© Royal Entomological Society
Edited By: Jane K. Hill, Francis Gilbert and Rebeca B. Rosengaus
Impact Factor: 1.967
ISI Journal Citation Reports © Ranking: 2013: 12/90 (Entomology)
Online ISSN: 1365-2311
Associated Title(s): Agricultural and Forest Entomology, Insect Conservation and Diversity, Medical and Veterinary Entomology, Insect Conservation and Diversity, Physiological Entomology, Systematic Entomology
The Editor's Choice
Effects of altered precipitation on insect community composition and structure in a meadow steppe
Hui Zhu, Deli Wang, Ling Wang, Jian Fang, Wei Sun and Bingzhong Ren
There are many studies showing how insects are responding to recent climate change, but most previous studies have focused on temperature effects. Climate change is also predicted to alter precipitation patterns, and this study examines the effects of variation in rainfall on insect communities in meadow steppe grasslands. The authors report findings from an experimental field manipulation in which they altered rainfall compared with natural precipitation patterns (control, +30% rainfall, and −30% rainfall). Results reveal complex responses of insects to altered precipitation, and both increased and decreased rainfall caused declines in insect diversity and shifts in trophic structure as a result of plant and habitat effects. In addition, the authors found inter-annual variation in the insect community, and the authors conclude that long-term experiments are important for drawing correct conclusions about the impacts of climate change on grassland ecosystems.
Images: Top Left: Corymbia dichroa Top Right: Graphosoma rubrolineata Bottom Left: Locusta migratoria Bottom Right: Meadow Steppe
Sooner or later, we all get sick. This certainty is what makes the topic of self-medication in animals so appealing to humans. The fact that even insects, with their (assumed) negligible brain power can respond prophylactically and/or therapeutically to prevent, ameliorate and/or cure the negative effects posed by pathogenic protozoa, viruses, fungi, bacteria and parasites is a growing area in the field of ecological immunology. In her review, Abbot systematically tackles five different examples of self-medication across the Insecta, from solitary to eusocial species. She provides clear criteria needed to invoke self-medication. She also details the dynamics and possible trade-offs between innate immune responses and self-medication, while reminding us that in some instances self-medication does not only benefit the “self” but can also protect its progeny and other kin. Her comparative approach identifies at least one common feature in those insect species exhibiting self-medication: the compounds used as “medicines” are both naturally consumed as part of a normal diet or are present and collected in the environment. This observation then provides insight into the evolutionary origins of self-medication. This timely review is relevant not only to researchers focusing on ecological immunology, phenotypic plasticity, trans-generational immunity, trade-offs, parental investment and the evolution of disease resistance, but also to everyone who gets sick.
Images: Left: Jessica Abbott Right:Drosophila melanogaster female (taken by Qinyang Li)
Optimal foraging by an aphid parasitoid affects the outcome of apparent competition
Sara G. Prado & Steven Frank
This important paper links two fields together, from behavioural ecology (optimal foraging) and from evolutionary ecology (apparent competition). They were predicted to be linked more than two decades ago, when the theoretical idea that herbivore community structure might result from apparent competition was mooted. Although much of the evidence for optimal foraging and for apparent competition come from work with insects, this is the first entomological test of their link, and apparently only the second test in any organism.
Images: Aphidius colemani parasitizing Rhopalosiphum padi on barley. Photographs by Adam Dale.
Responses of a native beetle to novel exotic plant species with varying invasion history
Hongjun Dai, Xinmin Lu, Jialiang Zhang, & Jianqing Ding
The invasion of alien plants can provide new opportunities to examine the evolution of insect-plant interactions. The study examines how a native species of beetle responds to two exotic plant species, introduced in the 1830s and more recently in the 1930s, that are closely related to its native host plants. Results show that the beetle oviposited on the older invader as frequently as on native host plants, but that larvae developed more slowly on both alien species. The authors conclude that the beetle has adapted behaviourally to the older invader but has failed to adapt physiologically to either species of invasive plant, and that it is important to consider time-since- invasion when examining interactions between alien plants and native herbivores.
Images - Left: Cassida piperata adult on a Chenopodium album leaf. Right: C. piperata larva on an Alternanthera philoxeroides leaf. Photographs by Xin-Min Lu.
Proximate effects of maternal oviposition preferences on defence efficacy and larval survival in a diet-specialised tortoise beetle. Who knows best: mothers or their progeny?
Fredric V. Vencl, Camila A. Plata C. and Robert B. Srygley
It is reasonable to assume that natural selection should result in a tight alignment of both maternal and offspring interests. This “common agenda” should be particularly important for specialist herbivorous insects where mothers need to ensure that their young larvae encounter and feed on a specific diet. Yet, a mother’s decision on where to oviposit is likely influenced by other more immediate environmental pressures besides her future offspring’s dietary restrictions and nutritional needs. Her oviposition decisions can be driven by the presence of predators, parasites, the age and toughness of the foliage and/or the amount of secondary compounds in the leaves, among other factors. Such factors can lead to females choosing seemingly sub-optimal oviposition sites. The work by Vencl, Plata and Srygley tackles the interesting question of whether some of these factors affect the oviposition behaviour of female tortoise beetle, Acromis sparsa. Through a series of field experiments, the researchers manipulated, singly or in combination, maternal guarding, larval shields and progeny density and recorded predation rates, larval migration and survival. The fact that mothers need to contend with a myriad of imminent factors while deciding on an oviposition site, may help explain the mismatch between maternal and progeny interests. It is not necessarily the case that “mother knows best”, but instead a matter of “mother does the best she can do” given the conditions and pressures she encounters during oviposition.
Images - Left: Third instar larvae with experimentally removed mother and shields in a large aggregation (>15 larvae) Right: Female guarding her shielded brood against Azteca ant attack
Plant neighbours mediate bird predation effects on arthropod abundance and herbivory
Brice Giffard, Luc Barbaro, Hervé Jactel and Emmanuel Corcket
Since the iconoclastic days of Dan Simberloff, ecologists have tried much harder to test experimentally whether community-level interactions matter. An abundance of evidence has resulted, first from simple interspecific interactions and then from more complex ones. This nice experiment shows the complexity and conditionality of the tritrophic interactions based on oak trees and involving plant neighbours, insect herbivores and insectivorous birds.
Images - Left: Bird exclusion equipment Right: Caterpillar on an oak leaf
Volume 38 Issue 3
Effects of climate warming on host–parasitoid interactions
Christopher T. Jeffs & Owen T. Lewis
In an increasingly warming Earth, its inhabitants along with their respective abiotoic and biotic interactions are and will surely continue to be affected. This review point out the research gaps that need to be addressed if we are to generate accurate models for predicting how elevated temperatures (and its associated physical factors such as acidification, precipitation, increased mineralization rates, nitrogen enrichment, etc.), will impact life as we know it. Although this article focuses on the effect of climate warming on host-parasitoid interactions, the reality is that the same arguments posed by the authors are applicable to many other biological associations, including, but not limited to, host-pathogen, host-mutualist, host-herbivore, predator-prey, male-female interactions, etc. Hence, this review reminds us about the complexity of nature and points several fundamental and confounding factors that require consideration when reliably predicting future impacts of a warming world.
Volume 38 Issue 2
The evolution of parental care in insects: the roles of ecology, life history and the social environment
Janine W. Y. Wong, Joël Meunier, Mathias Kölliker
Many insects exhibit parental care and increase the success of their offspring at a cost to themselves. This Review paper examines the hypotheses that have been put forward to explain the evolution of parental care, and reviews the empirical evidence. Parental care is often associated with social interactions, and the paper also examines how factors such as food availability and population density influence social interactions. The authors point out how insects provide great opportunities for carrying out experimental and comparative research to investigate key new questions in the evolution of parental care.
Volume 37 Issue 5
Egg size and composition in an ageing capital breeder – consequences for offspring performance
Heikki Pöykkö, Satu Mänttäri
Click on the image to enlarge the picture.
As entomologists, our research usually focuses on insects at one particular developmental stage during their life cycle: the immature larval period, the nymph or pupae phases, or the adult stage. Yet, many of the attributes we study during these specific phases are influenced and/or determined at the egg stage, a period that has significant "trickle-down effects" on post-hatching success. Egg size as well as egg composition may be significant predictors of offspring survival and developmental rates and ultimately, fitness of progeny. The work by Pöykkö and Mänttäri reminds us that maternal provisioning can be context-dependent, influenced by both intrinsic (i.e. genetics, female age) and extrinsic factors (i.e. female nutritional reserves). Their work addressed first, the question of whether differences in absolute egg size and/or differences in the concentration of certain nutrients were correlated with female age in the capital breeder geometrid moth, Cleorodes lichenari. Secondly, they studied whether these differences affected offspring’s performance. Given the vast diversity of insect species, their corresponding variable life-history traits and the significance that egg “quality” can have on future success of offspring, the study of non-genetic parental contributions (made not only by female but also male adults), ought to make this a fruitful and promising area for future research.
Images - Cleorodes lichenaria first instar larva, Cleorodes lichenaria adult female (both images taken by Ho Heikki Pöykkö)
Evaluating female remating rates in light of spermatophore degradation in Heliconius butterflies: pupal-mating monandry versus adult-mating polyandry
James R. Walters, Christine Stafford, Thomas J. Hardcastle, Chris D. Jiggins
Scientists often have contrasting views about the older literature: either it can be safely ignored because mostly it contains erroneous conclusions arrived at intuitively without the help of statistics; or "there is nothing new under the sun" - modern ideas have all been thought before, and lie hidden in the dusty corners of libraries. So it's reassuring when modern statistical analysis confirms what was concluded from pure observation. This paper reconsiders the idea that female heliconiines that mate while still emerging from the pupa are monandrous, while those that mate when fully post-teneral adults are more promiscuous, a conclusion derived largely from counting spermatophores in the female tract. However, spermatophores are now known to degrade fairly rapidly, putting this conclusion in doubt. Estimating the remating rate required a novel maximum-likelihood model that included age, remating and rates of degradation. Reassuringly, the evolution of pupal mating does indeed appear to evolve in concert with monandry, an important result in the study of just why females mate more than once.
Please click the picture above to access a short video of mating behaviour
Image - Heliconius melpomene mating behaviour – Chris Jiggins
Seasonal patterns of herbivory, leaf traits and productivity consumption in dry and wet Patagonian forests
Noemí Mazía, Enrique J. Chaneton, Cristina Dellacanonica, Luciano Dipaolo, Thomas Kitzberger
The study investigates herbivory in temperate Nothofagus forest in South America, and shows that herbivory is higher in ‘dry’ forest compared with ‘wet’ forest. This was unexpected because foliar production and nutritional quality was much higher in wet forests. The authors conclude that cooler conditions and a shorter growing period in wet forests may explain low herbivory rates.
Images - Left: Nothofagus forest in autumn Middle: Wet forest study site Right: Dry forest study site
Photos by: C. Noemí Mazía
A seed parasitoid wasp prevents berries from changing their colour, reducing their attractiveness to frugivorous birds
Etsuro Takagi, Kazunobu Iguchi, Masanori Suzuki, Katsumi Togashi
Parasites are well known for their ability to manipulate host physiology and behaviour to increase their own survival, dispersal and infective potential. Examples of such direct effects abound. Yet relatively little is known about the indirect effects that parasites have on mutualistic interactions of its host. The research by Takagi et al presents convincing evidence that the parasitoid wasp Macrodasyceras hirsutum disrupts the well-established mutualistic interaction between the plant Ilex integra and its seed-disperser, the frugivorous bird, Hypsipetes amaurotis. The plant produces fruits that normally change coloration from green to red as they ripen on the tree. Such red fruit are preferentially eaten by the birds, and thus, both the plant and the birds benefit from this interaction. Yet, female parasitoid wasps oviposit on the fruit’s seed preventing the fruit from attaining the typical red coloration. Through field exclusion and feeding experiments, the results indicate that the developing wasp larvae inhibit in a density-dependent fashion the coloration change of the fruit, but not its size or shape. The disruption of the plant/bird mutualistic interaction by wasp larvae has important ecological consequences for each member of this tripartite association.
Images - Left: Macrodasyceras hirsutum larva in winter Right: Macrodasyceras hirsutum female inserting ovipositor into an Ilex integra berry
Physical barriers and corridors in urban habitats affect colonisation and parasitism rates of a specialist leaf miner
Guadalupe Peralta, Maria Silvina Fenoglio, Adriana Salvo
Developing an understanding of the ecology of urban areas will become increasingly important as urban development continues to accelerate. Much attention has been focussed on birds and mammals although recent work has also examined the importance of urban areas to insect pollinators. This paper takes a broad ecological approach to understand how the ecology of urban areas might affect leaf miner colonisation and parasitism. The urban environment is detailed as a fragmented and heterogeneous mix of host plants, pavements, walls and yards, with the results showing that pavements act as corridors and constructions as barriers. The distinct physical environment found in urban areas is shown to play a role in the dispersal, colonisation and parasitism found in this system.
Images – Left: Chrysocharis flacilla; Right: C. erecta flower and mined leaf
Dispersal in the Glanville fritillary butterfly in fragmented versus continuous landscapes: comparison between three methods
Rongjiang Wang, Otso Ovaskainen, Yundong Cao, Houqiang Chen, Yan Zhou, Chongren Xu and Ilkka Hanski
Natural habitats are becoming increasingly fragmented and insects occupying these landscapes are showing evolutionary changes in dispersal. Harmonic radar techniques reveal that butterflies from a continuous landscape fly more slowly and have lower optimal temperatures for flight, and that the predicted distance these individuals fly at their optimal temperature is shorter than for individuals from fragmented landscapes. The study combines findings from three different methods – harmonic radar, MRR and rearing studies - to reveal evolutionary adaptations of insects in modern landscapes.
Image - Left: Glanville Fritillary with transponder attached. Right: Harmonic radar equipment used for tracking free-flying butterflies
Effects of different methods of non-lethal tissue sampling on butterflies
Daria Koscinski, Lindsay A. Crawford, Heidi A. Keller and Nusha Keyghobadi
In butterfly genetic studies, it is often assumed that removing legs or clipping wings from living individuals is both non-lethal and not detrimental. Although common practice, this assumption, like so many in ecology, has not been tested. This study tests the effects of these treatments in the field with Pieris rapae and Coenonympha tullia. It shows that such manipulations do not affect survival or flight behaviour, thereby giving credibility to the many studies underpinned by this previously untested assumption and providing a firm foundation for future studies.
Images – Left: Non-lethal tissue sampling (wing clipping) of a cabbage white butterfly (taken by Daria Koscinski); Right: Wing clip sample taken from a cabbage white butterfly (taken by Alan Noon)
Context-dependence in an ant–aphid mutualism: direct effects of tending intensity on aphid performance
Ho Jung S.Yoo and David A. Holway
Mutualistic associations are ubiquitous in nature. A prime example of these interactions includes the widespread phenomenon of aphid tending by ants. Historically, this association has been categorised as mutualistic since both partners of the association appear to draw significant benefits: ants receive nutritious honeydew from their aphids, while aphids benefit from predator protection and/or sanitation from their ants. This study points to the fine line and dynamic balancing act between mutualism and parasitism. By manipulating the per capita tending rates between the aphid Chaitophorus populicola and the ant, Linepithema humile, the authors provide evidence for context- and density-dependent factors influencing the nature of such inter-specific interactions. The work combines greenhouse and field observations and reminds us about nature’s complexity. Sliding back and forth between mutually beneficial and parasitic interactions may be more common than we realise. Considering which intrinsic and extrinsic factors favour one kind of association over another throughout the symbiosis continuum is particularly informative.
Images – Left: Clip cages used to enclose adult and neonate aphids during set-up of experiment; Right: Argentine ants tending poplar leaf aphids on cottonwood trees in the field (both images taken by Ho Jung Yoo)
Many insects have important associations with bacterial symbionts. This paper reviews the role of these important endosymbionts for insect nutritional ecology; for example, in relation to insect-plant interactions, in facilitating insect invasions, and insect immunity. New technological advances through metagenomic approaches open up great opportunities for future research on insects and their endosymbionts.
Images - Left: The ant Polyrachis ypsilon which harbours endosymbiontic bacteria of the genus Blochmannia
Right: Many phloem feeding insects like this membracid harbour primary as well as secondary endosymbionts