Browsing by Author "Adhikari, Ashish"

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Evaluation of trap crops for the management of wireworms in spring wheat in Montana
(Montana State University - Bozeman, College of Agriculture, 2017) Adhikari, Ashish; Chairperson, Graduate Committee: Gadi V. P. Reddy; Michael A. Ivie (co-chair); Gadi VP Reddy was a co-author of the article, 'Evaluation of trap crops for the management of wireworm in spring wheat in Montana' submitted to the journal 'Journal of economic entomology' which is contained within this thesis.
Wireworms, the larval stage of click beetles, have slender, shiny, hard bodies with three pairs of legs. They are polyphagous and have cryptic habitats. In recent years, increasing wireworm numbers and damage have become a major problem for growers in the Golden Triangle Region of Montana. The control of this pest is very difficult because after the removal of Lindane by US Environmental Protection Agency (USEPA) in 2009, the use of the second generation insecticides have not been able to provide effective control of wireworms. Thus, using insecticides to control wireworms has not been effective at high population levels. Also, little is known about the biology and feeding habit of wireworms. The goal of this study is to evaluate trap crops that can protect the spring wheat by attracting wireworms. First, field trials were conducted at two locations to investigate on the use of peas Pisum sativum L. (Fabaceae), lentils Lens culinaris L. (Fabaceae), canola/rapeseed Brassica napus L. (Brassicaceae), corn/maize Zea mays L. (Poaceae), durum Triticum durum Desf. (Poaceae) and barley Hordeum vulgare L. (Poaceae) as traps intercropped with spring wheat Triticum aestivum L. (Poaceae). The efficacy of trap cropping was determined by damage assessment in wheat plants along 1m transects and by counting wireworm populations on wheat and trap crop rows of a plot. Secondly, the effect of intercrop spacing on plant damage and the number of wireworms was determined for pea and lentil trap crops. To support field trials potted experiments were set up in the shade house to determine wireworm distributions in two-choice assays. Collectively the results from this study showed that pea and lentil trap crops resulted in significantly lower damage in wheat plants and they attracted more numbers of wireworms compared to other crops. Results from shade house trails supported observations from the field trials. An intercropping spacing of 0.5m between pea or lentil and the spring wheat crop produced highest density of spring wheat plants. The results from these experiments will add to the basic understanding of trap cropping for wireworms control.
Evaluation of trap crops for the management of wireworms in spring wheat in Montana
(2017-12) Adhikari, Ashish; Reddy, Gadi V. P.
The polyphagous larvae of click beetles (Coleoptera: Elateridae) are major pests of spring wheat in Montana, USA. Presently available insecticides are unable to provide control over wireworm populations, and the use of natural enemies has not been successful under field conditions. In this study, we examined the effect of seven trap crops: pea, lentil, canola, corn, durum, barley, and wheat, for their attractiveness to wireworms compared to spring wheat. Experimental plots were located in two commercial grain fields in Valier and Ledger, Montana, USA and the trials took place from May to August in 2015 and 2016. Wheat plants damaged by wireworms were recorded and their relative locations in wheat rows and adjacent trap crop rows within a plot were determined using destructive soil samples. In 2016, variable row spacing (0.25, 0.5, 0.75, and 1 m) between the trap crops (pea and lentil) and wheat was assessed. Shade house bioassays were conducted using potted pea, lentil, and wheat plants to support field trial results. Limonius californicus larvae, released at the center of each pot were sampled 4 and 10 days after sowing. Wheat intercropped with pea and lentil had significantly fewer damaged wheat plants. Wireworm numbers were lower in wheat intercropped with pea compared to the control for both locations and years. Shade house results corresponded with field results, with more wireworms collected from pea and lentil than wheat. In the spacing trials, wheat plant counts were also significantly higher when paired with pea and lentil, particularly at 0.5 m spacing. Regardless of inter-row spacing, significantly fewer wireworms were associated with wheat when intercropped with pea and lentil trap crops.