1613 Research Article Received: 25 June 2015 Revised: 19 November 2015 Accepted article published: 27 November 2015 Published online in Wiley Online Library: 3 February 2016 (wileyonlinelibrary.com) DOI 10.1002/ps.4197 Landscape effects on the abundance and larval diet of the polyphagous pest Helicoverpa armigera in cotton fields in North Benin Noelline Tsafack, a,b* Audrey Alignier, c Graham P Head, d Jae H Kim, d Michel Goulard, e Philippe Menozzi b and Annie Ouin a Abstract BACKGROUND: The noctuid Helicoverpa armigera is one of the key cotton pests in the Old World. One possible pest regulation method may be the management of host crop in the landscapes. For polyphagous pests such as H. armigera, crop diversity and rotations can offer sequential and alternate resources that may enhance abundance. We explore the impact of landscape composition and host crop diversity on the abundance and natal host plant use of H. armigera in northern Benin. RESULTS: Host plant diversity at the largest scale examined (500m diameter) was positively correlated with H. armigera abundance. Host plant diversity and the cover of tomato crops were the most important variables in relation to high abundance of H. armigera. Host plant (cotton, maize, tomato, sorghum) proportions and C 3 versus C 4 plants did not consistently correlate positively with H. armigera abundance. Moth proportion derived from cotton-fed larvae was low, 15% in 2011 and 11% in 2012, and not significantly related to H. armigera abundance. CONCLUSION: Cotton crop cover was not significantly related to H. armigera abundance and may be considered as a sink crop. Landscape composition and sequential availability of host plants should be considered as keys factors for further studies on H. armigera regulation. © 2015 Society of Chemical Industry Supporting information may be found in the online version of this article. Keywords: moth; natal host plant use; carbon isotope; gossypol; GLM-PLS 1 INTRODUCTION The proportion and arrangement of crops and natural vegeta- tion across the landscape has been proposed as an alternative or at least as a complement to reduce insecticide treatments and achieve biological pest control. 1 – 6 Indeed, landscape diversity has been shown to increase the population of natural enemies, 7 with a positive feedback on pest regulation. 8 However, other studies have found that landscape diversity plays a more ambivalent role. For example, previous studies showed that landscape diversity enhances not only large-scale aphid parasitism but also aphid populations, 9 and that landscape diversity had a positive effect both on pollen beetle abundance and parasitism rates. 10 Most of the studies on pest control by landscape diversity have concen- trated on monophagous pests. 11,12 Few have considered polyphagous pests, which may react to landscape diversity in different ways. It has been shown that cotton pest Helicoverpa armigera was more abundant in cotton fields found in a complex landscape than in a simple landscape. 13 In complex landscapes, diversity in host plants can offer successive resources that may foster pests at the landscape level but also reduce pest density of a specific crop at the field level. 14 The main scientific challenges for mobile pests using multiple host plants lies in tracking their successive use of host plants by determining the natal origin of the adults. Stable isotopes have previously been used to identify natal origin in studies of insect migration 15 and natal host plant use. 16 Biochemical markers can also be used, 17 as the analysis of gossypol residues in adult H. zea tissues showed that the majority of bollworm moths caught in pheromone traps adjacent to cotton fields did not develop as larvae on cotton. In this study, we investigated the effect of host crop diver- sity and landscape composition on the abundance and natal host plant use of H. armigera in North Benin, West Africa. H. armigera is a polyphagous pest that causes yield losses to many crops worldwide, 18 including cotton, 1,19 cereals such as maize ∗ Correspondence to: N Tsafack, INP-ENSAT, Avenue de l’Agrobiopole, BP 32607 Auzeville, 31326 Castanet-Tolosan Cedex, France. E-mail: noelline.tsafackmenessong@ensat.fr a INP-ENSAT, Auzeville, Castanet-Tolosan, France b CIRAD, Dpt PERSYST, UPR 115 AIDA - AFRICARICE - 08 BP 841, Cotonou, Benin c INRA UR 0980 SAD-Paysage, Rennes, France d Monsanto LLC, St Louis, MO, USA e INRA UMR 1201 DYNAFOR INRA, Castanet-Tolosan, France Pest Manag Sci 2016; 72: 1613–1626 www.soci.org © 2015 Society of Chemical Industry