Abstract
Sugarcane is attacked by a suite of nematode pests, but little is known of the mites and other soil microarthropods that feed on them. To address this deficit, we undertook a survey of the soil microarthropod fauna in 60 sugarcane fields in Queensland, Australia. The results showed that oribatid mites and springtails dominated the upper 10 cm of sugarcane mineral soils. Laboratory observations demonstrated avid nematophagy in Galumnidae (Galumna sp., Pergalumna sp.), Scheloribatidae (Scheloribates sp.), and one unidentified Isotomidae (Collembola). Mesostigmata, a group of mites with many known nematophages, were never very abundant. Most of the taxa identified were previously known from Australia, but Protogamasellus sigillophorus Mineiro, Lindquist and De Moraes is reported for the first time and was reared through several generations on nematodes. In addition, we reared ten other cane field mesostigmatans on nematodes: Antennolaelaps sp., Asca garmani, Asca major, Cheiroseius sp., Cosmolaelaps sp., Gaeolaelaps sp., Gamasellodes bicolor, Gamasiphis sp., Holaspulus tenuipes, Protogamasellus mica. Because Mesostigmata were present at higher population densities in mineral soil where a mulch layer was retained after harvest, we assessed the effect of mulching in two sugarcane fields. Mulching did not result in significant differences in total microarthropods in the upper 5 cm of mineral soil. However, the mulch contained large numbers of free-living nematodes and 10% of the microarthropods were nematophagous mites. Results from a pot experiment also suggested that differences in soil properties affect nematophagous mite communities. More microarthropods and greater numbers of Mesostigmata were recovered from a well-structured clay loam soil than a sandy loam soil, and populations were highest in surface soils with high carbon contents and high levels of microbial activity.
Highlights
‘Microarthropod’ is a convenient term for describing the minute arthropods that live in soil-litter systems and help regulate many decomposer subsystem processes through their feeding and other behaviours (Moore et al, 1988)
Our results indicate that Queensland sugarcane soils are dominated in numbers by our Fungivore/Detritivore Guild composed of oribatid mites (Acariformes: Oribatida) and springtails (Hexapoda: Collembola)
It seems likely that these animals function in cane soils as opportunistic nematophages, as they are known to do in other soils
Summary
‘Microarthropod’ is a convenient term for describing the minute arthropods that live in soil-litter systems and help regulate many decomposer subsystem processes through their feeding and other behaviours (Moore et al, 1988). (2018), Microarthropods in Australian sugarcane soils: A survey with emphasis on the Mesostigmata as potential regulators of nematode populations. In this paper we present survey results that show that sugarcane soils, at least those that have not been tilled for several years, contain a diverse community of microarthropods with the potential to improve crop health through their role in cycling nutrients and regulating populations of root pests and pathogens. Previous studies in natural and agricultural ecosystems have shown that the abundance and diversity of microarthropods is influenced by factors such as soil texture, soil carbon levels, depth in the soil profile and the presence of plant residues on the soil surface, and all these factors could have affected our survey results. Since Mesostigmata seem to be important predators of nematodes (Stirling et al, 2017), we were interested in the impact of mulching and soil properties on this group of mites
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