Field manipulations of fox and gray squirrel populations: how important is interspecific competition?

1985 ◽  
Vol 63 (9) ◽  
pp. 2134-2140 ◽  
Author(s):  
Bruce W. Brown ◽  
George O. Batzli
Keyword(s):  
Adult Female ◽  
Field Experiments ◽  
Sciurus Carolinensis ◽  
East Central ◽  
Dispersion Patterns ◽  
Fox Squirrels ◽  
Tree Squirrels ◽  
Survival And Reproduction ◽  
Central Illinois

The role of competition in free-living populations of tree squirrels was evaluated in two field experiments. (i) Numbers of adult female fox squirrels (Sciurus niger) were manipulated and the response of gray squirrels (Sciurus carolinensis) was monitored. (ii) Supplemental feeding with native mast was used to determine if food was limiting for squirrel populations in east-central Illinois. Although sample sizes were small, a trend towards increased survival and reproduction in supplemented woodlots lent support to the idea that food availability limits squirrel densities during some winters. The manipulation of adult female fox squirrels did not indicate that densities of either fox or gray squirrels could be explained simply by competition. Some dispersion patterns on the larger plots were consistent with competition, but other explanations could not be completely ruled out.

Growth Patterns of Fox Squirrels in East-central Illinois

1991 ◽  
Vol 125 (1) ◽  
pp. 168 ◽  
Author(s):  
Charles M. Nixon ◽  
Lonnie P. Hansen ◽  
Stephen P. Havera
Keyword(s):  
Growth Patterns ◽  
East Central ◽  
Fox Squirrels ◽  
Central Illinois

The Role of Minor Pheromone Components in Segregating 14 Species of Longhorned Beetles (Coleoptera: Cerambycidae) of the Subfamily Cerambycinae

2019 ◽  
Vol 112 (5) ◽  
pp. 2236-2252 ◽  
Author(s):  
Lawrence M Hanks ◽  
Judith A Mongold-Diers ◽  
Robert F Mitchell ◽  
Yunfan Zou ◽  
Joseph C H Wong ◽  
...  
Keyword(s):  
Minor Components ◽  
Adult Males ◽  
East Central ◽  
Antagonistic Effects ◽  
Independent Field ◽  
Pheromone Components ◽  
Longhorned Beetles ◽  
Minor Compounds ◽  
Central Illinois

Abstract We present research on the chemical ecology of 14 species of longhorned beetles (Coleoptera: Cerambycidae), in four tribes of the subfamily Cerambycinae, conducted in east-central Illinois over 8 yr. Adult males produce aggregation-sex pheromones that attract both sexes. Twenty independent field bioassays explored the pheromone chemistry of the species and tested the possible attractive or antagonistic effects of compounds that are not produced by a given species, but are pheromone components of other species. Analyses of beetle-produced volatiles revealed compounds that had not been reported previously from several of the species. The most common pheromone component was (R)-3-hydroxyhexan-2-one, but pheromones of some species included isomers of the related 2,3-hexanediols. Males of the congeners Phymatodes amoenus (Say) and Phymatodes testaceus (L.) produced pure (R)-2-methylbutan-1-ol. Enantiomers of 2-methylbutan-1-ol also proved to be powerful synergists for Megacyllene caryae (Gahan), Sarosesthes fulminans (F.), and Xylotrechus colonus (F.). The major components of pheromone blends were consistently present in collections of headspace volatiles from male beetles, and only the major components were inherently attractive to a subset of species when tested as single components. Minor components of some species acted as powerful synergists, but in other cases appeared not to influence attraction. Among the minor components identified in headspace extracts from males, 2,3-hexanedione and 2-hydroxyhexan-3-one appeared to be analytical artifacts or biosynthetic by-products, and were neither attractants nor synergists. The antagonistic effects of minor compounds produced by heterospecific males suggest that these compounds serve to maintain prezygotic reproductive isolation among some species that share pheromone components.

scholarly journals Chitin Synthases Are Critical for Reproduction, Molting, and Digestion in the Salmon Louse (Lepeophtheirus salmonis)

Life ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 47
Author(s):  
Hulda María Harðardóttir ◽  
Rune Male ◽  
Frank Nilsen ◽  
Sussie Dalvin
Keyword(s):  
Adult Female ◽  
Economic Losses ◽  
Lepeophtheirus Salmonis ◽  
Uridine Diphosphate ◽  
Functional Roles ◽  
Chitin Synthases ◽  
Survival And Reproduction ◽  
Specific Localization ◽  
Muscular Tissues

Chitin synthase (CHS) is a large transmembrane enzyme that polymerizes Uridine diphosphate N-acetylglucosamine into chitin. The genomes of insects often encode two chitin synthases, CHS1 and CHS2. Their functional roles have been investigated in several insects: CHS1 is mainly responsible for synthesizing chitin in the cuticle and CHS2 in the midgut. Lepeophtheirus salmonis is an ectoparasitic copepod on salmonid fish, which causes significant economic losses in aquaculture. In the present study, the tissue-specific localization, expression, and functional role of L. salmonis chitin synthases, LsCHS1 and LsCHS2, were investigated. The expressions of LsCHS1 and LsCHS2 were found in oocytes, ovaries, intestine, and integument. Wheat germ agglutinin (WGA) chitin staining signals were detected in ovaries, oocytes, intestine, cuticle, and intestine in adult female L. salmonis. The functional roles of the LsCHSs were investigated using RNA interference (RNAi) to silence the expression of LsCHS1 and LsCHS2. Knockdown of LsCHS1 in pre-adult I lice resulted in lethal phenotypes with cuticle deformation and deformation of ovaries and oocytes in adult lice. RNAi knockdown of LsCHS2 in adult female L. salmonis affected digestion, damaged the gut microvilli, reduced muscular tissues around the gut, and affected offspring. The results demonstrate that both LsCHS1 and LsCHS2 are important for the survival and reproduction in L. salmonis.

scholarly journals Relative potency of a novel acaricidal compound from Xenorhabdus, a bacterial genus mutualistically associated with entomopathogenic nematodes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Gamze Incedayi ◽  
Harun Cimen ◽  
Derya Ulug ◽  
Mustapha Touray ◽  
Edna Bode ◽  
...  
Keyword(s):  
Adult Female ◽  
Entomopathogenic Nematodes ◽  
Field Experiments ◽  
Petri Dish ◽  
Phytoseiulus Persimilis ◽  
Mortality Rates ◽  
Predatory Mites ◽  
The Novel ◽  
Compound Identification ◽  
Mutant Strains

AbstractOur study aimed to identify the novel acaricidal compound in Xenorhabdus szentirmaii and X. nematophila using the easyPACId approach (easy Promoter Activated Compound Identification). We determined the (1) effects of cell-free supernatant (CFS) obtained from mutant strains against T. urticae females, (2) CFS of the acaricidal bioactive strain of X. nematophila (pCEP_kan_XNC1_1711) against different biological stages of T. urticae, and females of predatory mites, Phytoseiulus persimilis and Neoseiulus californicus, (3) effects of the extracted acaricidal compound on different biological stages of T. urticae, and (4) cytotoxicity of the active substance. The results showed that xenocoumacin produced by X. nematophila was the bioactive acaricidal compound, whereas the acaricidal compound in X. szentirmaii was not determined. The CFS of X. nematophila (pCEP_kan_XNC1_1711) caused 100, 100, 97.3, and 98.1% mortality on larvae, protonymph, deutonymph and adult female of T. urticae at 7 dpa in petri dish experiments; and significantly reduced T. urticae population in pot experiments. However, the same CFS caused less than 36% mortality on the predatory mites at 7dpa. The mortality rates of extracted acaricidal compound (xenocoumacin) on the larva, protonymph, deutonymph and adult female of T. urticae were 100, 100, 97, 96% at 7 dpa. Cytotoxicity assay showed that IC50 value of xenocoumacin extract was 17.71 μg/ml after 48 h. The data of this study showed that xenocoumacin could potentially be used as bio-acaricide in the control of T. urticae; however, its efficacy in field experiments and its phytotoxicity need to be assessed in future.

Sign in / Sign up

Export Citation Format

Share Document