Govinda Shrestha

• MSc Agrobiology, PhD Agroecology (Biological Control)
• Hemp Extenison Specalist-Assistant Professor of Practice at Oregon State University

Alfalfa weevil, Hypera postica Gyllenhal, is an important pest in forage alfalfa worldwide, and especially so on the Northern Plains of North America. Neither the weevil-specific fungus, Erynia phytonomi, nor the weevil's parasitoids are able to routinely suppress outbreaks as they do in the eastern U.S. A new Bacillus thuringiensis var. galleriae,...

Abstract This study investigated the prey preference of 3(rd) instar green lacewing, Chrysoperla carnea Stephens (Neuroptera: Chrysopidae), between western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and lettuce aphids, Nasonovia ribisnigri (Mosley) (Hemiptera: Aphididae) in laboratory experiments at 25 ± 1° C an...

The lettuce aphid, Nasonovia ribisnigri (Mosley), is an economically important pest of lettuce worldwide. Recently, the entomopathogenic fungus, Beauveria bassiana strain GHA, and the aphelinid parasitoid, Aphelinus abdominalis Dalman, have been reported to be potential biological control candidates for use against N. ribisnigri. However, no inform...

The predominant cropping scheme for dryland wheat production in the Pacific Northwest (PNW) region of the United States includes winter wheat–summer fallow. Lack of crop diversification can deplete the soil organic matter and nutrients, while favoring the build-up of soilborne diseases. Cover crops are becoming more common within a standard rotatio...

The western tarnished plant bug, Lygus hesperus (Knight), has emerged as a pest of potatoes (Solanum tuberosum L.) in the Lower Columbia Basin of Oregon and Washington. This species is generally found infesting several other field-grown crops in the region; however, their host preference is poorly understood. Thus, greenhouse cage experiments were...

The Columbia Basin of Oregon and Washington is one of the most productive potatoes, Solanum tuberosum L., growing regions in the United States affected by numerous insect pests. Lygus bugs, Lygus spp. (Hemiptera: Miridae), are an increasing problem in potatoes. In 2015, after an outbreak of lygus bugs in potatoes in the Columbia Basin, potato produ...

Hemp (Cannabis sativa L.) is grown for cannabinoid oil production in Oregon. During the 2021 and 2022 growing seasons, plants with leaf curling, puckering, chlorotic mosaic, fasciation, and vein clearing were observed in disease surveys of Oregon hemp fields (Fig. 1). Symptoms were present on 1-10% of 2-4-month-old plants in fields located in Bento...

This chapter examines wheat midge and its management in the Northern Great Plains of the United States and Canada. The chapter first provides an overview of the morphology of wheat midge at each stage of its life cycle. It then moves on to discuss the life cycle of the pest in more depth. The damage that wheat midge causes to crops is also reviewed...

Hemiptera is an order of insects divided into three suborders: Auchenorrhyncha (leafhoppers, planthoppers, cicadas, treehoppers, spittlebugs), Sternorrhyncha (scales, aphids, whiteflies, psyllids), and Heteroptera (true bugs). Leafhoppers, other than aphids and psyllids, represent the most important hemipteran pests present in potatoes, Solanum tub...

The western tarnished plant bug, Lygus hesperus Knight, is an economically important pest of several agricultural crops in the western United States. It is an increasing threat to potato, Solanum tuberosum L. (Solanales: Solanaceae), in the diverse landscape of the Columbia Basin of Oregon and Washington. In this study, flight mills were used to in...

The potato crop (Solanum tuberosum L.) is affected by various hemipteran insect pests including Circulifer tenellus Baker, Lygus spp., Myzus persicae Sulzer, and Macrosiphum euphorbiae Thomas. These pests can cause direct foliage damage or vector plant pathogens, and consequently reduce potato yield. Gaining insights into which factors have the gre...

Developing plant germplasm that contains genetic resistance to insect pests is a valuable component of integrated pest management programs. In the last several decades, numerous attempts have been made to identify genetic sources of resistance to Colorado potato beetle Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae). This review focuses o...

This study was conducted at the Oregon State University Hermiston Agricultural Research and Extension Center, Hermiston, Umatilla County, OR, during the 2016 and 2017 potato, Solanum tuberosum L. (Solanales: Solanaceae), growing seasons. The objective was to determine the vertical distribution of hemipteran (Bactericera cockerelli Šulc, Circulifer...

BACKGROUND Understanding the spatio‐temporal dynamics of prey and predator distributions can provide valuable insights into pest management strategies and conservation of natural enemies in agro‐ecosystems. The alfalfa weevil, Hypera postica (Gyllenhal), is an economically important pest of alfalfa throughout the western United States. Coccinellids...

The pea leaf weevil, Sitona lineatus L., is an important pest of field peas and faba beans in most temperate regions. As no information is currently available on efficacy of biopesticides for S. lineatus control, laboratory bioassays were performed to evaluate the impact of biopesticides (spinosad, Beauveria bassiana strain GHA, pyrethrins, B. bass...

Nitrogen (N) availability is an important factor affecting the canola (Brassica napus L.) yield. While N fertilization is commonly used to enhance the yield and quality of canola, it is also known to influence the incidence of insect pests in the crop. The flea beetle Phyllotreta cruciferae (Goeze) and the cabbage seedpod weevil, Ceutorhynchus obst...

The wheat midge, Sitodiplosis mosellana, is a serious pest of wheat worldwide. In North America, management of S. mosellana in spring wheat relies on the timely application of pesticides, based on midge adults levels caught in pheromone traps or seen via field scouting during wheat heading. In this context, biopesticides can be an effective alterna...

nsect pests are one of the major limitations in agronomy and horticultural crop production. Intensive use of synthetic chemical insecticides for pest control has caused numerous well-known issues including increased insecticide resistance, environmental and human health concerns, and the resurgence of pest populations because natural control is dis...

Cultural methods are some of the most widely adopted approaches in integrated pest management. Trap cropping is based on the principle of using a relatively more preferred crop species to keep the pest away from the main crop and reduce pest damage. This technique has tremendous potential to keep the pest below the economic damage threshold and can...

Dargida diffusa (Walker), found throughout the United States, causes sporadic damage to cereal crops. Its larvae feed during summer (May-July) on the heads of the growing crop during night. In the present study, (Z)-11-hexadecenyl acetate (Z11-16Ac) and (Z)-11-hexadecenal (Z11-16Ald), as pheromone, was used to attract male adults in two counties of...

One complementary or alternative control measure to chemical insecticide is interplanting of plants that affect insect behavior. While few successes are known based on interplanting of different varieties of the same crop, such intra-crop interplanting may be effective against insects that feed on a limited range of plants and have persistent prefe...

Trap crops are plants grown along with the main crop in order to manipulate insect behavior to manage the insect pests and are used as a cultural management strategy in several crops. Trap crops also provide habitat to natural enemies and can reduce the need for insecticides and hence reduce the development of insecticide resistance. The attractive...

The wheat stem sawfly (WSS), Cephus cinctus Norton, is an important wheat pest in the Northern Great Plains of the USA. No single control measure effectively suppresses WSS damage. This study provides information on the effects on the WSS adult settling preference behavior on wheat plants under laboratory conditions from treatment with both synthet...

Wireworms (Coleoptera: Elateridae) and cutworms (Lepidoptera: Noctuidae) are significant soil insect pests of pulse crops including chickpea (garbanzo bean) (Cicer arietinum L.), field pea (Pisum sativum L.), and lentils (Lens culinaris Medikus). Integrated pest management strategies established for pest monitoring and nominal thresholds can be use...

The pea leaf weevil, Sitona lineatus, is an important pest of field peas and faba beans worldwide. Present sampling techniques that rely on detection of adult feeding damage are labor intensive, time consuming and require repeated sampling. Semiochemical-based pest monitoring systems could improve pea leaf weevil management. This study, which was c...

The crucifer flea beetle, Phyllotreta cruciferae (Goeze), is an economically important and dominant pest of canola (Brassica napus L) in the Northern Great Plains of the USA. The current flea beetle management strategy is based on using synthetic chemical treated seeds and if necessary, foliar spray of chemicals at canola seedlings in early spring...

We examined the effect of biopesticides used alone, mixed with other biopesticides, or in conjunction with an imidacloprid against wireworms (Coleoptera: Elateridae) in spring wheat Triticum aestivum Linnaeus (Poaceae) (variety: Duclair). The study was conducted at Ledger and Valier, Montana, United States of America in 2015 and 2016. Ten biopestic...

Montana is the second leading state in agricultural production in the United States behind Texas and crops provide one third of the estimated agricultural income in Montana. Wheat (Triticum aestivum) is the major field crop in Montana followed by barley (Hordeum vulgare), dry edible peas (Pisum sativum), canola (Brassica napus), sugarbeet (Beta vul...

Aphid species feeding on lettuce occupy distinct feeding sites: the lettuce aphid Nasonovia ribisnigri prefers to feed on heart leaves, whereas the potato aphid Macrosiphum euphorbiae feeds only on outer leaves. The aphid parasitoid Aphelinus abdominalis, known to be able to regulate M. euphorbiae on many crops, has recently been indicated as a pro...

Disseminating the research work to LT Governor of Montana

tThe alfalfa weevil, Hypera postica (Coleoptera: Curculionidae), is a major pest of alfalfa Medicago sativa L.(Fabaceae). While H. postica usually causes the most damage before the first cutting, in summer of 2015damaging levels of the pest persisted in Montana well after the first harvest of alfalfa. Although conven-tional insecticides can control...

The degree of parasitisation, host feeding, developmental time, adult emergence and female sex ratio of the parasitoid Aphelinus abdominalis were evaluated when different host stages of N. ribisnigri (1st, 2nd, 3rd, alatoid 4th instar or newly moulted apterous adult) were offered as hosts under no-choice conditions in the laboratory at 22 °C, 70 %...

The lettuce aphid, Nasonovia ribisnigri (Mosley), is an economically important pest of lettuce worldwide. Little documentation exists for the control efficacy of aphid parasitoids against N. ribisnigri. This laboratory study evaluated three commercially available parasitoid species: Aphidius colemani (Viereck), Lysiphlebus testaceipes (Cresson), an...