The Effect of Western Corn Rootworm (Coleoptera: Chrysomelidae) and Water Deficit on Maize Performance Under Controlled Conditions

Abstract

The western corn rootworm, Diabrotica virgifera virgifera LeConte, is the most important insect of maize, Zea mays L., but knowledge of its interaction with water deficit on maize production is lacking. A series of greenhouse experiments using three infestation levels of the western corn rootworm, D. virgifera virgifera, under well-watered, moderately dry, and very dry soil moisture levels were conducted to quantify the interaction of western corn rootworm and soil water deficit on B73×Mo17 maize growth and physiology. Three separate experiments were conducted. Soil moisture regimes were initiated 30 d postplanting for experiments using neonate and second-instar larvae and 30 d postinfestation in the experiment using eggs. In the neonate and second-instar experiments, there were no significant differences among western corn rootworm levels in their effects on leaf water potential, shoot dry weight, and root dry weight. The interaction of western corn rootworm and soil moisture significantly impacted the larval recovery in the neonate experiment, but no other significant interactions were documented between soil moisture levels and rootworm infestation levels. Overall, the results indicate that under the conditions of these experiments, the effect of water deficit was much greater on plants than the effect of western corn rootworm and that the interactions between water deficit and western corn rootworm levels minimally affected the measured parameters of plant performance.

Influence of drought on plant performance through changes in belowground tritrophic interactions

“…Potential interactive effects between water deficit and WCR attack have also been noted episodically in the field (Godfrey, Meinke, & Wright, 1993; Urías‐López, Meinke, Higley, & Haile, 2000). A detailed greenhouse study, however, did not find any significant interactive effects between WCR and soil moisture on vegetative growth and water potentials (Mahmoud et al., 2016). Compensatory root growth may have allowed plants to tolerate WCR under drought conditions in this case (Robert et al., 2014).…”

“…Interactions between soil moisture, plants, herbivores and natural enemies are expected to depend on a number of factors, including (a) the range of soil moisture levels (Aslam, Johnson, & Karley, 2013; Mahmoud et al., 2016; Schmitz & Barton, 2014), (b) the timing of changes in soil moisture relative to the development of all three trophic levels (Rosenblatt & Schmitz, 2016; Schmitz & Barton, 2014; Wade, Karley, Johnson, Hartley, & Bell, 2017) (c) the plant genotype (Stam et al., 2014), (d) the severity of herbivore attack (Soler, Bezemer, van der Putten, Vet, & Harvey, 2005) and (e) the abundance and diversity of herbivore natural enemies (Erb & Lu, 2013; Thomson, Macfadyen, & Hoffmann, 2010). Our study was conducted at low soil moisture close to the plant's wilting point, relatively low WCR infestation levels and a relatively short period between the application of EPNs and plant performance measurements.…”

“…Solenopsis molesta is omnivorous and can feed on other ants, insects and insect eggs (Rao & Vinson, 2009;Vinson & Rao, 2004;Zenger & Gibb, 2001) as well as plant seeds (Pacheco et al, 2013). Root biomass was increased in Interactions between soil moisture, plants, herbivores and natural enemies are expected to depend on a number of factors, including (a) the range of soil moisture levels (Aslam, Johnson, & Karley, 2013;Mahmoud et al, 2016;Schmitz & Barton, 2014), (b) the timing of changes in soil moisture relative to the development of all three trophic levels (Rosenblatt & Schmitz, 2016;Schmitz & Barton, 2014;Wade, Karley, Johnson, Hartley, & Bell, 2017) (c) the plant genotype (Stam et al, 2014), (d) the severity of herbivore attack (Soler, Bezemer, van der Putten, Vet, & Harvey, 2005) and…”

“…The addition of WCR and EPNs to the pots was performed following a full factorial design. Half of the maize plants (n = 60) were infested with 110 WCR eggs 28 days after planting (V4 stage) as described in Mahmoud et al (2016). Larval hatching was monitored by controlling field-incubated egg plates and infestation of a subset of pots.…”

“…Low soil moisture has been shown to reduce WCR survival and mobility at early developmental stages (Macdonald & Ellis, 1990; Spencer, Hibbard, Moeser, & Onstad, 2009). Conversely, the interactive effect of root herbivory by WCR and low soil moisture has been suggested to decrease maize performance in some cases (Mahmoud et al., 2016). Maize secondary metabolites, including benzoxazinoids (BXDs), and terpenoid phytoalexins such as zealexins and kauralexins, have been shown to increase in drought‐stressed maize plants (Erb et al., 2009; Vaughan et al., 2015), which in turn, may affect herbivore behavior and performance (Robert et al., 2012).…”