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Insect Prey (insect + prey)

Distribution by Scientific Domains

Life Sciences	80%

Selected Abstracts

How to Spoil the Taste of Insect Prey?

CHEMBIOCHEM, Issue 12 2010
A Novel Feeding Deterrent against Ants Released by Larvae of the Alder Leaf Beetle, Agelastica alni
Abstract Chemical defense of leaf beetle larvae (Chrysomelidae) against enemies is provided by secretions containing a wide range of deterrent compounds or by unpalatable hemolymph constituents. Here we report a new, very strong feeding deterrent against ants released by larvae of the alder leaf beetle Agelastica alni when attacked. The larvae release a defensive fluid from openings of pairwise, dorsolaterally located tubercles on the first to the eighth abdominal segments. The fluid, consisting of hemolymph and probably a glandular cell secretion, has previously been shown to contain a very stable, non-volatile feeding deterrent. The major deterrent component was isolated by repeated HPLC separation and analyzed by NMR and MS. The compound proved to be ,- L -glutamyl- L -2-furylalanine (1), a novel dipeptide containing the unusual amino acid L -2-furylalanine. This amino acid, although synthetically well known, has not previously been reported from natural sources. The absolute configuration of the natural compound was elucidated by enantioselective gas chromatography after derivatization. The structure of the dipeptide was verified by the synthesis of several isomeric dipeptides. In bioassays a concentration of 1 ,g,,L,1 was sufficient to deter polyphagous Myrmica rubra ants from feeding. [source]

Sensory ecology of prey rustling sounds: acoustical features and their classification by wild Grey Mouse Lemurs

FUNCTIONAL ECOLOGY, Issue 1 2007
H. R. GOERLITZ
Summary 1Predatory mammals and birds from several phylogenetic lineages use prey rustling sounds to detect and locate prey. However, it is not known whether these rustling sounds convey information about the prey, such as its size or profitability, and whether predators use them to classify prey accordingly. 2We recorded rustling sounds of insects in Madagascar walking on natural substrate and show a clear correlation between insect mass and several acoustic parameters. 3In subsequent behavioural experiments in the field, we determined whether nocturnal animals, when foraging for insects, evaluate these parameters to classify their prey. We used field-experienced Grey Mouse Lemurs Microcebus murinus in short-term captivity. Mouse Lemurs are generally regarded as a good model for the most ancestral primate condition. They use multimodal sensorial information to find food (mainly fruit, gum, insect secretions and arthropods) in nightly forest. Acoustic cues play a role in detection of insect prey. 4When presented with two simultaneous playbacks of rustling sounds, lemurs spontaneously chose the one higher above their hearing threshold, i.e. they used the rustling sound's amplitude for classification. We were not able, despite attempts in a reinforced paradigm, to persuade lemurs to use cues other than amplitude, e.g. frequency cues, for prey discrimination. 5Our data suggests that Mouse Lemurs, when foraging for insects, use the mass,amplitude correlation of prey-generated rustling sounds to evaluate the average mass of insects and to guide their foraging decisions. [source]

Size-dependent predation risk in tree-feeding insects with different colouration strategies: a field experiment

JOURNAL OF ANIMAL ECOLOGY, Issue 5 2009
Triinu Remmel
Summary 1. Body size is positively correlated with fecundity in various animals, but the factors that counterbalance the resulting selection pressure towards large size are difficult to establish. Positively size-dependent predation risk has been proposed as a selective factor potentially capable of balancing the fecundity advantage of large size. 2. To construct optimality models of insect body size, realistic estimates of size-dependent predation rates are necessary. Moreover, prey traits such as colouration should be considered, as they may substantially alter the relationship between body size and mortality risk. 3. To quantify mortality patterns, we conducted field experiments in which we exposed cryptic and conspicuous artificial larvae of different sizes to bird predators, and recorded the incidence of bird attacks. 4. The average daily mortality rate was estimated to vary between 4% and 10%. In both cryptic and conspicuous larvae, predation risk increased with prey size, but the increase tended to be steeper in the conspicuous group. No main effect of colour type was found. All the quantitative relationships were reasonably consistent across replicates. 5. Our results suggest that the size dependence of mortality risk in insect prey is primarily determined by the probability of being detected by a predator rather than by a size-dependent warning effect associated with conspicuous colouration. Our results therefore imply that warningly coloured insects do not necessarily benefit more than the cryptic species from large body size, as has been previously suggested. [source]

Nutritional value of cannibalism and the role of starvation and nutrient imbalance for cannibalistic tendencies in a generalist predator

JOURNAL OF ANIMAL ECOLOGY, Issue 1 2006
DAVID MAYNTZ
Summary 1Cannibalism is considered an adaptive foraging strategy for animals of various trophic positions, including carnivores. However, previous studies on wolf spiders have questioned the high nutritional value of cannibalism. We therefore analysed two different aspects of nutritional quality of conspecifics in the wolf spider Pardosa prativaga: their value for survival, growth and development; and the growth efficiency of feeding on conspecifics. We also measured the propensity for cannibalistic attacks and the consumption rate of conspecifics in an experiment where hunger level and nutrient balance were manipulated. In all experiments, cannibalism was compared with predation on fruit flies as control prey. 2The growth experiment gave ambiguous results regarding the nutritional quality of conspecifics. Spiders on pure cannibalistic diets split into two distinct groups, one performing much better and the other much worse than spiders on fruit fly diets. We discuss the possibility that the population is dimorphic in its cannibalistic propensity, with the latter group of individuals showing a high level of inhibition against cannibalistic attacks in spite of a high nutritional value of cannibalism. 3The food utilization experiment confirmed the high nutritional quality of conspecifics, as cannibalistic spiders had the same growth rate as spiders fed insect prey in spite of a much lower consumption rate. 4Inhibition against cannibalistic attacks was demonstrated in medium-sized juveniles: only half of the spiders attacked a prescribed victim of 50% the size of their opponents, and the latency for those that did attack was more than half an hour, compared with a few minutes for spiders fed fruit flies. 5Nutrient-imbalanced spiders utilized an alternative insect diet less efficiently than balanced spiders, whereas no difference was present in efficiency of utilizing conspecifics. This result indicates that spiders can remedy at least part of a nutrient imbalance through cannibalism. 6As spiders can escape nutritional imbalance as well as restore energy reserves through cannibalism, we predicted both nutrient imbalance and hunger to stimulate cannibalism. This prediction was confirmed only with respect to hunger. Nutrient-imbalanced spiders had reduced cannibalistic consumption, perhaps due to lowered predatory aggressiveness as a result of bad condition. [source]

Escape Behavior of Neotropical Homopterans in Response to a Flush,Pursuit Predator

BIOTROPICA, Issue 4 2004
Mark L. Galatowitsch
ABSTRACT Insect defenses against avian predators often include both a primary defense that reduces the probability of being attacked and a secondary defense, typically escape behavior, employed if the primary defense fails. Escape behavior, however, can make insects potentially vulnerable to specialized flush,pursuit predators. Neotropical Redstarts of the genus Myioborus (Parulidae) exploit insect escape behavior by using their contrasting black-and-white plumage and animated foraging behavior to startle insect prey that are then pursued and captured in flight. We examined how insect primary defense strategy and natural variation in Myioborus plumage pattern influence escape behavior in six species of homopterans from Monteverde, Costa Rica. The six homopterans included two aposematic species of the family Cercopidae (Ocoaxo sp. and Sphenorhina sp.), two cryptic species of the family Cixiidae (both Bothriocera spp.), and two structurally defended species of the family Membracidae (Camfylocentrus sp. and Vestistilus variabilis). We measured the distance at which models of Myioborus Redstarts elicited escape behavior in insects under field conditions. Response distances varied significantly with both homopteran primary defense and Myioborus plumage pattern. Structurally defended homopterans were the most sensitive to the models and cryptic homopterans were the least sensitive. The model simulating the plumage of endemic M. miniatus comptus of Costa Rica elicited greater responses than did models of other Myioborus taxa with either less or more white in the plumage. Our results suggest that (1) primary defense strategies can have a significant effect on insect vulnerability to flush-pursuit predators, and (2) geographic variation in the plumage pattern of Myioborus Redstarts may reflect adaptation to regional prey and habitat characteristics that maximizes flush-pursuit foraging performance. RESUMEN Las defensas de los insectos contra aves depredadoras, frecuentemente incluye dos tipos de defensa: una primaria, que disminuye la probabilidad de ser atacado, y una defensa secundaria tipica de comportamiento de escape, la cual es empleada si falla la defensa primaria. Sin embargo, el comportamiento de escape puede ocasionar que los insectos scan potencialmente vulnerables a depredadores especializados en vuelo y persecusión. Los colirrojos neotropicales del género Myioborus (Parulidae) explotan el comportamiento de escape de los insectos usando su plumaje contrastante bianco-negro, y su comportamiento de forrajeo animado para sobresaltar a los insectos a cazar, que luego son perseguidos y capturados en vuelo. Nosotros examinamos cómo la defensa primaria de insectos y la variación natural del plumaje en Myioborus influye en el comportamiento de escape en seis especies de homópteros de Monteverde, Costa Rica. Los seis homópteros estudiados incluyeron dos especies conspicuas de la familia Cercopidae (Ocoaxo esp. y Sphenorhina esp.), dos especies enigmáticas de la familia Cixiidae (ambos Bothriocera esp.), y dos especies de la familia Membracidae (Campylocentrus esp. y Vestistilus variabilis) que se defienden estructuralmente. Nosotros medimos la distancia en la cual los modelos colirrojos de Myioborus provocan el comportamiento de escape en insectos bajo de condiciones de campo. Las respuestas a las distancias variaron significativamente en ambas, en defensa primaria de los homópteros y el partón del plumaje de los Myioborus. Los homópteros que se defienden estructuralmente fueron los más vulnerables a los modelos, y los homópteros enigmáticos los menos vulnerables. El modelo simulando el plumaje del colirrojo M. miniatus comptus endémico de Costa Rica, produjo mayor respuesta que los otros modelos Myioborus de otras taxas con menos o más color bianco en su plumaje. Los resultados de este estudio sugieren que: (1) las defensas de estrategia primaria pueden tener un efecto significative en la vulnerabilidad de los insectos a los depredadores que vuelan y persiguen; y (2) la variación geografica en el partón del plumaje de los Myioborus colirrojos puede indicar adaptaciones a presas por regiones y a caracteristicas del hábitat que maximizan su habilidad de volar y perseguir. [source]