scholarly journals Drop when the stakes are high: adaptive, flexible use of dropping behaviour by aphids

Behaviour ◽  
2021 ◽  
pp. 1-21
Author(s):  
Rosalind K. Humphreys ◽  
Graeme D. Ruxton ◽  
Alison J. Karley

Abstract For herbivorous insects, dropping from the host plant is a commonly-observed antipredator defence. The use of dropping compared to other behaviours and its timing in relation to contact with a predator was explored in both pea aphids (Acyrthosiphon pisum) and potato aphids (Macrosiphum euphorbiae). Pea aphids dropped more frequently in response to ladybird adults (Adalia bipunctata) than lacewing larvae (Chrysoperla carnea). Potato aphids mainly walked away or backed-up in response to both predator types; but they dropped more frequently relative to other non-walking defences when faced with ladybird adults. Contact with a predator was an important influencer of dropping for both species, and most drops occurred from adjacent to the predator. Dropping appears to be a defence adaptively deployed only when the risk of imminent predation is high; factors that increase dropping likelihood include presence of faster-foraging predators such as adult ladybirds, predator proximity, and contact between aphid and predator.

2021 ◽  
Vol 34 (4) ◽  
pp. 223-239
Author(s):  
Rosalind K. Humphreys ◽  
Graeme D. Ruxton ◽  
Alison J. Karley

AbstractDropping behavior is an effective antipredator defense utilized by many insects including aphids, which drop from plants to lower plant parts or underlying substrates to avoid attack from predatory invertebrates. While research commonly focusses on triggers of dropping, less attention is given to what happens to prey individuals following escape drops. In this study, the duration of tonic immobility, recovery rates, and cases of “instant recovery” (re-clinging to lower plant parts) exhibited by potato aphids (Macrosiphum euphorbiae) that dropped from potted seedlings in response to introduced ladybird (Adalia bipunctata) adults, lacewing (Chrysoperla carnea) larvae, and a standardized tactile stimulus were investigated in relation to a range of environmental factors. Air temperature had a negative correlation with the duration of post-dropping tonic immobility; as temperature increased, time spent motionless decreased. Aphids also showed a pattern of increased recovery rate at higher temperatures. Aphids may be selected to move off the substrate quicker to avoid risks of overheating/desiccation at higher temperatures; and/or higher body temperature facilitates locomotion. Stimulus type also influenced recovery rate back to the original seedling, with aphids generally recovering after the standardized stimulus quicker than after dropping triggered by a real predator. Considering cases of instant recovery onto lower-reaches of the host seedling, seedling height influenced the likelihood of re-clinging, with aphids that managed to instantly recover dropping from, on average, taller seedlings than aphids that dropped to the substrate. Plant architecture could mitigate the costs of dropping for aphids, but further studies quantifying understory foliage cover are needed.


1982 ◽  
Vol 60 (10) ◽  
pp. 2245-2252 ◽  
Author(s):  
J. M. Clegg ◽  
C. A. Barlow

Pea aphids respond most effectively to the threat of a predator by walking away or dropping from their host plant. Simulating threat by using vibration and alarm pheromone, both separately and together, we found no evidence that escape responses are heritable, nor that individual aphids have characteristic escape behaviours. On the contrary, the amount of alarm pheromone influenced responses: the more pheromone, the more likely an immediate and effective escape. Vibration preceding alarm pheromone greatly increased responsiveness to pheromone, and aphids were more responsive to pheromone after vibration when feeding on stems than when feeding on the undersides of leaves.


2021 ◽  
Vol 01 ◽  
Author(s):  
Martin John Martin ◽  
Zuqing Hu ◽  
Zhiqiang Lu

Background: Pea aphids (Acyrthosiphon pisum) possess a weak immune system, but they can firmly mount immunological responses. However, the influence of different plants on their defense against different microbes remains largely unknown. In addition, no previous research has integrated the growth, reproduction, and defense responses of pea aphids feeding on different plants. Objective: This study aims to investigate the growth, reproduction, and defense responses of pea aphids feeding on different plants. Methods: Pea aphids were cultivated on both Medicago sativa and Vicia faba. Growth and reproduction were evaluated. Additionally, we monitored the survival and microbial loads of pea aphids after bacterial and fungal infections. Results : Pea aphids reared on M. sativa had lower growth, lower intrinsic rate of increase, and lower finite rate of increase when compared to aphids feeding on V. faba. The net reproduction was lower in aphids feeding on M. sativa, although the difference was not significant. The mean time of generation and pre-reproductive periods was longer for aphids reared on M. sativa than for aphids reared on V. faba. In the infection experiments, we found that aphid survival was not affected by the host plant. However, A. pisum reared on M. sativa generally harbored fewer microbial loads than those reared on V. faba. Conclusions: The growth and reproduction of pea aphids are affected by the host plant. Aphids feeding on different plants had different tolerances to microbial infections. Our study sheds light on improving biological control programs for aphids.


Insects ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 614
Author(s):  
Martin John Martin ◽  
Yueming Li ◽  
Li Ma ◽  
Yi Feng ◽  
Zhiqiang Lu

Non-immunological responses are important alternative strategies for animals to deal with pathogens. It has long been recognized that fecundity compensation and production of winged offspring are two common non-immunological responses used by aphids when confronted with predators or pathogens. However, the effects of host plant on these responses have received little attention. This study investigated the effects of host plant on non-immunological defense in the pea aphids, Acyrthosiphon pisum, after bacterial and fungal infections. The aphids were raised in two groups, with one group being raised on broad beans and the other group being raised on alfalfa. The secondary symbiont background was examined, and the aphids were then infected with bacteria and fungus to assess fecundity and winged offspring production. We found that aphids that had been fed alfalfa had fewer offspring than those fed broad beans. Alfalfa-fed aphids produced more winged offspring in response to S. aureus and B. bassiana infections. Our findings suggest that the host plant plays a key role in fecundity and winged offspring production in pea aphid colony.


2013 ◽  
Vol 103 (5) ◽  
pp. 578-583 ◽  
Author(s):  
Adalbert Balog

AbstractThe interplay between the host plant of an insect herbivore and an insect predator (here two-spot ladybird beetles; Adalia bipunctata (L).; Coleoptera: Coccinellidae), feeding upon such a herbivore was examined in the laboratory as factors possibly determining the differential abundance and success of green and red host races of pea aphid, Acyrthosiphon pisum Harris. The experiment comprised three treatments: two host plants (bean and clover), two treatment levels (control and predation) and three colour morph levels (green alone, red alone and green and red in mixture). Green morphs had higher fitness on the general host plant, bean Vicia faba, than on the derived host, clover (Trifolium pratense), in the absence of predation. Although green morph fitness was reduced by predation when infesting bean together with reds, there was no observable net fitness loss due to predation on clover in mixed colonies with red morphs. Red morphs exhibited fitness loss alone on both bean and clover, while clover plants seemingly prevented fitness loss in the presence of predation when red morphs were mixed with green ones. According to this scenario, when colour morphs existed as a mixed colony, the net fitness of either pea aphid morph was not influenced by predation on clover. Predators had significant effects only on red morphs on broad bean either when alone or were mixed together with green morphs. Thus, only red morphs experienced the benefits of switching from the general to the derived host red clover in the presence of predation. For green morphs, there was no apparent cost of switching host plants when they faced predation. Hence, the co-existence of green-red colour polymorphism of pea aphids on single host plants appears to be maintained by the morph gaining fitness on the derived host due to a host plant– and predation–reduction effect. These findings have important implications for understanding the ecology and evolution of host switching by different colour-plant host adapted races of pea aphids.


1978 ◽  
Vol 56 (1) ◽  
pp. 103-108 ◽  
Author(s):  
Bernard D. Roitberg ◽  
Judith H. Myers

Adult and fourth-instar pea aphids from Vancouver, B.C., responded to alarm pheromone by either dropping, running, or backing up. Younger instars showed almost no response to pheromone but all instars responded to a pheromone–vibratory stimulus, usually by dropping. We suggest that younger instars respond conservatively to alarm pheromone because they are less agile on the ground and are more likely to die there before finding a suitable food plant. Adult and fourth-instar aphids from the hot, dry region of British Columbia do not respond to alarm pheromone by dropping. This is due to the high risk associated with any instar leaving the host plant where ground temperatures and evaporation rates are high.Clones of aphids contained both individuals which do and do not drop in response to pheromone stimulus. This mixture of behaviour types allows part of the group to exploit new resources while others remain on a known resource.


1986 ◽  
Vol 64 (4) ◽  
pp. 937-939 ◽  
Author(s):  
Lynn M. Brodsky ◽  
C. A. Barlow

The escape responses exhibited by pea aphids were examined at three different temperatures, 15, 20, and 25 °C, using two different predators: syrphid larvae and coccinellid beetles. Coccinellid beetles foraged more vigorously at higher temperatures resulting in greater vibrations on the host plant as they searched for aphids. Foraging rates for syrphids were slower by comparison and did not vary with temperature. We found that most aphids dropped off the host plant when confronted by coccinellid beetles, especially at higher temperatures, and backed up when confronted by syrphid larvae regardless of temperature. We conclude that individual aphids do not have characteristic escape responses, but rather the response adopted depends in part on the foraging rate and species of predator.


2010 ◽  
Vol 278 (1706) ◽  
pp. 760-766 ◽  
Author(s):  
A. H. C. McLean ◽  
M. van Asch ◽  
J. Ferrari ◽  
H. C. J. Godfray

Aphids possess several facultative bacterial symbionts that have important effects on their hosts' biology. These have been most closely studied in the pea aphid ( Acyrthosiphon pisum ), a species that feeds on multiple host plants. Whether secondary symbionts influence host plant utilization is unclear. We report the fitness consequences of introducing different strains of the symbiont Hamiltonella defensa into three aphid clones collected on Lathyrus pratensis that naturally lack symbionts, and of removing symbionts from 20 natural aphid–bacterial associations. Infection decreased fitness on Lathyrus but not on Vicia faba , a plant on which most pea aphids readily feed. This may explain the unusually low prevalence of symbionts in aphids collected on Lathyrus . There was no effect of presence of symbiont on performance of the aphids on the host plants of the clones from which the H. defensa strains were isolated. Removing the symbiont from natural aphid–bacterial associations led to an average approximate 20 per cent reduction in fecundity, both on the natural host plant and on V. faba , suggesting general rather than plant-species-specific effects of the symbiont. Throughout, we find significant genetic variation among aphid clones. The results provide no evidence that secondary symbionts have a major direct role in facilitating aphid utilization of particular host plant species.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Belén Cotes ◽  
Gunda Thöming ◽  
Carol V. Amaya-Gómez ◽  
Ondřej Novák ◽  
Christian Nansen

AbstractRoot-associated entomopathogenic fungi (R-AEF) indirectly influence herbivorous insect performance. However, host plant-R-AEF interactions and R-AEF as biological control agents have been studied independently and without much attention to the potential synergy between these functional traits. In this study, we evaluated behavioral responses of cabbage root flies [Delia radicum L. (Diptera: Anthomyiidae)] to a host plant (white cabbage cabbage Brassica oleracea var. capitata f. alba cv. Castello L.) with and without the R-AEF Metarhizium brunneum (Petch). We performed experiments on leaf reflectance, phytohormonal composition and host plant location behavior (behavioral processes that contribute to locating and selecting an adequate host plant in the environment). Compared to control host plants, R-AEF inoculation caused, on one hand, a decrease in reflectance of host plant leaves in the near-infrared portion of the radiometric spectrum and, on the other, an increase in the production of jasmonic, (+)-7-iso-jasmonoyl-l-isoleucine and salicylic acid in certain parts of the host plant. Under both greenhouse and field settings, landing and oviposition by cabbage root fly females were positively affected by R-AEF inoculation of host plants. The fungal-induced change in leaf reflectance may have altered visual cues used by the cabbage root flies in their host plant selection. This is the first study providing evidence for the hypothesis that R-AEF manipulate the suitability of their host plant to attract herbivorous insects.


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