scholarly journals Investigation on Larvicidal Efficacy of Two Native Ornamental Murrels of Assam under Controlled Condition

Author(s):  
Aparajita Gogoi ◽  
Shyama Prasad Biswas

Background: It is widely reported that exotic larvicidal fishes like Gambusia and Poecilia have adverse impact on the native aquatic fauna. The present study highlights the efficacy of two colourful native murrels, primarily designated as ornamental fish, Channa bleheri and Channa stewartii as biocontrol agent of mosquito larvae. Methods: Live specimens of Channa bleheri and C. stewartii, collected from the wetlands of Tinsukia district of Upper Assam, were assessed for their larvivorous potential at individual and group levels during day and night by dividing the specimens into two size groups. After 12 hour and 24 hour starvation, the test specimens (mean size for small group 8.67 - 9.17 cm and that of large group 11.63-13.27 cm) were given known number of mosquito larvae and recorded the consumption rate. Result: The predation rate varied from 33.3±4.36 to 71.6±5.15/min for Channa bleheri and that of C. stewartii from 16.3±0.95 to 68.2±2.77/min. In both species, smaller sized specimens were better performers as predators. Predation rate at 12 and 24 hrs of starvation and between day and night proved that these native murrels are excellent predators of mosquito larvae.

2019 ◽  
Vol 24 (3) ◽  
pp. 508
Author(s):  
Wendy Lam ◽  
Quentin Paynter ◽  
Zhi-Qiang Zhang

Gorse, Ulex europaeus, is an invasive weed that has serious agricultural, economic and ecological impacts. Although various biological control agents have been released in New Zealand, these have showed no noticeable impact on gorse populations. One such agent, Sericothrips staphylinus, was introduced to New Zealand in 1990 and although laboratory impact studies indicated it was a highly promising gorse biological control agent, it has not been as effective as was hoped. We hypothesized this was due to predation by natural enemies. This study investigated the predation and oviposition rates of three phytoseiid mites (Amblydromalus limonicus, Amblyseius herbicolus, and Neoseiulus cucumeris) that have been found on gorse plants in New Zealand on three S. staphylinus stages (1st instar larvae, 2nd instar larvae, and prepupa) in both choice and non-choice conditions. In non-choice conditions, A. limonicus had the highest predation and oviposition rate across all three immature stages, and N. cucumeris had the lowest. Amblydromalus  limonicus, A. herbicolus, and N. cucumeris all had their highest predation rate when consuming 1st instar larvae, and their lowest predation rate when consuming prepupa. In the choice experiment, all three predatory mite species consumed their highest proportion of 1st instar larvae, and their lowest proportion of prepupae.  The oviposition rate of all three mite species in the choice experiment was similar to the oviposition rate when presented with 1st instar larvae only. The results from this study confirm that A. limonicus, A. herbicolus, and N. cucumeris can predate and reproduce on S. staphylinus 1st instar larvae, 2nd instar larvae, and prepupa. This indicates that predation may be the reason why S. staphylinus is an ineffective biocontrol agent in New Zealand. 


2017 ◽  
Vol 149 (5) ◽  
pp. 581-591
Author(s):  
Mona Moghadasi ◽  
Hossein Allahyari

AbstractIntraguild predation is a notable factor to proper application of biocontrol agents to reduce pest populations. Intraguild predation was studied between Typhlodromus bagdasarjani Wainstein and Arutunjan (Acari: Phytoseiidae) and Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) in presence and absence of Tetranychus urticae Koch (Acari: Tetranychidae) as well as pollen. Intraguild predation between two predators was bidirectional. The highest and the lowest predation rates of both predators in absence and presence of T. urticae as well as in the pollen treatments were on heterospecific eggs and deutonymphs, respectively. Typhlodromus bagdasarjani consumed more heterospecific eggs compared with P. persimilis. When pollen was added, predation of T. bagdasarjani significantly reduced on heterospecific eggs and deutonymphs in absence and presence of T. urticae treatments, respectively. However, predation rate of P. persimilis on heterospecific stages was not significantly affected by pollen addition. Oviposition of both predators was higher in presence of T. urticae than in its absence and oviposition of P. persimilis was significantly higher on heterospecific stages than T. bagdasarjani. Pollen addition had a significant effect on increasing the oviposition rate of T. bagdasarjani. Extraguild prey presence had a nonsignificant effect on the consumption rate of intraguild prey by the intraguild predators. However, presence of extraguild prey led to a significant increase in oviposition rate of both predators.


Mammalia ◽  
2014 ◽  
Vol 78 (2) ◽  
Author(s):  
Włodzimierz Jędrzejewski ◽  
Hugo Cerda ◽  
Angel Viloria ◽  
Jose Gertrudes Gamarra ◽  
Krzysztof Schmidt

AbstractKilling behavior and consumption rate are important components that determine the final predation rate. We studied the predatory behavior of a female jaguar with one offspring in Hato Piñero in Venezuelan Los Llanos. Seven carcasses of freshly killed calves were found over a period of 9 days. Automatic video recording was used to document the jaguar’s behavior. Our study revealed a detailed, repetitive sequence of female jaguar behavior while hunting for calves. The sequence started with the female killing a calf by biting through the skull or neck, then she dragged the carcass to concealment, eviscerated it and left it concealed; then, the next evening, the female returned with its cub, fed intermittently for a total time of about 90 min while in the meantime it hunted for new prey. All this sequence seems to have a highly adaptive significance for a female jaguar rearing cubs and utilizing large prey. During the short period of our observations, the estimated kill rate of the female jaguar with one offspring was from 0.67 to 1 calf per day. Proper cattle management is necessary to avoid high losses of calves from predation by jaguars.


2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Achini Koshila Ranasinghe ◽  
L. D. Amarasinghe

Development of microbiota assemblage usually occurs in all most all domestic and peridomestic mosquito breeding habitats. There may be parasitic, epibiont, pathogenic, or even predatory species among this biota, and to investigate their potential against the mosquito population is worth studying. This may contribute to formulating environmentally agreeable approaches in controlling mosquitoes which is a current need. Vorticella spp. is a peritrich ciliate, and its trophont stage has become epibiont to certain biota. Further, their existence in seasonal water bodies that dry off during drought in tropical weather conditions is not known. Therefore, the potential of the larvicidal effect of Vorticella microstoma on different species of mosquito larvae was studied. We found that V. microstoma causes the 100% death of the third instar larvae of Culex tritaeniorhynchus (Giles, 1901) within 48 h of exposure. In contrast to that, this species did not cause any mortality to Aedes albopictus (Skuse, 1894) and Aedes aegypti (Linnaeus in Hasselquist, 1762) mosquito larvae in repeated trials. The dynamics of polymorphism of V. microstoma was studied under induced environmental conditions. V. microstoma remained as trophont stage throughout at room temperature (25±2°C). When the temperature was reduced to 6°C, V. microstoma settled in the cyst stage. Evidently, V. microstoma is a good biocontrol agent of Culex species mosquito larvae, and they able to overcome drought periods in cyst forms. The findings of this study would be considered as the first step for a new avenue to work on environmentally agreeable manner in reducing the Culex spp. mosquito populations.


2019 ◽  
Vol 109 (05) ◽  
pp. 612-616 ◽  
Author(s):  
A.H. Abu Alloush

AbstractThe consumption rate, survival, and developmental duration of the coccidophagous coccinellid Rhyzobius lophanthae (Blaisdell) (Coleoptera: Coccinellidae), a predator of the armored scale insect, Aspidiotus nerii Bouche (Hemiptera: Diaspididae) were studied under laboratory conditions at two temperature regimes of 25 ± 1 and 30 ± 1°C, 50–65% RH, and 16L:8D. Developmental time (egg to adult) significantly decreased with increase in the temperature. It lasted 27.5 days at 25 ± 1°C and 21.3 days at 30 ± 1°C. The development threshold of R. lophanthae immature stages was 7.823°C, while the thermal constant was 472.379 degree-days. No mortality was recorded during the incubation period. The total mortality rate amongst the larval instars was with 3.33% at 25 ± 1°C and 6.77% at 30 ± 1°C. The sex ratio male to female was 1:1.06. The consumption rate significantly increased with increasing temperatures and within the larval instars. The four larval instar consumed 24.3 and 33.5 adults of A. nerii at 25 ± 1 and 30 ± 1°C, respectively. Overall, micro-climate temperature had a significant impact on the biological parameters of R. lophanthae.


Toxin Reviews ◽  
2021 ◽  
pp. 1-12
Author(s):  
Venkattan Esan ◽  
Chakkaravarthy Elanchezhiyan ◽  
Shahid Mahboob ◽  
Khalid A. Al-Ghanim ◽  
Fahad Al-Misned ◽  
...  

2019 ◽  
Vol 109 ◽  
Author(s):  
Maria I. Garcia ◽  
Albérico F. Murúa ◽  
Leonardo M. Díaz-Nieto ◽  
Juan C. Acosta ◽  
Claudia de Los Rios ◽  
...  

ABSTRACT Larvivorous fish have been studied as potential biocontrol agents of mosquito larvae and pupae through their trophic interactions. The use of native fish for mosquito control may have benefits for both aquatic biodiversity and human health. Evaluating the effect of vegetation on the predatory efficacy is fundamental to determine if this species can be used as a biocontrol agent. With the aim of evaluating Jenynsia multidentata (Jenyns, 1842) as a biocontrol agent of Culex pipiens Linnaeus, 1758, we tested its predatory capacity in the presence or absence of aquatic vegetation under laboratory conditions. Two independent experiments were conducted. Larval consumption at a density of 60 larvae (6 larvae/l) was significantly reduced with the vegetation increased. On the other hand, when the larval density was 120 (12 larvae/l), the predatory capacity of J. multidentata did not vary in the presence or absence of vegetation. This result indicated that vegetation effect on consumption could be related to prey density, since at the higher density of prey the probability of predator-prey encounter might be increased. Jenynsia multidentata is a good consumer in presence of vegetation and could be used as a potential biocontrol agent of mosquito larvae in natural environments with similar characteristics to the ones tested in these experiments.


2005 ◽  
Vol 4 (2) ◽  
pp. 1-7
Author(s):  
B. Victor ◽  
M. Mannar Mannan ◽  
M. Maridass ◽  
P. Murphy Alexander ◽  
J. M. A. P. Arachi

Feeding experiment conducted under laboratory conditions, to determine the suitability of live feed for the larvae of ornamental fish Puntius dorsalis, shows the increase of specific growth rate and weight gain when they were fed with mosquito larvae( 3.284 and 8.04%/day),chironomus larvae(3.308 and 6.24%/day),chopped earthworm (2.618 and 4.39%/day). The maximum growth rate,0.614g was observed in mosquito larvae feed followed by chironomus larvae(0.522 g),chopped earthworm(0.411g) and plankton(0.405g). The present study indicates that mosquito larvae could be used as a suitable live feed for feeding Puntius dorsalis larval fishes.


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