Exploitative Competition Strongly Affects the Herbivorous Insect Community on Baccharis halimifolia

Oikos ◽  
1997 ◽  
Vol 79 (3) ◽  
pp. 521 ◽  
Author(s):  
Eric E. Hudson ◽  
Peter Stiling
Keyword(s):  
Herbivorous Insect ◽  
Exploitative Competition ◽  
Insect Community ◽  
Baccharis Halimifolia

scholarly journals Contrasting effects of habitat management on different feeding guilds of herbivorous insects in cacao agroforestry systems

2016 ◽  
Vol 64 (2) ◽  
pp. 763 ◽  
Author(s):  
Samuel Novais
Keyword(s):  
Species Composition ◽  
Conservation Strategy ◽  
Herbivorous Insects ◽  
Herbivorous Insect ◽  
Native Forest ◽  
Insect Community ◽  
Natural Habitats ◽  
Native Forests ◽  
Pest Outbreaks ◽  
Rubber Agroforest

Human pressure on natural habitats increases the importance of agroforests for biodiversity conservation. The objective of this study was to evaluate the role of traditional cacao agroforests, known as “cabrucas,” on the conservation of the herbivorous insect community in compared with that of monodominant rubber agroforests. The insects were sampled in three habitats in southeastern Bahia, Brazil: native forests, cabrucas and rubber agroforests. In each habitat, 18 plots of 10 m<sup>2 </sup>were established, and the structural measures were collected and herbivorous insects were sampled with a Malaise/window trap. The diversity of folivores decreased with the simplification of vegetation structure, but species composition was similar among habitats. In addition to a decrease in the availability of resources in monodominant rubber agroforests, the latex present in these systems limits the occurrence of species that cannot circumvent latex toxicity. The diversity of sap-sucking insects was similar among habitats, but species composition was similar only in the cabruca and native forest, and it was different in the rubber agroforest. We observed turnover and a higher frequency of individuals of the family Psyllidae in the rubber agroforest. The biology and behavior of psyllids and absence of natural enemies enable their diversity to increase when they are adapted to a new host. We observed a shift in the composition of xylophagous insects in the rubber agroforest compared with that of the other habitats. Moreover, this agroforest has low species richness but high individual abundance. Latex extraction is likely an important additional source of volatile compounds discharged into the environment, and it increases the attraction and recruitment of coleoborers to these sites. We conclude that cabrucas have an herbivorous insect community with a structure similar to the community found in native forests of the region, and they present a more interesting conservation strategy when compared with the rubber agroforests. We also emphasize the potential risk of local pest outbreaks in rubber agroforests for both the rubber trees and associated cacao tress.

scholarly journals Intraspecific Behavioral Variation Mediates Insect Prey Survival via Direct and Indirect Effects

Diversity ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 152 ◽  
Author(s):  
Benjamin J. Toscano ◽  
James L. L. Lichtenstein ◽  
Raul Costa-Pereira
Keyword(s):  
Herbivorous Insect ◽  
Insect Community ◽  
Behavioral Differences ◽  
Predator Species ◽  
Behavioral Trait ◽  
Individual Level ◽  
Insect Prey ◽  
Trait Variance ◽  
Negative Effect ◽  
Positive Effect

Conspecific individuals often exhibit behavioral differences that influence susceptibility to predation. Yet, how such trait differences scale to affect prey population regulation and community structure remains unclear. We used an 8 day field mesocosm experiment to explore the effects of intraspecific prey behavioral trait variation on survival in an herbivorous insect community. We further manipulated spider predator composition to test for top-down context-dependence of behavioral effects. Insect prey behavioral trait variance influenced survival through both direct (i.e., variation among conspecifics) and indirect (i.e., variation among heterospecifics) mechanisms. The behavioral variance of two prey species, Philaenus and Orchelimum, directly reduced their survival, though for Philaenus, this direct negative effect only occurred in the presence of a single spider predator species. In contrast, the survival of Scudderia was enhanced by the behavioral trait variance of the surrounding insect community, an indirect positive effect. Taken together, these results emphasize the importance of accounting for intraspecific variation in community ecology, demonstrating novel pathways by which individual-level behavioral differences scale to alter population and community level patterns.

scholarly journals High honeybee abundances reduce wild bee abundances on flowers in the city of Munich

Oecologia ◽  
2021 ◽  
Author(s):  
Susanne S. Renner ◽  
Marie Sophie Graf ◽  
Zoe Hentschel ◽  
Helen Krause ◽  
Andreas Fleischmann
Keyword(s):  
Apis Mellifera ◽  
Adjacent Area ◽  
Exploitative Competition ◽  
Wild Bees ◽  
European Cities ◽  
Urban Garden ◽  
Wild Bee ◽  
June July ◽  
The City ◽  
Clear Support

AbstractThe increase in managed honeybees (Apis mellifera) in many European cities has unknown effects on the densities of wild bees through competition. To investigate this, we monitored honeybees and non-honeybees from 01 April to 31 July 2019 and 2020 at 29 species of plants representing diverse taxonomic and floral-functional types in a large urban garden in the city of Munich in which the same plant species were cultivated in both years. No bee hives were present in the focal garden, and all bee hives in the adjacent area were closely monitored by interviewing the relevant bee keepers in both 2019 and 2020. Honeybee numbers were similar in April of both years, but increased from May to July 2020 compared to 2019. The higher densities correlated with a significant increase in shifts from wild bee to honeybee visits in May/June/July, while visitor spectra in April 2019 and 2020 remained the same. Most of the species that experienced a shift to honeybee visits in 2020 were visited mostly or exclusively for their nectar. There were no shifts towards increased wild bee visits in any species. These results from a flower-rich garden have implications for the discussion of whether urban bee keeping might negatively impact wild bees. We found clear support that high honeybee densities result in exploitative competition at numerous types of flowers.

scholarly journals Root-associated entomopathogenic fungi manipulate host plants to attract herbivorous insects

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Belén Cotes ◽  
Gunda Thöming ◽  
Carol V. Amaya-Gómez ◽  
Ondřej Novák ◽  
Christian Nansen
Keyword(s):  
Host Plant ◽  
Entomopathogenic Fungi ◽  
Host Plants ◽  
Near Infrared ◽  
Delia Radicum ◽  
Host Plant Selection ◽  
Herbivorous Insects ◽  
Herbivorous Insect ◽  
Insect Performance ◽  
Leaf Reflectance

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.

Taxonomic sufficiency and effects of environmental and spatial drivers on aquatic insect community

2019 ◽  
Vol 107 ◽  
pp. 105624
Author(s):  
B.S. Godoy ◽  
A.P.J. Faria ◽  
L. Juen ◽  
L. Sara ◽  
L.G. Oliveira
Keyword(s):  
Aquatic Insect ◽  
Insect Community ◽  
Taxonomic Sufficiency

scholarly journals Caterpillar salivary enzymes: "eliciting" a response

2004 ◽  
Vol 85 (1) ◽  
pp. 33-37 ◽  
Author(s):  
Magali Merkx-Jacques ◽  
Jacqueline C. Bede
Keyword(s):  
Artificial Diet ◽  
Spodoptera Exigua ◽  
Induced Defense ◽  
Defense Responses ◽  
Beet Armyworm ◽  
Herbivorous Insect ◽  
Plant Responses ◽  
Plant Defense Responses ◽  
Induced Defense Responses ◽  
Bertha Armyworm

Abstract Plants exhibit remarkable plasticity in their ability to differentiate between herbivorous insect species and subtly adjust their defense responses to target distinct pests. One key mechanism used by plants to recognize herbivorous caterpillars is elicitors present in their oral secretions; however, these elicitors not only cause the induction of plant defenses but recent evidence suggests that they may also suppress plant responses. The absence of “expected changes” in induced defense responses of insect-infested plants has been attributed to hydrogen peroxide produced by caterpillar salivary glucose oxidase (GOX). Activity of this enzyme is variable among caterpillar species; it was detected in two generalist caterpillars, the beet armyworm (Spodoptera exigua) and the bertha armyworm (Mamestra configurata), but not in other generalist or specialist caterpillar species tested. In the beet armyworm, GOX activity fluctuated over larval development with high activity associated with the salivary glands of fourth instars. Larval salivary GOX activity of the beet armyworm and the bertha armyworm was observed to be significantly higher in caterpillars reared on artificial diet as compared with those reared on Medicago truncatula plants. This implies that a factor in the diet is involved in the regulation of caterpillar salivary enzyme activity. Therefore, plant diet may be regulating caterpillar oral elicitors that are involved in the regulation of plant defense responses: our goal is to understand these two processes.

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