Trap Crops and Insectary Plants in the Order Brassicales

Abstract

This paper reviews the most important cases of trap crops and insectary plants in the order Brassicales. Most trap crops in the order Brassicales target insects that are specialist in plants belonging to this order, such as the diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), the pollen beetle, Meligethes aeneus Fabricius (Coleoptera: Nitidulidae), and flea beetles in the genera Phyllotreta and Psylliodes (Coleoptera: Chrysomelidae). In most cases, the mode of action of these trap crops is the preferential attraction of the insect pest for the trap crop located next to the main crop. With one exception, these trap crops in the order Brassicales have been used with brassicaceous crops. Insectary plants in the order Brassicales attract a wide variety of natural enemies, but most studies focus on their effect on aphidofagous hoverflies and parasitoids. The parasitoids benefiting from insectary plants in the order Brassicales target insects pests ranging from specialists, such as P. xylostella, to highly polyfagous, such as the stink bugs Euschistus conspersus Uhler and Thyanta pallidovirens Stål (Hemiptera: Pentatomidae). In the order Brassicales, the three most common trap crops are Indian mustard, Brassica juncea (L.) Czern, Chinese cabbage, Brassica rapa L., and yellow rocket, Barbarea vulgaris R. Br., while the three most common insectary plants are sweet alyssum, Lobularia maritima (L.) Desv., white mustard, Sinapis alba L, and B. vulgaris. Except for Tropaeolum majus L. (Tropaeolaceae) and Capparis decidua (Forssk.) Edgew. (Capparaceae), the tested trap crops and insectary plants in the order Brassicales belong to the family Brassicaceae.

The ‘Botanical Triad’: The Presence of Insectary Plants Enhances Natural Enemy Abundance on Trap Crop Plants in an Organic Cabbage Agro-Ecosystem

“…In our study, although no statistical differences were detected across treatments, E. rimosalis larvae were found in higher numbers on the Kale trap crop when adjacent to insectary plants (Figure 2). The effect of greater diversity of natural enemies in areas with greater diversity has been documented [43]. For example, in Philippine rice fields greater numbers of adult yellow stemborers, Scirpophaga incertulas (Lepidoptera: Pyrausdtidae), and parasitism by Trichogramma japonicum have been documented in diversified farming landscapes compared to conventional rice fields [44], which coincides with our results ( Figure 2; Figure 3).…”

“…The higher number of E. rimosalis on trap crops adjacent to insectary plants could be due to the nectar availability for adult moths. For example, sweet alyssum appears to be highly attractive to P. xylostella adults, possibly for feeding purposes (on floral nectar), as survival of P. xylostella larvae developing on sweet alyssum is low [43].…”

Alyssum (Lobularia maritima) selectively attracts and enhances the performance of Cotesia vestalis, a parasitoid of Plutella xylostella

“…Our results show that alyssum may be a particularly useful and selective food plant to enhance the performance of C. vestalis in the field, due to its positive effect on the performance of the beneficial, C. vestalis but not on the pest, P. xylostella. Alyssum alone or combined with buckwheat also could enhance the abundance of other natural enemies 64,77,78 and attractiveness of nectar plants, combined with the chemical signs from hosts, could prolong the residence period of parasitoids in host patches 76 . Further field work is now important to measure the ultimate level of P. xylostella control and effects on other pests and natural enemies.…”

Selection of insectary plants for the conservation of biological control agents of aphids and thrips in fruit orchards

“…Out of these species, three of them belonged to Brassicaceae. Numerous studies demonstrate the benefits of the Brassicaceae for natural enemies (Araj et al ., 2019; Badenes-Pérez, 2019). Their nectar favored the longevity and fertility of parasitoids, such as Diadegma insulare Cresson (Hymenoptera: Ichneumonidae), and Cotesia marginiventris Cresson and Diaeretiella rapae Mcintosh (Hymenoptera: Braconidae) (Idris and Grafius, 1997; Johanowicz and Mitchell, 2000; Araj and Wratten, 2015).…”