In Louisiana during the last decade, the redbanded stink bug, Piezodorus guildinii (Westwood), has become a significant and yield-limiting pest of so

The redbanded stink bug, Piezodorus guildinii (Westwood) (Hemiptera: Heteroptera: Pentatomidae), is a rapidly growing pest damaging southern US agriculture. Pentatomid stink bugs are known to vector bacterial, fungal, and viral plant diseases. However, bacteria associated with redbanded stink bugs and their vector potential have not yet been assessed. In this study, we 1) cultured and identified bacteria transmitted by feeding of redbanded stink bug and 2) described bacteria from guts of redbanded stink bug individuals using next-generation sequencing of 16S rRNA genes. Nineteen bacteria transmitted by feeding of redbanded stink bug on soybean agar were isolated and identified via Sanger sequencing of near full length 16S RNA genes. The transmitted bacteria belonged to at least a dozen species in eight genera and included potential plant pathogens (Phaseolibacter flectens), plant beneficials (Bacillus atropheus), and possible insect beneficials (Acinetobacter sp. and Citrobacter farmeri). A total of 284,448 reads were captured from Illumina MiSeq sequencing of the uncultured gut bacteria community. Fifty-one putative bacteria species (74% of the estimated total species richness) were identified via matches to NCBI databases. The bacteria metagenome contained potential plant and insect pathogens (Erwinia persicina, E. rhaponici, Brenneria nigrifluens, Ralstonia picketti, and Serratia marcescens) and beneficials (Pantoea dispersa, Klebsiella oxytoca, Clostridium butyricum, and Citrobacter farmeri).

The soybean looper, Chrysodeixis includens (Walker) (Lepidoptera: Noctuidae), is a major defoliating pest of soybeans, Glycine max (L.) Merrill, in Louisiana. However, other alternate host crops in the agroecosystem have the potential to impact C. includens populations. Life table statistics of C. includens on four host plants were evaluated. C. includens larvae were fed leaves of three cotton Gossypium hirsutum L. cultivars ‘DP 143 B2RF,’ ‘DP 174 RF,’ and ‘PHY 485 WRF’; cowpea Vigna unguiculata (L.) Walpers ‘California Blackeye’; three soybean cultivars ‘Lyon,’ ‘PI 227687,’ and ‘RC 4955’; and sweetpotato Ipomoea batatas (L.) Lamarck ‘Evangeline.’ All C. includens larvae reared on cotton cultivars DP 143 B2RF and PHY 485 WRF experienced 100% mortality during the first instar. Total developmental period of preadult C. includens was significantly shorter on cotton DP 174 RF and cowpea California Blackeye but longer on sweetpotato Evangeline. Sweetpotato Evangeline had the highest amount of leaf tissue consumed and soybean Lyon had the least. Pupal weight was highest when insects fed on cotton DP 174 RF and lowest on soybean PI 227687. Life table statistics showed that the highest intrinsic rate of increase and net reproductive rate were attained when insects were reared on cotton DP 174 RF and cowpea California Blackeye whilst the lowest were recorded on soybean PI 227687. This study provides valuable information on the role of alternative host crops on the partial life history of C. includens in Louisiana agroecosystems.

The sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), is an invasive pest of grain sorghum, Sorghum bicolor (L.) Moench (Poaceae). Since its first outbreak in sorghum in 2013, severe infestations have spread throughout the southern USA, causing major economic losses. Whereas insecticide applications can mitigate some of the pest's impacts, a sustainable ecology-based management program is needed to reduce reliance on chemical control. Two greenhouse assays examined the influence of selected host plant characteristics on M. sacchari life table parameters. We studied the effects of silicon (rates equivalent to 0 and 3,360 kg silicon per ha) and nitrogen (rates equivalent to 0, 110, and 224 kg nitrogen per ha) on M. sacchari growth and reproduction on a susceptible cultivar (SP 7868) in 2 phenological stages (5-leaf stage and boot stage). A second experiment examined the same silicon and nitrogen treatments on resistant (DKS 37-07) and susceptible (DKS 38-88) cultivars of grain sorghum. We calculated M. sacchari life table parameters including the intrinsic rate of increase, finite rate of increase, doubling time, and mean generation time for each treatment. Aphid population growth parameters were greater for plants in the 5-leaf stage than in the boot stage. In both experiments, nitrogen fertilization had a positive effect on M. sacchari fecundity, but effects of nitrogen on other parameters were less consistent. Silicon had a negative effect on life table parameters on sorghum plants in the boot stage, but effects were not consistent across treatments. Sorghum cultivar DKS 37-07 showed a high level of resistance, because no aphids survived to adulthood. These results suggest that resistant sorghum cultivars and nitrogen management could have a role in integrated pest management of M. sacchari.