Plant volatiles guide the new pest Dichelops furcatus to feed on corn seedlings

Abstract

BACKGROUND Recently, in temperate and neotropical regions of South America the generalist stink bug Dichelops furcatus (Hemiptera: Pentatomidae) became a new pest of corn (Zea mays) seedlings. Implementation of no‐tillage cultivation system left organic matter covering the soil, which shelters adults of stink bugs during winter. In spring, corn is sowed under soybean stubble and D. furcatus adults start to feed on seedlings. To determine corn‐derived volatile organic compounds (VOCs) that attract this stink bug species, we evaluated stink bug preferences from two corn hybrids with contrast germplasm backgrounds, a temperate and a tropical hybrid. RESULTS Stink bugs preferred to feed on temperate seedlings rather than on the tropical ones. GC–MS and PCA analysis of VOCs suggested that hybrids emitted contrasting blends. Linalool represented 68% of total VOCs emitted from temperate corn, while in the tropical hybrid this compound represented 48%. Olfactometer experiments demonstrated that linalool was attractive to stink bugs. However, 2 h of D. furcatus attack induced emission of 14 additional VOCs in temperate seedlings, and olfactometer bioassay and blend of VOCs emission suggested that perceived volatiles by stink bugs induced feeding avoidance. The increment of VOCs emission was associated with the induction of JA, JA‐Ile, ABA, and IAA, and decreasing of SA concentrations. CONCLUSION This is the first time showing a complete profile of defensive phytohormones induced by stink bugs feeding on corn, and further demonstrating that a blend of corn seedling‐associated VOCs, mainly composed by linalool, modulates D. furcatus adults' behavior and feeding preferences. © 2021 Society of Chemical Industry

The stink bug Dichelops furcatus: a new pest of corn that emerges from soybean stubble

“…Current information suggests that D. furcatus (Hemiptera; Pentatomidae) is abundant in the south of Brazil, including the southern regions of Rio Grande do Sul, Santa Catarina and Paraná, 21 while in Argentina is more frequent in temperate regions, with high corn and soybean production levels, 20,28 more specifically, in a region called 'the core area of soybean production' in the provinces of Santa Fe, Córdoba, and Buenos Aires. As the climate variables are the main ecological factor that can limit the geographical distribution of the species, 29 we modeled the geographical distribution of D. furcatus and the main climate variables that shape the suitability of their habitat in South America (Fig.…”

“…40 However, not only does D. furcatus take advantage of spending the colder months in the field, but it also benefits from subsequent crop practices, by finding alternative hosts for feeding. 20,21,28 The activation of D. furcatus' metabolism during springtime allows them to feed on corn seedlings. In 'the core area of soybean production' and other temperate regions, planting corn into soybean stubble is very common.…”

“…9,[12][13][14][15][16] Besides, D. melacanthus and E. heros have become corn pests in tropical areas of Brazil, 17 while D. furcatus has become a pest of corn in temperate and subtropical areas both in Brazil and Argentina. [18][19][20] No-tillage agriculture leaves crop residues on the field that do not disturb the soil, while mitigating erosion and even favoring organisms associated with crop stubble and soil conservation. In temperate regions, D. furcatus uses the crop stubble for shelter in unfavorable conditions, even as a cover against insecticides.…”

“…Moreover, multiple cropping practices encourage soybean-corn crop rotation, and therefore, the D. furcatus overwintered adult starts to feed on corn seedlings in early spring. 20,21 Dichelops furcatus feeds on seedlings mainly near the coleoptile, causing damage and inducing morphological changes in seedlings that reduce corn yield. Similarly, a recent study highlights the ability of H. halys to cause substantial damage on sweet corn seedlings, suggesting the potential role of this stink bug species as a corn pest in the USA.…”

“…9 Although some information available on the impact of D. furcatus on corn is present in technical reports designed to give guidance to farmers, interest of the scientific community is growing. 20,21,27,28 Here we summarize the current knowledge of D. furcatus, including its biology, life cycle, and geographical distribution in South America. Additionally, we describe the general causes and consequences of conservation agriculture practices (e.g., multiple cropping, no-tillage agriculture, and crop stubble cover) and of the emergence of D. furcatus as a new pest of corn.…”