Comparison of sampling methods of Aphis glycines predators across the diel cycle

Abstract

Nocturnal predators are often overlooked in biological control studies, despite evidence that they can make important contributions to insect pest suppression in agroecosystems. Many sampling methods are only employed during the daytime hours due to limitations of time and labour. Additionally, different sampling methods can provide contrasting information about natural enemy community composition and relative abundance. Here, we use Aphis glycines and its arthropod predators as a model system to compare natural enemy community composition described by vacuum samples, direct observations and video observations across the diel cycle in soybean. All sampling methods identified several common taxa. Anthocorids were dominant in vacuum samples and direct observations, and both methods indicated that this taxa may be more active in the afternoon. In contrast, anthocorids were recorded infrequently on video, possibly due to their small size. On video samples, lacewing larvae were the most active taxa during the day and lacewing larvae, spiders, opiliones and carabids were the most active taxa at night. We directly observed 22 predation events on soybean aphid: 17 by anthocorids, two by chrysopid larvae, and one each by a coccinellid, spider and predatory mite. The differences between the sample methods suggest that vacuum samples may represent predator abundance more accurately, while video data may miss small predators, but can be used to better assess relative time spent foraging.

Predators and alate immigration influence the season-long dynamics of soybean aphid (Hemiptera: Aphididae)

“…The impact of each predator species within the assemblage on soybean aphid remains 105 unclear, as most previous studies used predator exclusion cages 106 Desneux et al, 2006;Gardiner et al, 2009a), rely solely on correlations (e.g. Maisonhaute et al, 2017;Yoo and O'Neil, 2009), or used short term assessments of predation Harwood et al, 2009;Petersen and Woltz, 2015;Woltz and Landis, 2013).…”

Day length constrains the time budget of aphid predators

“…In contrast to E. balteatus , C. carnea does not appear to have a clear diurnal pattern. Three independent studies, all constrained by limited sample size, indicate a bimodal distribution of activity (Schotzko & O'Keeffe, ; Joachim & Weisser, ; Woltz & Landis, ), though the timing of the peak activities varies among the three studies. Thus, the constraints of shorter days are not explained by strictly diurnal activity.…”

Functional identity of dominant species in a predator community prevails over functional diversity in shaping the top‐down control of herbivores

“…Based on the literature, we selected Adalia bipunctata , Pterostichus melanarius , Drusilla canaliculata , Anthocoris nemoralis , Chrysoperla carnea , Forficula auricularia , Phalangium opilio , Tenuiphantes tenuis , Xysticus kochi , Xerolycosa minita and Pisaura mirabilis (Allard & Yeargan, 2005; Anderson, 1962; Balog et al, 2013; Blackman, 1967; Dib et al, 2011; Dixon & McKinlay, 1992; Ximenez‐Embun et al, 2014). In order to assemble three‐species communities that represent three contrasted levels of functional richness, we first characterised these species using six functional traits involved in the predation (Drieu & Rusch, 2017; Schmitz, 2008; Woltz & Landis, 2014; Wootton et al, 2023). We collected information about body size (mm), circadian activity (diurnal, nocturnal), habitat domain (soil, foliage), hunting mode (ambush hunters, active hunters), averaged handling time (low, high) and starvation ability (yes, no) (Table S1).…”