Populational Fluctuation and Distribution of Epitrix spp.Foudras(Coleoptera:Chrysomelidae)in the Organic Tobacco Management in Santa Cruz do Sul,RS,Brazil

Among the chrysomelids, some species are considered agricultural pests, such as some representatives of Epitrix spp. Popularly known as tobacco flea, these beetles cause damage to tobacco (Nicotiana tabacum L.) by feeding on the leaf surface, causing injuries, reducing productivity and the final quality of the product to be marketed. However, studies of the biology and interactions of these individuals with the environment become essential in order to develop effective and sustainable control measures. The objective of this study was to analyze the distribution and population fluctuation of Epitrix spp., as well as to evaluate the possible influence of temperature, rainfall and adjacent vegetation on the population dynamics of this beetle in organic tobacco growing in the municipality of Santa Cruz of the South, RS. The collections were carried out weekly during the 2011/2012 harvest, using Malaise and Pit-fall traps, distributed in four points along three lines. A total of 1584 individuals belonging to the genus Epitrix were collected, and their greatest abundance was observed in late January and early February 2012 due to climatic factors, such as rainfall and temperature, favorable to the development of specimens and the tobacco leaf harvesting reduced the availability of food and conditioned a greater movement of these individuals in the crop. The results presented here are of great importance for deciding the best methodology for controlling the smoke flea, as well as knowing the influence of abiotic factors on the behavior of these organisms in the field.

Inheritance patterns of secondary symbionts during sexual reproduction of pea aphid biotypes

Herbivorous insects frequently harbor bacterial symbionts that affect their ecol- ogy and evolution. Aphids host the obligatory endosymbiont Buchnera, which is requiredfor reproduction, together with facultative symbionts whose frequencies vary across aphid populations. These maternally transmitted secondary symbionts have been particularlystudied in the pea aphid, Acyrthosiphon pisum, which harbors at least 8 distinct bacterial species （not counting Buchnera） having environmentally dependent effects on host fitness.In particular, these symbiont species are associated with pea aphid populations feeding on specific plants. Although they are maternally inherited, these bacteria are occasionallytransferred across insect lineages. One mechanism of such nonmaternal transfer is paternal transmission to the progeny during sexual reproduction. To date, transmission of secondarysymbionts during sexual reproduction of aphids has been investigated in only a handful of aphid lineages and 3 symbiont species. To better characterize this process, we investigatedinheritance patterns of 7 symbiont species during sexual reproduction of pea aphids through a crossing experiment involving 49 clones belonging to 9 host-specialized biotypes, and117 crosses. Symbiont species in the progeny were detected with diagnostic qualitative PCR at the fundatrix stage hatching from eggs and in later parthenogenetic generations.We found no confirmed case of paternal transmission of symbionts to the progeny, and we observed that maternal transmission of a particular symbiont species （Serratia symbiotica）was quite inefficient. We discuss these observations in respect to the ecology of the pea aphid.

Plant-herbivorous insect networks: who is eating what revealed by long barcodes using high-throughput sequencing and Trinity assembly

Interactions between plants and insects are among the most important life functions for all organism at a particular natural community.Usually a large number of samples are required to identify insect diets in food web studies.Previously,Sanger sequencing and next generation sequencing(NGS)with short DNA barcodes were used,resulting in low species-level identification;meanwhile the costs of Sanger sequencing are expensive for metabarcoding together with more samples.Here,we present a fast and effective sequencing strategy to identify larvae of Lepidoptera and their diets at the same time without increasing the cost on Illumina platform in a single HiSeq run,with long-multiplexmetabarcoding(COI for insects,rbcL,matK,ITS and trnL for plants)obtained by Trinity assembly(SHMMT).Meanwhile,Sanger sequencing(for single individuals)and NGS(for polyphagous)were used to verify the reliability of the SHMMT approach.Furthermore,we show that SHMMT approach is fast and reliable,with most high-quality sequences of five DNA barcodes of 63 larvae individuals(54 species)recovered(full length of 100%of the COI gene and 98.3%of plant DNA barcodes)using Trinity assembly(up-sized to 1015 bp).For larvae diets identification,95%are reliable;the other 5%failed because their guts were empty.The diets identified by SHMMT approach are 100%consistent with the host plants that the larvae were feeding on during our collection.Our study demonstrates that SHMMT approach is reliable and cost-effective for insect-plants network studies.This will facilitate insect-host plant studies that generally contain a huge number of samples.

Comparative analyses of the venom components in the salivary gland transcriptomes and saliva proteomes of some heteropteran insects

Salivary gland-specific transcriptomes of nine heteropteran insects with distinct feeding strategies (predaceous, hematophagous, and phytophagous) were analyzed and annotated to compare and identify the venom components as well as their expression profiles. The transcriptional abundance of venom genes was verified via quantitative real-time PCR. Hierarchical clustering of 30 representative differentially expressed venom genes from the nine heteropteran species revealed unique groups of salivary gland-specific genes depending on their feeding strategy. The commonly transcribed genes included a paralytic neurotoxin (arginine kinase), digestive enzymes (cathepsin and serine protease), an anti-inflammatory protein (cystatin), hexamerin, and an odorant binding protein. Both predaceous and hematophagous (bed bug) heteropteran species showed relatively higher transcription levels of genes encoding proteins involved in proteolysis and cytolysis, whereas phytophagous heteropterans exhibited little or no expression of these genes, but had a high expression of vitellogenin, a multifunctional allergen. Saliva proteomes from four representative species were also analyzed. All venom proteins identified via saliva proteome analysis were annotated using salivary gland transcriptome data. The proteomic expression profiles of venom proteins were in good agreement with the salivary gland-specific transcriptomic profiles. Our results indicate that profiling of the salivary gland transcriptome provides important information on the composition and evolutionary features of venoms depending on their feeding strategy.