Modern techniques in colorado potato beetle (Leptinotarsa decemlineata say) control and resistance management: History review and future perspectives

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. Colorado potato beetle, CPB (Leptinotarsa decemlineata Say), is one of the most important pests of the potato globally. Larvae and adults can cause complete defoliation of potato plant leaves and can lead to a large yield loss. The insect has been successfully suppressed by insecticides; however, over time, has developed resistance to insecticides from various chemical groups, and its once successful control has diminished. The number of available active chemical control substances is decreasing with the process of testing, and registering new products on the market are time-consuming and expensive, with the possibility of resistance ever present. All of these concerns have led to the search for new methods to control CPB and efficient tools to assist with the detection of resistant variants and monitoring of resistant populations. Current strategies that may aid in slowing resistance include gene silencing by RNA interference (RNAi). RNAi, besides providing an efficient tool for gene functional studies, represents a safe, efficient, and eco-friendly strategy for CPB control. Genetically modified (GM) crops that produce the toxins of Bacillus thuringiensis (Bt) have many advantages over agro-technical, mechanical, biological, and chemical measures. However, pest resistance that may occur and public acceptance of GM modified food crops are the main problems associated with Bt crops. Recent developments in the speed, cost, and accuracy of next generation sequencing are revolutionizing the discovery of single nucleotide polymorphisms (SNPs) and field of population genomics. There is a need for effective resistance monitoring programs that are capable of the early detection of resistance and successful implementation of integrated resistance management (IRM). The main focus of this review is on new technologies for CPB control (RNAi) and tools (SNPs) for detection of resistant CPB populations

Changes in corn rootworm wing morphology are related to resistance development

The western corn rootworm, Diabrotica virgifera virgifera LeConte, is the most serious pest of maize across the US Corn Belt and now Europe. The beetle has repeatedly demonstrated its ability to adapt to pest management strategies through evolution of resistance to conventional insecticides, the cultural practice of crop rotation and now to the Bacillus thuringiensis (Bt) toxin which is produced by genetically modified maize. In this study, the wing morphology of 358 western corn rootworm adults from Iowa, Indiana and Illinois, USA, was investigated using geometric morphometric procedures. The populations investigated comprised resistant (i.e. soybean-maize rotation and Bt-maize variants) and non-resistant beetle populations. Data analysis was divided into two groups: (1) resistant versus non-resistant and (2) rotation-resistant versus Bt-maize rootworm populations. Results showed that morphological differences exist in the hind-wing shape of both rotation and Bt-maize-resistant versus non-resistant populations and rotation-resistant versus Bt-maize-resistant variants. Across all three types of rootworm variants investigated, the movement of landmarks 8, 9 and 14 drove the wing shape differences found. These landmarks relate to the basal radial vein and are a key anatomical character used to distinguish different wing morphotypes in rootworm. This study demonstrates the utility of hind-wing morphology/shape as an inexpensive and accessible population biomarker for rootworm. With simple equipment (camera mounted microscopes or flatbed scanners) and readily available free software to capture and analyse landmark (shape and size) data, it is possible to effectively monitor pest resistance development and associated field-based population-level differences. The biological implications of the differences in wing shape found and how this relates to rootworm flight and consequently its dispersal and invasion capabilities are also explored

Diabrotica virgifera virgifera LeConte wing shape variation reveals multiple populations across the European expansion front

Unterschiedliche Flügelausprägungen bei Diabrotica virgifera virgifera LeConte offenbaren das Vorhandensein multipler Populationen entlang der europäischen Ausbreitungsfron

Sredstva za zaštitu bilja na poljoprivrednim površinama – rezidue u gujavicama i procjena potencijalno toksičnih učinaka na okoliš

The environmental risk assessment of plant protection products for soil organisms is mainly based on the results of laboratory and extended laboratory studies while the link from the laboratory to realistic field conditions over several seasons is not well established. The current environmental risk assessment is applied to a single active ingredient and does not consider that soil organisms are exposed to varying degrees to a mixture of active ingredients from different pesticides. In this study, earthworm samples were collected from eight fields in Croatia during two growing seasons and analyzed for 300 active ingredients. The concentrations of 26 analyzed active ingredients ranged between 0.000 and 0.247 mg/kg earthworm fresh weight with a mean of 0.005 mg/kg earthworm fresh weight. The percentage of samples with values below the limit of detection (LOD = ½ LOQ), values below the limit of quantification (LOQ = 0.001 mg/kg) and values above LOQ were 33, 44 and 23 %, respectively. Based on publicly available draft assessment reports from European Commission and European Food Safety Authority, degradation parameters (DT50, DT90) were used to calculate degradation curves and the current concentration in soil at the date of earthworm sampling. Subsequently, compoundspecific bioconcentration factors in soil were determined by dividing the analyzed pesticide residues in earthworms by the calculated concentrations in soil. The results of the study showed that most active ingredients do not pose a risk to earthworms and have no secondary poisoning potential to birds and mammals that feed on them. The retrospective analysis method of analytically measured neonicotinoid residues in earthworm samples can be reliably used to calculate degradation and concentration curves in soil at the time of sampling.Procjena ekološkog rizika sredstava za zaštitu bilja za organizme u tlu uglavnom se temelji na rezultatima laboratorijskih i proširenih laboratorijskih studija dok veza između laboratorija i realnih poljskih uvjeta tijekom nekoliko sezona nije dobro utvrđena. Trenutna procjena rizika za okoliš primjenjuje se na pojedinačne aktivne tvari i ne uzima u obzir da su organizmi u tlu izloženi mješavini mješavini aktivnih tvari različitih pesticida. U istraživanju su prikupljeni uzorci gujavica s osam polja u Hrvatskoj tijekom dvije vegetacijske sezone. Analizirani su na 300 aktivnih tvari. Koncentracije 26 analiziranih aktivnih tvari kretale su se od 0,000 do 0,247 mg/kg svježe mase gujavica sa srednjom vrijednosti od 0,005 mg/kg svježe mase gujavica. Postotak uzoraka s vrijednostima ispod granice detekcije (LOD = ½ LOQ), vrijednosti ispod granice kvantifikacije (LOQ = 0,001 mg/kg) i vrijednosti iznad LOQ iznosio je 33, 44 and 23%. Na temelju javno dostupnih nacrta izvješća o procjeni Europske komisije i Europske agencije za sigurnost hrane, parametri degradacije (DT50, DT90) korišteni su za izračunavanje krivulja razgradnje i koncentracije u tlu u vrijeme uzorkovanja gujavica. Potom su određeni faktori biokoncentracije specifičnih za spoj u tlu dijeljenjem analiziranih ostataka pesticida u gujavicama s izračunatim koncentracijama u tlu. Rezultati istraživanja pokazali su da većina aktivnih tvari ne predstavlja rizik za gujavice i nema sekundarni potencijal trovanja za ptice i sisavce koji se njima hrane. Metoda retrospektivne analize analitički izmjerenih rezidua neonikotinoida u uzorcima gujavica može se pouzdano koristiti za izračunavanje krivulja razgradnje i koncentracije u tlu u vrijeme uzorkovanja

Prvi nalaz smeđe mramoraste stjenice i veličina populacije u višegodišnjim nasadima u Hrvatskoj

The brown marmorated stink bug, Halyomorpha halys Stål, is an invasive Pentatomidae species that causes damage to economically important agricultural crops. It originated in East Asia but has successfully spread to many European countries. It has been present in Croatia since 2017, and its first mass emergence was detected in a soybean field in 2019. Therefore, the aim of this study was to determine the occurrence and population size of H. halys in perennial crops in important fruit growing areas in Croatia. According to the monitoring data, H. halys was detected in all surveyed areas and crops (apple, apricot, cherry, fig, grapevine, pear, plum, olive, and hazelnut). The largest population size was detected for hazelnut in the locality of Tovarnik, Vukovar-Syrmia County (79 individuals), for pear in the locality of Marijanci, OsjekBaranja County (31 individuals), and for apple in the locality of Staro Čiče, Zagreb County (25 individuals). In view of the fact that the weekly catches at some monitoring sites exceeded the established treatment threshold, control measures must be taken to prevent an increase in the population and significant damage in the future. In addition to hazelnuts, crops such as pears, apples and cherries are particularly threatened by this pest.Smeđa mramorasta stjenica (Halyomorpha halys Stål) je invazivna vrsta iz porodice Pentatomidae koja pričinjava štete na mnogim ekonomski značajnim poljoprivrednim kulturama. Porijeklom je iz istočne Azije, ali se uspješno proširila i u mnoge europske zemlje. U Hrvatskoj je prisutna od 2017. godine, a prva masovna pojava zabilježena je u usjevu soje 2019. godine. Stoga je cilj ovog istraživanja bio utvrditi pojavu i veličinu populacije vrste H. halys u višegodišnjim nasadima u važnijim voćarskim područjima u Hrvatskoj. Prema podacima praćenja, vrsta H. halys utvrđena je na svim istraživanim površinama i kulturama (jabuka, marelica, trešnja, smokva, vinova loza, kruška, šljiva, maslina i lijeska). Najveća populacija štetnika utvrđena je u nasadu lijeske na lokalitetu Tovarnik u Vukovarsko-srijemskoj županiji (79 jedinki), u nasadu kruške na lokalitetu Marijanci u Osječko-baranjskoj županiji (31 jedinka), te u nasadu jabuke na lokalitetu Staro Čiče u Zagrebačkoj županiji (25 jedinki). S obzirom na to da su tjedni ulovi na nekim lokalitetima praćenja bili iznad kritičnih brojeva, potrebno je poduzeti mjere suzbijanja kako bi se spriječio rast populacije i pojava značajnih šteta u budućnosti. Osim lijeske, kruška, jabuka i trešnja su kulture koje su najviše ugrožene od napada ovog štetnika

Širenje, masovna pojava i štete od vrste Ophraella communa LeSage, 1986 na vrsti Ambrosia artemisiifolia L. u kontinentalnoj Hrvatskoj

Based on targeted faunistic surveys, 34 new occurrences of ragweed leaf beetles (Ophraella communa, LeSage) in ten counties of continental Croatia are presented. From mid-July to the end of September 2022, the 34 locations, where ragweed (Ambrosia artemisiifolia L.) regularly occurs, were visually inspected. All developmental stages of the insect were found at all locations during July and August, while only adults were found at all locations in September. At 12 locations, ragweed infestation was estimated to be less than 10%. At 10 locations, damage caused by feeding ranged from 10 to 50%, and at seven locations from 50 to 80%. The mass occurrence of ragweed leaf beetles and complete destruction of common ragweed plants in Croatia was recorded at five monitored locations in four counties. A high level of foliar damage indicates that the species has been well established in the monitored area. The ragweed leaf beetle appears to be spreading rapidly over large areas and is capable of effectively controlling invasive common ragweed. Future work should focus on monitoring the spread, establishment, and impact of this species in Croatia and its inclusion in biological ragweed control measures.Na temelju ciljanih faunističkih istraživanja prikazane su 34 nove pojave ambrozije zlatice (Ophraella communa, LeSage) u deset županija kontinentalne Hrvatske. Od sredine srpnja do kraja rujna 2022. vizualno su pregledane 34 lokacije na kojima se ambrozija (Ambrosia artemisiifolia L.) redovito pojavljuje. Na svim lokacijama pregledanim u srpnju i kolovozu pronađeni su svi razvojni stadiji kukca, dok su na svim lokacijama pregledanim u rujnu pronađene samo odrasle jedinke. Na 12 lokacija oštećenje ambrozije uzrokovano ishranom ambrozijinom zlaticom procijenjena je na manje od 10%. Na 10 lokaliteta oštećenje uzrokovano ishranom se kretalo od 10 do 50%, a na sedam lokaliteta od 50 do 80%. U Hrvatskoj je, na pet praćenih lokaliteta u četiri županije, zabilježena prva masovna pojava ambrozijine zlatice i potpuno uništenje biljaka ambrozije. Visoka razina oštećenja lišća ukazuje na to da je vrsta već neko vrijeme prisutna na promatranom području. Ambrozijina zlatica se ubrzano širi na velikim površinama i sposobna je vrlo učinkovito suzbiti invazivnu biljnu vrstu ambrozije. Budući rad trebao bi biti usmjeren na praćenje širenja, uspostavljanja populacije i utjecaja ove vrste u Hrvatskoj te njezino uključivanje u biološke mjere suzbijanja ambrozije

European corn borer and its parasites overwintering abundance and damages on different corn FAO maturity groups

European corn borer (ECB) is one of the most significant maize pests in the world and also in Croatia. ECB causes yield reduction from 2 to 25%, even more in years favorable for its development. According to estimations, these losses are around 7%. About 90% of the hybrids had some resistance to whorl-leaf feeding (first-generation ECB) and 75% had some resistance to sheath and sheath-collar feeding (second-generation ECB). Along with resistance, modern maize hybrids possess certain level of tolerance. The main aim of this paper was to determine moth eclosion of the overwintering generation and presence of the parasites of ECB larvae during the overwintering as well as to estimate population density of ECB on maize growing area in Croatia. Also, we aimed to establish the differences among different maize FAO maturity groups in damage caused by ECB larvae. Estimated overwintering population was over 8,000 moths/ha i.e. more than 4 million larvae of first generation. During the overwintering four different parasites attacked the larvae. Two species belong to the order Hymenoptera (Cotesia marginiventris Cresson and Eriborus terebrans Gravenhorst) and two species belong to the order Diptera (Ramonda spathulata Fallén and Lydella thompsoni Herting). One caterpillar predator species Paragymnomerus spiricornis Spinola (Hymenopetra) overwinters in maize stalks as well. The highest attack of the first ECB generation was recorded on FAO maturity group 500. The damage from second ECB generation was the highest on FAO groups 400 and 500. The maize of the higher FAO groups has high and robust stems with large number of big leaves. That intensive vegetative growth is a biological characteristic that attracts first generation of ECB to intensifying egg lying. High population level of the first generation also leads to high level of second ECB generation which ultimately caused yield reduced on the hybrids of longer vegetation period (medium-late FAO maturity groups)

Neonicotinoid Residues in Earthworms and Ground Beetles under Intensive Sugar Beet Production: Preliminary Study in Croatia

Neonicotinoids are pesticides widely used for pest control in agriculture with undesirable effects on pollinators. However, other beneficial insects are exposed to insecticides that are not lethal to them but may accumulate and affect their vital characteristics. The objective of this study was to determine neonicotinoid residues in two types of beneficial soil organisms. The first group includes ground beetles (family: Carabidae, order: Coleoptera). They are important in the food web within existing ecosystems, especially in agricultural areas. The second group includes earthworms (family: Lumbricidae, order: Opisthopora) as humifiers, important members of the soil fauna. Fauna was collected at two sugar beet growing areas in Croatia under intensive sugar beet management. Ground beetles were collected from six plots of sugar beet fields treated with imidacloprid and thiamethoxam or left untreated with neonicotinoids. Earthworms were collected from the eight fields involved in four-year sugar beet crop rotation (sugar beet, maize, soybean, oilseed rape). Detection of neonicotinoid residues was performed by LC-MS/MS, SPE-QuEChERS method. The limit of quantification (LOQ) was 0.001 mg/kg. In ground beetles, the highest concentration of imidacloprid was detected at 0.027 mg/kg, while the residues of thiamethoxam and clothianidin were below LOQ. The highest concentration of imidacloprid in earthworms was 0.2141 mg/kg, while residues of thiamethoxam did not exceed 0.0008 mg/kg. This is the first study of this kind on Croatian territory and provides a valuable first insight into the ecotoxicological status of beneficial soil fauna. More comprehensive studies are needed to assess the extent of accumulation in and to take further steps regarding conservation programs for beneficial soil organisms

Neonicotinoid Residues in Earthworms and Ground Beetles under Intensive Sugar Beet Production: Preliminary Study in Croatia

Neonicotinoids are pesticides widely used for pest control in agriculture with undesirable effects on pollinators. However, other beneficial insects are exposed to insecticides that are not lethal to them but may accumulate and affect their vital characteristics. The objective of this study was to determine neonicotinoid residues in two types of beneficial soil organisms. The first group includes ground beetles (family: Carabidae, order: Coleoptera). They are important in the food web within existing ecosystems, especially in agricultural areas. The second group includes earthworms (family: Lumbricidae, order: Opisthopora) as humifiers, important members of the soil fauna. Fauna was collected at two sugar beet growing areas in Croatia under intensive sugar beet management. Ground beetles were collected from six plots of sugar beet fields treated with imidacloprid and thiamethoxam or left untreated with neonicotinoids. Earthworms were collected from the eight fields involved in four-year sugar beet crop rotation (sugar beet, maize, soybean, oilseed rape). Detection of neonicotinoid residues was performed by LC-MS/MS, SPE-QuEChERS method. The limit of quantification (LOQ) was 0.001 mg/kg. In ground beetles, the highest concentration of imidacloprid was detected at 0.027 mg/kg, while the residues of thiamethoxam and clothianidin were below LOQ. The highest concentration of imidacloprid in earthworms was 0.2141 mg/kg, while residues of thiamethoxam did not exceed 0.0008 mg/kg. This is the first study of this kind on Croatian territory and provides a valuable first insight into the ecotoxicological status of beneficial soil fauna. More comprehensive studies are needed to assess the extent of accumulation in and to take further steps regarding conservation programs for beneficial soil organisms

Durum wheat cultivars express different level of resistance to granary weevil, sitophilus granarius (Coleoptera; curculionidae) infestation

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. The granary weevil, Sitophilus granarius Linnaeus 1875, is a primary pest of stored grains worldwide. Feeding damage and progeny production of S. granarius was estimated to identify the levels of resistance of the insect on different durum wheat cultivars. Insect attack on four different durum wheat cultivars was investigated over a period of 20 weeks. Durum wheats were artificially infected with 20 individuals of S. granarius. Every two weeks the sample weight, hectoliter weight, moisture and the number of live weevils, including their number of progenies, were recorded. Overall findings revealed different levels of resistance of different durum wheat cultivars to S. granarius infestation. The Primadur cultivar had the highest resistance, followed by the Marco Aurelio and Cesare cultivars followed finally by the Tito Flavio cultivar which was highly susceptible to S. granarius. For all cultivars, apart from Primadur, S. granarius metabolism increased humidity and temperature, leading to grain degradation and resulting in the potential complete loss of market value if under field conditions. Evidently, durum wheat characteristics affect the life cycle of S. granarius, primarily their progeny, and thus the damage they undertake to the wheat itself. These findings are important because they enable the strategic selection of wheat cultivars that can be stored for a longer time period, while more sensitive wheat cultivars can be selected for shorter storage time and thus faster delivery to market