scholarly journals The Effects of Population Density on the Incidence of Developmental Deformities in Chemosensory Organs of Tobacco Hornworm Larvae (Lepidoptera: Sphingidae)

2020 ◽  
Vol 20 (4) ◽  
Author(s):  
Frank Hanson ◽  
Elizabeth Stanwyck ◽  
Alexander Bohorquez

Abstract Cultures of Manduca sexta Johanssen in our laboratory were found to have larvae with missing or deformed mouthparts or antennae. Hypothesizing that these developmental deformities were caused by crowded rearing conditions, we reared larvae in four different population densities and recorded the incidence (% of larvae affected) and types of chemoreceptor deformities. Results showed that the incidence of these deformities was directly proportional to larval population density. Deformities of the maxilla and palp were the most frequent, followed by those of the antenna, epipharynx and maxillary styloconica. Life history traits of larval mass, food consumption, and rate of development were inversely related to larval density for both normal and deformed larvae. We discuss possible causes and mechanisms of these deformities and of changes to life history traits.

1973 ◽  
Vol 51 (11) ◽  
pp. 1189-1193 ◽  
Author(s):  
J. A. Baxter ◽  
A. M. Mjeni ◽  
P. E. Morrison

The expression of autogeny in S. bullata was influenced by the larval rearing conditions. Low larval population densities resulted in large flies that were autogenous. On the other hand, high larval population densities produced small flies that were anautogenous, In anautogenous females the size and stage to which the follicles developed varied with the size of the fly. When reared on a sucrose–water diet, the females from an intermediate larval population density possessed larvae, mature eggs, degenerate follicles, or undeveloped follicles.


2006 ◽  
Vol 85 (1) ◽  
pp. 53-56 ◽  
Author(s):  
Sutirth Dey ◽  
Snigdhadip Dey ◽  
J. Mohan ◽  
Amitabh Joshi

2021 ◽  
Author(s):  
Juliano Morimoto ◽  
Lucy Kerr

Natural history information is essential for ecologically-relevant inferences about (adaptive) responses in organismal biology. Yet, natural history data can be difficult to obtain, particularly for the developmental stages of holometabolous insects. This gap can compromise our ability to design controlled experiments that provide useful understanding of insect responses to changing environments and precludes our ability to understand how natural populations may respond to unpredictable climatic changes in their natural environment. In this study, we collated data from previous reports from the Butterfly Conservation Upper Thames Branch on the larval population density of Shargacucullia lychnis (Lepidoptera: Noctuidae) in Buckinghamshire. In the UK, S. lychnis is a protected species, for which natural history information can be invaluable for its effective conservation. We report here that the natural range of larval densities observed for S. lychnis across locations and years is 0.001 to 6.417 larvae per spike. More importantly, S. lychnis larval density has overall declined from 1996 to 2020, which could support previous reports of a contraction in population range for this species. Overall, this study provides invaluable information about larval population density for an important protected Lepidopteran species of the UK.


2021 ◽  
Vol 8 ◽  
Author(s):  
Andrea J. Roth-Monzón ◽  
Mark C. Belk ◽  
J. Jaime Zúñiga-Vega ◽  
Jerald B. Johnson

Life-history traits are directly linked to fitness, and therefore, can be highly adaptive. Livebearers have been used as models for understanding the evolution of life histories due to their wide diversity in these traits. Several different selective pressures, including population density, predation, and resource levels, can shape life-history traits. However, these selective pressures are usually considered independently in livebearers and we lack a clear understanding of how they interact in shaping life-history evolution. Furthermore, selective pressures such as interspecific competition are rarely considered as drivers of life-history evolution in poeciliids. Here we test the simultaneous effects of several potential selective pressures on life-history traits in the livebearing fish Poeciliopsis prolifica. We employ a multi-model inference approach. We focus on four known agents of selection: resource availability, stream velocity, population density, and interspecific competition, and their effect on four life-history traits: reproductive allocation, superfetation, number of embryos, and individual embryo size. We found that models with population density and interspecific competition alone were strongly supported in our data and, hence, indicated that these two factors are the most important selective agents for most life-history traits, except for embryo size. When population density and interspecific competition increase there is an increase in each of the three life-history traits (reproductive allocation, superfetation, and number of embryos). For individual embryo size, we found that all single-agent models were equivalent and it was unclear which selective agent best explained variation. We also found that models that included population density and interspecific competition as direct effects were better supported than those that included them as indirect effects through their influence on resource availability. Our study underscores the importance of interspecific competitive interactions on shaping life-history traits and suggests that these interactions should be considered in future life-history studies.


2020 ◽  
Vol 34 (5) ◽  
pp. 659-680 ◽  
Author(s):  
Anh The Than ◽  
Fleur Ponton ◽  
Juliano Morimoto

Abstract Population density modulates a wide range of eco-evolutionary processes including inter- and intra-specific competition, fitness and population dynamics. In holometabolous insects, the larval stage is particularly susceptible to density-dependent effects because the larva is the resource-acquiring stage. Larval density-dependent effects can modulate the expression of life-history traits not only in the larval and adult stages but also downstream for population dynamics and evolution. Better understanding the scope and generality of density-dependent effects on life-history traits of current and future generations can provide useful knowledge for both theory and experiments in developmental ecology. Here, we review the literature on larval density-dependent effects on fitness of non-social holometabolous insects. First, we provide a functional definition of density to navigate the terminology in the literature. We then classify the biological levels upon which larval density-dependent effects can be observed followed by a review of the literature produced over the past decades across major non-social holometabolous groups. Next, we argue that host-microbe interactions are yet an overlooked biological level susceptible to density-dependent effects and propose a conceptual model to explain how density-dependent effects on host-microbe interactions can modulate density-dependent fitness curves. In summary, this review provides an integrative framework of density-dependent effects across biological levels which can be used to guide future research in the field of ecology and evolution.


2017 ◽  
Vol 284 (1866) ◽  
pp. 20172087 ◽  
Author(s):  
Tamara L. Johnson ◽  
Matthew R. E. Symonds ◽  
Mark A. Elgar

Developmental plasticity provides individuals with a distinct advantage when the reproductive environment changes dramatically. Variation in population density, in particular, can have profound effects on male reproductive success. Females may be easier to locate in dense populations, but there may be a greater risk of sperm competition. Thus, males should invest in traits that enhance fertilization success over traits that enhance mate location. Conversely, males in less dense populations should invest more in structures that will facilitate mate location. In Lepidoptera, this may result in the development of larger antennae to increase the likelihood of detecting female sex pheromones, and larger wings to fly more efficiently. We explored the effects of larval density on adult morphology in the gum-leaf skeletonizer moth, Uraba lugens , by manipulating both the number of larvae and the size of the rearing container. This experimental arrangement allowed us to reveal the cues used by larvae to assess whether absolute number or density influences adult responses. Male investment in testes size depended on the number of individuals, while male investment in wings and antennae depended upon larval density. By contrast, the size of female antennae and wings were influenced by an interaction of larval number and container size. This study demonstrates that male larvae are sensitive to cues that may reveal adult population density, and adjust investment in traits associated with fertilization success and mate detection accordingly.


2019 ◽  
Vol 112 (6) ◽  
pp. 505-510 ◽  
Author(s):  
Brittny M Jones ◽  
Jeffery K Tomberlin

Abstract The black soldier fly, Hermetia illucens (L.), is economically important due to its use in waste management and as an alternative protein source for livestock, poultry, and aquaculture. While industry promotes mass production of the black soldier fly, little is known about the impact of larval competition on development time, resulting immature and adult weight, or adult longevity. The goal of this research was to examine the life-history traits of black soldier flies when reared at four densities (500, 1,000, 1,500, and 2,000 larvae/4-liter container) provided 54-g Gainesville diet at 70% moisture (feed rates of 0.027, 0.036, 0.054, and 0.108 g) every other day. Results were as expected with the lowest larval density (500) producing heavier individuals (by 26%) than the greatest larval density (2,000) across all life stages. In addition to weights, larvae reared at the lowest density developed 63% faster than those reared at the greatest density. In regard to pupal development time, those reared at the lowest larval density developed 3% slower than the greatest density. A 21% difference between the two extreme densities was found in survivorship to prepupal stage, with the lowest larval density having the greatest survivorship (92%) compared with the greatest larval density (70%). All densities displayed over 90% adult emergence rates. Such information is vital for optimization of the process of converting waste products to protein at an industrial scale with the black soldier fly.


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