The Effect of Simulated Seasonal Temperatures On Metarhizium Brunneum-Associated Mortality In Two Click Beetle Species, And A Degree-Day Infection Model

Wireworms (Coleoptera: Elateridae), the larvae of adult click beetles are subterranean and generalist crop pests that can be difficult to target. Targeting adult beetles, however, may be an effective method to lower wireworm populations. Metarhizium brunneum (Petch) kills click beetles but the mortality rate was expected to vary according to temperature. Using a thermal gradient plate to simulate daily oscillating temperatures for April, May, and June, the effectiveness of M. brunneum strains LRC112 and F52 in causing mortality to Agriotes obscurus (L.) and A. lineatus (L.) beetles was studied. Mortality was fastest in beetles exposed to June temperatures and slowest in those exposed to April temperatures, with differences among beetle species x M. brunneum strain combinations. Warmer temperatures resulted in more rapid mycelial outgrowth and conidiation in beetle cadavers, with only A. obscurus infected with M. brunneum LRC112 attaining near 100% conidiation. The number of degree days required to kill 50% of the beetles (LDD50) was least for A. obscurus infected with M. brunneum LRC112 (176) followed by A. obscurus x M. brunneum F52 (212), A. lineatus x M. brunneum LRC112 (215), and A. lineatus x M. brunneum F52 (292). Hypothetical calculations showed that M. brunneum exposure earlier in the season resulted in a longer LT50 but the earliest LT50 calendar date. Later M. brunneum exposure dates resulted in lower LT50’s, but later LT50 dates. This conceptual work demonstrates the importance of considering daily temperature oscillations, seasonality, and degree days in predicting the efficacy of entomopathogens to manage agricultural pests.

ВИДОВИЙ СКЛАД ШКІДЛИВОЇ ЕНТОМОФАУНИ БУРЯКА СТОЛОВОГО В ПОЛІССІ УКРАЇНИ

Мета. Встановити видовий склад шкідливої ентомофауни буряка столового в зоні Полісся України в залежності від сортових особливостей культури та виділити серед них домінуючі види. Методи. Польові, лабораторні, математично-статистичні, розрахункові. Результати. На основі багаторічного моніторингу в зоні Полісся України вперше встановлено видовий склад шкідливої ентомофауни буряка столового в залежності від стиглості сорту культури, виділено 9 домінуючих видів та визначена їх чисельність. Досліджено, що в посівах буряка столового найсприятливіші умови були для розвитку таких фітофагів, як бурякова листкова попелиця, частка якої у видовому складі становила 18,2 %, звичайна бурякова блішка – 7,8 %, бурякова мінуюча муха – 3,4 %, совки (озима – 5,8 %, люцернова – 10,8 %), ковалики (темний – 4,6 %, смугастий – 4,3 %), західний травневий хрущ – 4,6 %, мертвоїд темний – 0,3 % та ківсяки – 22,5 %. Висновки. Визначено, що в Поліссі України у таксономічній структурі шкідливого ентомокомплексу домінували фітофаги із рядів Coleoptera (ковалик темний – Agriotes obscurus L., ковалик смугастий – Agriotes lineatus L., західний травневий хрущ – Melolontha melolontha L., звичайна бурякова блішка – Chaetocnema concinna March) – 34,3 %, Homoptera (бурякова листкова попелиця – Aphis fabae Scop.) – 17,1 %, Lepidoptera (совка озима – Scotia segetum Schiff, совка люцернова – Heliothis viriplaca Hfn.) – 16,3 % та Diptera (бурякова мінуюча муха – Pegomyіa betae Curt.) – 6,3 %. Серед них є як багатоїдні, так і спеціалізовані види. Із класу Diplopoda значної шкоди завдавали ківсяки (ряд Julida – 22,5 %). Досліджено, що ранньостиглі сорти буряка столового більшою мірою заселяли ґрунтові шкідники (личинки коваликів за чисельності 4 екз./м2, західного травневого хруща – 1,9 екз./м2 , совки озимої – 2,4 екз./м2); пізнього терміну дозрівання – шкідники надземних органів (звичайна бурякова блішка – 3,3 екз./м2, бурякова мінуюча муха – 1,3 екз./рослину,гусениці совки люцернової – 3,7 екз./м2, бурякова листкова попелиця –20,5 %).

Broflanilide, a Meta-Diamide Insecticide Seed Treatment for Protection of Wheat and Mortality of Wireworms (Agriotes obscurus) in the Field

Following the deregistration of lindane, several neonicotinoid insecticides have been registered as seed treatments for controlling wireworms in cereal crops. Unlike lindane, which did both, neonicotinoids provide crop protection but do not reduce wireworm populations. Hence populations of various economic species are growing in key wheat production areas of the United States and Canada, and there is a need for novel seed treatments that match the efficacy of lindane. Herein we evaluated broflanilide, a novel GABA-gated Cl- channel allosteric modulator that differs from the cyclodienes (e.g., lindane) in that it binds to a unique site in the GABA receptor. As such, broflanilide confers a new mode of insecticidal action (Group 30 MOA), and is the first meta-diamide insecticide developed. When evaluated in field trials over 7 yr at various rates, broflanilide at 5.0 g [AI]/100 kg wheat seed was as effective at protecting wheat stand from wireworm (Agriotes obscurus) injury as the current industry standard thiamethoxam at 20–30 g [AI]/100 kg seed. In addition, broflanilide at 5.0 g reduced neonate wireworms (produced from eggs laid in established wheat during the growing season) and resident wireworms (in the field at time of planting) by 73.1 and 81.1%, respectively, which is comparable to that reported for the previous industry standard lindane (75.3 and 57.6%, respectively). These studies show that broflanilide at 5.0 g [AI] will provide consistent wheat stand protection (equal to thiamethoxam at 20–30 g [AI]), and A. obscurus wireworm population reduction (equal to lindane at 59 g [AI]), and will do so at far lower dosages per hectare.

Effect of Collection Month, Visible Light, and Air Movement on the Attraction of Male Agriotes obscurus L. (Coleoptera: Elateridae) Click Beetles to Female Sex Pheromone

Elaterid female sex pheromone, while currently used for monitoring the adult life stage (click beetle), has only recently been explored as a potential management tool. Consequently, there is little understanding of how abiotic and biotic conditions influence the response of click beetles to the pheromone. We examined whether the response of male Agriotes obscurus L. (Coleoptera: Elateridae) beetles to a cellulose-based formulation of female sex pheromone (‘pheromone granules’) is influenced by air movement, presence of visible light, and month of beetle collection. In addition, we investigated the distance from which beetles were attracted to the pheromone granules. Click beetle response was determined by measuring movement parameters in free-walking arena experiments. The response to pheromone was not affected by the presence or absence of visible light. We found that beetles collected earlier in the season had increased activity and interaction with pheromone under moving air conditions, compared to beetles collected later. When controlling for storage time, we confirmed that individuals collected in May were less active than beetles collected in March and April. In the field, beetles were recaptured from up to 14 m away from a pheromone granule source, with over 50% being recovered within 4.4 h from a distance of 7 m or less. Understanding how abiotic and biotic factors affect pest response to pheromone can lead to more effective and novel uses of pheromone-based management strategies.

Local Depletion of Click Beetle Populations by Pheromone Traps Is Weather and Species Dependent

Several Agriotes click beetle species are important pests of vegetables and field crops. Monitoring for beetles is generally done with pheromone-baited traps maintained in permanent locations. Since dispersal is mostly by walking, such traps may deplete populations around them, leading to underestimations of populations relative to nontrapped areas, and of concomitant risk of wireworm damage to nearby crops. We placed sets of five pitfall traps in field headland areas in 2015–2017, of which two were baited with Agriotes obscurus (L) or Agriotes lineatus (L) (Coleoptera: Elateridae) pheromone. Of these, one was maintained in a permanent location, while the other moved among the remaining positions. Traps were checked weekly over the emergence period. For A. obscurus, fixed and moving traps initially collected similar numbers, but the latter collected significantly more later in the season, indicating depletion around fixed traps. Depletion was most pronounced after a period of cold weather, and around the peak swarming period. Depletion observed for A. lineatus was not statistically significant. This indicates pheromone-baited traps used for walking insects can underestimate populations, but depletion rates vary with species and temperature and should be accounted for when traps are used to develop action thresholds or time control strategies.

Fauna of click beetles (Coleoptera: Elateridae) in the interfluve of Rivers Moksha and Sura, Republic of Mordovia, Russia

Ruchin AB, Egorov LV, Semishin GB. 2018. Fauna of click beetles (Coleoptera: Elateridae) in the interfluve of Rivers Mokshaand Sura, Republic of Mordovia, Russia. Biodiversitas 19: 1352-1365. The results of the study of fauna of click beetles in the Republicof Mordovia are presented. By now, 58 species of click beetles have been recorded here. Adrastus pallens is a new record for therepublic. As per the literature information, 6 species of click beetles (Agriotes pilosellus, Melanotus crassicollis, Melanotus fusciceps,Liotrichus affinis, Pseudanostirus globicollis, Stenagostus rufus) are known and these indications require confirmation. Two species(Agriotes acuminatus, Limoniscus suturalis) are excluded from the fauna. Taking into account the literary information in the fauna ofMordovia, 64 species of Elateridae are known. Agrypnus murinus, Agriotes lineatus, Agriotes obscurus, Agriotes sputator, Dalopiusmarginatus, Ampedus balteatus, Ampedus pomorum, Hemicrepidius niger, Athous subfuscus, Prosternon tessellatum, Selatosomusaeneus are among the mass species. A list of the species is presented, which with a high degree of probability can still be found in therepublic

Effects of soil preparation, food availability, and temperature on survival of Agriotes obscurus (Coleoptera: Elateridae) larvae in storage

Field collected wireworms (Coleoptera: Elateridae) intended for laboratory studies often die during storage from Metarhizium Sorokin (Clavicipitaceae) infection and other causes. To determine optimal storage conditions for Agriotes obscurus (Linnaeus), freshly collected larvae were stored in regular and sterilised soil, with and without access to food (potato slices), at 12 °C and 16 °C, for six months to determine which conditions resulted in the lowest wireworm mortality. Survival was highest when wireworms were stored in sterilised soil, at 12 °C, in the absence of food. Food availability increased wireworm mortality from Metarhizium infection and other causes, but decreased the number of missing wireworms. Wireworm weight change during the study was highest in treatments where wireworms had access to food. The expected effect of food deprivation on wireworm energetic state and immune response are discussed in context with these findings.

DISTRIBUTION AND DYNAMICS OF THE GROUND BEETLE (COLEOPTERA, CARABIDAE) AND THE CLICK BEETLE (COLEOPTERA, ELATERIDAE) SPECIES ABUNDANCE IN ORGANIC AND INTENSIVELY CULTIVATED CEREAL CROPS

The research has been carried out in 2013–2014 in an organic farm located in Medsėdžiai village, Klaipėda district, and intensive farm located in Laiviai village, Kretinga district. Four agrocenoses have been investigated: wheat, triticale, oat, and multiannual grassland. Five pitfall traps were set out in each of agrocenosis and the traps were active from the last decade of April until the last decade of August. Ground beetle adults that were detected during the study belonged to 27 species and 15 genera. The most abundant ground beetle species were Poecilus cupreus L., Pterostichus melаnаrius Ill, Аmаrа аeneа Deg, Cаrаbus cаncellаtus Ill., Hаrpаlus rufipes Deg., Аnchomenus dorsаlis Pontop. and Bembidion properаns Steph., representatives of which were detected in large numbers in all without an exception investigated agrocenoses and in both types of farming. Two seasonal activity peaks of P. cupreus L. abundance were distinguished in the organic farm: first in the beginning of June and the second in the mid-July. Meanwhile, in the intensive farm it was observed in late May. Click beetle adults, identified in the study, were prescribed to 6 species and 4 genera. The most abundant click beetle species were Agriotes obscurus L., Agriotes lineatus L. and Agriotes sputator L. which occurred without an exception in all the agrocenoses and both types of farms. It was determined that the highest click beetle adults’ activity in the intensive farm was observed in the end of July while the maximum of click beetle adults’ activity in the organic farm was defined in June.