Effect of aqueous extract of Azadirachta indica A. Juss (neem) leaf on oocyte maturation, oviposition, reproductive potentials and embryonic development of a freshwater fish ectoparasite Argulus bengalensis Ramakrishna, 1951 (Crustacea: Branchiura)

Abstract

In present study, a microcosm experiment is carried out to investigate the efficacy of 120 and 250-ppm crude aqueous extract of Azadirachta leaf on oocyte maturation, oviposition, embryonic development and hatching of the eggs of a fish ectoparasite Argulus bengalensis. Relative abundance of different maturing oocyte stages in the ovary of the parasite from different age groups was enumerated, and marked variations were obtained. Significant depletion in the abundance of pre-vitollogenic, vitellogenic and post-vitellogenic oocytes was recorded, which indicates impairment in maturation. Chromatin condensation of the oocytes of treated parasite indicates apoptosis of oogenic cells. Strong oviposition deterrence was evident by the elevated oviposition deterrence index of 0.18 and 0.52 at respective toxin levels. The treated parasites invested less number of eggs per oviposition, and hatching percentage of the eggs reduced markedly. In vitro treatment of eggs within 70 min of incubation exhibited coagulation of yolk material and subsequent reduction in hatching percentage. However, treatment applied after this critical period, hatching was not significantly altered. In vitro treatment of eggs at 80 min of incubation resulted in normal development. It signifies that azadirachtin affects the early developmental events but not the later. Presumably, azadirachtin either affects early gene expression of the embryo or antagonizes any of the substances of the zygote required for sustaining early developmental process. The result of the present experiment suggests that azadirachtin could be a promising agent to control argulosis through inhibition of the reproductive maturity of the parasite as well as through interference of its embryonic development.

Azadirachtin effects on mating success, gametic abnormalities and progeny survival in Drosophila melanogaster (Diptera)

“…Previously, azadirachtin was reported to impair, with variable effects, the survival of different insect species . Strong variations in insects' susceptibility to azadirachtin were noted depending on insect order, species, formulation, or the method of application . Sensitivity of insects to insecticides varies also with the regulation of plasma membrane receptor and/or ion channels, penetration rate through the cuticle, absorption by insects, transport in tissues of the body and metabolism …”

“…9,[11][12][13][14][44][45][46][47][48][49][50][51] Strong variations in insects' susceptibility to azadirachtin were noted depending on insect order, species, formulation, or the method of application. 9,[11][12][13][14][25][26][27][28][29][44][45][46][47][48][49][50][51] Sensitivity of insects to insecticides varies also with the regulation of plasma membrane receptor 52 and/or ion channels, 34,52 penetration rate through the cuticle, 23 absorption by insects, 23 transport in tissues of the body 23 and metabolism. 23 Several mechanisms may be at play in causing acute azadirachtin toxicity.…”

“…However, because azadirachtin acts as an insect growth disruptor, negative side effects on beneficial arthropods are expected. Studies have reported various effects of neem products on non‐target species, such as mites, parasitoids and bees . For example, behaviour and morphological alterations have been highlighted in bees, while Bernades et al .…”

“…Studies have reported various effects of neem products on non-target species, such as mites, parasitoids and bees. [24][25][26][27][28][29] For example, behaviour and morphological alterations have been highlighted in bees, 29 while Bernades et al 27 did not detect any effect on worker bee mortality, flight, or respiration rate. The large panel of potentially affected functions and apparent contradictory conclusions are caused by the level of action of azadirachtin.…”

Histological and ultrastructural investigation of the female reproductive system of Argulus bengalensisRamakrishna, 1951 (Crustacea: Branchiura)

“…In insect pests, the accessory gland is highly specialized and its function is important in their reproductive process (Adiyodi and Adiyodi, 1975;Lococo and Huebner, 1980;Takaoka et al, 1989;Kaulenas, 1992). Concerning other aspects of their reproductive biology, a detailed study of egg laying, development, hatching and the temperature-dependent life cycle was done earlier by Shafir and van As (1986) in Argulus japonicus, and recently by Banerjee and Saha (2013) and Banerjee et al (2014aBanerjee et al ( , 2015a in Argulus bengalensis. Many researchers, even prior, had conducted studies on the reproduction and population dynamics of Argulus spp.…”