Ingrid H. Williams

Estonian University of Life Sciences | EMU · Institute of Agricultural and Environmental Sciences

Agriculture began organically. For many centuries, humans farmed without synthetic biocides or inorganic fertilizers, relying on fertilizers derived from plants and animals, and protecting crops from pests and diseases using naturally-occurring materials. From the second half of the nineteenth century, growers around the world successfully develope...

Environmental thermal conditions play a major role at all levels of biological organization; however, there is little information on noxious high temperature sensation crucial in behavioral thermoregulation and survival of small ectothermic animals such as insects. So far, a capability to unambiguously encode heat has been demonstrated only for the...

Twelve selected cultivated or wild solanaceae (Solanum dulcamara, Solanum nigrum, Solanum villosum, Solanum lycopersicum, Solanum muricatum, Solanum melongena, Datura innoxia, Datura metel, Physalis spp., Capsicum annuum, Nicotiana alata, and Petunia spp.) (all species Solanales: Solanaceae) were tested as potential alternative host plants against...

In this study, the effects of a winter cover crop (CC) and its combination with composted cattle manure (CC-M) on the development of potato late blight (Phytophthora infestans) and crop yield were investigated and compared with a system with no cover crop (NC). In the CC and CC-M systems, winter oilseed rape (Brassica napus L) was used as the winte...

Potato crop losses can be substantial when conditions for late blight (Phytophthora infestans) development and spread are favourable. We investigated what drives the differences in P. infestans population structure in Latvia and Lithuania, two neighbouring countries with similar potato growing traditions. P. infestans genotypes and population genet...

The aim of this study was to evaluate foliar late blight resistance and yield of selected foreign and Estonian potato cultivars, to determine the most promising cultivars for the northern Baltic region. We hypothesized that local cultivars have higher potato late blight (Phytophthora infestans) resistance and yield due to higher blight resistance....

We compare standard metabolic rate (VCO2) and gas exchange patterns in the Colorado potato beetle (Leptinotarsa decemlineata Say) in winter diapause (i.e. lasting only one overwintering period) with those of beetles in prolonged diapause (i.e. diapause lasting 2 or 3 years). The length of diapause is estimated by the behaviour of the beetles: burro...

Agelastica alni L. (Coleoptera: Chrysomelidae) is a common beetle pest of alder trees (Alnus incana L.) in forests and parks across Estonia. The supercooling ability and capacity to survive low temperature exposure changes temporally. Relatively high unimodal supercooling point (SCP) levels (with a mean value of -6 to -8°C) were characteristic of t...

In this study, the Estonian population of Phytophthora infestans was characterized with mating type, sensitivity to metalaxyl, virulence on 11 potato R-gene differentials and 12 SSR markers to show the outcome of potential sexual reproduction in the population. During the three years 2010–2012, 141 P. infestans isolates, collected from 23 potato fi...

The main purpose of this study was to explain the internal fine structure of potential antennal thermo- and hygroreceptive sensilla, their innervation specifics, and responses of the sensory neurons to thermal and humidity stimuli in an elaterid beetle using focused ion beam scanning electron microscopy and electrophysiology, respectively. Several...

Little information is available regarding sublethal effects of neonicotinoids on insect predators, many of which perform important roles in ecosystem functioning and biocontrol. In this study, dose-dependent sublethal effects of a dietary administered neonicotinoid insecticide thiamethoxam on two basic behaviours, locomotion and feeding, were quant...

Pesticide treatments before and during the flowering of honey bee forage crops may lead to residues in honey. In northern regions oilseed rape belongs to the main forage crops that is mostly cultivated by means of intensive agriculture, including several pesticide treatments. However, in addition to the focal forage crops, pesticides from non-forag...

Despite thermosensation being crucial in effective thermoregulation behaviour, it is poorly studied in insects. Very little is known about encoding of noxious high temperatures by peripheral thermoreceptor neurons. In carabids, thermo- and hygrosensitive neurons innervate antennal dome-shaped sensilla (DSS). In this study, we demonstrate that sever...

Tomato can be injured by two very important physiological disorders, namely blossom end rot (BER) and fruit cracking (FC). The purpose of this review is to describe these physiological disorders and to assess whether cultivar and cropping system can minimise their symptoms. Physiological Ca deficiency is usually related to the inability of the plan...

The opening-closing rhythms of the subelytral cavity and associated gas exchange patterns were monitored in diapausing Leptinotarsa decemlineata beetles. Measurements were made by means of a flow-through CO2 analyser and a coulometric respirometer. Under the elytra of these beetles there is a more or less tightly enclosed space, the subelytral cavi...

Gas exchange patterns in the ladybird beetle, Adalia bipunctata (L.) (Coleoptera: Coccinellidae), were investigated using an infrared gaseous analyser (IRGA) and a coulometric O2 respirometer (manometric–volumetric system). Before testing, the beetles were kept either in dry (dehydrated) or moist (hydrated) conditions for 1 day. Their subsequent ga...

The great web‐spinning pine‐sawfly A cantholyda posticalis M ats. ( H ymenoptera: P amphiliidae) is one of the major defoliating insects of pine forests. Mass outbreaks of this species have occurred in S cots pine ( P inus sylvestris L .) stands in C entral E urope and in the southern parts of E astern E urope and S iberia. R ecently, the outbreak...

Before its establishment in Estonia at the beginning of the twenty-first century, the Colorado potato beetle Leptinotarsa decemlineata Say was a notifiable quarantine pest for many years. In high-latitude environments it encounters strong evolutionary pressure to adapt to low temperatures due to high overwintering mortality and periodic influx of n...

We compared the efficacy of wintering honey bee colonies in wooden cylinders and wooden oblong box hives. Five colonies in “cylinders” and three colonies in “box-hives” were compared over two winters. The cylinders were 450 mm high with an internal diameter of 280 mm. The oblong box hives were Estonian standard one-box long hives with a frame size...

Before its establishment in Estonia at the beginning of the twenty-first century, the Colorado potato beetle Leptinotarsa decemlineata Say was a notifiable quarantine pest for many years. In high-latitude environments it encounters strong evolutionary pressure to adapt to low temperatures due to high overwintering mortality and periodic influx of n...

Potato late blight, caused by the oomycete Phytophthora infestans, is a destructive potato disease, causing considerable crop loss worldwide. As the late blight pathogen population is diverse and variable in Estonia, changes in the population should be monitored regularly. In this study, the Estonian population of P. infestans was characterised wit...

Vegetation rehabilitation of harvested peat fields is globally important because it facilitates the restoration of natural biodiversity. The objective of this study was to determine the occurrence of mosses, lichens and arthropods in blueberry plantations of differing age on an abandoned peat production area. In the experiment, two lichen and five...

The six major pests of winter rape in Europe: cabbage stem flea beetle (Psylliodes chrysocephala), cabbage stem weevil (Ceutorhynchus pallidactylus), rape stem weevil (C. napi), pollen beetle (Meligethes spp.), cabbage seed weevil (C. obstrictus) and brassica pod midge (Dasineura brassicae) are partly, sometimes fully, controlled by natural enemies...

Potato late blight, caused by the oomycete Phytophthora infestans (Mont.) de Bary, is one of the most serious potato (Solanum tuberosum L.) diseases, causing considerable yield loss in potato production worldwide, including Latvia. At present, the data on the population characteristics of P. infestans in Latvia is sparse. Therefore, the main aim of...

Meligethes aeneus, the pollen beetle, is a major pest of cruciferous oilseed crops in Europe. Two sampling methods for estimating the abundance of pollen beetle adults on Brassica napus, B. nigra, B. juncea, Sinapis alba were compared: beating plants over a tray and yellow water traps (YWT). The dynamics of beetle abundance at different plant growt...

The concerns about pollinator decline worldwide over recent decades have now been acknowledged internationally at the highest level. The Convention on Biological Diversity has recognized pollination as a key driver in the maintenance of biodiversity and ecosystem function within its Agricultural Biological Diversity programme. At the recent sixth m...

The first genetically modified (GM) crops and foods are now being grown and marketed in the European Union (EU) and more widespread production is expected over the next decade. Public interest in the food chain has grown considerably in recent years. Consumers are not only demanding a secure supply of safe, affordable, high quality, nutritious food...

The past five years has seen the commercialization of the first GM crops and their products in Europe. The next five years may well see their more widespread cultivation and use. Some of these crops, particularly GM oilseed rape and GM maize, are or will be visited by bees. This will have implications for beekeepers harvesting and marketing honey a...

In two earlier articles on GMOs, I examined the regulatory framework that controls the releases and marketing of GM crops and GM foods in the EU with particular reference to risk assessment in relation to bees and bee products. In this article, I focus on the new GM cultivars of oilseed rape and maize, which are already commercially available in th...

ICPBR is thriving. Membership is increasing and its Working Groups have been very active, proof that ICPBR still has an important role to play in networking scientists involved in plant-bee relationships and in organising meetings and other activities for them. ICPBR produce a regular Newsletter for members, and extracts of the latest one are repro...

This is the first characterisation of Lithuanian populations of Phytophthora infestans with mating type and virulence on a differential set of 11 R genes of Solanum demissum. The sensitivity to metalaxyl was also determined. In 2010–2012, 93 Phytophthora infestans isolates, collected from all over Lithu-ania, showed quite high and stable frequency...

In recent years, potato early blight [Alternaria solani (Ellis & G. Martin) L.R. Jones, A lternaria alternata (Fr.) Keissl.] has occurred with increasing frequency in European potato fields, including those in northern regions. In our study, early blight was evaluated during the two years 2010-2011 on potato plants in a conventional farming experim...

Kaolin is an inert material with a broad range of applications, e.g. as an insecticide and as a filling substance in the formulation of biopesticides. Hence, bees that dispense biopesticides to the field in the context of entomovectoring are exposed to elevated risks because of side-effects of those products. Here, we investigated with use of bumbl...

Abstract The cold tolerance of different seasonal groups (pre-diapause, diapauses and post-diapause) of Colorado potato beetle (Leptinotarsa decemlineata Say) was assessed by exposing them either to a constant temperature of –3°C for 48 to 624 h, or to –3, −4, −5, −6 or −7 °C for a constant 24 h. Cold survival was affected by the length of exposure...

Gas exchange is studied in diapausing pupae of Mamestra brassicae L., whose larvae are reared under identical conditions. The release of CO2 gas is recorded with infrared gaseous analyzers. Oxygen convective uptake into the tracheae and oxygen consumption rates are recorded by means of a constant-volume coulometric respirometer. Outputs from both o...

Flea beetles are significant insect pests of cruciferous oilseed crops in northern Europe. A two-year small-scale field experiment was performed to determine the species complex and abundance of flea beetles (Chrysomelidae: Alticinae) associated with eight cruciferous oilseed plants: Brassica juncea (L.) Czern., Brassica napus L. var. oleifera subv...

In sustainable pest management, orientation of insect pests can be manipulated by utilizing the relative attractiveness of different host plants. Plants attractive for oviposition but not offering a suitable resource for the development of larvae are called dead-end trap crops. In this study, the number of eggs and larvae and larval survival of Mel...

Nowadays, organically produced products have become more popular than ever and interest in them is still growing fast. The early blight causal pathogen Alternaria solani has not been considered a great threat to potato in northern climate conditions in the past and has not been routinely sprayed against. During our study early blight was evaluated...

Sub-lethal effects of pesticides on behavioural endpoints are poorly studied in carabids (Coleoptera: Carabidae) though changes in behaviour caused by chemical stress may affect populations of these nontargeted beneficial insects. General motor activity and locomotion are inherent in many behavioural patterns, and changes in these activities that r...

This paper reviews plant protection methods for organic cultivation of potatoes. Colorado potato beetle (CPB), the most important insect pest of potatoes worldwide, can be controlled by using the following techniques: organic soil management, lower fertilizer rates, treatment with spinosad, an insecticide based on chemical compounds found in the ba...

In Estonia and Finland, 386 and 671 isolates, respectively, of Phytophthora infestans were collected during the growing seasons of 2001-2007. Collection was from groups of potato cultivars of different origin from field plots at two research institutions in eastern and northern Estonia and from variety trials at two locations and commercial potato...

The United Kingdom has a diverse agriculture which supplies a variety of high quality food and other products. Agricultural land is integrated within an ecosystem of semi-natural vegetation which supports a varied wildlife. Here we examine why bees are an essential part of this agroecosystem, what types of bee are in the UK, and what they need to s...

We have established for the first time that Colorado potato beetle (CPB) (Leptinotarsa decemlineata Say) (Coleoptera: Chrysomelidae) produced a distinct second generation in 2010 in Estonia. This species has a history, in Estonia, of less than 50 years. Due to their great ability to adapt to variable environmental conditions, the beetles spread ver...

We have established for the first time that Colorado potato beetle (CPB) (Leptinotarsa decemlineata Say) (Coleoptera: Chrysomelidae) produced a distinct second generation in 2010 in Estonia. This species has a history, in Estonia, of less than 50 years. Due to their great ability to adapt to variable environmental conditions, the beetles spread ver...

This review aims to describe the nature of effective microorganisms (EM) and how EM influence the growth, yield, quality, and protection of vegetable plants. EM comprise a mixture of live natural cultures of microorganisms isolated from fertile soils that are used to improve crop production. EM technology was developed over 40 years ago by Dr. Tero...

The effect of different food plants on various parameters of development and hibernation in the cabbage moth, Mamestra brassicae L. (Lepidoptera Noctuidae), a serious polyphagous pest, was tested. Brassica oleracea, Brassica napus, Beta vulgaris, Allium cepa and Pisum sativum, differed in their influence on larval development rate, on body mass, ma...

Altogether 365 isolates of Phytophthora infestans were sampled from potatoes propagated from seed potatoes of high (multiplied for two years in open field after meristem phase) and low (commercial certified seed multiplied for several consecutive years in open field) phytosanitary quality at different phases of epidemic progress during the growing...

The amount of water condensed in the hives of overwintering honey bee colonies was investigated. In autumn, condensers of thin sheet metal were placed in hives above and below the frames of the winter nests of the experimental colonies. The condensed water could flow into plastic bottles for collection. Most of the water collected during the winter...

Discontinuous gas exchange (DGE) is the main (23 individuals) breathing mode in resting adult Platynus assimilis. Few of the beetles tested (13 individuals) displayed a pattern of cyclic gas exchange or CGE. The burst of CO2 release in DGE and CGE was always accompanied by abdominal pumping (active ventilation or V). Seven individuals displayed a p...

The trap crop strategy is based on host plant discrimination by pests and their parasitoids, which may respond differently to various host plant cues, thus affecting their respective population distributions. We conducted a three-year study to compare the responses of the most damaging pest of oilseed rape (Brassica napus L.), the pollen beetle (Me...

The occurrence of salt‐, sugar‐sensitive neurones and a mechanoreceptor neurone in the antennal hair‐like gustatory sensilla of the click beetle Agriotes obscurus L. (Coleoptera, Elateridae) is demonstrated using the electrophysiological sensillum tip‐recording technique. The stimulating effect of 13 water soluble sugars at 100 mm is tested on the...

Using electrophysiology, the stimulating effect of 13 sugars and three sugar alcohols (each at a concentration of 100 mm) to antennal gustatory receptor neurones (GRNs) is tested in the carabid beetle Anchomenus dorsalis (Pontoppidan, 1763) (Coleoptera, Carabidae). Maltose, sucrose, glucose and raffinose are the most stimulating sugars for the suga...

Agriculture began organically. For many centuries, humans farmed without synthetic biocides or inorganic fertilizers, relying on organic fertilizers derived from plants and animals, and protecting crops from pests and diseases using naturally-occurring materials. From the second half of the nineteenth century growers around the world successfully d...

Oilseed rape (Brassica napus) is a valuable crop, attacked by several insect pests, of which the pollen beetle (Meligethes aeneus) is one of the most widespread and important in Europe. The relative attractiveness for the pollen beetle of Brassica nigra, Eruca sativa and Raphanus sativus was compared with that of spring oilseed rape, to assess the...

Supercooling ability and cold hardiness in the horseradish flea beetle Phyllotreta armoracia (Koch) ( Coleoptera : Chrysomelidae : Alticinae ) was investigated.Mean supercooling points (SCP) varied from −10.1 to −23.9°C depending on the season: SCP started to decrease in August, achieved their lowest value in mid-January after four months at 5°C, i...

The potato late blight pathogen Phytophthora infestans was collected from a region of Eastern Estonia during a period of seven years (2001-07). In total, 180 isolates were assessed for virulence, 133 for mating type and 171 for metalaxyl resistance. The average frequencies of mating types A1 and A2 were 59% and 38%, respectively. Considerable diffe...

The main aim of this research was to evaluate foliar resistance of Dutch breeding company Agrico potato varieties to find those most resistant to late blight in order to diminish the number of fungicide sprays required while obtaining a high yield in North-East European conditions. In the trial at the Einola Farm in 2010 and 2011, 10 potato varieti...

Spring oilseed rape (Brassica napus L. var. oleifera) is an important oilseed crop whose cultivation area has increased significantly in Estonia. It is predominantly autogamous but cross-pollination can have several positive effects, including higher seed yield. We studied the effect of fertilization with different foliar microfertilizers on the fl...

The electrophysiological response of chemoreceptor neurones from the antennal chaetoid taste sensilla of the omnivorous ground beetle Pterostichus oblongopunctatus to several plant alkaloids and glucosides is investigated. A quinine‐sensitive neurone responding to quinine and quinine hydrochloride is found, most probably related to the granivorous...

The potato rot nematode, Ditylenchus destructor, may experience extreme environmental stress caused by freezing temperatures when overwintering in the field. A series of laboratory experiments were conducted in order to clarify overwintering strategies of the nematode. The current study aimed to examine the cold tolerance of this species in various...

Oxygen convective uptakes in gas exchange cycles were directly recorded in early diapause pupae of Pieris brassicae L. (Lepidoptera; Pieridae) by means of O2 coulometric respirometry. This method was combined with flow-through CO2 respirometry, the two systems being switchable one to the other. During recording with both systems, measurements were...

Exchanging the queens of honeybees (Apis mellifera L.) between colonies with few and many eggs influenced the number of eggs the queens laid, but the queens did not completely adapt to the previous egg-laying rates of their recipient colonies. DER EINFLUSS EINES HONIGBIENENVOLKES (APIS MELLIFERA) AUF DIE EIABLAGE SEINER KÖNIGIN Der Austausch von Kö...

Ceutorhynchus obstrictus (Marsham) (Coleoptera: Curculionidae) is a major pest of oilseed rape in Europe and North America. The last decade has seen growing interest in the occurrence, importance and efficiacy of its parasitoids as biocontrol agents. The infestation of pods by C. obstrictus larvae and their parasitism rates were assessed in a total...