Extensive use of various insecticides to manage aphids led to resistance to many insecticides with different modes of action (Wei et al. 2017). As a result, introducing alternative novel insecticides such as flupyradifurone is of great necessity. Thus, investigating different toxicity profiles such as sublethal effects is essential to delay resistance development (Liang et al. 2018). Sublethal effects of flupyradifurone have been reported in several target pests, including the sweet potato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) (Smith and Giurcanu 2013), the cotton aphid, Aphis gossypii (Glover) (Hemiptera: Aphididae) (Liang et al. 2018), and the green peach aphid, M. persicae (Tang et al. 2019). The obtained results indicated that flupyradifurone proved high toxicity with LC50 value of 1.82 mg. liter− 1. In addition, the sublethal concentration used in the current work (LC10 and LC25) recorded 0.62 and 1.05 mg. liter− 1, respectively. The previous toxicity results of flupyradifurone are in harmony with that reported by (Liang et al. 2018) against A. gossypii and by(Tang et al. 2019) against M. persicae .
In the present study, the sublethal concentrations (LC10 and LC25) induced fecundity and adult longevity of F0 generation. A similar finding was noted with A. gossypii after exposure to nitenpyram sublethal concentrations (Wang et al. 2017). Also, imidacloprid, acetamiprid and beta-cypermethrin sublethal concentrations increased fecundity and other population growth parameters of M. persicae and Aphis glycines Matsumura (Hemiptera: Aphididae) (Ayyanath et al. 2013; Qu et al. 2015, 2017; Sial et al. 2018). On the other hand, the negative effects of sublethal concentrations were noticed in several insects including A. gossypii after exposed to thiamethoxam and cycloxaprid (Yuan et al. 2017; Ullah et al. 2020).
The present work investigated the transgenerational effects of flupyradifurone sublethal concentrations on A. craccivora. The developmental durations include adult period, total longevity, and ovi-days of F1 generation were significantly increased after exposed F0 generation with LC10 and LC25 compared with control. While, certain developmental durations, including the adult pre-reproduction period of female adult (APRP) and total pre-reproduction period of females (TPRP) were significantly decreased due to LC25 treatment, but LC25 treatment significantly increased fecundity in the F1 generation. The previous results clarified that (F0) generation treatments with sublethal concentrations of flupyradifurone induced stimulatory effects on reproduction of (F1) generation. Similar stimulation on the reproduction of progeny generation was observed with M. persicae following parental adults’ treatments with LC25 of flupyradifurone (Tang et al. 2019). The transgenerational stimulatory effects were also observed in A gossypii as a response to sublethal concentrations of acetamiprid, imidacloprid, nitenpyram, and bifenthrin(Kerns and Stewart 2000; Wang et al. 2017; Ullah et al. 2019a). In addition, increased aphid reproduction and survival as a result of parental treatments with sublethal concentrations of imidacloprid (Janmaat et al. 2011; Rix and Cutler 2018). In several other insect pests, sublethal concentrations of phosphoric acid-exhibited hormetic effects on citrus thrip Scirtothrips citri Moulton (Thysanoptera: Thripidae) (Morse and Zareh 1991) and Twospotted spider mite, Tetranychus urticae Koch (Trombidiformes: Tetranychidae) (Maggi and Leigh 1983). Triazophos and fenvalerate had hormetic effects on the brown planthopper, Nilaparvata lugens Stål (Hemiptera: Delphacidae) (Bao et al. 2009).
Demographic indexes for (F1) which include intrinsic rate of increase (r)net reproductive rate (R0), finite rate of increase (λ), mean generation time T (d) were significantly increased with parental aphids treated with LC25. While only the Mean generation time T (d) was increased with LC10 treatment. As a result, the doubling time (DT) for LC10 and LC25 treatments was decreased compared with control. Increasing these parameters indicate that parental aphids treated with LC10 and LC25 of flupyradifurone stimulate an A craccivora population growth in progeny generation. The obtained results are in line with Tang et al. (2019), who stated that treatment of A. craccivora parent generation with LC25 of flupyradifurone stimulates hermetic effects in the progeny generation. Similarly, significant transgenerational hormetic effects were observed in A. gossypii as a result of parental treatments with nitenpyram and acetamiprid (Wang et al. 2017; Ullah et al. 2019b). Additionally, the population growth parameters of A. glycines were significantly increased after exposure to beta-cypermethrin and imidacloprid sublethal concentrations (Qu et al. 2015, 2017). Hormesis effects after exposure to sublethal concentrations might be due to the uptake of a small amount of the pesticides that contribute to developing embryos through female bodies (Ayyanath et al. 2013; Wang et al. 2017). The previous hypothesis was supported by (Ullah et al. 2020) who found a relationship between hormesisand increased levels of vitellogenin and ecdysone after exposure to ublethal concentrations of thiamethoxam in A. gossypii. In addition, adult exposure to sublethal concentrations of pesticides gets rid of low-vital individuals in parental and, consequently, stimulating reproduction in F1 progeny (Calabrese 2005).
Curved plots of sxj, lx, mx, lxmx, vxj, and exj are potentially express changes in the biological fitness of insect pest populations as a result of any environmental influences. Due to different environmental factors such as pesticides exposure, variations in these parameters have been noticed in several pests such as A. gossypii (Chen et al. 2016; Shang et al. 2021), Schizaphis graminum Rondani (Hemiptera: Aphididae)(Atta et al. 2021), Lygus pratensis L.(Hemiptera: Miridae), Polymerus cognatus Fieber .(Hemiptera: Miridae) (Tan et al. 2021), Spodoptera littoralis Boisduval (Lepidoptera: Noctuidae), and Trogoderma granarium Everts (Coleoptera: Dermestidae )(Mokbel and Huesien 2020; Mokbel et al. 2020).