A scaffold-level genome assembly of a minute pirate bug, Orius laevigatus (Hemiptera: Anthocoridae), and a comparative analysis of insecticide resistance-related gene families with hemipteran crop pests

Background Orius laevigatus, a minute pirate bug, is a highly effective beneficial predator of crop pests including aphids, spider mites and thrips in integrated pest management (IPM) programmes. No genomic information is currently available for O. laevigatus, as is the case for the majority of beneficial predators which feed on crop pests. In contrast, genomic information for crop pests is far more readily available. The lack of publicly available genomes for beneficial predators to date has limited our ability to perform comparative analyses of genes encoding potential insecticide resistance mechanisms between crop pests and their predators. These mechanisms include several gene/protein families including cytochrome P450s (P450s), ATP binding cassette transporters (ABCs), glutathione S-transferases (GSTs), UDP-glucosyltransferases (UGTs) and carboxyl/cholinesterases (CCEs). Methods and findings In this study, a high-quality scaffold level de novo genome assembly for O. laevigatus has been generated using a hybrid approach with PacBio long-read and Illumina short-read data. The final assembly achieved a scaffold N50 of 125,649 bp and a total genome size of 150.98 Mb. The genome assembly achieved a level of completeness of 93.6% using a set of 1658 core insect genes present as full-length genes. Genome annotation identified 15,102 protein-coding genes - 87% of which were assigned a putative function. Comparative analyses revealed gene expansions of sigma class GSTs and CYP3 P450s. Conversely the UGT gene family showed limited expansion. Differences were seen in the distributions of resistance-associated gene families at the subfamily level between O. laevigatus and some of its targeted crop pests. A target site mutation in ryanodine receptors (I4790M, PxRyR) which has strong links to diamide resistance in crop pests and had previously only been identified in lepidopteran species was found to also be present in hemipteran species, including O. laevigatus. Conclusion and significance This assembly is the first published genome for the Anthocoridae family and will serve as a useful resource for further research into target-site selectivity issues and potential resistance mechanisms in beneficial predators. Furthermore, the expansion of gene families often linked to insecticide resistance may be an indicator of the capacity of this predator to detoxify selective insecticides. These findings could be exploited by targeted pesticide screens and functional studies to increase effectiveness of IPM strategies, which aim to increase crop yields by sustainably, environmentally-friendly and effectively control pests without impacting beneficial predator populations.

Investigation on the Natural Enemies of Jute Yellow Mite and Their Performances and Seasonal Incidence

The jute yellow mite Polyphagotarsonemus latus constitutes one of the major pests of jute crop in Bangladesh. The objective of this work was to investigation on the natural enemies of jute yellow mite. The investigation on the natural enemies of jute yellow mite were studied in the laboratory of Bangladesh Jute Research Institute during March 2011 to September 2013. As many as six predators of jute yellow mite viz, Predatory mite, Thrips, Minute pirate bug, Lady bird beetle, Mirid bug and Spider were collected and identified. The predation rate of the predatory mite Amblyseius sp. showed an average of 8.8 jute yellow mite per hour in laboratory condition. Predatory mite reached the peak on the 20th June. The highest population was 25 predatory mite/25 leaves. The population of predatory mite declined sharply in the 1st week of July. The nymph and adult of Scolothrips consumed an average of 15.4 and 20.10 yellow mite per hour. Scolothrips sp reached its peak population on 30th June and declined occurred in the 1st week of July. Both nymph and adult stage of Orius sp. predate 24.5 and 21 jute yellow mite respectively. The highest number of Minute pirate bug 20 was recorded at 30th June. Both the grubs and adults of lady bird beetle predate on all the stage of yellow mite. Grub was found as voracious feeder showing a predation efficiency of 35 per hour. The highest and lowest number of Ladybird beetle was recorded on 25th June and 5th May respectively. The highest 15 Mirid bug was recorded at 30th June. An unidentified species of spider was found to consume yellow mite.