of small prey).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44946/1/10905_2004_Article_492406.pd

Ants Nesting on Cecropia purpurascens (Cecropiaceae) in Central Amazonia: Influence of Tree Height, Domatia Volume and Food Bodies

Patterns of presence of ant colonies on Cecropia purpurascens CC Berg (Cecropiaceae) were investigated in central Amazonia. All individuals of C. purpurascens along a 14.3 km transect were searched for ants and their height, internode volume, and number of trichilia were recorded. Of the 50 C. purpurascens individuals studied, 32 (64%) were colonized by ants of four species: Azteca alfari Emery (Dolichoderinae) (N = 16), Camponotus balzani Emery (Formicinae) (N = 14), C. abdominalis (Fabricius) (Formicinae) (N = 1) and Crematogaster brasiliensis Mayr (Myrmicinae) (N = 1). Probability of C. purpurascens being colonized by ants increases with tree height, internode volume, and trichilium number. Of the three variables recorded, tree height was the most important in determining the presence of ants. Trees colonized by the two most common ant species (A. alfari and C. balzani) did not differ in height, internode volume, or number of trichilia. The patterns observed, the association between the identity of the ants and plant fitness, as well as the usefulness of this particular system for future studies are discussed