Gap junctions are integral membrane proteins that play a role in cell-to-cell communication. They are coded by the functional genes called connexins in chordates and innexins in invertebrates. However, recently pannexins were also found in mammalian genomes, which are homologous to insect innexins. Gap junction intercellular communication (GJIC) has different functions ranging from their role in ontogenesis to the transfer of intracellular signal molecules and minimizing the adverse effects of xenobiotics by dilution and steady-state catabolism. Perturbations of these gap junctions are known to promote cancers besides, and many tumor inducers reduce the functioning of these gap junctions. Insect gap junctions play a crucial role in the development of insects and perhaps might be one of the reasons for the success of insects on terrestrial habitats. Majority of the work on innexins was done on Drosophila melanogaster Meigen, 1830 (Diptera: Drosophilidae), and its innexins regulate size of the central nervous system, embryonic gut formation, metamorphosis, and the fertility of germ lines in the reproductive system. There are several insecticides like cyclodienes, organochlorines, phenypyrazoles, synthetic pyrethroids, avermectins, milbemycins, oxadiazines, semicarbazones, meta-diamides, isoxazolines which target ion channels in the insects, but there is no evidence that supports the possible toxic effects of insecticides on insect gap junctions. In this review, we discuss the importance of insect gap junctions and how they could be a potential target for chemical pest management.

Nicotine is a highly addictive alkaloid and a neurostimulator found in tobacco that causes addiction in humans and makes tobacco a high-demand commercial product. It is popularly used for recreational purposes and is a harmful substance (Oral LD50 value for rat is 50 mg/kg) and causes addiction. The metabolites of nicotine such as the Tobacco-specific Nitrosamines (TSNAs) are hazardous substances whose metabolites are highly electrophilic and form DNA adducts, which will initiate the process of carcinogenesis. TSNAs are formed during curing, storage and fermentation due to the nitrosation of nicotine and other tobacco alkaloids. TSNAs are used as biomarkers for cancer risk assessment in humans exposed to tobacco and its products. To determine the occasional formation of TSNAs in tobacco-feeding insects, 5th instar larvae of Spodoptera litura and their faeces were analyzed for the presence of N′-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) along with the stored tobacco leaves (PT-76) using an Agilent 6470B LC–MS/MS system following ISO/DIS 19290:2015 protocol. The larvae are extracted in a buffered acetonitrile–water extraction and the amount of TSNAs are quantified in multiple reaction monitoring (MRM) mode. 20 $$\upmu$$ μ l of each extracted and cleaned up sample was injected into the LC–MS/MS system for quantification. The Limit of Detection (LOD) and Limit of Quantification (LOQ) were 0.001 mg/kg and 0.005 mg/kg for all the tested nitrosamines. NNN was found to be 0.361 mg/kg, 0.340 mg/kg, and 5.66 mg/kg in insect whole-body samples, faeces, and tobacco leaves, respectively. NNK was found to be 0.060 mg/kg, 0.035 mg/kg and 0.93 mg/kg in insect whole body samples, faeces and tobacco leaves, respectively. However, NNAL was not detected in both the insect’s whole body and faeces. Recoveries ranged between 95 and 98% for all compounds when spiked at LOD and LOQ. The presence of TSNAs is a biomarker for cancer risk and their presence in insects would point to cancer risk assessment in tobacco feeding insects and any possible TSNA-detoxifying pathways in insects that might prevent mutagenesis caused these compounds.

Nicotine is a highly addictive alkaloid and a neurostimulator found in tobacco that causes addiction in humans and makes tobacco a high-demand commercial product. It is popularly used for recreational purposes and is not a harmful substance except for the addiction it causes. The metabolites of nicotine such as the Tobacco-specific Nitrosamines (TSNAs) are hazardous substances whose metabolites are highly electrophilic and form DNA adducts, which will initiate the process of carcinogenesis. TSNAs are formed during curing, storage and fermentation due to the nitrosation of nicotine and other tobacco alkaloids. TSNAs are used as biomarkers for cancer risk assessment in humans exposed to tobacco and its products. To determine the occasional formation of TSNAs in tobacco-feeding insects, 5th instar larvae of Spodoptera litura and their faeces were analyzed for the presence of NNN, NNK, and NNAL along with the stored tobacco leaves (PT-76) using an Agilent 6470B LC-MS/MS system following ISO/DIS 19290:2015 protocol. The LOD and LOQ were 0.001 mg/kg and 0.005 mg/kg for all the tested nitrosamines. NNN was found to be 0.365 mg/kg, 0.344 mg/kg, and 5.71 mg/kg in insect whole-body samples, faeces, and tobacco leaves, respectively. NNK was found to be 0.062 mg/kg, 0.036 mg/kg and 0.97 mg/kg in insect whole body samples, faeces and tobacco leaves, respectively. However, NNAL was not detected in both the insect’s whole body and faeces. Recoveries ranged between 95-98% for all compounds when spiked at LOD and LOQ. The presence of TSNAs is a biomarker for cancer risk and their presence in insects would point to cancer risk assessment in tobacco feeding insects and any possible TSNA-detoxifying pathways in insects that might prevent mutagenesis caused these compounds.