| 1. |
- Javal, Marion, et al.
(författare)
-
A preliminary assessment of the physiological and morphological correlates of beetle aggression in an emerging sugarcane pest, Cacosceles newmannii ( Thomson, 1877) (Coleoptera: Cerambycidae)
- 2022
-
Ingår i: African Entomology. - : ENTOMOLOGICAL SOC SOUTHERN AFRICA. - 1021-3589 .- 2224-8854. ; 30
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding the morphological and physiological correlates of competitive behaviours can provide important insights into the ecology of competition, home range size and resource consumption. Here we first estimated and defined sexual dimorphism in a poorly studied African cerambycid species, Cacosceles newmannii (Thomson, 1877). We then assessed morphological and physiological attributes of male beetles in relation to their fighting behaviour. Suites of morphological and energetic measurements were carried out on adult males, the latter before and after male-male interactions. Aggressive behaviour and the outcomes of male fighting trials were assessed under controlled conditions. The species is highly sexually dimorphic in relation to mandible size. During male-male interactions, a continuum of behaviours with an increasing risk of injury and metabolic cost was observed. Grasping was prolonged in males with larger fighting apparatus, who also tended to use more energy during the encounter than males displaying other behaviours. Our results indicate that the mandible size in C. newmannii serves as an honest signal of fighting ability in this species. Additionally, energetic assessments in preparation for fighting, costs during a fight, and persistence of metabolic costs postfighting may be useful for understanding the relative fitness costs of competition.
|
|
| 2. |
- Fisher, D. N., et al.
(författare)
-
Determinants of Contests in Ugandan Female Ground-Nesting Bees (Tetralonia sp. n.)
- 2017
-
Ingår i: African Entomology. - : Academy of Science of South Africa. - 1021-3589. ; 25:2, s. 319-327
-
Tidskriftsartikel (refereegranskat)abstract
- Many animals engage in contests with conspecifics for access to resources. Understanding which resources individuals are contesting for, and what influences the outcome is central to our understanding of contest behaviour. We initially observed female bees of the genus Tetralonia (sp. n.) aggressively competing for access to burrows in the ground, without any clear indication of exactly which resources were being contested, or what factors might predict the outcome.We then individually marked bees and assigned ownership of burrows to individuals, before observing over 100 aggressive interactions. After excavating burrows cast with molten wax, we concluded that burrows were nests for provisioning larvae. We found that ownership (as putatively designated by us) had no influence on contest outcome, but rather that the position of the bees in the burrow was decisive; whichever bee was already in the burrowwhenthe contest beganwonthe vast majority of interactions. Furthermore, bees that were designated ownership of a burrow did not engage in longer fights for possession of that specific burrow, indicating either that they were not committing any kind of 'Concorde fallacy' by basing decisions on past investment, or that the assignment of ownership was incorrect. Instead, fights were longer later in the day, presumably as the value of the burrow as a refuge from the cold and/or predation increased as night approached. Nest parasitism does not seem to be a common strategy in this species, as owners were not more likely to attempt ejecting an intruder than vice versa. This indicates that contest settlement may not always follow theoretical predictions, but rather that insights and inferences into a species' ecology can be made from observations of dyadic contests.
|
|
| 3. |
- Glinwood, Robert, et al.
(författare)
-
Visual cues and host-plant preference of the bird cherry-oat aphid, Rhopalosiphum padi (Hemiptera: Aphididae)
- 2014
-
Ingår i: African Entomology. - : Academy of Science of South Africa. - 1021-3589. ; 22, s. 428-436
-
Tidskriftsartikel (refereegranskat)abstract
- Mate aphids respond to short (UV) and long (green yellow) wavelength stimuli during host-plant searching behaviour. Although many aphids are attracted to yellow, the bird cherry-oat aphid, Rhopalosiphum padi, is attracted to green. As part of identifying suitable plant species for crop border plants for seed potatoes, the attraction of R. padi to different shades of green in relation to differences in spectral reflectance of three cultivars of a non-host, potato, and two host-plant species, maize and wheat, were determined. Choice experiments were carried out under laboratory conditions to evaluate aphid landing preference for stimuli of different colours. Rhopalosiphum padi alates preferred to land on the colour targets with the highest reflectance. Significantly more alates landed on yellow and lime colour targets with a maximum wavelength reflectance of 46 % from 600-610 rim and 26 % from 525-531 nm, respectively. The peak light reflectance of the crop plants ranged between 12 % (potato; 532-555 nm) and 20 % (wheat; 537-553 nm). The results on aphid landing preference for different colour targets suggest that R. padi will land in higher numbers on the wheat plants, compared to potato, due to their higher peak percentage reflectance. In addition, the study indicates that the wavelength reflectance curves of plants can be used as a characteristic to select possible crop border plants when making choices between seemingly equally suitable plant species/cultivars.
|
|
