Harvester ants (Latreille) (Formicidae: Hymenoptera) have traditionally been labeled as pests within their native ranges from perceived effects on crop production and rangeland productivity.Yet, modern research casts doubt on many of these perceived detrimental effects and instead suggests that harvester ants act as keystone species that largely benefit both ecosystems and human activities.Through nest engineering and trophic interactions (such as seed harvesting and predation), harvester ants have considerable direct and indirect effects on community structure and ecosystem functioning. Here we summarize the ecological roles of harvester ants and review their services and disservices to ecosystems and human activities. In doing so, we help clarify perceived keystone and pest roles of harvester ants and their implications for rangeland management. We find the numerous keystone roles of harvester ants to be well-supported compared to perceived pest roles.We also highlight areas where further research into their roles in natural and managed systems is needed.

In recent years, insect immunology has expanded rapidly in research interest, and available literature has expanded in kind. Insects combat pathogens through a range of behavioral and physiological immune defenses. The need for robust immunity is especially important to eusocial insects; nestmate proximity increases exposure to and transmission of pathogens. Further, eusociality involves cohabitation of thousands of individuals with characteristically reduced genetic variability, in turn increasing susceptibility to epidemic disease outbreaks. To combat this, they have developed diverse responses to pathogens, including individual innate immune defenses, social immunity, and secretion of potent glandular chemicals.The range of immune responses is as diverse as the pathogens presenting the threat, and of these, viruses may present the greatest challenge. Social immunity employed by Hymenoptera and has been reviewed whereas a review has not been developed to our knowledge addressing innate immunity of eusocial Hymenopterans to viral pathogenic invaders. We argue that such a review is important to advancement of understanding of Hymenopteran biology and is critical to applied interests. We argue further that the implications of eusocial Hymenopteran innate immunity are far-reaching; their success is a source of both substantial economic loss in the case of invasive ants and significant economic gain in the case of the honey bee Apis mellifera.

Wolbachia (Hertig) (Rickettsiales: Anaplasmataceae) are maternally inherited endosymbiotic bacteria that are widely present in nematodes and arthropods. These endosymbiont bacteria receive significant research attention because they can have important effects on the biology of their hosts. Here, we present the first detailed analyses of Wolbachia in crickets from China, with screening of 23 species from eight genera. In total, 21 species from the eight genera were positive for Wolbachia. Significant diversity was observed among Wolbachia strains from the crickets based on five multilocus sequence typing (MLST) genes, with 15 different sequence types (STs), of which 12 STs were new to the MLST database. Five species were infected with Wolbachia of supergroup A, 11 species were infected with Wolbachia of supergroup B, and seven species were infected with Wolbachia of supergroup F. Some of the same host species harbored distinctly different Wolbachia strains, suggesting multiple infections of crickets by Wolbachia. Different cricket hosts also harbored closely related Wolbachia strains, and there were three gene recombinations. Horizontal transmission and gene recombination may allow crickets to acquire new Wolbachia strains and have increased the genetic diversity of Wolbachia.

Sexual selection is central to many theories on mate selection and individual behavior. Relatively little is known, however, about the impacts that human-induced rapid environmental change are having on secondary sexually selected characteristics. Honest signals function as an indicator of mate quality when there are differences in nutrient acquisition and are thus potentially sensitive to anthropogenically altered nutrient inputs. We used the cabbage white butterfly, Pieris rapae (L.) (Lepidoptera: Pieridae), to investigate differences in color and testes size in a system that is often exposed to agricultural landscapes with nitrogen addition. We collected individuals from four sites in California and Nevada to investigate variation in key traits and the possibility that any relationship between wing color and a reproductive trait (testes size) could vary among locations in the focal butterfly. Coloration variables and testes size were positively albeit weakly associated across sites, consistent with the hypothesis that females could use nitrogen-based coloration in the cabbage white as an indicator for a male mating trait that has the potential to confer elevated mating success in progeny. However, variation in testes size and in the relationship between testes size and wing color suggest complexities that need exploration, including the possibility that the signal is not of equal value in all populations. Thus these results advance our understanding of complex relationships among environmental change and sexual selection in the wild.

Histochemical staining of histological sections of Varroa destructor (Anderson andTrueman, 2000) mites reveal the internal body plan and are used to contrast the internal organs associated with feeding and reproduction of starved versus recently fed female mites.The gnathosoma is comprised of a powerful sucking pharynx, which employs 11 alternating dilator and constrictor muscles, the chelicerae, the salivary ducts, and the salivarium. Coronally, the esophagus is visible through the synganglion between its supraesophageal and subesophageal regions and connects posteriorly to the midgut.The midgut is devoid of food particles in starved mites, but in fed mites, the midgut epithelial cells are filled with innumerable globular spheroids replete with lipoproteins, including polyunsaturated lipids, whereas the lumen is filled with saturated lipids or other unidentified nutrients. In the opisthosomal body region of the fed female, the bilobed lyrate organ lies adjacent to the midgut on one side and the ovary on the opposite side, with very close cell to cell linkages that appear to form a syncytium. The fed female ovary contains an enormously enlarged ovum, and numerous elongated nurse cells extending from the lyrate organ. Dyes staining selectively for lipoproteins suggests rapid incorporation of neutral and polyunsaturated lipids and lipoproteins. Also evident near the ovary in fed females is the spermatheca filled with elongated, fully capacitated spermatozoa. The histological and histochemical findings reported in this study provide a fresh insight into the body structure, nutrition, and reproductive activity of the female of this harmful honey bee parasite and disease vector.

Graphical Abstract

Representative images histological atlas varroa destructor (Mesostimate:Varroidae): A. Anterior body region showing the pharynx, esophagus, sunganglion and salivary gland (sagittal view); B. Mid-section of body showing intracellularvesicles (lipoproteins) in epithelial cells of the midgut (sagittal view). C. Posterior region of body showing of the ovary with developing oocytes connected by elongated nurse cells to the lyrate organ: D. Posterior region of body showing the ovary with a very large developing oocyte, adjacent spermatheca and lyrate organ. All images are fed females.

Darwin in his book, The Descent of Man and Selection in Relation to Sex, described his fascination with a male Chiasognathus grantii Stephens (Coreptera, Lucanidae), a stag beetle species with enormous mandibles. Wallace in his book, The Malay Archipelago, recorded his enchantment with a male Euchirus longimanus L. (Coreptera, Scarabaeoidae), a ‘chafer’ species with ‘immense fore-arms’ (tibia or femora). These oversized traits have been interpreted as the results of allometry through sexual selection. Both Darwin and Wallace were aware that there was a large variation in these oversized traits intraspecifically, leading to the question of the role of variability in species-level evolution. To answer this question, I studied the variation in developmental plasticity (DP; the individual ability to react to external environment) of the stag beetles, which shows a great variation in external morphology. These observations indicated that 1) DP (measured in body length) is independent of allometry of the mandibles, 2) allometry of the mandibles had been ingrained in most members of the Family before the differentiation of DP took place, 3) DP is indirectly related to sexual selection through elongated mandibles that are used for fighting or securing the mate, as evidenced by the close correlation of DP with the mandible length, and 4) the enormous mandibles of stag beetles are the product of enlarged DP through allometry and sexual selection. From these results, I add enhanced DP as an independent element in the evolution of seemingly oversized traits seen in many beetle species.

The activities of social insect colonies are supported by exocrine glands and the tremendous functional diversity of the compounds that they secrete. Many social wasps in the subfamilies Vespinae and Polistinae have two sternal glands—the van der Vecht and Richards' glands—that vary in their features and function across the species in which they are found. Field observations suggest that giant hornets use secretions from the van der Vecht gland to chemically mark targeted nests when workers initiate group attacks on social insect prey. However, descriptions of giant hornets' sternal glands and details about their recruitment behavior are lacking. We describe the morphology of the sternal glands of the giant hornet Vespa soror du Buysson and consider their potential to contribute to a marking pheromone. We also assess the gastral rubbing behavior of workers as they attacked Apis cerana F. (Hymenoptera: Apidae) colonies. V. soror workers have well-developed van der Vecht and Richards' glands on their terminal gastral sternites, with morphologies that robustly support the synthesis, storage, and dissemination of their secretory products. Observations confirm that the van der Vecht gland is exposed during gastral rubbing, but that the Richards' gland and glands associated with the sting apparatus may also contribute to a marking pheromone. Workers briefly but repeatedly rubbed their gasters around hive entrances and on overhead vegetation. Colonies were heavily marked over consecutive attacks. Our findings provide insight into the use of exocrine secretions by giant hornets as they recruit nestmates to prey colonies for group attacks.