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Carp of the individual weigh of 92-625 g were subjected to lethal concentrations of deltametrin and lambda-cyhalotrin. Moribund fish were killed and their pectoral fins along with the associated muscles were dissected. Such preparations were stimulated electrically. No effect of the pyrethroids studied was observed on the value of the muscle stimulation threshold. Similarly, no effect was visible on the ergographic records of the work performed.
Cabbage (Brassica oleracea Linn.) is one of the important vegetables grown worldwide. Insect pests have been a major constraint to its production with some reported to have developed resistance to commonly available synthetic insecticides. In order to find alternative control for these pests, field experiments were conducted in the early seasons of 2011 and 2012, to evaluate the efficacy of three plant extracts, Tephrosia vogelli Hooks, Zingiber officinales Rosh and Lantana camara Spanish flag, applied at 5, 10 and 25 % w/v concentrations Delthamethrin (a synthethic insecticide) and an unsprayed plot were included as positive and negative controls respectively. Plots were arranged in a Randomized Complete Block Design (RCBD), with three replications. Mean Data over the two planting seasons were subjected to the analysis of variance and significant means were compared using the least significant difference (L.S.D) at P < 0.05. Z. officinales extract effectively control P. xylostella larvae at all concentrations with 25 % w/v gave the best yield of 0.50 kg/ha while T. vogelii and L. camara extracts were as effective as Deltamethrin at different concentrations and hours on diamondback-moth (P. xylostella) adult The present findings indicated that effective botanicals against Diamondback moth adult and larvae of cabbage can be formulated from extract of T. vogelii, L. camara and Z. officinales at 25 % concentration respectively.
Background. Animals acquire new skills due to conditioned responses resulting from a sequence of neutral and unconditioned stimuli affecting their bodies; there is a constant time interval between the stimuli. Both stimuli become associated after a number of repetitions and animal bodies start to respond to the initially neutral stimulus as to the unconditioned one. The aim of this study was to determine whether exposure of fish to a pyrethroid—deltamethrin (an active ingredient in Decis 2.5 EC pesticide that disturbs the proper operation of the nervous system) affects the ability to learn in common carp. Materials and Methods. Production of new types of behaviour was triggered in fish by using the unconditioned stimulus (an irritating electric impulse) and the conditioned stimulus (light). The experiment was performed in a tank divided into two compartments where fish could swim freely from one compartment to another. The ability to learn was assessed on the basis of the following types of behaviour evoked in response to the conditioned stimulus: locomotor agitation, preference to occupy or avoid certain areas in the tank, an escape response, etc. Results. In fish exposed to 0.35 μg · L–1 deltamethrin (for common carp concentration 10 times lower than lethal) for 35 min the ability to produce and remember the conditioned defence response was reduced and time interval since presenting the conditioned stimulus till occurring the initial signs of the conditioned response was prolonged. Conclusion. The classical conditioning method revealed that sublethal concentration of deltamethrin restricted ability to learn and retain information in common carp, despite absence of observable intoxication symptoms.
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