Annual Research & Review in Biology 5(3): 189-206, 2015, Article no.ARRB.2015.021 ISSN: 2347-565X SCIENCEDOMAIN international www.sciencedomain.org Evolutionary Ecology of Diamondback Moth, Plutella xylostella (L .) and Diadegma insulare (Cresson) in North America: A Review Sadia Munir 1* , Lloyd M. Dosdall 1 and John T. O’Donovan 2 1Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, T6G 2P5, Canada. 2Lacombe Research Centre, Agriculture and Agri-Food Canada, 6000 C and E Trail, Lacombe, AB, T4L 1W1, Canada. Authors’ contributions This work was carried out in collaboration between all authors. Author SM managed the literature searches and wrote the first draft of the manuscript. Author LMD supervised and critically reviewed the manuscript and author JTO helped in editing and final revision of manuscript. All authors read and approved the final manuscript. Article Information DOI: 10.9734/ARRB/2015/11834 Editor(s): (1) George Perry, Dean and Professor of Biology, University of Texas at San Antonio, USA. Reviewers: (1) Anonymous, Osmania University, India. (2) Anonymous, Southwest University, China. (3) Isabel Bertolaccini, Department of Plant Production, Facultad de Ciencias Agrarias (U.N.L.), Kreder 2805, (3080) Esperanza (Santa Fe), Argentina. Complete Peer review History: http://www.sciencedomain.org/review-history.php?iid=668&id=32&aid=6211 Received 5th June 2014 th Review Article Accepted 7 July 2014 Published 24 th September 2014 ABSTRACT The diamondback moth (DBM), Plutella xylostella (L.), is recognized as a widely distributed destructive insect pest of Brassicaceae. The frequency and severity of P. xylostella outbreaks has increased in recent years, due to climate changes, high production of host plants (vegetable and oilseed Brassica crops), genetic flexibility of the pest that enables it to develop resistance to almost all known insecticides and establish quickly and easily in new environment. All life stages of P. xylostella are attacked by natural enemies but Diadegma insulare (Cresson) is one of the principal, effective and efficient larval parasitoids in North America. In this review, we synthesize published information on the primary aspects of P. xylostella origin, dispersal, migration, biology, and host plants and mainly focus on evolutionary ecology of bitrophic and tritrophic interactions among P. xylostella , its host plants and natural enemies. _____________________________________________________________________________________________________ *Corresponding author: Email: [email protected]; Munir et al.; ARRB, 5(3): 189-206, 2015; Article no.ARRB.2015.021 Keywords: Evolution; ecology; Diamondback moth; host plant; Diadegma insulare. 1. INTRODUCTION population in an area is regulated by climate, availability and quality of host plants and the Plutella xylostella is not only the most destructive presence of its natural enemies [10]. pest of brassicaceous crops throughout the world but is also among the most difficult to manage 3. BIOLOGY [1,2]. It was first introduced from Europe to North America (Illinois), in 1854. Plutella xylostella now The biology of P. xylostella has been studied occurs throughout North America, wherever its extensively in both laboratory and natural host plants are cultivated [3]. Its management conditions in relation to ecological factors. result in a US$4-5 billion annual cost to the However, its biological and developmental world economy [4]. A few review articles on P. parameters vary due to differences in host plant xylostella host-plant interactions, management species, temperature, and geographical and ecology have been published but a focus on population distribution [11]. The moth is detailed evolutionary ecology of tritrophic multivoltine and can produce four to 20 interactions among P. xylostella , its host plants generations per year in temperate and tropical and its principle parasitoid are lacking. The main regions, respectively [12,13]. In North America, it objective of this review paper is to address the can produce three to five generations per year gaps in the knowledge and understanding of P. [14]. At constant temperature, development can xylostella and D. insulare evolutionary ecology occur from 8-32ºC and under fluctuating and tritrophic interactions. It is believed that the temperature from 4 to 38ºC [15]. Plutella information presented here will encourage xylostella development has been studied by researchers to work on important aspects of P. Bahar et al. [16] at different constant (7,22,30ºC) xylostella and its natural enemies and help and fluctuating temperatures (0-14,15-29ºC, and designing appropriate management strategies 23-37ºC). The development was very slow at involving complete and in depth awareness of lowest constant (7ºC) and fluctuating tritrophic interactions in a particular agro- temperatures (0-14ºC) while fast development of ecosystem. P. xylostella was recorded at highest constant (30ºC) and fluctuating temperatures (23-30ºC). 2. DISTRIBUTION AND ORIGIN OF P. xylostella Plutella xylostella has four life stages: egg, larva, pupa and adult. Oviposition mainly occurs at Plutella xylostella is believed to be the most night in the first 24 to 48 hours of mating and widely distributed species of Lepidoptera, then declines gradually. Egg laying reaches zero occurring universally wherever Brassicaceae are in 10 days after adult emergence [11]. Each grown [1]. Six economically important species of female can lay more than 200 eggs either singly the Genus Plutella (Schrank) have been or in small clusters [17,18]. Oviposition is greatly recorded worldwide but only P. xylostella is influenced by host plant species. For instance, cosmopolitan in distribution [5]. It has been oviposition on brassicaceous host plant (Brassica recorded throughout tropical and temperate napus L.) is reported to be higher than non- zones, as far north as Iceland (60°N) and as far brassicaceous hosts (Cleome hassleriana Chod. south as New Zealand (45ºS) [6]. The and Tropaeolum majus L.) [19]. geographical origin of P. xylostella is uncertain. Some have speculated its origin in Europe [7], Eggs are oval and pale to strong yellow in color the Mediterranean area [8] or China [9]. It is also [11]. Egg hatching occurs in 4-8 days [14]. assumed to have evolved in South Africa, based Larvae are pale yellow in color having a dark on the diversity of endemic Brassica plants and head in early instars, and are light to dark green its indigenous diverse parasitoid fauna [5]. North colored in later instars. The larva has V-shaped American populations are most probably of anal legs. First-instar larvae are leaf miners, European origin and were introduced about 150 feeding in the spongy mesophyll tissue of leaves. years ago [7]. Recently, some climatic models Other larval instars feed on all tissues of leaves, have been developed to predict P. xylostella buds, flowers, stems, and siliques [11,20]. The distribution and seasonal phenology in areas of average development time from first to fourth its occasional occurrence. However, the instar is reported as 4.0, 3.6, 3.4, and 4.2 days abundance and distribution of the P. xylostella respectively, under Canadian field conditions; pupation takes place over 7.8 to 9.8 days [14]. 190 Munir et al.; ARRB, 5(3): 189-206, 2015; Article no.ARRB.2015.021 The adult moth is slender and greyish [21]. The 5. EVOLUTIONARY ECOLOGY OF mean longevity of females is significantly INTERACTIONS AMONG P. xylostella reduced relative to males [11]. Development and AND ITS HOST PLANTS survival vary greatly depending on quality of food, quantity of adult feeding, difference in host Plutella xylostella has a wide ecological host plant cultivar and sources of carbohydrate range. The genetic and phenotypic flexibility of P. [22,11]. xylostella , and its ability to modify traits of its life history according to environmental conditions 4. DISPERSAL AND MIGRATION during development enables the pest to survive throughout the year in areas where Migration may evolve as a mechanism that environmental conditions are favorable and host permits individuals to avoid probable failures in plants are easily available, in the absence of survival [23]. Insects may develop migratory other ecological and evolutionary pressures characteristics when their habitat deteriorates [28,37]. The moth feeds almost exclusively on [24]. Plutella xylostella possesses a high plants of the family Brassicaceae , particularly the migratory ability to disperse over long distances genus Brassica , which are widely distributed in a very short time. This can explain why it gets geographically, and include 338 genera and easily established in novel environments and 3709 species [38] (Table 1). newly planted Brassica crops [7,25,26]. Plutella xylostella does not diapause; therefore long- Plutella xylostella is commonly considered a distance immigration through aerial currents is a specialist on Brassicaceae . However, evidence major process affecting population outbreaks of its occasional occurrence on sugar snap peas [27,28]. Plutella xylostella migration and (Pisum sativum L., Fabaceae) in Kenya [70], population seasonality is well documented [1]. Taiwan and the Philippines [55,64], the Similar seasonal migrations have been reported chenopodiaceous vegetable Salsola kali L. in Japan's south western islands [29], in the (prickly saltwort, Russian thistle) in Russia [71], United Kingdom [7,30], New Zealand, South and okra in Ghana [72] have been recorded.