Maize fields are a potential sink for an outbreaking mirid bug pest in Chinese Bt-cotton agricultural landscapes

Abstract

Agricultural landscapes are fast-changing systems due to crop planting and harvesting. These events strongly influence movements of arthropod pests and their natural enemies, yet they are insufficiently considered to implement informed pest management strategies. In China, the adoption of Bt-cotton crops at very large scales has given rise to the recent pest status of mirid bugs such as Apolygus lucorum in cotton fields. In this study we relied on carbon 13 stable isotope analysis to estimate the dispersal of A. lucorum in the Bt-cotton agricultural landscape, composed of a mosaic of cotton and maize and other minor crops. We showed that a diet on C 3-plants including cotton induced a significantly different signature than the C 4-plant maize. Based on δ 13 C ratios, we showed that more than 75% of mirid bugs caught in maize fields did not originate in situ, since they had a C 3-diet and therefore most likely dispersed from neighbouring cotton fields. Conversely, less than 10% of mirid bugs in cotton fields had a diet on C 4-plants, so the vast majority of them did not disperse from maize fields but instead likely stayed in cotton fields. We also observed a delayed establishment of A. lucorum populations in maize fields compared to cotton fields, likely due to host phenology. Indeed we showed in laboratory that juveniles' survival rate and adults' fecundity are high on maize silk and grain only, whose resources are available in the field shortly before harvest. Unidirectional movements of mirids from cotton to maize associated with poor developmental success on maize highlight the high potential of maize fields to act as a sink for A. lucorum mirid bug pests. This could be wisely implemented in IPM programs to enhance the management of mirid bug population outbreaks in cotton fields and reduce yield loss on cotton.

Molecular tracking of insect dispersal to verify arthropod predator movement from an alfalfa field to a peach orchard

“…A wide range of marking techniques have been developed to evaluate the dispersal patterns of arthropods (Lavandero et al, 2004;di Lascio et al, 2016;Madeira and Pons, 2016;Jiao et al, 2019;Kenne et al, 2019;Tavares et al, 2019;Hagler and Machtley, 2020). El Sheikha (2019) reviews the advantages and disadvantages of several tracking techniques.…”

Landscape Effects on the Abundance of Apolygus lucorum in Cotton Fields

“…Maize area was positively associated with the abundance of the fourth generation of A. lucorum, but it appeared to have no effect on the third generation. Mirid bugs can only feed on corn ears and tassel under field conditions [44,45], and this may make maize fields a suitable habitat for A. lucorum at the landscape level in a particular period. August coincides with the silking stage for maize in our study region, maize fields can provide alternative food resources for A. lucorum and increase population abundance in cotton fields.…”

Three-way interactions between crop plants, phytopathogenic fungi, and mirid bugs. A review

“…Pruning might also have a direct effect on mango bug/powdery mildew through microclimatic effects, but also effects via changes in tree phenology (particularly flowering dynamics), and effects on vegetation soil cover growth (increased available light), resulting in potential indirect effects on mango bugs through natural enemies, e.g., predatory Campylomma leucochila and potential parasitoid Leiophron sp. (Atiama 2016;Jacquot 2016;Ratnadass et al 2018;Williams et al 2003 ;Demirel et al 2005). As for elicitors, a literature review suggests that JA sprays could balance endogenic SA production triggered by powdery mildew infection, without affecting flowering synchronization (Singh et al 2001;Mohammadi et al 2015), which is another indirect way of minimizing MB damage by reducing the duration of the susceptible stage.…”