CORE Metadata, citation and similar papers at core.ac.uk Provided by UNL | Libraries University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln U.S. Department of Agriculture: Agricultural Publications from USDA-ARS / UNL Faculty Research Service, Lincoln, Nebraska 2008 Acute lethal and behavioral sublethal responses of two stored- product psocids to surface insecticides Raul Narciso C. Guedes Universidade Federal de Vicosa, [email protected] James F. Campbell USDA-ARS, [email protected] Frank H. Arthur USDA-ARS George P. Opit Oklahoma State University Kun Yan Zhu Kansas State University See next page for additional authors Follow this and additional works at: https://digitalcommons.unl.edu/usdaarsfacpub Guedes, Raul Narciso C.; Campbell, James F.; Arthur, Frank H.; Opit, George P.; Zhu, Kun Yan; and Throne, James E., "Acute lethal and behavioral sublethal responses of two stored-product psocids to surface insecticides" (2008). Publications from USDA-ARS / UNL Faculty. 2070. https://digitalcommons.unl.edu/usdaarsfacpub/2070 This Article is brought to you for free and open access by the U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Publications from USDA-ARS / UNL Faculty by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Authors Raul Narciso C. Guedes, James F. Campbell, Frank H. Arthur, George P. Opit, Kun Yan Zhu, and James E. Throne This article is available at DigitalCommons@University of Nebraska - Lincoln: https://digitalcommons.unl.edu/ usdaarsfacpub/2070 Pest Management Science Pest Manag Sci 64:1314–1322 (2008) Acute lethal and behavioral sublethal responses of two stored-product psocids to surface insecticides Raul Narciso C Guedes,1,2∗ James F Campbell,1 Frank H Arthur,1 George P Opit,1,3 Kun Yan Zhu4 and James E Throne1 1USDA-ARS, Grain Marketing and Production Research Center, 1515 College Avenue, Manhattan, KS 66502, USA 2Departamento de Biologia Animal, Universidade Federal de Vicosa, ¸ Vicosa, ¸ MG 36751-000, Brazil 3Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078-3033, USA 4Department of Entomology, Kansas State University, Manhattan, KS 66506-4004, USA Abstract BACKGROUND: The psocids Liposcelis bostrychophila Badonnel and L. entomophila (Enderlein) (Liposceli- didae) are emerging pests of stored products. Although their behavior, particularly their high mobility, may contribute to the reported relatively low efficacy of insecticides against them, studies to investigate this have not been conducted. The present study aimed to assess the label rate efficacy of three commercial insecti- cides (β-cyfluthrin, chlorfenapyr and pyrethrins) applied on concrete surfaces against L. bostrychophila and L. entomophila, and also their sublethal effect on the mobility of these species. RESULTS: The synthetic insecticides β-cyfluthrin and chlorfenapyr showed high short-term efficacy (LT95 ≤ 15 h) against both psocid species, unlike the natural pyrethrins (LT95 ≥ 4days).Liposcelis bostrychophila was slightly more tolerant (≥1.2×)thanL. entomophila to all three insecticides. Behavioral assays with fully sprayed and half-sprayed concrete arenas indicated that the insecticides reduced the mobility of both species. Pyrethrins seem to elicit weak repellence in L. bostrychophila. CONCLUSION: β-Cyfluthrin and chlorfenapyr were effective against both psocid species, but not pyrethrins. The mobility of both species does not seem to play a major role in the differential selectivity observed, but the lower mobility of L. bostrychophila may be a contributing factor to its higher insecticide tolerance. Published in 2008 by John Wiley & Sons, Ltd. Keywords: Psocoptera; differential selectivity; mobility; repellence; β-cyfluthrin; chlorfenapyr; pyrethrins 1 INTRODUCTION such as stored-product psocids. The rapid life cycle Historically, psocids (Psocoptera) have been consid- of stored-product psocids allows rapid colonization of ered to be scavengers and mold feeders of negligible new habitats and potential recovery after insecticide importance. However, they have emerged as pests applications.5,6,11 In addition, their high mobility can of stored products over the last decade in tropi- reduce their level of exposure to insecticides, which cal countries, particularly Australia, Singapore, India, reduces efficacy. For example, movement of psocids Indonesia, China and Zimbabwe.1–5 Subsequent stud- from dry products undergoing fumigation to absorb ies indicated that the status of psocids had changed ambient atmospheric moisture impairs fumigation effi- from nuisance pests to that of worldwide pests of cacy in open-top silos.12 Delayed egg hatching in the stored products.6–9 The genus Liposcelis (Liposceli- presence of the fumigant phosphine, as well as phos- didae) contains the species of psocids that are the phine resistance, further compromise psocid control major cause of concern in stored products, and L. with fumigants.12 bostrychophila Badonnel and L. entomophila (Ender- A series of studies exploring residual application lein) are the most prevalent worldwide in stored of conventional insecticides for use as both grain commodities.5,6,9 admixtures and structural treatments showed over- Insecticides are frequently used for pest manage- all poor efficacy against the main liposcelidid species, ment, particularly in the tropics where alternatives are including L. bostrychophila and particularly L. ento- often not feasible.10 However, control with insecti- mophila, which is usually the species most difficult cides has proven to be elusive owing to behavioral to control.13– 19 Several organophosphates frequently and physiological traits of some insect pest species, used in stored-product protection worldwide, in ∗ Correspondence to: Raul Narciso C Guedes, Departamento de Biologia Animal, Universidade Federal de Vicosa, ¸ Vicosa, ¸ MG 36571-000, Brazil E-mail: [email protected] (Received 27 March 2008; revised version received 16 May 2008; accepted 22 May 2008) Published online 7 August 2008; DOI: 10.1002/ps.1634 This article is a US Government work and is in the public domain in the USA. Pest Manag Sci 1526–498X/2008/$30.00 Lethal and sublethal responses of psocids to insecticides addition to the carbamate carbaryl and the pyrethroids been tested against stored-product psocids on con- bifenthrin, deltamethrin and permethrin, have been crete surfaces, therefore justifying the present study. tested against stored-product psocids, particularly as Furthermore, the fast mobility of Liposcelis, which con- surface treatments.13,14,16,18 They all showed only tributes to the impairment of the efficacy of fumigants, low to moderate efficacy against Liposcelis species, as may also compromise insecticide treatments on con- was also demonstrated for the microorganism-derived crete surfaces, which has not yet been considered in insecticide spinosad (used in grain treatment), hence studies with the main species of stored-product pso- requiring the use of insecticide mixtures for effective cid pests – L. bostrychophila and L. entomophila.These control.13– 19 Concrete flooring, which is common in were the objectives of the present study, in which the food processing plants, warehouses and grain storage neurotoxic activity of pyrethrins and pyrethroids in facilities, is probably one factor that compromises the general are expected to increase the mobility of both efficacy of stored-product insecticides, in addition to psocid species, increasing their exposure and insecti- the peculiarities of the insect pest targeted.13,14,18,20 cide efficacy, unless significant repellence is elicited The concrete surface is porous and alkaline, favoring by these compounds, which was also assessed. The insecticide loss from the surface by absorption, and potency of pyrethrins was expected to be lower than rapid hydrolysis and breakdown of the insecticide.20 that of the more active pyrethroid β-cyfluthrin, and the Organophosphates were preferred for concrete-surface broad spectrum of high activity of chlorfenapyr is also applications until the recognition of their reduced effi- suggestive of high potency against psocids, although cacy on this surface by the 1990s.20,21 Later studies with slower effect. The respiratory impairment caused indicated the superior performance of pyrethroids for by chlorfenapyr was expected to lead to reduced psocid concrete-surface treatments, leading to their current mobility, consequently leading to their lower exposure prevalence in the USA.20,21 to this compound, compromising even more its short- Deltamethrin and permethrin applied as surface term efficacy, although this outcome will also depend treatments provided poor protection against stored- on the spatial distribution of the insecticide. product psocids, particularly L. entomophila, in stud- ies conducted in Australia.13 These were the only pyrethroid insecticides previously tested against pso- cids on concrete surfaces, whereas the use of another 2 MATERIAL AND METHODS pyrethroid, cyfluthrin, prevails in the USA and the use 2.1 Insects and insecticides of pyrethrins is also common.20,22 Pyrethrins, partic- Two species of stored-product psocids were used in the ularly pyrethrins I and II, are the main insecticidal study – L. bostrychophila and L. entomophila. Cultures esters of the oleoresin extracted from dried flowers of of both species were maintained on a cracked wheat the pyrethrum