Rising global temperatures driven by anthropogenic carbon emissions are creating new challenges for food crop agriculture and forest management around the world. Droughts and other severe weather events are becoming more common and more extreme, causing both chronic stress and acute damage in cultivated and natural plant life, whereas warmer temperatures favor outbreaks of plant diseases and insect pests in many situations. At the same time, growing awareness of the health and environmental risks associated with broad-spectrum chemical pesticides has led crop growers and forest managers to seek out more selective, sustainable alternative techniques to mitigate the impact of harmful arthropods. Arthropod repellents have proven an efficacious strategy to reduce these impacts in the field of public health, where they are a key tactic in the suppression of diseases transmitted by hematophagous arthropods, but repellents are comparatively rarely employed to manage pests of agriculture and forestry. This chapter describes several cases in which repellents using beetle semiochemicals antiaggregation pheromones have been developed and evaluated in the field by the authors, successfully reducing tree mortality and/or crop damage induced by coffee berry borer (Hypothenemus hampei Ferrari) in Arabica coffee (Coffea arabica L.); by aggressive Dendroctonus bark beetles in single trees and small stands of North American forest species; and by ambrosia beetles on apple and avocado crops, as well as southeastern forest species.

Climate change is associated with increases in temperature and the frequency and intensity of abiotic disturbances such as drought that can affect forest resilience at multiple scales. Higher temperatures leading to extended growing seasons alter the phenology, distribution, and population dynamics of herbivorous insects. Bark beetles (Coleoptera: Curculionidae: Scolytinae) are among the most ecologically and economically important herbivorous insect taxa and can undergo population eruptions and cause widespread coniferous tree mortality. Specifically, Ips bark beetles preferentially attack conifers that are stressed, dying, or dead—such tree conditions are predicted to become more common due to climate change. Our chapter objectives were to synthesize knowledge on the effects of drought on (1) the incidence of Ips beetle outbreaks and (2) changes in conifer host physiology that increase their susceptibility to bark beetles. We documented 132 Ips beetle outbreaks globally between 1919 and 2018 that were reported in association with drought or water stress. However, very few studies quantitatively demonstrated this relationship and/or defined the mechanisms using experiments. Alterations in host physiology that lead to tree stress will increase colonization by Ips beetles, but their responses may be dependent on attributes at the tree, stand to landscape level. Given the shifts in precipitation and temperature regimes worldwide, we argue for more in-depth studies that quantify the damage and drivers of Ips beetle outbreaks, assessing simultaneous changes in host trees and Ips beetles, ways to mitigate damage for beetle outbreaks, and urgently needed proactive adaptive management strategies in drought-prone forests worldwide.

The southern pine beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae: Scolytinae) is a major destructive pest of Pinus L. In the southeastern United States, numbers of this species and a major predator, Thanasimus dubius (Fabricius) (Coleoptera: Cleridae), captured during an annual springtime trapping survey are used to make forecasts of the likelihood and severity of an outbreak during the following summer. We investigated responses by both species to six lure formulations to evaluate their suitability for the survey and allow integration of historical data sets produced with differing lure compositions. Trapping trials were performed at four locations across three states (Louisiana, Mississippi, and Alabama) during spring, and at these and one additional location (North Carolina) in fall 2016. All lures included the pheromone component frontalin. Southern pine beetle preferred lures that additionally included the pheromone component endo-brevicomin and turpentine as a source of host odors (rather than a 7:3 mixture of monoterpenes alpha- and beta-pinene). Thanasimus dubius displayed little discrimination among lure compositions. Lure preferences by southern pine beetle did not differ significantly among locations in spring but were influenced by season. Gas chromatography (GC)-electroantennographic detection analyses with southern pine beetle and GC-mass spectrometry identified numerous known and potential semiochemicals that distinguished volatiles released by the tested host odor devices. The lure combination that included endo-brevicomin and alpha/beta-pinene is recommended for the trapping survey because of its high sensitivity for southern pine beetle and potential for greater data integrity resulting from its reproducible composition.

The southern pine beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae: Scolytinae), is among the most destructive bark beetle pests of pines (Pinaceae) of the southeast and mid-Atlantic United States of America, Mexico, and Central America. Numerous volatile compounds can stimulate or reduce attraction of the beetle, but efforts to incorporate these into effective, practical technologies for pest management have yielded mixed results. Attractants have been incorporated into lures used in monitoring traps that are employed operationally to forecast outbreaks and detect emerging populations. The attraction inhibitor, verbenone, shows efficacy for suppressing southern pine beetle infestations but has not yet been adopted operationally. No effective semiochemical tree protectant has been developed for the beetle. We discuss complexities in the chemical ecology of the beetle that likely have impeded research and development of semiochemical management tools, and we describe basic science gaps that may hinder further progress if not addressed. We also report some supporting, original experimental data indicating (1) that a verbenone device can inhibit the beetle's response to sources of attractant in a radius of at least several metres, (2) similar olfactory responses by the beetle to both enantiomers of verbenone, and (3) that pheromone background can cause conflicting results in semiochemical field tests.

Cut-and-remove has been the recommended suppression technique for the suppression of infestations of the southern pine beetle (SPB), Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae), with cut-and-leave applied when conditions prevent removal of the felled pines. Changes in forest management practices and the timber industry, plus the expansion of SPB northward have led to an increased reliance on cut-and-leave in recent years. This change has resulted in an exploration of methods to improve the efficacy of cut-and-leave and the development of new tactics for suppressing SPB infestations. We describe these revised and new techniques and discuss their potential applications given current forest management conditions.

Since 1987, as many as 16 southeastern US states participate in a 4 wk annual spring Dendroctonus frontalis (Zimmerman) (Coleoptera: Curculionidae) trapping survey. The purpose of the survey is to assess the current D. frontalis outbreak potential, and anticipate prevention and suppression needs for the coming yr. This prediction system relies on capturing the peak D. frontalis spring dispersal, thus timing of trap deployment is crucial. Forest managers traditionally attempt to deploy traps at the onset of flowering dogwood (Cornus florida L.; Cornaceae) bloom, which is commonly assumed to coincide with peak D. frontalis spring dispersal. The objective of this study is to examine the validity of dogwood bloom as an indicator of peak D. frontalis spring dispersal. Yr-round trapping data in 2014 and 2015 from Mississippi and Florida were used to identify peak D. frontalis and Thanasimus dubius (Fabricius) (Coleoptera: Cleridae) dispersal periods. Peak D. frontalis dispersal then was compared with dogwood blooming dates from the USA National Phenology Network and personal records. Then, both dogwood bloom dates and peak D. frontalis dispersal were compared with timing of actual historic state D. frontalis trapping efforts. We also compared peak D. frontalis dispersal with T. dubius peak dispersal, because T. dubius trap captures are used in the prediction model. Last, we examined the utility of extending the spring survey to 6 wk by comparing the 4 wk peak D. frontalis trap captures with a corresponding 6 wk peak. On average, mean onset of dogwood bloom occurred 3 wk after the peak 4 wk period of D. frontalis flight activity. The average T. dubius peak dispersal occurred 1.5 wk after peak D. frontalis dispersal. The 6 wk extension provided only a 12% overall average increase in D. frontalis trap captures. Eastern redbud (Cercis canadensis L.; Fabaceae) also had been suggested as a replacement trap deployment cue; therefore, eastern redbud and flowering dogwood blooming dates in 2019 were monitored on a Mississippi State University property in Oktibbeha County, Mississippi, USA. On this site eastern redbud trees bloomed on average 2.3 wk before the average bloom date of flowering dogwood trees.

The southern pine beetle (SPB) Dendroctonus frontalis Zimmermann, is the most important insect pest of pines in the southeastern United States, with outbreaks often resulting in thousands of hectares of pine mortality. Natural enemies and competitors have been cited as significant regulators of SPB populations and, therefore, outbreaks. A recent outbreak on the Homochitto National Forest (NF) in Mississippi provided an opportunity to undertake a case study comparing population fluctuations of SPB, its major predator Thanasimus dubius, and its competitors, Ips bark beetles. Trap catches of all three were tracked through the course of the outbreak on the Homochitto NF as well as in two other forests with low or no SPB activity. The number of predators collected initially increased on the Homochitto NF in response to the SPB outbreak, but their impact on reducing infestation numbers was unclear. Numbers of Ips trapped were similar across all three forests, indicating that other factors were regulating SPB populations. The outbreak only lasted a single year, and its brevity likely limited the availability of host resources for natural enemy and competitor populations. Additional studies are warranted to explore the mechanisms affecting the extent and duration of SPB outbreaks, such as active forest management.

The southern pine beetle (Dendroctonus frontalis) (SPB) is an eruptive pest of pine forests in the southeastern United States. Numerous studies have been conducted on the relationships among SPB population dynamics, climatic factors, natural enemies, and competitors, but the influence of changes in forest management through time on SPB activity has received little attention. Forest management dictates the configuration and condition of hosts available for SPB populations, whereas suppression has an impact on population levels of SPB and their associates and also affects the area and distribution of the susceptible host type remaining after treatment. In contrast to the frequent and widespread SPB outbreaks in the last half of the 20th century, recent SPB activity in the Southeast has been localized and short-lived. Reports from the mid-1800s through the mid-1900s indicate that outbreaks then were also less common. In this review, we examine how changes in forest management practices have played a significant role in the history of SPB outbreaks.

Bacterial virulence is a multifaceted trait where the interactions between pathogen and host factors affect the severity and outcome of the infection. Toxin secretion is central to the biology of many bacterial pathogens and is widely accepted as playing a crucial role in disease pathology. To understand the relationship between toxicity and bacterial virulence in greater depth, we studied two sequenced collections of the major human pathogen Staphylococcus aureus and found an unexpected inverse correlation between bacterial toxicity and disease severity. By applying a functional genomics approach, we identified several novel toxicity-affecting loci responsible for the wide range in toxic phenotypes observed within these collections. To understand the apparent higher propensity of low toxicity isolates to cause bacteraemia, we performed several functional assays, and our findings suggest that within-host fitness differences between high- and low-toxicity isolates in human serum is a contributing factor. As invasive infections, such as bacteraemia, limit the opportunities for onward transmission, highly toxic strains could gain an additional between-host fitness advantage, potentially contributing to the maintenance of toxicity at the population level. Our results clearly demonstrate how evolutionary trade-offs between toxicity, relative fitness, and transmissibility are critical for understanding the multifaceted nature of bacterial virulence.

AbstractDendroctonus frontalis Zimmermann is considered one of the most important economic and ecological forest pests in the United States, Mexico, and Central America. Recently, two apparent morphological variants of this species were discovered occurring syntopically in Central America and southern Mexico. Morphotype A beetles lack a series of fine parallel ridges on the episternal area of the prothorax that are present on morphotype B. The goal of the present work was to clarify the taxonomic status of the morphotypes of the D. frontalis species complex. Geometric morphometric analyses of seminal rod and spermatheca shape together with the characterization of 16 attributes of external morphology revealed differences in quantitative and qualitative characters that distinguished adults of the two morphotypes from each other as well as from the closely related species Dendroctonus vitei Wood and Dendroctonus mexicanus Hopkins. Karyotype analysis of morphotype B revealed a chromosomal formula (5AA + Xyp) distinct from that found in morphotype A previously reported for D. frontalis (7AA + Xyp). In the laboratory, forced intermorphotype crosses produced F1 progeny but at lower frequency than intramorphotype pairings, and dissections of spermatheca revealed a lower frequency of insemination at least one type of heterotypic cross. Phylogenetic analysis of the D. frontalis species complex based on 786 bp of the cytochrome oxidase I gene indicated that morphotypes B and A are two independent groups with 98% nodal support within D. frontalis. These data provide compelling evidence that the two syntopic morphotypes represent two distinct sibling species.

Dendroctonus frontalis Zimmermann is considered one of the most important economic and ecological forest pests in the United States, Mexico, and Central America. Recently, two apparent morphological variants of this species were discovered occurring syntopically in Central America and southern Mexico. Morphotype A beetles lack a series of fine parallel ridges on the episternal area of the prothorax that are present on morphotype B. The goal of the present work was to clarify the taxonomic status of the morphotypes of the D. frontalis species complex. Geometric morphometric analyses of seminal rod and spermatheca shape together with the characterization of 16 attributes of external morphology revealed differences in quantitative and qualitative characters that distinguished adults of the two morphotypes from each other as well as from the closely related species Dendroctonus vitei Wood and Dendroctonus mexicanus Hopkins. Karyotype analysis of morphotype B revealed a chromosomal formula (5AA + Xyp) distinct from that found in morphotype A previously reported for D. frontalis (7AA + Xyp). In the laboratory, forced intermorphotype crosses produced F1 progeny but at lower frequency than intramorphotype pairings, and dissections of spermatheca revealed a lower frequency of insemination at least one type of heterotypic cross. Phylogenetic analysis of the D. frontalis species complex based on 786 bp of the cytochrome oxidase I gene indicated that morphotypes B and A are two independent groups with 98% nodal support within D. frontalis. These data provide compelling evidence that the two syntopic morphotypes represent two distinct sibling species.

The mealybug, Oracella acuta Lobdell, is native to southern USA. It was unintentionally introduced to Guangdong Province, southern China, in 1988 as a result of the importation of infested scions of slash pine, Pinus elliottii Engelm. Infestations were first detected in 1990, rapidly spreading in P. elliottii plantations throughout Guangdong and inflicting severe damage. The mealybug has damaged or threatened both native and introduced pine species in its invaded range because of the suitability of climate, presence of hosts as well as the lack of effective natural enemies. In this paper, we review the current literature and government reports and data to summarize the history, present status and ecology of the species. We then analyze the potential O. acuta invasion in Asia. Available studies are mostly centered on the invasion timing and pathway of this species from USA to China, its current distribution in China, the biological and ecological traits of the species, damage and impacts on forests and ecosystems, and the strategies for its prevention and control. There remain substantial gaps in scientific knowledge of the invasion mechanisms and cost-effective measures for early detection and practical management of O. acuta, including options for biological control. Research on these aspects is required in order to prevent further spread of this pest in China and neighboring countries, and to provide better management in invaded regions. (C) 2013 Elsevier B.V. All rights reserved.

If the actual statistics can be reproduced with a mathematical model, then that is evidence the players are behaving in a similar way to the assumptions underlying the model.