Termites and ectoparasitic fungi have been at odds for millions of years. Surprisingly, fungi rarely kill their host and termites are continuously parasitized, albeit at low rates. ‘Termitophilous’ fungi have succeeded in the difficult task of infiltrating the ecological fortress of social immunity that is the termite colony. Here we review 34 definitive ectoparasitic fungal species from nine genera specialized to infest the cuticle of 50 + termite species. In general, reports of fungal ectoparasites on termites are underestimated and the actual prevalence of infestation is likely much greater in nature. In this review, we synthesize >120 yr of reports and studies on ectoparasitic fungi and their termite hosts to present an update to where our knowledge rests and where the proceeding steps should be focused. In reviewing this material, we aim to unite knowledge from two disciplines, entomology and mycology, creating a literary source useful for entomologists and mycologists alike. We provide a comprehensive summary of all fungal genera, illustrations showing morphological distinctions and development on the termite host, a glossary of mycological terminology, and an updated chart of the biogeography of these groups. Additionally, we provide a phylogenetic summary of parasite lineages and their known hosts as well as the first review of molecular evidence obtained from these fungal species.

Despite the critical role that contact between hosts and vectors, through vector bites, plays in driving vector-borne disease (VBD) transmission, transmission risk is primarily studied through the lens of vector density and overlooks host–vector contact dynamics. This review article synthesizes current knowledge of host–vector contact with an emphasis on mosquito bites. It provides a framework including biological and mathematical definitions of host–mosquito contact rate, blood-feeding rate, and per capita biting rates. We describe how contact rates vary and how this variation is influenced by mosquito and vertebrate factors. Our framework challenges a classic assumption that mosquitoes bite at a fixed rate determined by the duration of their gonotrophic cycle. We explore alternative ecological assumptions based on the functional response, blood index, forage ratio, and ideal free distribution within a mechanistic host–vector contact model. We highlight that host–vector contact is a critical parameter that integrates many factors driving disease transmission. A renewed focus on contact dynamics between hosts and vectors will contribute new insights into the mechanisms behind VBD spread and emergence that are sorely lacking. Given the framework for including contact rates as an explicit component of mathematical models of VBD, as well as different methods to study contact rates empirically to move the field forward, researchers should explicitly test contact rate models with empirical studies. Such integrative studies promise to enhance understanding of extrinsic and intrinsic factors affecting host–vector contact rates and thus are critical to understand both the mechanisms driving VBD emergence and guiding their prevention and control.

Blowfly larvae of Lucilia sericata (Meigen) (Diptera: Calliphoridae) are well established as debridement agents in nonhealing wounds. Maggot therapy (MT) experienced reduced application following adoption of Penicillin and other antibiotics, but the advent of antibiotic resistance and the growing global wound burden have boosted demand for new therapies. The mechanisms of action are well accepted, with debridement, disinfection, biofilm destruction, and inhibition, as well as the stimulation of tissue growth uniformly acknowledged as a remarkable biotherapy. The mechanisms of action, while well-recognized, are still being examined. The efforts to understand isolated aspects of a complex system, have resulted in a tendency to approach the field from simplified viewpoints that remove the holistic system of the larvae. Furthermore, clinical studies have conflated wound debridement and healing in definitions of ‘success'. Thus, both in vitro and clinical studies have reported mixed results, presenting some uncertainty regarding the utility of MT that prohibits routine clinical adoption. This review builds from the generally accepted basic mechanisms to justify a future for MT that encompasses larval-bacterial symbioses as the basis to a holistic system. Symbioses are well documented in the Insecta, and literature in MT supports the existence of established symbiotic associations that provide enhanced debridement action. The future of MT requires consideration of a biological system that confers enhanced antimicrobial action on larvae when selective pre-exposure to carefully selected symbionts is adopted. In treating contemporary infections, there is much to be gained from reflecting on the natural biology of the organism, as MT was used with success long before we sterilized the system.

The Psylloidea (Hemiptera) comprise ∼4,000 species of small sap-feeding insects known as psyllids or jumping plant-lice. We summarize species composition of the nonnative psyllid fauna in North America and review detection records, current distributions, host use, life histories, and geographical sources. Forty-six species are considered to be nonnative accounting for ∼10% of the known North American psyllid fauna. The family Psyllidae is overrepresented in the pool of exotics (52% of exotic species) relative to global psyllid diversity, whereas Triozidae (at 11% of exotic species) is underrepresented. Records of initial detection range from the 1832 detection of a European pear psyllid to the 2016 detection of a Ficus specialist from Asia. Many species exhibit discontinuous distributions in North America presumably caused by multiple introductions or by secondary spread of established populations. Host plants of nonnative species are almost exclusively trees and shrubs. The factor most correlated with introduction is presence of hosts from the psyllid's native region. Virtually all host plants in North America have been imported intentionally for human-related use, with initial importation beginning in the 1500s and 1600s. Arrival of host plants in North America often preceded psyllid detection or arrival by decades or centuries. There has been almost no spillover by psyllids onto native plant species reflecting the narrow host range of Psylloidea. A glaring exception is the recent damaging colonization of a native Fraxinus closely related to the psyllid's European Fraxinus host. Biological and geographical traits correlated with arrival and establishment of nonnative psyllids have shifted through time. Temperate Europe was the source of the earliest arriving species, with initial detection records primarily in New England and eastern Canada. In contrast, recent arrivals are mostly Myrtaceae- and Fabaceae-feeding species from the Neotropics or Australia, with detection records limited mostly to Florida or California. Early-arriving, temperate zone species exhibit a formal winter diapause while recent arrivals from the Neotropics and Australia appear to reproduce more-or-less continuously.

Soil as a shared habitat of white grubs and entomopathogenic nematodes (EPNs) is a double-edged sword from the biological control point of view. Soil encompasses a diverse array of EPNs that could be exploited in grub microbial control; on the other hand, soil promotes the natural resistance of grubs to EPNs via the battle between both sides within the soil matrix. White grubs and EPNs have been armed in this battle by a multifaceted range of mechanisms, namely grub structural and physiological barriers, antagonism of grub gut microbiota toward the nematode bacterial symbionts, EPN excreted/secreted proteins, surface coat proteins, ascaroside pheromones produced by EPNs, and evolution of EPN resistance to herbivore self-defense. From the evolutionary point of view, EPN–grub interactions, the most advanced (sophisticated) association among others, could have evolved from other types of associations. Entomophilic nematode (e.g., Pristionchus spp.), the cognate bacterium and scarab associations along with the formation of dauer juveniles, are proof of preadaptation to entomopathogeny in a continual evolution. Here, we delve into the salient features of each component of EPN-white grub–host plant tripartite interactions as well as hints to improved exploitation of EPNs for grub management. Also, evolutionary associations between nematodes and scarabs will be reviewed, in short.

Graphical Abstract

Ants (Hymenoptera: Formicidae) are a conspicuous group of ectotherms whose behavior, distribution, physiology, and fitness are regulated by temperature. Consequently, interest in traits like thermal tolerance that enable ants to survive and thrive in variable climates has increased exponentially over the past few decades. Here, we synthesize the published literature on the thermal tolerance of ants. We begin our review with discussion of common metrics: critical thermal limits, lethal thermal limits, knock-down resistance, chill-coma recovery, and supercooling. In particular, we highlight the ways each thermal metric is quantified and offer a set of methodological caveats for consideration. We next describe patterns and hypotheses for ant thermal tolerance along spatial and temporal temperature gradients. Spatially, we focus on relationships with latitude, elevation, urbanization, and microclimate. Temporally, we focus on seasonal plasticity, daily variation, dominance-thermal tolerance tradeoffs, and acclimation. We further discuss other sources of variation including evolutionary history, body size, age, castes, and nutrition. Finally, we highlight several topics of interest to ant thermal biologists, ranging in scope from methods development to the impacts of climate change.

Molecular techniques are powerful tools that can address many research problems in insect ecology. Mitochondrial DNA (mtDNA) is a widely used molecular marker. It is easy to use and has favorable biological properties, such as near-neutrality, lack of recombination, and a clock-like evolutionary rate. However, there are some issues involved when using mtDNA data in population genetics, species delimitation, and estimating the evolutionary history of populations and species. Exceptions to the simplicity of mitochondrial inheritance and other limitations include small effective population sizes, maternal inheritance, and complex evolutionary processes. Combining mtDNA and nuclear DNA markers can improve the power of molecular data to test phylogenetic and phylogeographic hypotheses. We review the applications of mtDNA in insect ecology and conclude that a better understanding of the properties of mitochondria is essential for the application of mtDNA.

Historically, most North American periodical cicada (Hemiptera: Cicadidae: Magicicada spp. Davis 1925) distribution records have been mapped at county-level resolution. In recent decades, Magicicada brood distributions and especially edges have been mapped at a higher resolution, aided by the use of GIS technology after 2000. Brood VI of the 17-yr cicadas emerged in 2000 and 2017 and is the first for which detailed mapping has been completed in consecutive generations. Overlaying the records from the two generations suggests that in some places, Brood VI expanded its range slightly between 2000 and 2017, although the measured changes are close to the lower limit of detectability given the methods used. Even so, no simple alternative to range expansion easily accounts for these observations. We also bolster Alexander and Moore's assertion that M. cassini does not occur in Brood VI.

In heterogonic gall wasps, the gall structure, phenology, and adult morphology differ between the asexual and sexual generations, even within the same species. Dryophanta japonica Ashmead and Dryophanta mitsukurii Ashmead were described in 1904, but their heterogonic life cycles were uncertain. To match their asexual and sexual generations, we compared the type specimens of both species with specimens of gall wasps reared to demonstrate heterogonic life cycles. This revealed that these two species are the respective asexual and sexual generations of a single heterogonic species. Based on the morphological characteristics, we transferred D. japonica to Cerroneuroterus Melika and Pujade-Villar as Cerroneuroterus japonicus (Ashmead, 1904) comb. nov. and treated the sexual generation as a junior synonym: Dryophanta mitsukuriiAshmead, 1904syn. nov. Moreover, we examined the type specimens of other species previously suggested to be synonymous with D. mitsukurii. This showed that Neuroterus vonkuenburgiDettmer, 1934syn. nov. (and N. vonkuenburgi wakayamensis Monzen, 1954 syn. nov.) is the asexual generation of C. japonicus and that Neuroterus bonihenriciDettmer, 1934syn. nov. is the sexual generation. Judging from the original descriptions, Andricus asakawae Shinji, 1943 syn. nov., Andricus kanagawaeShinji, 1943syn. nov., Andricus asakawaeShinji, 1944syn. nov., Andricus kanagawaeShinji, 1944syn. nov., and Neoneuroterus kashiyamaiMonzen, 1954syn. nov. were also regarded as the sexual generation of C. japonicus. Finally, we discussed how matching asexual and sexual generations in heterogonic gall wasps not only avoids taxonomic confusion but also contributes to progress in gall wasp biology.

Secondary population outbreaks of Panonychus citri (McGregor) (Acari: Tetranychidae) are triggered by synthetic chemical applications (dose and method), which also elicited a change in mites' behavioral responses. This study aimed to understand the dispersal pattern of P. citri and how changes in dispersal behavior may influence secondary pest outbreaks in the field with or without chemicals. We found positive density and time-dependent dispersal within the inoculated leaflet. Dispersion from inoculated leaflets to the last leaflet depends on initial density and time. A significant difference was observed in the composite dispersal index data and preferred midrib region. The minimum dispersal was observed by P. citri in no direct contact with treated surfaces, whereas attraction was observed on treated surfaces (right). All chemicals gave different dispersal and feed disruption responses depending on the treatment application pattern. The maximum number of mites dispersed and avoid surfaces treated with abamectin and vegetable oil, respectively. Vegetable and EnSpray 99 had a positive impact on toxicity, repellency, and irritancy. The fecundity rate of P. citri boosted with a high dose and direct exposure. Panonychus citri colonization as a single individual or gregarious distribution resulted in a rapid fecundity rate, which may explain why citrus orchards were severely damaged and how suddenly a whole citrus plantation can be highly infested. This study concluded that change in treatment application patterns leads to a change in the behavioral responses in P. citri.

Insect diversity levels and change in remnant urban habitats have been poorly examined in Neotropical regions. The aim of this study was to evaluate the diversity and composition of foliage/shrub dwelling beetles (Insecta: Coleoptera) regarding the influence of patch attributes (i.e., patch size, connectivity, and surrounding matrix) and within-patch habitat complexity, in an urban landscape at Chetumal, Yucatán peninsula, Mexico. Despite the potential species-specific responses to urban landscape pattern, our study reveals that there are effects of patch spatial features and habitat complexity on overall beetle diversity.These effects are as follows: 1) relatively larger urban patches contained higher overall beetle richness, 2) beetle species composition varied significantly regarding understory vegetation structure and tree richness, and 3) patches of intermediate vegetation age had highest beetle richness.This research provides a case study of patch and habitat features related to Neotropical insect assemblages in urban settlements, underlying the importance of using ecological information to offer management recommendations in ever-expanding urban tropical settlements.

Finding a partner to mate with may be only part of ensuring successful siring of offspring. Females often exhibit cryptic female choice (CFC) during or after copulation, which can influence whose sperm from her multiple partners is chosen for egg fertilization. Known behavioral mechanisms for CFC include assessment of males by their nuptial gifts, duration of copulation, and seminal fluid contents. In this study, the glassy-winged sharpshooter, Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), behaviors during the course of copulation were investigated. Glassy-winged sharpshooter (GWSS) use vibrational communication before copulation occurs. However, little is known about behaviors that occur during and after copulation. Results from this study determined that vibrational signaling also occurs during copulation. Vibrational signals similar to those emitted during precopulatory communication were identified during copulation alongside a new, ‘hum-like’ signal that typically occurred within 10 s after the pair joined in copulation. In addition, results determined the duration of copulation was on average of 15 h, though with a 10-h range (8.5–18.5 h) among observed male–female pairs. Finally, both males and females mated more than once. Collectively, results identified key reproductive parameters required for CFC to occur in GWSS.The study expands on the known animals that use CFC and emphasizes the role that copulatory vibrational communication may play setting the foundations for future more in-depth studies. Understanding of insect behaviors necessary for successful production of offspring is important from an ecological perspective and for development of pest control methods.

Leafhoppers in the tribe Erythroneurini are a concern for grape growers in California due to direct feeding damage by piercing the leaves. Management of leafhopper populations in vineyards may be accomplished by insecticide applications, the release of natural enemies, conservation biological control, exploitation of controlled deficit irrigation, or a combination of the above. Based on research on other leafhopper species, a behavioral mating disruption is a viable option, but nothing is known about the mating communication and circadian signaling of these species in vineyards. The objectives of this study were to identify and describe vibrational signals associated with mate selection behavior of Erasmoneura variabilis and Erythroneura ziczac, and evaluate the occurrence of vibrational signals within sympatric populations of E. variabilis, E. ziczac, and Homalodisca vitripennis on grapevines. Analysis of vibrational communication signals revealed that 1) one female signal and two distinct male signals are used in E. variabilis pair formation, 2) the pair formation process in E. variabilis is divided into three communication phases, 3) E. variabilis pre-copulatory communication is longer in the presence than in the absence of male-male rivalry, 4) two distinct signals are used in E. ziczac pair formation, and 5) E. variabilis, E. ziczac, and H. vitripennis sing at night and during the day. Results include detailed descriptions of leafhopper communication signals that are relevant for future development of vibrational disruption as a novel method to suppress populations under field conditions.