Search for: All records

ABSTRACT Most mosquito species are anautogenous, which means they must blood feed on a vertebrate host to produce eggs, while a few are autogenous and can produce eggs without blood feeding. Egg formation is best understood in the anautogenous mosquito Aedes aegypti, where insulin-like peptides (ILPs), ovary ecdysteroidogenic hormone (OEH) and 20-hydroxyecdysone (20E) interact to regulate gonadotrophic cycles. Circulating hemocytes also approximately double in abundance in conjunction with a gonadotrophic cycle, but the factors responsible for stimulating this increase remain unclear. Focusing on Ae. aegypti, we determined that hemocyte abundance similarly increased in intact blood-fed females and decapitated blood-fed females that were injected with ILP3, whereas OEH, 20E or heat-killed bacteria had no stimulatory activity. ILP3 upregulated insulin-insulin growth factor signaling in hemocytes, but few genes – including almost no transcripts for immune factors – were differentially expressed. ILP3 also stimulated circulating hemocytes to increase in two other anautogenous (Anopheles gambiae and Culex quinquefasciatus) and two facultatively autogenous mosquitoes (Aedes atropalpus and Culex pipiens molestus), but had no stimulatory activity in the obligately autogenous mosquito Toxorhynchites amboinensis. Altogether, our results identify ILPs as the primary regulators of hemocyte proliferation in association with egg formation, but also suggest this response has been lost in the evolution of obligate autogeny. 

The parasitoid wasp Muscidifurax raptorellus (Hymenoptera: Pteromalidae) is a gregarious species that has received extensive attention for its potential in biological pest control against house fly, stable fly, and other filth flies. It has a high reproductive capacity and can be reared easily. However, genome assembly is not available for M. raptorellus or any other species in this genus. Previously, we assembled a complete circular mitochondrial genome with a length of 24,717 bp. Here, we assembled and annotated a high-quality nuclear genome of M. raptorellus , using a combination of long-read (104× genome coverage) and short-read (326× genome coverage) sequencing technologies. The assembled genome size is 314 Mbp in 226 contigs, with a 97.9% BUSCO completeness score and a contig N50 of 4.67 Mb, suggesting excellent continuity of this assembly. Our assembly builds the foundation for comparative and evolutionary genomic analysis in the genus of Muscidifurax and possible future biocontrol applications. 

Jewel wasps in the genus of Nasonia are parasitoids with haplodiploidy sex determination, rapid development and are easy to culture in the laboratory. They are excellent models for insect genetics, genomics, epigenetics, development, and evolution. Nasonia vitripennis ( Nv ) and N. giraulti ( Ng ) are closely-related species that can be intercrossed, particularly after removal of the intracellular bacterium Wolbachia , which serve as a powerful tool to map and positionally clone morphological, behavioral, expression and methylation phenotypes. The Nv reference genome was assembled using Sanger, PacBio and Nanopore approaches and annotated with extensive RNA-seq data. In contrast, Ng genome is only available through low coverage resequencing. Therefore, de novo Ng assembly is in urgent need to advance this system. In this study, we report a high-quality Ng assembly using 10X Genomics linked-reads with 670X sequencing depth. The current assembly has a genome size of 259,040,977 bp in 3,160 scaffolds with 38.05% G-C and a 98.6% BUSCO completeness score. 97% of the RNA reads are perfectly aligned to the genome, indicating high quality in contiguity and completeness. A total of 14,777 genes are annotated in the Ng genome, and 72% of the annotated genes have a one-to-one ortholog in the Nv genome. We reported 5 million Ng-Nv SNPs which will facility mapping and population genomic studies in Nasonia . In addition, 42 Ng -specific genes were identified by comparing with Nv genome and annotation. This is the first de novo assembly for this important species in the Nasonia model system, providing a useful new genomic toolkit. 

The stable fly,Stomoxys calcitrans, is a major blood-feeding pest of livestock that has near worldwide distribution, causing an annual cost of over $2 billion for control and product loss in the USA alone. Control of these flies has been limited to increased sanitary management practices and insecticide application for suppressing larval stages. Few genetic and molecular resources are available to help in developing novel methods for controlling stable flies.

This study examines stable fly biology by utilizing a combination of high-quality genome sequencing and RNA-Seq analyses targeting multiple developmental stages and tissues. In conjunction, 1600 genes were manually curated to characterize genetic features related to stable fly reproduction, vector host interactions, host-microbe dynamics, and putative targets for control. Most notable was characterization of genes associated with reproduction and identification of expanded gene families with functional associations to vision, chemosensation, immunity, and metabolic detoxification pathways.

The combined sequencing, assembly, and curation of the male stable fly genome followed by RNA-Seq and downstream analyses provide insights necessary to understand the biology of this important pest. These resources and new data will provide the groundwork for expanding the tools available to control stable fly infestations. The close relationship ofStomoxysto other blood-feeding (horn flies andGlossina) and non-blood-feeding flies (house flies, medflies,Drosophila) will facilitate understanding of the evolutionary processes associated with development of blood feeding among the Cyclorrhapha.