Chromosome length genome assembly of the redbanded stink bug, Piezodorus guildinii (Westwood).

Objective: The redbanded stink bug, Piezodorus guildinii (Hemiptera: Pentatomidae), is native to Caribbean Basin and is currently considered an invasive pest in Florida, Louisiana, Mississippi, and Texas in the southern United States. Although P. guildinii is an economically important invasive pest in the USA, a relatively few studies have been conducted to understand genetic, population genetic structure, and genetic basis of resistance to insecticides. The objective of this work was to obtain a high-quality genome assembly to develop genetic resources to conduct genetic, population genetic, and physiological studies of the RBSB. Results: The genome of RBSB was sequenced with Pacific Biosciences technology followed by two rounds of scaffolding using Chicago libraries and HiC proximity ligation to obtain a high-quality assembly. The genome assembly contained 800 scaffolds larger than 1 kbp and the N50 was 170.84 Mbp. The largest scaffold was 222.22 Mbp and 90% of the genome was included in the 7 scaffolds larger than 1 Mbp. The number of megabase scaffolds also matched the number of chromosomes in this insect. The genome sequence will facilitate the development of resources to conduct studies on genetics, transcriptomics, and physiology of RBSB.

Alkane-priming of Beauveria bassiana strains to improve biocontrol of the redbanded stink bug Piezodorus guildinii and the bronze bug Thaumastocoris peregrinus

Insect Epicuticle hydrocarbons (CHC) are known to be important determinants in the susceptibility degree of insects to fungal entomopathogens. Five Beauveria bassiana isolates were phenotypically analyzed regarding their response to CHC nutrition and their pathogenicity and virulence towards high fungal-susceptible Thaumastocoris peregrinus and low fungal-susceptible Piezodorus guildinii, which are important hemipteran pests in eucalyptus and soybean plantations, respectively. Two of these isolates, resulting the most (ILBB308) and the least (ILBB299) virulent to P. guildinii, were also evaluated at gene expression level after growth on n-pentadecane. B. bassiana most virulent isolate ILBB308 showed the lowest growth on most evaluated CHC media. However, this isolate distinctively induced most of the analyzed genes involved in CHC assimilation, cuticle degradation and stress tolerance. Virulence towards low susceptibility P. guildinii was enhanced in both hypervirulent ILB308 and hypovirulent ILBB299 isolates after growth on n-pentadecane as the sole carbon source, whereas virulence enhancement towards high susceptibility T. peregrinus was not observed in alkane-grown fungi. Virulence enhancement towards P. guildinii could be mostly explained by a priming effect produced by CHC on the induction of some genes related to hydrocarbon assimilation in ILB 205 and ILB 308, such as hydrophobin (Bbhyd2) and cytochrome P450 genes (BbCyp52g11 and BbCyp52x1), and partially by the induction of genes related to cuticle degradation (Bbchit and Bbcdep1) and stress tolerance (Bbsod1) observed only in ILB308.

Evaluating Behavioral Responses of Selected Stink Bugs (Hemiptera: Pentatomidae) to Spinosad

Southern green stink bug, Nezara viridula (L.) and redbanded stink bug, Piezodorus guildinii (Westwood) are two of the most important seed sucking pests affecting Louisiana soybean production and rice stink bug, Oebalus pugnax (F.) is an important late season pest in Louisiana rice. Exploration of chemicals that exhibit attraction or repellent activities toward major stink bug species would be beneficial in developing push–pull strategies. Spinosad is a commercially available natural insecticide that may have arrestant, attractant, or phagostimulant properties against stink bugs. To test this, a series of laboratory experiments were conducted to investigate the tactile, olfactory, and feeding responses of these stink bugs toward two commercial spinosad products (Entrust and Tracer) and technical grade spinosad. In tactile assays, female and male redbanded stink bug were arrested by Entrust, Tracer, and technical grade spinosad, whereas only rice stink bug and southern green stink bug males were arrested by Entrust. Y-tube assays revealed no attraction to any of the products by either male or female rice stink bug, redbanded stink bug, or southern green stink bug. In paired (treated or untreated soybean seed) feeding preference experiments, southern green stink bug showed no preference for any treatment, whereas redbanded stink bug fed more on Entrust- and Tracer-treated seed. From these results, spinosad appears to have an arrestant and phagostimulant effect on redbanded stink bug in the laboratory.