Population Dynamics in the Carabid Beetle: Pasimachus punctulatus

1970 ◽  
Vol 15 (1) ◽  
pp. 55 ◽  
Author(s):  
David H. Nelson
2011 ◽  
Vol 143 (3) ◽  
pp. 211-223 ◽  
Author(s):  
Kôji Sasakawa ◽  
Hiroshi Ikeda ◽  
Mitsuaki Sutou ◽  
Shigeto Dobata ◽  
Motomi Itô

AbstractWe report the presence and effects of parasitoid larvae (Hymenoptera) in the carabid beetle Poecilus versicolor (Sturm). Dissection of one female and one male live host found 33 and 25 hymenopteran larvae, respectively. Although eggs were absent in the female host, likely because of consumption by parasitoids, distinct corpora lutea (present in parous females) were observed. In the male host, reproductive organs were undamaged. These observations suggest incomplete “parasitic castration” of the host beetle by the parasitoids. Parasitism rates in specimens from three localities were markedly low (0%–3.2%). At one locality, only one male and three female beetles containing parasitoids were found; those individuals each contained 9–27 larvae (mean 19.3). These results suggest that hymenopterous parasitoids in adult P. versicolor have little effect on the population dynamics of this beetle. The parasitoid larvae included two morphological types belonging to at least two taxa. Mitochondrial DNA analyses suggested that one of the types represented two species of Microctonus Wesmael (Braconidae: Euphorinae). The result of the genus-level identification, however, requires confirmation because the analyzed data set did not cover all braconid genera.


2020 ◽  
Vol 646 ◽  
pp. 79-92
Author(s):  
RE Scheibling ◽  
R Black

Population dynamics and life history traits of the ‘giant’ limpet Scutellastra laticostata on intertidal limestone platforms at Rottnest Island, Western Australia, were recorded by interannual (January/February) monitoring of limpet density and size structure, and relocation of marked individuals, at 3 locations over periods of 13-16 yr between 1993 and 2020. Limpet densities ranged from 4 to 9 ind. m-2 on wave-swept seaward margins of platforms at 2 locations and on a rocky notch at the landward margin of the platform at a third. Juvenile recruits (25-55 mm shell length) were present each year, usually at low densities (<1 m-2), but localized pulses of recruitment occurred in some years. Annual survival rates of marked limpets varied among sites and cohorts, ranging from 0.42 yr-1 at the notch to 0.79 and 0.87 yr-1 on the platforms. A mass mortality of limpets on the platforms occurred in 2003, likely mediated by thermal stress during daytime low tides, coincident with high air temperatures and calm seas. Juveniles grew rapidly to adult size within 2 yr. Asymptotic size (L∞, von Bertalanffy growth model) ranged from 89 to 97 mm, and maximum size from 100 to 113 mm, on platforms. Growth rate and maximum size were lower on the notch. Our empirical observations and simulation models suggest that these populations are relatively stable on a decadal time scale. The frequency and magnitude of recruitment pulses and high rate of adult survival provide considerable inertia, enabling persistence of these populations in the face of sporadic climatic extremes.


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