Impact of reduced calcium during development in snakes

In squamate reptiles, the evolutionary transition from oviparity to viviparity is accompanied by loss of the calcareous outer eggshell, which suggests significant implications for the role of calcium during embryonic development (Packard et al., 1977). An experiment was designed to evaluate the impact of reduced calcium availability during development in the oviparous corn snake, Pantherophis guttatus (Stewart and Ecay, 2013). Results from that study showed significant decreases in the mass and length of hatchling corn snakes when the outer calcareous eggshell layer was removed during development. In vertebrates, variation in total body length reflects skeletal differences---primarily differences in the number or sizes of vertebrae and/or differences in length of the skull. Skeletal components obviously are affected by the availability of calcium during development. My study was designed to determine the anatomical and developmental bases for the smaller size observed in hatchling snakes subjected to reduction of eggshell calcium during embryonic development. My hypotheses were, as follows: 1) Differences in mass reflected differences in overall length of hatchlings; 2) Differences in length resulted from decreased size of vertebrae---rather than decreased number---and/or decreased length of skulls in hatchlings with reduced calcium. Hatchlings were prepared for skeletal analysis via clearing-and-staining. Vertebrae of each hatchling were counted and size measurements obtained for separate spinal regions (cervical, thoracic, and caudal). Results demonstrate a significant treatment effect on size of vertebrae in the thoracic and anterior caudal regions, as well as length of the skull. These findings suggest that reduced developmental calcium, comparable to the condition in viviparous species, impacts ossification and growth of skeletal elements in late development

Current Understanding and Future Prospects of Host Selection, Acceptance, Discrimination, and Regulation of Phorid Fly Parasitoids That Attack Ants

Phorid fly parasitoids (Diptera: Phoridae) have evolved a diverse array of cues used to successfully parasitize their ant hosts. Successful parasitism often involves (a) host habitat location, (b) host location, (c) host acceptance, (d) host discrimination, and (e) host regulation. In this paper we discuss our current understanding of how phorid flies use each of these steps to successfully parasitize ant hosts. We examine the wide variety of strategies and cues used by a multiple species of phorid flies within three separate genera that most commonly parasitize ants (Apocephalus, Pseudacteon, and Neodohrniphora) and discuss future directions within this field of study

The effects of land use change on ant communities in New England

Urbanisation and agricultural expansion are two of the most prevalent and intense forms of land use change worldwide and can have dramatic consequences on biodiversity and biotic community structure. Ants are extremely widespread, ecologically diverse and small ectotherms that are sensitive to changes from a wide range of environmental factors. Therefore, ants make an ideal study organism to examine the effects of anthropogenic land use change on biotic communities. In this study, we examined differences in ant species richness and community composition between urban parks, farms and forest fragments, and related these differences to environmental factors that vary among each of these three habitat types. We sampled 46 sites across Worcester County and found farms have significantly lower ant species richness than parks, and all habitat types had different ant community compositions. We also identified higher plant species richness is associated with higher ant species richness, and both plant species richness and air temperature are associated with differences in community composition. Our findings support that habitats affected by human land use will host different assemblages of ant species compared to those found in nearby natural habitats, as seen in our New England forest fragments. © 2023 The Authors. Insect Conservation and Diversity published by John Wiley & Sons Ltd on behalf of Royal Entomological Society

The Community Ecology of Herbivore Regulation in an Agroecosystem: Lessons from Complex Systems

AbstractWhether an ecological community is controlled from above or below remains a popular framework that continues generating interesting research questions and takes on especially important meaning in agroecosystems. We describe the regulation from above of three coffee herbivores, a leaf herbivore (the green coffee scale, Coccus viridis), a seed predator (the coffee berry borer, Hypothenemus hampei), and a plant pathogen (the coffee rust disease, caused by Hemelia vastatrix) by various natural enemies, emphasizing the remarkable complexity involved. We emphasize the intersection of this classical question of ecology with the burgeoning field of complex systems, including references to chaos, critical transitions, hysteresis, basin or boundary collision, and spatial self-organization, all aimed at the applied question of pest control in the coffee agroecosystem

Cuticular Hydrocarbon Cues Are Used for Host Acceptance by Pseudacteon spp. Phorid Flies that Attack Azteca sericeasur Ants

Parasitoids often use complex cues to identify suitable hosts in their environment. Phorid fly parasitoids that develop on one or a few host species often use multiple cues, ranging from general to highly specific, to home in on an appropriate host. Here, we describe the hierarchy of cues that Pseudacteon phorid flies use to identify Azteca ant hosts. We show, through behavioral observations in the field, that phorid flies are attracted to two cryptic Azteca species, but only attack Azteca sericeasur (Hymenoptera: Formicidae: Dolichoderinae). To test whether the phorid flies use cuticular hydrocarbons (CHCs) to distinguish between the two Azteca taxa, we first documented and compared cuticular hydrocarbons of the two Azteca taxa using gas chromatography/mass spectrometry. Then, using cuticular hydrocarbon-transfer experiments with live ants, we characterized the cuticular hydrocarbons of A. sericeasur as a short-range, host location cue used by P. lasciniosus (Diptera: Phoridae) to locate the ants

Parasite Lost: Chemical and Visual Cues Used by Pseudacteon in Search of Azteca instabilis

An undescribed species of phorid fly (genus: Pseudacteon) parasitizes the ant Azteca instabilis F Smith, by first locating these ants through the use of both chemical and visual cues. Experiments were performed in Chiapas, Mexico to examine a) the anatomical source of phorid attractants, b) the specific chemicals produced that attract phorids, and c) the nature of the visual cues used by phorids to locate the ants. We determined that phorid-attracting chemicals were present within the dorsal section of the abdomen, the location of the pygidial gland. Further experiments indicate that a pygidial gland compound, 1-acetyl-2-methylcyclopentane, is at least partially responsible for attracting phorid flies to their host. Finally, although visual cues such as movement were important for host location, size and color of objects did not influence the frequency with which phorids attacked moving targets

Behavioral and chemical ecology of ants (Hymenoptera, Formicidae) and their natural enemies in dynamic coffee agroecosystems.

Social insects rank among the most ubiquitous and ecologically dominant terrestrial animals on Earth. Complex communication and social organization are two defining features of social insect societies and ants, in particular, have evolved extensive systems of chemical communication. In both natural and agricultural systems, including coffee agroecosystems, ants are important predators and often have strong and complex effects on pest species. In this dissertation, I explore how chemical communication plays a role in dynamics between ants and their natural enemies within these coffee agroecosystems, to gain a better understanding of both how ants utilize their own chemical communication systems and how natural enemies of ants take advantage of these systems to exploit ants.In the first dissertation chapter, I review the literature on chemical and visual cues that one natural enemy of the ant, the phorid fly, uses to successfully parasitized its host ants. Phorid fly parasitoids that use ants as hosts often require the use of multiple cues, ranging from general to highly specific, to home in on an ideal host. Here I outline the five common steps in which phorid flies use cues: (a) host habitat location, (b) host location, (c) host acceptance, (d) host discrimination and (e) host regulation. I then discuss our current understanding of how phorid flies use each of these steps to successfully parasitize ant hosts. Finally, I examine the wide variety of strategies and cues used by a multiple species of phorid flies within three separate genera (Apocephalus, Pseudacteon, and Neodohrniphora) and discuss future directions within this field of study. In the second dissertation chapter, I investigate the role of Azteca ant cuticular hydrocarbon cues as a short-range cue for a suite of Pseudacteon spp. phorid fly parasitoids commonly found within coffee agroecosystems. Here I describe the hierarchy of cues Pseudacteon spp. phorid flies use to successfully identify Azteca host ants. I use behavioral observations in the field to show phorid flies are attracted to two cryptic Azteca taxa, but will only attack Azteca sericeasur (Hymenoptera: Formicidae: Dolichoderinae). To test whether the phorid flies are able to distinguish between the two Azteca taxa using their cuticular hydrocarbons, I first document and compare the cuticular hydrocarbons of two cryptic Azteca taxa using gas chromatography-mass spectrometry (GC/MS). Using cuticular hydrocarbon transfer experiments with live ants from both Azteca taxa, I identify the cuticular hydrocarbons of Azteca sericeasur as a short-range host location cue used by Pseudacteon lasciniosus (Diptera: Phoridae) to locate the ants. In the third chapter, I describe two new species of Myrmedonota (Coleoptera: Staphylinidae) that are also natural enemies of Azteca sericeasur ants. Here I record this genus of beetle in Mexico for the first time, and describe M. xipe and M. shimmerale for the first time. This chapter also documents that both Myrmedonota species will aggregate towards agitated ants, to prey on Azteca sericeasur and these species will form mating swarms, either with no apparent landmark or in the vicinity of ants.My fourth chapter examines the role of the beetle, Myrmedonota xipe, in Azteca ant-phorid fly interactions. Here I use pheromone bioassays to show that M. xipe is attracted to a component of A. sericeasur alarm pheromone. In the field experiments, I determine that the beetles are able to locate parasitized ants as prey items but not healthy ants. In choice tests in the lab, I also show that beetles will preferentially attack parasitized ants over healthy ants. Analysis of the choice tests also indicates that the aggression in parasitized ants is so reduced that beetles are essentially able to eat these ants alive without interruption. These results suggest that, although beetles are predators of the ants, by preying primarily on ants harboring phorid fly eggs, the beetles may also provide indirect positive effects for the ant colonies as a whole. In my final dissertation chapter I examine the variation in cuticular hydrocarbon blends of three species of arboreal twig nesting ants, Pseudomyrmex simplex, Pseudomyrmex ejectus and another Pseudomyrmex sp. (referred to as PSW-53) commonly found within the coffee agroecosystems of Southern Mexico. In this study, I examined whether variation in the ecology and social structure of these species is reflected in the variation in their cuticular hydrocarbon profiles. I tested the hypothesis that the more abundant species with higher nest densities exhibit lower cuticular hydrocarbon variation. The results showed that worker ants of abundant P. ejectus and P. simplex from the study site exhibit significantly lower variation in cuticular hydrocarbon profiles than workers of the rare ant species P. PSW-53. Our study reinforces the idea that examining cuticular hydrocarbon profiles can provide insight into the colony structure of social insects. Overall, the results from my dissertation provide insight into the complex interactions between ants and their natural enemies, particularly shedding light on how these interactions are facilitated through the use of ant pheromones as cues and signals. The ants and their natural enemies that I focus on in my dissertation are also important players within the greater coffee agroecosystems in which they inhabit, and this body of work is thus critical for understanding how their network of interactions involving ants and their natural enemies may impact coffee pest control