Sugar preferences of western corn rootworm larvae in a feeding stimulant blend

Abstract

Feeding behaviour, feeding intensity and staying behaviour of neonate western corn rootworm larvae (Diabrotica virgifera virgifera LeConte) were evaluated in response to synthetic feeding stimulant blends to determine larval preferences among the three maize root sugars (glucose, fructose and sucrose) in the active blend and to determine whether any single sugar can substitute for the 3‐sugar combination in a feeding stimulant blend. These experiments demonstrated the strong affinity that western corn rootworm larvae have for the natural sugars found in maize roots and also showed that sucrose is the most preferred of the three primary maize root sugars. The blend containing sucrose at 30 mg/ml elicited feeding that was not significantly different than the natural glucose:fructose:sucrose blend. In subtraction bioassays, removal of sucrose from the blend resulted in significantly fewer larvae feeding. When the three‐sugar blend was substituted with one of the number of various mono‐, di‐ or trisaccharides, fewer larvae fed on all of the treatments compared to the blend with sucrose, except for the blend with maltose. In feeding choice tests, larvae preferred a blend containing sucrose over blends with either glucose or fructose, but larvae chose equally between a blend with sucrose and a blend containing the three‐sugar mixture found in maize roots. Based on these results, a feeding stimulant blend with glucose (30 mg/ml), fructose (4 mg/ml) and sucrose (4 mg/ml) elicits the strongest feeding response, but sucrose alone, in amounts equivalent to the total maize root sugar concentration (30 mg/ml), could serve as a substitute for the 3‐sugar mixture in a synthetic feeding stimulant blend.

Plant-derived CO2mediates long-distance host location and quality assessment by a root herbivore

“…2D). Responsiveness to non-volatile attractants, Fe(III)(DIMBOA) 3 and a blend of glucose, fructose and sucrose (Bernklau et al, 2018b;Hu et al, 2018) was also unaltered in DvvGr2-silenced larvae (Figs 2E, F), demonstrating that knocking down DvvGr2 expression does not alter the capacity of WCR larvae to respond to other important chemical cues. Second, we assessed the contribution of DvvGr2 to CO2 responsiveness using synthetic CO 2 at different concentrations (Fig.…”

“…To investigate larval responses to non-volatile root chemicals, we tested two well established attractants, Fe(III)(DIMBOA) 3 and a sugar blend (Bernklau et al, 2018b;Hu et al, 2018). To evaluate the attractive effects of Fe(III)(DIMBOA)3, we released six 2 nd -3 rd instar WCR larvae in the middle of a moist sand-filled Petri plate (6 cm diameter, Greiner Bio-One GmbH, Frickenhausen, DE) where they had a choice between a filter paper disc treated with 10 μl of Fe(III)(DIMBOA) 3 (1 µg/ml of water) or, on the opposite side, a filter paper disc treated with water only.…”

“…Larval preferences were recorded 1h after releasing the larvae. To evaluate attractive effects of soluble sugars for WCR larvae, we followed the procedure described by (Bernklau et al, 2018b). Briefly, we released six 2 nd -3 rd instar WCR larvae in the middle of a moist sand-filled petri plate (6 cm diameter, Greiner Bio-One GmbH, Frickenhausen, DE) where they had a choice between a filter paper disc treated with 10 μl of a mixture of glucose, fructose, and sucrose (30 mg/ml of each sugar), or, on the opposite side, a filter paper treated with water only.…”

“…The larvae rely on a number of volatile and non-volatile chemicals to identify and locate host plants, distinguish between suitable and less-suitable maize plants and forage within the maize root system (Hiltpold et al, 2013;Johnson and Nielsen, 2012;Robert et al, 2012c;Schumann et al, 2018). Non-volatile primary metabolites such as sugars and fatty acids as well as secondary metabolites such as benzoxazinoids and phenolic acid conjugates modulate larval behaviour (Bernklau et al, 2011;Bernklau et al, 2015;Bernklau et al, 2016a;Bernklau et al, 2018b;Erb et al, 2015b;Hu et al, 2018;Huang et al, 2017;Robert et al, 2012c). Volatiles including (E)-β-caryophyllene, ethylene and CO2 attract the larvae Bjostad, 1998a, 1998b;Robert et al, 2012b;Robert et al, 2012a), while methyl anthranilate repels them (Bernklau et al, 2016b).…”

Management of house fly, Musca domestica L. (Muscidae: Diptera), through botanical baits

“…Sugar is phagostimulant for house flies, however, with development of taste aversion-related behavioral resistance in house fly (Burgess and King, 2017), high caloric sweeteners have been suggested for inclusion in baits against house fly (Fisher et al, 2017). Corn syrup is another alternative to replace low caloric sugar (Bernklau et al, 2018), and its phagostimulant property is not well established. Studies with other sugary materials have demonstrated differences in effectiveness in baits, like solutions of molasses that were more attractive to house flies than honey, maple syrup, or jaggery (date palm sugar) (Geden et al, 2009).…”