Azadirachtin-induced effects on various life history traits and cellular immune reactions of Galleria mellonella (Lepidoptera: Pyralidae)

Abstract

The effects of the botanical insecticide azadirachtin were examined on the life history traits, fecundity and immune parameters of Galleria mellonella L. (Lepidoptera: Pyralidae). We determined that for the topical application of azadirachtin, the LC 50 was 16.564 ppm; at 100 ppm the adult emergence time was prolonged, however the longevity of adults remained unchanged above sublethal concentrations. The mean number of healthy eggs and the fecundity of adults decreased, whereas the number of defective eggs increased with azadirachtin treatment. At concentrations >50 ppm female G. mellonella adults laid no eggs. Azadirachtin reduced total hemocyte counts at 24 and 48 h posttreatment, however the alterations in differential hemocyte counts were only significant at 100 ppm. Laminarin-induced nodulation response and the spreading ability of hemocytes were also suppressed with azadirachtin treatment. Our results suggest that azadirachtin, as a good candidate for integrated pest control, has the capability to affect the biological parameters and cellular immunity of the model insect G. mellonella.

Boric acid‐induced immunotoxicity and genotoxicity in model insectGalleria mellonellaL. (Lepidoptera: Pyralidae)

“…Therefore, the suppression of cell‐mediated immune responses may be associated with the inhibition of eicosanoids synthesis and increasing oxidative stress in BA‐treated larval groups. Our results are in agreement with previous studies which reported similar findings for G. mellonella larvae exposed to various environmental compounds (Altuntaş et al, ; Er et al, ; Mizerska‐Dudka & Andrejko, ). We, therefore, argue that BA treatment suppresses melanization, nodule and capsule formation in larval hemocytes.…”

“…Arguably, the observed suppression of cell viability in our study is a viable explanation for the decrement in the circulating THC in G. mellonella larvae. Consistent with our findings, recent studies about the effects of several insecticides on the hemocyte numbers of G. mellonella larvae have reported similar findings (Coates et al, 2018;Er et al, 2017;Kurt & Kayis, 2015;Yücel & Kayis, 2018).…”

“…Arguably, the observed suppression of cell viability in our study is a viable explanation for the decrement in the circulating THC in G. mellonella larvae. Consistent with our findings, recent studies about the effects of several insecticides on the hemocyte numbers of G. mellonella larvae have reported similar findings (Coates et al, ; Er et al, ; Kurt & Kayis, ; Yücel & Kayis, 2018). Interestingly, despite the observed decrease in THC, no significant change in hemocyte mitotic indices were observed following BA administration in this study, although, studies in literature reported that boron inhibited cell proliferation by inhibition of mitosis (Fail et al, ; Ying et al, ).…”

“…Due to their direct and immediate involvement in insect defense, hemocytes are a good indicator of systemic toxicity due to xenobiotics. Studies have also reported effects of various chemicals/xenobiotics using cellular immune responses as bioindicators studies (Altuntaş et al, ; Er et al, ; Lavine & Strand, ; Pech & Strand, ; Salem, Hussein, Hafez, Hussein, & Sayed, ). Similar to previous studies the current study identified granulocytes, plasmatocytes, sperulocytes, oenocytes, and prohemocytes as the circulating hemocytes of G. mellonella larvae.…”

“…GR, granulocyte; MI, mitotic hemocyte; ON, onositoid; PL, plasmatocyte; Pro: prohemocyte; SP, spherulocytes 2.7 | Nodulation Laminarin (Sigma, St. Louis, MO) was used to induce nodulation in larvae exposed to the selected concentrations of BA and those in the control group. The assay was carried out according to Er, Deniz, andOlga (2017) andFranssens et al (2006). We conducted preliminary experiments to ascertain the effects of incubation times and laminarin concentrations on the nodulation responses of G. mellonella larvae and for this, we studied how G. mellonella larvae respond to different volumes/doses of laminarin at different times.…”