1 Flufenerim, a Novel Insecticide Acting on Diverse Insect Pests: 2 Biological Mode of Action and Biochemical Aspects † 3 Murad Ghanim,* Galina Lebedev, Svetlana Kontsedalov, and Isaac Ishaaya 4 Department of Entomology, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel 5 ABSTRACT: A new chemical compound was tested for its insecticidal activity against several major insect pests. The compound, 6 called “flufenerim”, has a core pyrimidine structure and an unknown mode of action and showed potent activity against the sweet 7 potato whitefly Bemisia tabaci (Gennadius), the green peach aphid Myzus persicae (Sulzer), and the African cotton leafworm 8 Spodoptera littoralis (Boisduval); however, it did not show any activity against two thrips species: western flower thrips Frankliniella 9 occidentalis (Pergande) and tobacco thrips Thrips tabaci (Lindeman). The compound was relatively potent against the three tested 10 pests and caused mortality rates that reached up to 100% at concentrations under 10 mg of active ingredient (ai) L -1 . The action of 11 the compound was very fast, and mortality was observed within 48 h after exposure of the insects to treated leaves. A unique 12 characteristic of this compound is its very short residual activity, which approximates to 4 days after application under laboratory 13 conditions and to 2 days under outdoor conditions for both B. tabaci and S. littoralis. Although this new compound’s mode of action 14 is yet unknown, its rapid and potent action against sap-sucking pests suggests that it acts on a very important target site in the insect 15 body and possibly could be applied very close to harvesting. 16 KEYWORDS: flufenerim, Bemisia tabaci, Myzus persicae, biological activity, ovicidal activity, cross-resistance 17 18 19 ’ INTRODUCTION 20 One of the main drawbacks for using chemical insecticides is 21 their toxicity to the environment, humans, and beneficial organ- 22 isms. Repeated use of these insecticides is one of the main 23 reasons for developing resistance among many insect pests. In 24 most cases, the dynamics of resistance vary and may well depend 25 on the insecticide, repeated use, the pest, and many other factors. 26 Although many control methods and agents have been devel- 27 oped in recent years, some of which are in favor of the environ- 28 ment and beneficial organisms, including many biological control 29 organisms, 1 organic insecticides, 2 and other physical and horti- 30 cultural activities, 3 using and developing new chemical insecti- 31 cides are still major activities for coping with insect pest damages 32 in many agricultural systems. Furthermore, new chemical in- 33 secticides, which are based on better knowledge of their target 34 sites, are being developed, and they constitute a major compo- 35 nent in preventing and delaying resistance and increasing resis- 36 tance incidences among insect pests. These newly developed 37 biorational insecticides, 4,5 which are suitable for integrated pest 38 management (IPM), and integrated resistance management 39 (IRM) programs, have been developed in the past 20 years, 40 and the structure of the active molecules in these insecticides is 41 mainly based on targeting specific chemical compounds and 42 essential systems for the normal development of the insect. The 43 most commonly targeted sites are the nervous system, in the case 44 of neonicotinoids, 6 the chitin synthesis system, in the case of the 45 benzoyl phenyl ureas, 7 and the hormonal system, in the case of 46 juvenoids and edysteroids. 8 Despite the potency and the specific 47 activity of the newly developed insecticides, insect pests have 48 developed resistance to all major insecticidal groups developed in 49 recent years. 9 The resistance problems lead in many cases to field 50 failures; however, these failures can be observed only many years 51 after the first resistance incidence, and this depends on the 52 dynamics of the pest populations, the genetics of the resistance 53 developed, and the IRM strategies undertaken. 54 Developing new insecticides acting on selective targets in 55 insects is of utmost importance for improving our pest manage- 56 ment programs. In this paper we report the potency of a newly 57 developed insecticide called flufenerim (Figure 1 F1 ) against a 58 diversity of important insect pests including the sweetpotato 59 whitefly Bemisia tabaci, the green peach aphid Myzus persicae, and 60 the African cotton leafworm Spodoptera littoralis. We report also 61 preliminary results regarding flufenerim’s mode of action in 62 whiteflies. 63 ’ MATERIALS AND METHODS 64 Insect Strains. A susceptible strain of B. tabaci (biotype B), used in 65 all bioassays, was collected in 1987 from cotton fields and thereafter 66 reared in isolation, with no exposure to any insecticides. 10,11 The 67 whiteflies were reared on cotton seedlings (Gossypium hirsutum L. cv. 68 Acala) under standard laboratory conditions of 26 ( 2 °C and a 14:10 h 69 light/dark photoperiod. A susceptible strain of the green peach aphid M. Special Issue: Casida Symposium Received: July 1, 2010 Revised: September 28, 2010 Accepted: September 30, 2010 † Part of the Symposium on Pesticide Toxicology in Honor of Professor John Casida. I.I. collaborated with Professor Casida at the University of California Berkeley (1973-1985), where spent two sabbatical leaves, which were followed by two international cooperation projects (Binational Science Foundation (BSF) and Binational Agricultural Research and Development Fund (BARD)). During this period, they evaluated biochemical and bio- logical aspects of novel insecticides such as benzoylphenyl ureas and pyrethroids and published 12 scientific papers and 8 scientific reports. Journal of Agricultural and Food Chemistry | 3b2 | ver.9 | 12/2/011 | 0:10 | Msc: jf-2010-025482 | TEID: emr00 | BATID: 00000 | Pages: 5.91 ARTICLE pubs.acs.org/JAFC rXXXX American Chemical Society A dx.doi.org/10.1021/jf1025482 | J. Agric. Food Chem. XXXX, XXX, 000–000