NOVELTY - Controlling plant pests comprises contacting the pest with a Bacillus thuringiensis (Bt) toxin together with a composition (A) comprising one or more compounds comprising benzodioxole derivatives (I) or substituted aryl compounds (II) and their salts, solvates and/or photo-degradation products.    USE - (A) is useful for controlling plant pests, where: the pests are Bt resistant pests, preferably an insect or arachnid; the plants are outdoor plants, commercial crops, Bt transgenic plants or non Bt transgenic plants; the plant is preferably cotton (comprising Ingard (RTM: Insecticidal cotton), Bollgard II (RTM: Insect-resistant genetically modified cotton) (preferred), WideStrike (RTM: Insect protected cotton) or Bollgard III (RTM: Insect resistant cotton)), maize, tomato, potato eggplant, rice or soybean; the pest belongs to an order comprising Class Insecta or Class Arachnida, including Lepidoptera, Coleoptera, Hemiptera, Thysanoptera or Acarina; and the pest is preferably one or more of Helicoverpa armigera, Helicoverpa zea, Helicoverpa punctigera, Heliothis virescens, Pectinophora gossypiella, Spodoptera littoralis, Leptinotarsa decemlineata, and Plutella xylostella (all claimed). The ability of (I) to control pest was tested against damage to Bollgard II (RTM: Insect-resistant genetically modified cotton) from resistant Helicoverpa armigera. The result showed that a mean of 5.6 damaged cotton bolls/m of row from the non-piperonyl butoxide (PBO) treated plots, while 0.25 damaged bolls/m row were recorded for non-photostabilized PBO emulsifiable concentrate.    ADVANTAGE - (A) is non-photostabilized, and substantially free of other non-Bt insecticides, pesticides and/or insecticide synergists, hence reduces costs and detrimental environmental effects.    DETAILED DESCRIPTION - Controlling plant pests comprises contacting the pest with a Bt toxin together with a composition (A) comprising one or more compounds comprising benzodioxole derivatives of formula (I) or substituted aryl compounds of formula (II) and their salts, solvates and/or photo-degradation products.    R1-R3 = H, alkyl, or CH2OR4;    R4 = H or (CH2CH2O)n-R5;    n = 1-4;    R5 = H, alkyl, aralkyl or aryl (optionally substituted by one or more substituents of alkyl, halo, CN, carboxylate or amine);    R7 = H;    R8 = H, -CH2CH2CH3, -CH2OCH2CH2OCH2CH2OCH2CH2CH2CH3, -CH2CH2CH3, -CH2CH2CH2CH3 or -CH2CH2CH2CH2CH2CH3;    R9 = phenyl or -CH2OCH2CH2CH2CH3;    R10, R12 = -CH2 or O; and    R11 = CH2 or -CH2CH2-.    INDEPENDENT CLAIMS are included for:    (1) controlling Bt resistant pests on Bt transgenic plants comprising applying (A) to the pest;    (2) controlling Bt resistant pests on non Bt-transgenic plants comprising applying (A), one or more Bt toxins; and optionally one or more further non-Bt insecticides to the pest; and    (3) composition comprising (I) or (II), one or more Bt toxins, and optionally one or more non-pyrethroid insecticides.