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There is increasing evidence that acylsugars deter insect pests and plant virus vectors, including the western flower thrips (WFT), Frankliniella occidentalis (Pergande), vector of tomato spotted wilt virus (TSWV). Acylsugars are sugar-polyesters composed of saturated, un-saturated, and variously branched short and long chain fatty acids (FAs) esterified to a glucose (acylglucose) or sucrose (acylsucrose) moiety. We sought to understand how acylsucrose amount and composition of associated FA profiles interacted to mediate resistance to WFT oviposition and TSWV inoculation on tomato leaves. Towards this goal, we examined WFT oviposition and TSWV inoculation behavior on tomato lines bred to exude varying amounts of acylsucrose in association with diverse FA profiles. Our data show that as acylsucrose amounts increased, WFT egg-laying (oviposition) decreased and TSWV inoculation was suppressed. Western flower thrips also responded to FA profiles that included iC4, iC11, nC12 and nC10 FA. These findings support improving acylsugar-mediated resistance against WFT by breeding tomatoes exuding greater amounts of acylsucrose associated with specific FA profiles. We show that increasing acylsucrose amount output by type IV trichomes and selecting for particular FA profiles through advanced breeding profoundly affects WFT behavior in ways that benefit management of WFT as direct pests and as TSWV vectors.

Insect trap networks targeting agricultural pests are commonplace but seldom optimized to improve precision or efficiency. Trap site selection is often driven by user convenience or predetermined trap densities relative to sensitive host crop abundance in the landscape. Monitoring for invasive pests often requires expedient decisions based on dispersal potential and ecology to inform trap placement. Optimization of trap networks using contemporary analytical approaches can help users determine the distribution of traps as information accumulates and priorities change. In this study, a Bayesian optimization (BO) algorithm was used to learn more about the optimal distribution of a fine-scale trap network targeting Helicoverpa zea (Boddie), a significant agricultural pest across North America. Four years of pheromone trap monitoring was conducted at the same 21 locations distributed across ~7,000 square kilometers in a five-county area in North Carolina, USA. Three years of data were used to train a BO model with a fourth year designated for testing. For any quantity of trap locations, the approach identified those that provide the most information, allowing optimization of trapping efficiency given either a constraint on the number of locations, or a set precision required for pest density estimation. Results suggest that BO is a powerful approach to enable optimized trap placement decisions by practitioners given finite resources and time. [ABSTRACT FROM AUTHOR]

Colletotrichum is a globally significant genus of plant pathogens known for causing anthracnose across a diverse array of hosts. Notably, Colletotrichum graminicola is a pathogen affecting maize. Annually, the global economic impact of this pathogen reaches billions of US dollars. C. graminicola produces conidia that have a characteristic falcate shape and are dispersed by rain. Upon attachment to maize leaves, these conidia develop melanized appressoria to penetrate the leaf surface to initiate disease. Recent findings have emphasized the existence of an adhesive strip on only one side of C. graminicola conidia. This strip colocalizes with an actin array, playing a crucial role in facilitating attachment and germination. This asymmetrical adhesive was postulated to enhance spore dispersal by assuring that some conidia do not attach to their initial deposition site. The extent of this asymmetric adhesive phenotype in other Colletotrichum species remains unknown, raising questions about its conservation within the genus. This study reveals the ubiquitous presence of an asymmetric adhesive on the conidia across nine isolates of Colletotrichum , representing eight species. Morphological differences in conidium shape and adhesive distribution were observed. Significantly, Colletotrichum truncatum is unique from other observed species by exhibiting an adhesive strip on both sides of its conidium. Furthermore, in C. graminicola , we noted a simultaneous development of the actin array and detachment from its mother cell after spore development. We posit that the study of other Colletotrichum members holds promise in elucidating the evolutionary trajectory of this phenotype. Furthermore, these insights may prove instrumental in understanding spore dispersal dynamics across diverse hosts, shedding light on the intricate web of host specificity within the genus. [ABSTRACT FROM AUTHOR]

Tomatoes (Solanum lycopersicum L.) have been bred to exude higher amounts or different types of the specialized plant metabolites, acylsugars, from type IV trichomes. Acylsugars are known to deter several herbivorous insect pests, including the western flower thrips (WFT), Frankliniella occidentalis (Pergande); however, all previous studies investigated the effect of acylsugars on leaves, or acylsugar extracts obtained from leaves. In spite of the WFT predilection for flowers, there is a gap in knowledge about flower defenses against thrips damage. This is especially important in light of their capacity to acquire and inoculate viruses in the genus Orthotospovirus, such as Tomato spotted wilt orthotospovirus (TSWV), in flowers. Therefore, we turned our attention to assessing thrips oviposition differences on flowers of 14 entries, including 8 interspecific hybrids, 5 tomato lines bred for specific acylsugar-related characteristics (type IV trichome densities, acylsugar amount, sugar moiety and fatty acid profile), and a fresh market tomato hybrid, Mt. Spring, which only produces trace amounts of acylsugars. Our results show that the density of the acylsugar droplet bearing type IV trichomes is greatest on sepals, relative to other flower structures, and accordingly, WFT avoids oviposition on sepals in favor of trichome-sparse petals. In concordance with past studies, acylsugar amount was the most important acylsugar-related characteristic suppressing WFT oviposition. Certain acylsugar fatty acids, specifically i-C5, i-C9 and i-C11, were also significantly associated with changes in WFT oviposition. These results support continued breeding efforts to increase acylsugar amounts and explore modifications of fatty acid profile and their roles in deterring thrips oviposition. The finding that acylsugar production occurs and reduces thrips oviposition in tomato flowers will be important in efforts to use acylsugar-mediated resistance to reduce incidence of orthotospoviruses such as TSWV in tomato by deterring virus transmission and development of thrips vector populations in the crop.

Previously, it has been shown that transmissible and harmful misinformation can be viewed as pathogenic, potentially contributing to collective social epidemics. In this study, a biological analogy is developed to allow investigative methods that are applied to biological epidemics to be considered for adaptation to digital and social ones including those associated with misinformation. The model's components include infopathogens, tropes, cognition, memes, and phenotypes. The model can be used for diagnostic, pathologic, and synoptic/taxonomic study of the spread of misinformation. A thought experiment based on a hypothetical riot is used to understand how disinformation spreads. [ABSTRACT FROM AUTHOR]

Simple Summary: Historically, the pesticidal Bacillus thuringiensis proteins in transgenic cotton cultivars have shown no activity on mirid pests such as the cotton fleahopper. Therefore, control options are limited to foliar applied insecticides, which are often not optimized for reducing potential yield losses. With the inclusion of the Mpp51Aa2 protein, termed ThryvOn, damage from cotton fleahopper feeding can be mitigated. While the effect of the protein has been observed in field studies, there is a limited understanding of the interaction of the protein and the insect. Therefore, the focus of this study was the use of electropenetrography to monitor the feeding behaviors of the cotton fleahopper on both ThryvOn and a non-ThryvOn cotton cultivars. We found that although attempts were made by insects to feed on ThryvOn cotton, they exhibited shorter durations of plant fluid ingestion when feeding. Additionally, the percentage of ingestion events per insect that were sustained was lower. These findings indicate potential damage to the insect gut, consistent with the known symptoms associated with the activity of Bt proteins. Prior to the recent implementation of the Mpp51Aa2 pesticidal protein (ThryvOn), transgenic cotton cultivars have historically offered no control of the cotton fleahopper (Pseudatomocelis seriatus (Reuter)). To evaluate the feeding behavior of cotton fleahoppers on ThryvOn cotton, electropenetrography (EPG) using a Giga-8 DC instrument was used to monitor the probing activity of fourth- and fifth-instar cotton fleahopper nymphs on both ThryvOn and non-ThryvOn cotton squares. Nymphs were individually placed on an excised cotton square for 8 h of EPG recording, after which resulting waveforms were classified as non-probing, cell rupturing, or ingestion. Although there were significantly more cell rupturing events per insect on ThryvOn (mean ± SEM, 14.8 ± 1.7) than on non-ThryvOn squares (mean ± SEM, 10.3 ± 1.6), there was no difference attributable to ThryvOn in the average number of ingestion events per insect. However, the average duration of ingestion events was significantly shorter on squares with ThryvOn (mean ± SEM, 509 ± 148 s) than on squares without (mean ± SEM, 914 ± 135 s). This suggests that cotton fleahoppers continued to probe despite their inability to sustain ingestion. These results provide conclusive evidence that the Mpp51Aa2 pesticidal protein affects the feeding behavior of cotton fleahopper nymphs. [ABSTRACT FROM AUTHOR]

Acylsugars are important insect defense compounds produced at high levels by glandular trichomes of the wild tomato, Solanum pennellii. Marker-assisted selection was used to select for plants containing the three AGQTL named AG3QTL, AG4QTL, and AG11QTL from self-pollinated populations derived from an interspecific backcross population of CU071026 x (CU071026 x S. pennellii LA716). High acylglucose-accumulating lines were selected from these populations that possess these three AGQTL and the fewest number of extraneous S. pennellii LA716 introgressions. Incorporation of these three acylglucose QTL in the presence of the five standard S. pennellii introgressions of CU071026 altered acylsugar level and sugar moiety, demonstrating epistatic interactions between the acylglucose QTL on both of these traits. Comparison of the lines generated from the two breeding techniques indicated the three acylglucose QTL are essential but not necessarily sufficient for the production of elevated levels of acylglucose acylsugars. Fine-mapping of AG3QTL, AG4QTL, and AG11QTL resulted in less than 1 Mbp intervals for the locations of AG4QTL and AG11QTL; proposals of the causal genes underlying these acylglucose QTL are discussed. Characterization of the fatty acid profile of lines selected out of the interspecific backcross populations revealed an increase in the proportion of acylsugar n-C10 fatty acid acyl chains, possibly governed by one or more of the three acylglucose QTL. Characterization of the acylsugar profile of acylglucose lines selected from the interspecific backcross populations also demonstrated interactions among the acylglucose QTL to further modulate the diversity of acylsugars accumulated. Evaluation of an acylglucose line and controls against the tomato insect pest Frankliniella occidentalis demonstrated that levels of resistance differed among these lines and that the acylsugars accumulated by the acylglucose line were effective at reducing both F. occidentalis oviposition and incidence of Tomato spotted wilt orthotospovirus. However, of some of the acylglucose lines and hybrids tested against Spodoptera exigua did not indicate differences for larval weight gain and survival. [ABSTRACT FROM AUTHOR]

BACKGROUND The codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), is a major worldwide pest of apples, pears and walnuts. A temperature-driven phenological model of codling moth, developed in Michigan, has been utilized in North Carolina and other states for decades. Systematic inaccuracy of this model in predicting moth emergence in North Carolina suggests that the relationship between emergence and temperature differs between the American midwest and southeast, or that additional factors may influence the system. RESULTS A method was developed to optimize the estimation of generation turnover intervals. Emergence was modeled as a function of heat unit accumulation. Significant differences between emergence predictions based on the resultant model and the existing model developed in Michigan were found. CONCLUSION A new model of codling moth emergence, incorporating improved estimates for generation turnover for North Carolina, offers predictive improvement with practical importance to management. Differences between the emergence of susceptible and resistant moth populations were also investigated, leading to the suggestion that resistance to insecticides should be considered in future studies of emergence phenology. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]