Strip-intercropping canola with annual alfalfa improves biological control of Plutella xylostella (L.) and crop yield

Abstract

The population density of the diamondback moth (DBM),Plutella xylostella(L.), the species diversity of its predators, parasitism on eggs, larvae and pupae, and associated yield of canola were evaluated in experimental plots where spring canola was grown either as a monoculture or strip-intercropped with annual alfalfa in the ratio of 3C:3A, 6C:3A and 9C:3A over a 2-year period. The egg density was significantly higher in monoculture than in intercrops. The highest and lowest densities of larvae and pupae of DBM were recorded in monoculture (2.9–3.2 larvae per plant and 1.14–1.20 pupae per plant) and intercrop 3C:3A (0.7–0.6 larvae per plant and 0.34–0.29 pupae per plant), respectively. Shannon diversity index (H') for species composition of the predators of DBM immature stages was lower in monoculture than in intercrops, and was similar amongst the three intercrops. Moreover, the percent parasitism for eggs, larvae and pupae was higher in intercrops than in monoculture. The dry seed weight loss was higher in monocrop (37.6–40.1%) compared to 3C:3A (7.9–8.6%), 6C:3A (19.5–21.4%) and 9C:3A (21.6–25.4%). Our results indicate that intercropping canola with annual alfalfa, especially in the ratio 3C:3A, can increase the species diversity, parasitism rates of DBM immature stages, and enhance the yield of canola. The implications of these findings, in relation to integrated pest management (IPM) in canola cropping systems, are discussed.

Strip intercropping of wheat and oilseed rape enhances biodiversity and biological pest control in a conventionally managed farm scenario

“…Strip intercropping can provide yield benefits for farmers beyond supporting reductions in resource concentration, enhanced natural predator communities and higher biological pest control (Liang et al, 2016; Ning et al, 2017). Economic benefits of strip intercropping are commonly measured in terms of land use efficiency or harvested yields (Noman et al, 2013; Tajmiri et al, 2017b; Yu et al, 2015; Zhou et al, 2013), and reports of yield losses for one of the crops involved are frequent (Noman et al, 2013; Ramalho et al, 2012; Tajmiri et al, 2017a, 2017b). Noteworthy, yield data for all crops used in the mixture are rarely reported or considered in intercropping studies.…”

A Review of Crop Protection Methods against the Twospotted Spider Mite—Tetranychus urticae Koch (Acari: Tetranychidae)—With Special Reference to Alternative Methods

“…Therefore, it is necessary to develop new, natural control methods as an alternative to chemical products. One example of such a novel approach is the use of intercropping systems to minimize resistance to pesticides [20,87,88], reduce pest population densities [87][88][89][90], increasing the diversity and efficiency of natural enemies [61,[91][92][93][94][95][96][97] and to improve crop yield [61,88,97].…”

“…Surface deposits on Taxus baccata L. (Taxaceae) needles removed by dipping in water had a detrimental effect on the total fecundity and oviposition period of T. urticae [148]. Many experimental studies have demonstrated that fragrances of phylogenetically distant plants are most effective in repelling certain pests on host plants [17,20,[95][96][97]. When selecting potentially pesticidal plant extracts, several properties should be considered, including the efficiency of low concentrations in controlling mites, and lack of toxicity to other animals, ensuring safe use in sustainable agriculture [17].…”

Effects of floral resources on the efficacy of a primary parasitoid and a facultative hyperparasitoid

“…Many studies have shown that adding plant diversity to cropping systems, one of the main strategies of conservation biological control, can increase the lifespan of natural enemies and improve parasitism of pests in the laboratory or greenhouse (Araj, Wratten, Lister, & Buckley, ; Irvin & Hoddle, ; Jamont, Crépellière, & Jaloux, ) and in the field (see review by Andow, ; Berndt, Wratten, & Scarratt, ; Idris & Grafius, ; Lee & Heimpel, ; Leius, ; Tajmiri, Fathi, Golizadeh, & Nouri‐Ganbalani, ). Targeted use of appropriate plant species (reviewed in Landis, Wratten, & Gurr, ) can help to provide alternative or additional hosts or prey, plant‐derived food sources (e.g., pollen, floral and extrafloral nectar, honeydew) and shelter for natural enemies.…”