Quantifying insect predation with predator exclusion cages: the role of prey antipredator behavior as a source of bias

2015 ◽  
Vol 157 (3) ◽  
pp. 360-364 ◽  
Author(s):  
Ignacio Castellanos ◽  
Pedro Barbosa ◽  
Iriana Zuria ◽  
Astrid Caldas
2015 ◽  
Vol 213 ◽  
pp. 59-64 ◽  
Author(s):  
Lorin A. Neuman-Lee ◽  
Amber N. Stokes ◽  
Sydney Greenfield ◽  
Gareth R. Hopkins ◽  
Edmund D. Brodie ◽  
...  

2005 ◽  
Vol 21 (3) ◽  
pp. 255-262 ◽  
Author(s):  
Kim R. McConkey

The natural seed shadow created by gibbons (Hylobates mulleri×agilis) in Central Kalimantan, Indonesia, was monitored over 11 mo to discern the role of gibbons and post-dispersal events in the spatial pattern of seed germination. Variability in the content and distribution of 183 scats was used to determine which, if any, scat characteristics influenced seed fate. Nine scat characters were evaluated: (1) seed number; (2) number of seed species per scat; (3) scat weight; (4) seed load; (5) rainfall; (6) scat density; (7) distance to nearest fruiting tree; (8) ripe fig abundance; (9) non-fig fruit abundance. More than 99% of monitored seeds were killed, removed, or had germinated during the monitoring period. Vertebrates killed or removed most seeds (86%) and the probability of them moving seeds was highly dependent on non-fig fruit abundance at the time of deposition; factors (2), (6) and (7) also influenced seed removal/predation by vertebrates, depending on whether seeds were deposited in peak or non-peak times of consumption. Insect predation (2% of seeds) occurred mainly in scats that were deposited in months of high ripe fig abundance, while the actual chance of a seed germinating (11% of seeds) was influenced by non-fig fruit abundance at time of deposition and number of species in the original scat. The gibbon-generated seed shadow was profoundly altered by post-dispersal events and variation in the characteristics of the shadow had little lasting impact on the probability of seeds germinating.


Behaviour ◽  
1999 ◽  
Vol 136 (1) ◽  
pp. 1-21 ◽  
Author(s):  
Reginald Cocroft

Parental care of post-hatching offspring is widespread in insects, but the role of communication in parent-offspring interactions remains largely unknown. I have found that, in the subsocial treehopper Umbonia crassicornis , aggregated nymphal offspring produce substrate-borne, vibrational signals in synchronized bursts that elicit the mother's antipredator behavior. In this study I describe the signals used by nymphs and explore their role in mother-offspring interactions and within-brood communication. Nymphs were stimulated to signal in the laboratory in response to light contact, simulating the approach of a predator. Signals of nymphs at the site of disturbance triggered a rapid wave of signaling by many individuals within the aggregation. This coordinated signaling was associated with the mother's defensive behavior. Signaling was limited to the vibrational channel: when transmission of vibrations was blocked between signaling nymphs and the mother, the mothers' response was abolished. Nymphs signaled not only in response to contact, but also in response to playback of signals from their siblings. Nymphs in otherwise undisturbed aggregations signaled only in response to signals coordinated into synchronized, group displays, and not to signals in random temporal patterns. However, nymphal signaling thresholds were lowered after a recent experience of simulated predation. After a period in which nymphs were stimulated to signal (by light contact simulating a predator's approach), playback of one individual signal could trigger a coordinated burst within the aggregation. It remains unknown if coordination among siblings to produce synchronized, group signals is completely cooperative, or if siblings compete for the mother's proximity. But it is clear that a complex system of communication among siblings, and between siblings and their parent, is an important feature of maternal care in these subsocial insects.


2006 ◽  
Vol 12 (4) ◽  
pp. 279 ◽  
Author(s):  
S. J. S. Debus

A study of open-nesting Eastern Yellow Robins Eopsaltria australis and Scarlet Robins Petroica multicolor, on the New England Tablelands of New South Wales in 2000?02, found low breeding success typical of eucalypt woodland birds. The role of intense nest predation in the loss of birds from woodland fragments was investigated by means of predator-exclusion cages at robin nests, culling of Pied Currawongs Strepera graculina, and monitoring of fledging and recruitment in the robins. Nest-cages significantly improved nest success (86% vs 20%) and fledging rate (1.6 vs 0.3 fledglings per attempt) for both robin species combined (n = 7 caged, 20 uncaged). For both robin species combined, culling of currawongs produced a twofold difference in nest success (33% vs 14%), a higher fledging rate (0.5 vs 0.3 per attempt), and a five-day difference in mean nest survival (18 vs 13 days) (n = 62 nests), although sample sizes for nests in the cull treatment (n = 18) were small and nest predation continued. Although the robin breeding population had not increased one year after the cull, the pool of Yellow Robin recruits in 2001?03, after enhanced fledging success, produced two emigrants to a patch where Yellow Robins had become extinct. Management to assist the conservation of open-nesting woodland birds should address control of currawongs.


2015 ◽  
Vol 72 (8) ◽  
pp. 2322-2331 ◽  
Author(s):  
T. Mendo ◽  
J. M. Lyle ◽  
N. A. Moltschaniwskyj ◽  
J. M. Semmens

Abstract Early post-settlement mortality is one of the main processes determining distribution and abundance patterns of marine benthic invertebrates. Most scallops have an attached phase as spat before they release the byssus and move onto the soft sediments. Thus, spat differ from other stages of life in their use of microhabitat, lack of mobility, and therefore in their vulnerability to mortality processes such as predation. However, the contribution of predation to explain levels of mortality experienced by spat and early juvenile scallops is unknown. Complex habitats such as seagrasses and algae provide a substrate upon which spat can attach and might confer an advantage as a refuge from predation. This study investigates the contribution of early post-settlement predation on abundance of Pecten fumatus and determines the role of the algae Hincksia sordida as a refuge from predation. Data were collected using field observations, a predator exclusion experiment, and tethering techniques. Mortality of up to 85% during the first weeks after settlement appeared to have prevented the establishment of an adult population at our study site. Mats of the macroalgae H. sordida provided a settlement substrate for P. fumatus spat. However, increased algal biomass did not provide greater protection from predation to juvenile scallops than lower algal biomass. Our study suggests that prey survival in submersed vegetation is likely to be dynamic among years, and affected by prey behaviour and density as well as the characteristics of the submerged vegetation.


2021 ◽  
Vol 17 ◽  
Author(s):  
Kati Hewitt ◽  
Cory Matthew ◽  
Catherine McKenzie ◽  
Wade Mace ◽  
Alison Popay

The literature on the importance of Epichloë grass endophytes during pasture renewal is reviewed. Perennial ryegrass endophyte strains such as AR1, NEA2, and Standard Endophyte (SE) as well as tall fescue and meadow fescue endophytes, significantly increase seedling survival at establishment under insect pressure, for example from adult Argentine stem weevil, grass grub, and African black beetle. However, in endophyte-infected ryegrass, insect-derived plant damage increases 10–43 days after sowing despite the presence of endophyte. Insecticidal seed treatments can mitigate the vulnerability to insect predation during this time.


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