Additive interactions of some reduced-risk biocides and two entomopathogenic nematodes suggest implications for integrated control of Spodoptera litura (Lepidoptera: Noctuidae)

Abstract

Higher volumes of conventional and novel chemical insecticides are applied by farmers to control resistant strains of armyworm (Spodoperta litura) in Pakistan without knowing their risks to the environment and to public health. Ten reduced-risk insecticides were tested for their compatibility with two entomopathogenic nematodes (EPNs); Heterorhabditis indica and Steinernema carpocapsae against S. litura. The insecticide emamectin benzoate was highly toxic (LC50 = 2.97 mg/l) against 3rd instar S. litura larvae when applied alone whereas, novaluron and methoxyfenozide were the least toxic (LC50 = 29.56 mg/l and 21.06 mg/l), respectively. All the insecticides proved harmless against the two EPNs even 96 h after treatment. Indoxacarb, flubendiamide and spinetoram produced the greatest mortalities (72–76%) of S. litura larvae after 72 h when applied in mixtures with H. indica. Lowest mortalities (44.00 ± 3.74% and 48.00 ± 2.89) were observed for mixtures of H. indica with methoxyfenozide and chlorfenapyr, respectively. The positive control treatments with both EPNs (S. carpocapsae and H. indica) produced > 50% mortality 96 h after treatment. For insecticide mixtures with S. carpocapsae, only indoxacarb produced 90% mortality of larvae, whereas, indoxacarb, flubendiamide, emamectin benzoate, and spinetoram produced 90–92% mortality of larvae when applied in mixtures with H. indica. Additive interactions (Chi-square < 3.84) of EPN mixtures with reduced volumes of reduced-risk insecticides suggest opportunities to develop more environmentally favorable pest management programs for S. litura.

Efficacy of entomopathogenic nematodes combined with insecticides against Bradysia odoriphaga larvae

“…In this study, the dose effects were also found in the other three nematodeinsecticide interactions but with lower control efficacy compared with imidacloprid (Figs 1, 2). Additive interactions of EPN with reduced amount of low-toxic insecticides were observed in other pest controls as well, e.g., S. carpocapsae-indoxacarb and H. indica-indoxacarb, flubendiamide, emamectin benzoate, or spinetoram mixtures against the armyworm Spodoptera litura (Lepidoptera: Noctuidae) in an additive effect (Khan et al, 2021); S. feltiae-piperonyl butoxide or diethyl maleate mixture increased control efficacy against the Colorado potato beetle (Leptinotarsa decemlineata Say) (Ozdemir et al, 2021). The compatibility of nematode and chem- ical insecticide is not only a species-specific, but also a strain-specific characteristic, which is a very common phenomenon in nematode-insecticide interaction against pests (Laznik & Trdan, 2014).…”

“…Synergistic or additive control effects of the combination of nematodes and insecticides on soil-inhabiting pests have been reported when compared with insecticides or nematodes alone (Koppenhöfer & Kaya, 1998;Koppenhöfer et al, 2000Koppenhöfer et al, , 2002Guo et al, 2016;Yan et al, 2019;Khan et al, 2021;Ozdemir et al, 2021). However, some insecticides with detrimental impact on the infectivity and survival of EPN have been observed (Rovesti et al, 1988;Rovesti & Deseö, 1990;Li et al, 1994;Yan et al, 2012;Kwizera & Susurluk, 2017).…”

The Humoral Immunological Response and Bio-Efficiency Evaluation to Entomopathogenic Nematodes as A Biopesticide on Spodoptera littoralis (Boisd)

“…These findings came in accordance with the data of susceptibility test carried out by Taha (2021) that exhibited potent lethal effects on the 5 th instar larvae of S. littoralis treated by the range of 200 up to 1600 IJs of each of S. carocapsae and H. indica after 48 hrs. Nevertheless, Khan et al (2021) found that the mortality responses in S. litura to 500 IJs of each of S. carocapsae and H. indica at 72 hrs were limited at 38.00 and 44.00 %, respectively. Meantime, the selected binary mixture of the tested EPNs at field rate (≡ LC50 realized highest additive effect) transcends all the individual treatments of EPN at rates ≡ LC90 along the 12 th DATs.…”

Insecticidal Activity of Pyriproxyfen, A Juvenoid, and Its Suppressive Effect on Growth and Development of The Black Cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae)

“…LD50 values of the ecdysone agonists RH-5849 and RH-5992 (tebufenozide) against E. kuehniella were 0.05 and 0.005 μg/insect, respectively (Tazir et al, 2016); LC50 of the ecdysone agonist methoxyfenozide against Cx. pipiens was 24.54 µg/L (Hamaidia and Soltani, 2016); LC50 of Lufenuron against G. pyloalis was 19 ppm (Aliabadi et al, 2016); LC50 values of chlorfluazuron, cyromazine, lufenuron and precocene I against the cat flea Ctenocephalides felis were 0.19, 2.66, 0.20, and 10.97 ppm, respectively (Rust and Hemsarth, 2016); LD50 values of RH-5849 and tebufenozide against E. kuehniella were 0.05 and 0.005 μg/insect, respectively (Taziret al, 2016); LC50 of teflubenzuron against P. gossypiella was 78.59 ppm (Said et al, 2017); LC50 values of Novaluron against P. gossypiella were 0.187 ppm and 0.765 ppm, after treatment of newly hatched and full grown larvae, respectively (Ghoneim et al, 2017a); LC50 values of flufenoxuron, chlorfluazuron and triflumuron against 4 th instar larvae of S. littoralis were 0.14 ppm, 0.42 and 1661.58 ppm, respectively (Abdel-Mageed et al, 2018); LC50 of pyriproxyfen against the mosquitoes Aedes aegypti and Aedes albopictus were 1.63ppm and 1,56ppm, respectively (Sucipto et al, 2018); LC50 values of diofenolan against P. gossypiella were 0.028 ppm and 0.036 ppm, after treatment of newly hatched and full grown larvae, respectively (Tanani and Bakr, 2018); LC50value of methoxyfenozide against last instar (6 th ) larvae of P. unionalis was 0.176 ppm (Hamadah and Abo Elsoud, 2018); LD50 values of pyriproxyfen against the false stable fly Muscina stabulans were 0.242 & 0.444µg/stage, after treatment of early last (3 rd ) instar larvae and prepupae, respectively (Hamadah, 2018); LD50 of novaluron against 9 th instar larvae of the red palm weevil Rhynchophorus ferrugineus was 14.77 ppm (Hussain et al, 2019); LC50 values of hexaflumuron, lufenuron and chlorfluazuron against H. armigera larvae were 6.16, 61.31 and 31.75 mg ai/l, respectively (Khorshidi et al, 2019); LC50 of fenoxycarb against 4 th instar larvae of S. littoralis was 25.943 ppm (Gad et al, 2019); LC50 values of novaluron and methoxyfenozide against 3 rd instar S. litura larvae were 29.56 mg/l and 21.06 mg/l, respectively (Khan et al, 2021); etc. However, LC50 value depends on several factors, such as susceptibility of the insect and its treated stage or instar, lethal potency of the tested compound and its concentration levels, method and time of treatment, source of stock insect referring to potential genetical/geographical variations, as well as the experimental conditions.…”