scholarly journals Glyphosate inhibits melanization and increases susceptibility to infection in insects

PLoS Biology ◽  
2021 ◽  
Vol 19 (5) ◽  
pp. e3001182
Author(s):  
Daniel F. Q. Smith ◽  
Emma Camacho ◽  
Raviraj Thakur ◽  
Alexander J. Barron ◽  
Yuemei Dong ◽  
...  

Melanin, a black-brown pigment found throughout all kingdoms of life, has diverse biological functions including UV protection, thermoregulation, oxidant scavenging, arthropod immunity, and microbial virulence. Given melanin’s broad roles in the biosphere, particularly in insect immune defenses, it is important to understand how exposure to ubiquitous environmental contaminants affects melanization. Glyphosate—the most widely used herbicide globally—inhibits melanin production, which could have wide-ranging implications in the health of many organisms, including insects. Here, we demonstrate that glyphosate has deleterious effects on insect health in 2 evolutionary distant species, Galleria mellonella (Lepidoptera: Pyralidae) and Anopheles gambiae (Diptera: Culicidae), suggesting a broad effect in insects. Glyphosate reduced survival of G. mellonella caterpillars following infection with the fungus Cryptococcus neoformans and decreased the size of melanized nodules formed in hemolymph, which normally help eliminate infection. Glyphosate also increased the burden of the malaria-causing parasite Plasmodium falciparum in A. gambiae mosquitoes, altered uninfected mosquito survival, and perturbed the microbial composition of adult mosquito midguts. Our results show that glyphosate’s mechanism of melanin inhibition involves antioxidant synergy and disruption of the reaction oxidation–reduction balance. Overall, these findings suggest that glyphosate’s environmental accumulation could render insects more susceptible to microbial pathogens due to melanin inhibition, immune impairment, and perturbations in microbiota composition, potentially contributing to declines in insect populations.

2020 ◽  
Author(s):  
Daniel F. Q. Smith ◽  
Emma Camacho ◽  
Raviraj Thakur ◽  
Alexander J. Barron ◽  
Nichole A. Broderick ◽  
...  

SUMMARYMelanin is a black-brown pigment found throughout all kingdoms of life playing diverse roles including: UV protection, thermoregulation, oxidant scavenging, arthropod immunity, and microbial virulence. Given melanin’s broad functions in the biosphere, particularly in insect immune defenses, it is important to understand how environmental conditions affect melanization. Glyphosate, the most widely used herbicide, inhibits melanin production. Here we elucidate the mechanism underlying glyphosate’s inhibition of melanization demonstrate the herbicide’s multifactorial effects on insects. Glyphosate acts as an antioxidant and disrupts the oxidation-reduction balance of melanization. The drug reduced wax moth larvae survival after infection, increased parasite burden in malaria-transmitting mosquitoes, and altered midgut microbiome composition in adult mosquitoes. These findings suggest that glyphosate’s environmental accumulation could contribute to the so called insect apocalypse, characterized by species declines, by rendering them more susceptible to microbial pathogens due to melanization inhibition, immune impairment, and perturbations in microbiota composition.


2018 ◽  
Vol 20 (2) ◽  
pp. 91-101
Author(s):  
Andressa Lima de Brida ◽  
Silvia Renata Siciliano Wilcken ◽  
Luis Garrigós Leite

Nematoides entomopatogênicos (NEPs) são alternativas eficientes para o controle de pragas. O emprego de novas técnicas da produção in vivo, permite o progresso da tecnologia de formulação de bioinseticidas. O objetivo do trabalho, foi avaliar a influência da luminosidade e do substrato na capacidade de infecção de juvenis infectantes (JIs) de Steinernema brazilense IBCBn 06, Steinernema carpocapsae IBCBn 02, Steinernema feltiae IBCBn 47 e Heterorhabditis amazonensis IBCBn 24 em lagartas de Galleria mellonella (Lepidoptera: Pyralidae). O delineamento experimental foi inteiramente casualizado com quatro tratamentos e oito repetições. As parcelas, constituídas por placa de Petri com, substrato-areia e substrato-papel filtro, com e sem luminosidade, inoculados com suspensão de 1,5 mL contendo 400JIs e quatro lagartas de G. mellonella. O número de JIs foi quantificado após a mortalidade das lagartas. A taxa de infecção de JIs de S. carpocapsae IBCBn 02 e S. feltiae IBCBn 47 variaram de 2,14 a 3,28 e de 11,04 a 13,09 JIs/lagarta. O substrato-areia com e sem luminosidade permitiu a maior taxa de infeção dos JIs de S. brazilense IBCBn 06 de 7,86 e 9,44 JIs/lagarta, e 13,49 JIs/lagarta com luminosidade para H. amazonensis IBCBn 24. O substrato-areia, permite a maior taxa de infecção por JIs de NEPs.


2013 ◽  
Vol 104 (2) ◽  
pp. 203-212 ◽  
Author(s):  
A. Valigurová ◽  
V. Michalková ◽  
P. Koník ◽  
M.L. Dindo ◽  
M. Gelnar ◽  
...  

AbstractThe tachinid fly Exorista larvarum (L.) (Diptera: Tachinidae) is a polyphagous larval endoparasitoid that deposits its eggs on the host exoskeleton of lepidopteran and tenthredinid larvae. The attachment of larval E. larvarum and the formation of the respiratory funnel were studied during infestation in the last larval instar of the wax moth, Galleria mellonella (L.) (Lepidoptera: Pyralidae). The tachinid larvae burrow through the host integument after hatching, using their robust cephalopharyngeal skeleton, leaving a dark spot at the point of their penetration as a result of host cuticle melanization. Endoparasitoid penetration induces the host cellular defence, resulting in the formation of a haemocyte capsule consisting of multi-cellular sheaths. This enveloping capsule later undergoes melanization, which is mostly obvious towards the posterior part of the endoparasitoid. The endoparasitoid uses the host encapsulation response to build a respiratory funnel from the modified host integument, leading to the host surface. The encapsulated larva remains attached to the respiratory funnel via an anal hook and cuticular spines until fully developed. Additional immunohistochemical analyses were used to study host–parasitoid interactions. Indirect immunofluorescence showed no labelling of potential tachinid antigens and confirmed no effect on the surrounding host tissues. A simulated parasitization with coated polybead microspheres revealed the mortal impact of tachinid antigens to the host. Hosts injected with antigen-coated polybeads died as a consequence of an acute and extensive immunological response to the tachinid antigens and not due to the trauma caused by foreign objects inside their body.


PEDIATRICS ◽  
1957 ◽  
Vol 20 (3) ◽  
pp. 431-438
Author(s):  
Benjamin H. Landing ◽  
Harry S. Shirkey

The clinical and pathologic findings in two white male children with repeated infections, including lymphadenitis, aphthous stomatitis, enteritis, pneumonitis, osteomyelities, etc. are described. Tissue removed at laparotomy in one patient, and at necropsy in the other, showed infiltration of organs by lipid histiocytes containing yellow-brown pigment. Although the histochemical properties of the cells show similarities to the lipid histiocytes of Niemann-Pick disease, the condition described is considered to differ from other forms of lipid histiocytosis, as well as from other conditions producing susceptibility to infection. Concentrations of gamma-globulin in the serum of one of the patients were elevated, but whether the globulin is functionally effective is not known. The onset of symptoms in early infancy suggests that the disorder is genetically determined rather than acquired, but no evidence of familial occurrence has been obtained.


2018 ◽  
Vol 157 ◽  
pp. 1-3 ◽  
Author(s):  
Yuri S. Tokarev ◽  
Ekaterina V. Grizanova ◽  
Anastasia N. Ignatieva ◽  
Ivan M. Dubovskiy

Author(s):  
Karem Ghoneim ◽  
Khalid Hamadah ◽  
Mohammad Tanani ◽  
Dyaa Emam

The greater wax moth, Galleria mellonella (Linnaeus) (Lepidoptera: Pyralidae) is the most destructive pest of honey bee, Apis mellifera Linnaeus (Hymenoptera: Apidae), throughout the world. The present study was conducted to determine the quantitative and qualitative impairing effects of the arthropod venoms, viz., death stalker scorpion Leiurus quinquestriatus (Hemprich & Ehrenberg) venom (SV), oriental Hornet (wasp) Vespa orientalis Linnaeus venom (WV) and Apitoxin of A. mellifera (AP) on the larval haemogram. For this purpose, the 3rd instar larvae were treated with LC50 of each of these venoms (3428.9, 2412.6, and 956.16 ppm, respectively). The haematological investigation was conducted in haemolymph of the 5th and 7th (last) instar larvae. The important results could be summarized as follows. Five basic types of the freely circulating haemocytes in the haemolymph of last instar (7th) larvae of G. mellonella had been identified: Prohemocytes (PRs), Plasmatocytes (PLs), Granulocytes (GRs), Spherulocytes (SPs) and Oenocytoids (OEs). All venoms unexceptionally prohibited the larvae to produce normal hemocyte population (count). No certain trend of disturbance in the differential hemocyte counts of circulating hemocytes in larvae of G. mellonella after treatment with the arthropod venoms. Increasing or decreasing population of the circulating hemocytes seemed to depend on the potency of the venom, hemocyte type and the larval instar.  In PRs of last instar larvae, some cytopathological features had been observed after treatment with AP or WV, but SV failed to cause cytopathological features. With regard to PLs, some cytopathological features had been observed after treatment with AP while both SV and WV failed to cause cytopathological features in this hemocyte type. No venom exhibited cytopathological effects on GRs, SPs or OEs.


Author(s):  
T.N. Klementeva ◽  
◽  
A.S. Artemchenko ◽  
M.V. Tyurin ◽  
E.S. Kosman ◽  
...  

The wax moth (Galleria mellonella; Lepidoptera: Pyralidae) lines have been obtained as a result of the artificial diet with broad-spectrum antibiotic selection. An influence of that diet on the insect’s physiological parameters was examined through several generations. A significant increase in the activity of a number of enzymatic and non-enzymatic antioxidants because of artificial diet with antibiotic has been observed in the midgut of the wax moth daughter generations. Observed changes in the midgut enzymes activity and increase of antioxidants level are denote a damage in the gut tissues.


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