scholarly journals An examination of the effectiveness of traps and baits as a possible means of harvesting crayfish, Cherax quadricarinatus in Sanyati Basin, Lake Kariba, Zimbabwe

Water SA ◽  
2020 ◽  
Vol 46 (4 October) ◽  
Author(s):  
L Mhlanga ◽  
L Marufu ◽  
G Mupandawana ◽  
T Nhiwatiwa
Keyword(s):  
Sex Ratio ◽  
Cherax Quadricarinatus ◽  
Lake Kariba ◽  
Adverse Impacts ◽  
Lack Of Information ◽  
Opera House ◽  
Gear Technology

Although Cherax quadricarinatus is now established in Lake Kariba, there is a lack of information on the appropriate gear technology and bait for its exploitation for either management or commercial purposes. The effectiveness of three trap designs and three bait types was investigated in order to identify the best means for harvesting C. quadricarinatus in Lake Kariba. The cylindrical and rectangular traps had higher and similar CPUE, which were significantly higher than those of the Opera house trap at all sites. Trap type did not influence sex ratio. Liver, sadza and fish heads were all similarly effective as bait. Either sadza-baited cylindrical or rectangular traps can be effectively employed to either harvest crayfish in order to maintain a low population, thereby mitigating potential adverse impacts, or for commercial purposes. This should be corroborated with monitoring and further research.

scholarly journals Sex determination in crayfish: are intersex Cherax quadricarinatus (Decapoda, Parastacidae) genetically females?

2003 ◽  
Vol 82 (2) ◽  
pp. 107-116 ◽  
Author(s):  
S. PARNES ◽  
I. KHALAILA ◽  
G. HULATA ◽  
A. SAGI
Keyword(s):  
Sex Ratio ◽  
Sex Determination ◽  
Genetic Basis ◽  
Male And Female ◽  
Cherax Quadricarinatus ◽  
Male Ratio ◽  
Males And Females ◽  
Normal Males ◽  
Red Claw Crayfish ◽  
Female Genital

In the Australian red-claw crayfish Cherax quadricarinatus (von Martens) (Decapoda, Parastacidae), a gonochoristic species, seven different combinations of intersex individuals (with both male and female genital openings) have been described. However, to date, the genetic basis for this phenomenon has not been investigated. This study was designed to test a simple chromosome-based sex-determination model for C. quadricarinatus that assumes the male to be the homogametic (ZZ) sex. According to our model, intersex individuals that are functionally males are genetically females (WZ). Individual crosses were performed between intersex and female crayfish, with control crosses being performed between normal males and females. The control crosses yielded, in most cases, the expected 1[ratio ]1 sex ratio in the F1 progeny. Crosses between intersex individuals and females yielded a 1[ratio ]3 (male[ratio ]female) sex ratio in most crosses. According to our hypothesis, one-third of the females produced in a cross of a female with an intersex animal should be WW females. The hypothesis was tested by crossing normal males with F1 females, which were progeny of intersex fathers. These crosses yielded almost 100% females, a finding that conforms to the above-suggested sex determination model for C. quadricarinatus and the female WZ genotype of intersex individuals.

scholarly journals Non-lead rifle ammunition: Danish hunters’ attitudes

2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Niels Kanstrup ◽  
Thorsten Johannes Skovbjerg Balsby ◽  
Kavi Askholm Mellerup ◽  
Hans Peter Hansen
Keyword(s):  
Negative Attitude ◽  
Formal Approach ◽  
Zinc Alloys ◽  
Change Communication ◽  
Adverse Impacts ◽  
Lack Of Information ◽  
Lead Ammunition ◽  
Willingness To Change ◽  
Copper Zinc ◽  
The Individual

Abstract Background Lead particles from hunting rifle ammunition become embedded in the tissue of shot animals and pose a health risk to predators and scavengers that eat discarded offal or parts of non-retrieved carcasses of shot game animals, as well as to humans who consume game. Copper and copper–zinc alloys are the most widely used alternatives to leaded ammunition. In Denmark, there has been a growing awareness of the toxic environmental effects of lead ammunition and the Danish government, supported by the Danish Hunters’ Association, announced in November 2020 a forthcoming ban on the use of lead-based bullets for hunting purposes intended to take effect in 2023. The question that remains to be addressed is how the Danish hunting community perceives lead ammunition as a problem and non-lead alternatives as a solution, and whether the willingness to change demonstrated by the hunters’ representatives reflects the attitude of the individual hunters. We studied this in a survey targeting 6000 randomly selected Danish rifle hunters, mapping their knowledge and concerns regarding lead rifle ammunition as well as their use of lead and non-lead ammunition. Results We found that approximately one-fifth of the use of rifle ammunition for hunting in Denmark in 2019 was non-lead. Hunters’ knowledge of and concern for the adverse impacts of lead ammunition and the opportunities to switch to non-lead alternatives were generally limited. However, some showed an open-minded attitude and we found that such knowledge and concern increased the likelihood of hunters deciding to use non-lead ammunition. Hunters mainly got their information from hunting organizations and colleagues and expressed a distinct lack of information and guidance on the topic from ministerial authorities responsible for hunting administration. Conclusions Some hunters have already changed to use non-lead rifle ammunition completely or in part, and others show an open attitude to discussing the issue and receiving more information particularly from hunting authorities. Some hunters demonstrated a critical or negative attitude towards a change. Communication of the adverse impacts of leaded ammunition in terms of the risk of lead poisoning to wildlife and humans and the opportunities of switching to the existing efficient and safe alternatives is essential regardless of the formal approach and will be crucial for the effectiveness of the regulation announced by the Danish government.

The population dynamics of a recently introduced crayfish, Cherax quadricarinatus (von Martens, 1868), in the Sanyati Basin of Lake Kariba, Zimbabwe

2018 ◽  
Vol 53 (1) ◽  
pp. 17-22
Author(s):  
Lightone Marufu ◽  
Maxwel Barson ◽  
Portia Chifamba ◽  
Michael Tiki ◽  
Tamuka Nhiwatiwa
Keyword(s):  
Population Dynamics ◽  
Cherax Quadricarinatus ◽  
Lake Kariba

scholarly journals Telenomus remus (Hymenoptera: Platygastridae) parasitism on Spodoptera frugiperda (Lepidoptera: Noctuidae) eggs: different parasitoid and host egg ages

2019 ◽  
Vol 40 (6Supl2) ◽  
pp. 2933
Author(s):  
Ana Paula de Queiroz ◽  
Bruna Magda Favetti ◽  
Pamela Gislaine Luski ◽  
Jaciara Gonçalves ◽  
Pedro Manuel Oliveira Janeiro Neves ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Spodoptera Frugiperda ◽  
Choice Test ◽  
Host Age ◽  
Lack Of Information ◽  
Randomized Design ◽  
Completely Randomized Design ◽  
Lepidoptera Noctuidae ◽  
Old Females ◽  
Telenomus Remus

Abstract: Release of egg parasitoids for biological control of pests is a promising technique in integrated pest management (IPM). However, there is a lack of information on the performance of parasitoid females of different ages, and specifically on the behavior of the parasitoid Telenomus remus towards pest eggs at different stages of embryonic development. Thus, the relationships between host age, parasitoid age, and parasitism by T. remus on Spodoptera frugiperda eggs were evaluated. Three separate bioassays were performed, each in a completely randomized design. In the first bioassay, T. remus females grouped by age in days (ranging from 1 to 10 days old) were offered 100 ± 20 eggs of S. frugiperda for 24 hours. In the second bioassay, 100 ± 20 eggs of S. frugiperda (24, 48 or 72 hours old) were offered to females of T. remus for 24 hours. In the third bioassay, 24, 48- and 72-hour-old host eggs of S. frugiperda were offered to T. remus females in a choice test. The variables evaluated were: number of parasitized eggs, parasitoid emergence (%), and sex ratio of progeny in bioassays 1 and 2, and the number of eggs parasitized in bioassay 3. The age of T. remus females did not affect the number of S. frugiperda eggs parasitized or emergence of the progeny. However, the sex ratio was more male-biased in the progeny of 1- and 2-day-old females compared to older wasps. In bioassay 2, the highest parasitism was observed in 24- and 48-hour-old eggs. Percentage emergence and sex ratios were not influenced by the ages of the eggs tested. Telenomus remus preferred to parasitize 24-hour-old eggs in bioassays 3. Overall, the age of T. remus females tested did not affect the parasitism of S. frugiperda eggs, but the number of eggs parasitized decreased with increasing host age.

scholarly journals Pengaruh Penambahan Madu Dalam Pakan Induk Jantan Lobster Air Tawar Red Claw (Cherax quadricarinatus) Terhadap Rasio Jenis Kelamin Larva

2019 ◽  
Vol 1 (1) ◽  
pp. 37 ◽  
Author(s):  
A.Taufiq Mukti, A.Shofy Mubarak, Adde Ermawan
Keyword(s):  
Survival Rate ◽  
Sex Ratio ◽  
Analysis Of Variance ◽  
Cherax Quadricarinatus ◽  
Replicated Data ◽  
Male Sex

Abstract The aim of this research was to know the effect of honey supplementation in feed of male main freshwater cray fish red claw to larva sex ratio and the level of survival of freshwater cray fish and to get the best doses of honey to give highest male sex ratio. This research was done at Laboratory of Fishery Education, Fishery and Marines Faculty, Airlangga University in October 2007 until March 2008. Methods of this research was experimental and used completely randomized designed with 7 treatments. Giving of honey with differences doses were A ( 0 ml/kg) control, B ( 50 ml /kg), C ( 100 ml /kg), D ( 150 ml /kg), E ( 200 ml /kg), F ( 250 ml/kg) and G ( 300 ml/kg) which each treatment got three times replicated. Data processed by Analysis of Variance (ANOVA). The result of this research showed that supplementation of honey in feed male main freshwater cray fish red claw not significantly different to larva sex ratio and survival rate of freshwater cray fish. Otherwise, result of the supplementation of honey in feed of male main freshwater cray fish showed the increasingly male sex ratio of freshwater cray fish red claw larvae.

scholarly journals Larval and pupal stage of Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) in sweet and field corn genotypes

2003 ◽  
Vol 63 (4) ◽  
pp. 627-633 ◽  
Author(s):  
L. M. Santos ◽  
L. R. Redaelli ◽  
L. M. G. Diefenbach ◽  
C. F. S. Efrom
Keyword(s):  
Sex Ratio ◽  
Spodoptera Frugiperda ◽  
Sweet Corn ◽  
Fall Armyworm ◽  
Pupal Stage ◽  
Phase Duration ◽  
Larval Phase ◽  
Field Corn ◽  
Lack Of Information ◽  
And Control

Spodoptera frugiperda, the fall armyworm, is a very significant polyphagous pest due to the damages it causes, and control difficulties. Lack of information about its impact on sweet corn motivated a comparison of its biology, with respect to the larval and pupal stages, among the genotypes ELISA, BR 400 (sweet corns), and BR PAMPA (field corn). In laboratory conditions (25 ± 1ºC; 70 ± 10% RH; photophase 12 hours), 35 caterpillars were individualized and fed daily with 3.14 cm² sections of corn leaves from the referred-to genotypes, cultivated in plots in the experimental area of the Departament of Fitossanidade, UFRGS, Porto Alegre, RS from October to November 2000. The caterpillars were weighed daily; after each molt, the cephalic capsules were collected and measured (in width), to establish growth rate; pupae were weighed and sexed when 24 hours old. The duration of the larval instars, the pupal sex ratio, and the mortality of larvae and pupae were evaluated. In the first three instars there were no differences registered in capsule width. In the fourth and fifth instars, capsules of caterpillars kept in BR 400 were smaller. The weight of caterpillars and pupae, instar duration and sex ratio did not differ among the genotypes. Pupal phase duration was less in females kept in BR 400. Mortality was greater in the larval phase in ELISA and in the pupal phase in BR PAMPA.

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