Studies on the Feculae of Selected Michigan Acrididae (Orthoptera)

Feculae have been used for some years in the study of insect food-habits and biology. Among the past authors who have used them are Frost (1928), Hodson and Brooks (1956), and Morris (1942), who discussed the use of feculae and frass in the identification of insect species in general; Boldyrev (1928), who figured the feculae of the bradyporine katydid Bradyporus multituberculatus; Brown (1937), who described in detail fecular microstructure in the spine-breasted grasshopper Melanoplus bivittatus; Weiss and Boyd (1 950. 1 952), who figured the feculae of representatives of selected insect orders; Gangwere (1 962). who described the various factors responsible for shaping and coloring feculae, and with Morales (Gangwere and Morales, 1964) erected the first formal classification of orthopteroid feculae, and later (Gangwere, 1969) discussed the use of feculae of museum specimens as a shortcut method for determining food-habit; Scott (1964), who constructed a pictorial key to the droppings of cockroaches; Simeone (1964), who described the frass of posting beetles; Bhatia and Chandra (1967), who discussed the effect of food plants on the color, structure, and size of feculae in the locust Schistocerca gregaria; and Sardesai (1 969) who reported on size variation in feculae of larval Lepidoptera. With the partial exception of Gangwere and Morales (1964) and Bhatia and Chandra (!967), investigators have paid scant attention to variations in fecular structure within given species. The present study fills, in part, this gap in our knowledge. It describes those differences in fecular size and structure in selected Michigan acridids that relate to sex of defecator and type of food. It also attempts a statistical measurement of such differences

The Behavior of Atlanticus Testaceus (Orthoptera: Tettigoniidae) on the E.S. George Reserve, Michigan

Several reports deal in part with the systematics, distribution, or habits of one or another of the shield-backed katydids of the orthopteran genus Atlanticus. Included are Blatchley (1920), Cantrall (1943), Caudell (1907), Davis (1893), Hebard (1934), McNeill (1891), Rehn and Hebard (1916), and Scudder (1894). One species of the genus, A. testaceus (Scudder), is found commonly throughout Michigan and has interesting habits. As the species\u27 feeding behavior was poorly understood, the author undertook an investigation dealing with that subject. The results are in press. During the course of that study much information was obtained on certain non-feeding aspects of the species\u27 behavior. Findings with respect to the latter are given below. The project was carried out during the 1958-1961 field seasons at the University of Michigan\u27s Edwin S. George Reserve, a biological preserve near the village of Pinckney, Livingston County, Michigan. The general area is described in detail in Cantrall\u27s excellent report on the Reserve\u27s Orthoptera (1943) and in less detail in the author\u27s monograph on food selection in Orthoptera (1961). The specific sites of study, Southwest Field and Southwest Woods, are described in Gang- were (1965) and Gangwere (in press), respectively. The latter two re- ports may also be consulted for information on the techniques used during the study

Relationships between the Mandibles, Feeding Behavior, and Damage Inflicted on Plants by the Feeding of Certain Acridids (Orthoptera)

[excerpt] In 1960 the author described three fundamental patterns of feed- ing in Orthoptera and their allies and emphasized the close correlation that exists between the insects\u27 mouthpart structure, food, and feeding pattern. An article by Anderson (1964) made reference to these described patterns and discussed possible modifications of them. To the author\u27s knowledge these are the only reports available that make other than casual mention of the characteristic damage by Orthoptera to food plants. Numerous other papers include figures that depict orthopteran damage, and still others verbally describe the damage inflicted by various economically important species. In all these reports at least one basic consideration has been all but ignored: the possible relationships between mandibular form, pattern of use, and the resulting damage to food plants

A study of the feculae of Orthoptera, their specificity, and the role which the insects'mouthparts, alimentary canal, and food-habits play in their formation

2 láminasMany physiological studies have been carried out on different aspects of the feculae ("feces") and their formation in Orthoptera (sens. lat.). Among the more important of these researches are ones by Nenjukov and Parfentjev (1929), Nielsen (1943), and Snipes and Tauber (1937), who described for various species the speed of transit of food through the alimentary canal, i. e., rate of formation of feculae; Chauvin (1946), the periodicity of defecation in four species ; Bro-wn (1937) and Chauvin (1941), the biochemistry of feculae ; Brown (1937), their structure ; and numerous authors, the general physiology of digestion and excretion in Orthoptera. Surprisirigly, however, purely descriptive studies on feculae have lagged. Frost (1928; 1959) reviewed insect "scatology", but included scant material relative to Orthoptera ; Weiss and Boyd (1950) described and figured the feculae of three species of Orthoptera, and Boldyrev (1928) did the same for a species of katydid ; and Day (1950) described, but did not figure, those of a species of cockroach.Peer reviewe

The Food-Habits and Biology of Acrididae in an Old-Field Community in Southeastern Michigan

(excerpt) Inasmuch as the earth supports a wide variety of terrestrial communities differing in size and species composition, and because no two of these communities are identical in terms of foods and feeders, a correspondingly great complexity of feeding relationships is to be expected. Consequently, food-habit studies must take cognizance of dynamic interplay among many factors which vary with place and time, including that between food availability and the food preferences of consumers. Although ecologists have developed some sophisticated models of the various feeding interactions (e.g., Holling, 1963, 1964, 1966), the number of species whose food-habits and preferences have been carefully studied is small. Further knowledge is needed, particularly of the feeding biology of organisms in specific, limited communities and ecosystems

The influence of diet and environment on the gut microbial community of field crickets

The extent to which diet and environment influence gut community membership (presence or absence of taxa) and structure (individual taxon abundance) is the subject of growing interest in microbiome research. Here, we examined the gut bacterial communities of three cricket groups: (1) wild caught field crickets, (2) laboratory-reared crickets fed cat chow, and (3) laboratory-reared crickets fed chemically defined diets. We found that both environment and diet greatly altered the structure of the gut bacterial community. Wild crickets had greater gut microbial diversity and higher Firmicutes to Bacteroidetes ratios, in contrast to laboratory-reared crickets. Predictive metagenomes revealed that laboratory-reared crickets were significantly enriched in amino acid degradation pathways, while wild crickets had a higher relative abundance of peptidases that would aid in amino acid release. Although wild and laboratory animals differ greatly in their bacterial communities, we show that the community proportional membership remains stable from Phylum to Family taxonomic levels regardless of differences in environment and diet, suggesting that endogenous factors, such as host genetics, have greater control in shaping gut community membership

Premating Reproductive Barriers between Hybridising Cricket Species Differing in Their Degree of Polyandry

Understanding speciation hinges on understanding how reproductive barriers arise between incompletely isolated populations. Despite their crucial role in speciation, prezygotic barriers are relatively poorly understood and hard to predict. We use two closely related cricket species, Gryllus bimaculatus and G. campestris, to experimentally investigate premating barriers during three sequential mate choice steps. Furthermore, we experimentally show a significant difference in polyandry levels between the two species and subsequently test the hypothesis that females of the more polyandrous species, G. bimaculatus, will be less discriminating against heterospecific males and hence hybridise more readily. During close-range mating behaviour experiments, males showed relatively weak species discrimination but females discriminated very strongly. In line with our predictions, this discrimination is asymmetric, with the more polyandrous G. bimaculatus mating heterospecifically and G. campestris females never mating heterospecifically. Our study shows clear differences in the strength of reproductive isolation during the mate choice process depending on sex and species, which may have important consequences for the evolution of reproductive barriers

Male Weaponry in a Fighting Cricket

Sexually selected male weaponry is widespread in nature. Despite being model systems for the study of male aggression in Western science and for cricket fights in Chinese culture, field crickets (Orthoptera, Gryllidae, Gryllinae) are not known to possess sexually dimorphic weaponry. In a wild population of the fall field cricket, Gryllus pennsylvanicus, we report sexual dimorphism in head size as well as the size of mouthparts, both of which are used when aggressive contests between males escalate to physical combat. Male G. pennsylvanicus have larger heads, maxillae and mandibles than females when controlling for pronotum length. We conducted two experiments to test the hypothesis that relatively larger weaponry conveys an advantage to males in aggressive contests. Pairs of males were selected for differences in head size and consequently were different in the size of maxillae and mandibles. In the first experiment, males were closely matched for body size (pronotum length), and in the second, they were matched for body mass. Males with proportionately larger weaponry won more fights and increasing differences in weaponry size between males increased the fighting success of the male with the larger weaponry. This was particularly true when contests escalated to grappling, the most intense level of aggression. However, neither contest duration nor intensity was related to weaponry size as predicted by models of contest settlement. These results are the first evidence that the size of the head capsule and mouthparts are under positive selection via male-male competition in field crickets, and validate 800-year-old Chinese traditional knowledge