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Simple Summary The popularity of brassicaceous leafy greens has grown in recent years due to health benefits and the local food movement. However, for many producers and especially organic producers, flea beetles represent a major challenge to production because they chew small holes in the leaves reducing quality and appearance. The goal of our project was to assess the efficacy of row covers and essential oils in controlling flea beetles as an alternative to organic and conventional insecticides. We grew Arugula and Mizuna mustard greens in replicated experimental plots in the spring and fall of 2019. We found that in most cases, plants within the Agribon and ProtekNet row cover treatments had the least amount of flea beetle damage and the highest yields, while plants within the essential oil treatments and organic insecticides did not differ from unsprayed, uncovered control plots. Conventional insecticides had an intermediate level of control against flea beetles, but did not perform as consistently as row cover treatments. We believe that row covers could provide a strong management method for all growers of brassicaceous leafy greens, especially where quality standards are high. Abstract Brassicaceous leafy greens are an important crop for small growers but are difficult to produce due to damage by flea beetles. Flea beetles are problematic for growers as they chew many small holes through leaves rendering produce unmarketable. We tested the efficacy of several essential oils, the woven-mesh row cover ProtekNet, and the spunbonded row cover Agribon, compared to organic and conventional insecticides and no spray controls in the spring and fall of 2019. We found that the two row cover treatments (Agribon and ProtekNet) provided the best control of flea beetles and associated damage. Thyme oil was highly phytotoxic and killed the crop entirely and rosemary and neem essential oils caused mild phytotoxic burns. Organic insecticides rarely performed better than the no spray control. While conventional insecticides controlled most flea beetles, the crop was often still too highly damaged to sell. The results of our study suggest row covers offer producers an effective method of flea beetle control that reduces their dependence on insecticides for conventional and organic production.

Describes two species of flea beetles, Phyllotreta cruciferae, and P. striolata, their life cycles, distribution, and damage to crop plants such as cabbage, collards, broccoli, radish, mustard and turnip. Also notes chemical and non-chemical control methods.

The flea beetles Phyllotreta cruciferae (Goeze) and Phyllotreta striolata (F.) (Coleoptera: Chrysomelidae) are serious pests infesting canola (Brassica napus L.; Brassicales: Brassicaceae) in the Northern Great Plains of the United States. In Montana, P. cruciferae is the only flea beetle species that attacks canola during the crop growing stage. Management of P. cruciferae is usually focused on treating adults feeding on canola seedlings, which is the stage most vulnerable to flea beetle damage. In the Golden Triangle area in Montana, canola growers traditionally use seed treatments or calendar based spraying to control P. cruciferae. Here, we compared calendar-based spraying with seed treatment and threshold-based treatment. The experiment treatments included threshold levels (15e20, 25, 45% of leaf area damaged), calendar based sprays (15, 30 and 45 day intervals after plant emergence), seed treatments (imidacloprid), and untreated controls. The trials were done at two locations (Conrad and Western Triangle Agricultural Research Center). We found that calendar-based spraying at a 15-day interval did not differ significantly in yields from threshold-based treatment at 15e20% leaf damage. Also, the seed treatment did not give significantly higher yields compared to calendar-based sprays. A negative correlation was detected between leaf damage and yield in each treatment. Overall, calendar-based and threshold-based treatments were most effective in improving yields. However, treatment made at the threshold of 15e20% leaf area damage is recommended in order to reduce the number of chemical applications and also to reduce the possibility of selecting for resistance in flea beetles. © 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

This thesis is an investigation into the understanding of flea beetle (Phyllotreta spp.) resistance in spring-type and winter-type canola quality Brassica napus L.. Canola is one of the world’s most widely grown oilseed crops and an economically important crop in Western Canada. Genetic resistance to this common pest would add to the available tactics for integrated pest management of flea beetles in canola. The purpose of this research was to better understand the interactions of the flea beetle with canola at key feeding times in the life cycle of the flea beetle and identify genetic components related to flea beetle herbivory on canola seedlings. The objectives were to: 1) investigate seasonal effects of flea beetle herbivory on both spring-type and winter-type canola; and 2) identify quantitative trait loci (QTL) for flea beetle herbivory in two winter-type doubled haploid (DH) populations using simple sequence repeat (SSR) markers and single nucleotide polymorphic (SNP) markers. Year and seasonal effects were noted but overall trends amongst entries were similar concluding that flea beetle feeding patterns did not change throughout its life cycle. Spring-type and winter-type germplasm reacted similarly under flea beetle feeding. As such, there does not appear to be any novel resistance mechanisms that evolved as a result of divergent growth habit types in canola. Seven QTL were identified over the iii two DH populations studied. Linkage group (LG) N13 had multiple QTL identified. The remaining QTL were located on LG N04, N06, N15 and N17. It is unknown as to what mechanisms these QTL are associated with. The results of this thesis provide insight into flea beetle-canola plant interactions and identify some genetic areas of interest related to flea beetle herbivory in canola. DuPont Pioneer

Remarkable similarities have been found in the pheromonal communication of Phyllotreta vittula Redtenbacher and of Ph. cruciferae Goeze (European population) (Coleoptera, Chrysomelidae). In previously published European field tests with Ph. cruciferae, only the major male-produced sesquiterpene identified from North American Ph. cruciferae [compound A, (6R,7S)-2,2,6,10-tetramethylbicyclo[5.4.0]undeca-1(11),9-diene] was behaviourally active; unexpectedly, the European species Ph. vittula also responded in these tests and in the same way. In the present study, both the European population of Ph. cruciferae and Ph. vittula were shown to produce the same blend of compounds found in North American Ph. cruciferae and in similar proportions. Compound A is concluded to be a pheromone component for Ph. vittula as well as for Ph. cruciferae. In previously published tests with host compounds, Ph. vittula preferred 3-butenyl isothiocyanate to allyl isothiocyante whereas the reverse was true for Ph. cruciferae. It was also learned earlier that compound A enhanced the response of both species toward allyl isothiocyanate. The present study further explored interactions between compound A and the two isothiocyanates. Thus, the highest catches of Ph. vittula were recorded in traps with the combination of racemic compound A with 3-butenyl isothiocyanate, while highest Ph. cruciferae catches (and of Ph. nigripes Fabr.) were observed in traps with the combination of compound A with allyl isothiocyanate. Therefore, with the optimal combination of pheromonal and host-derived stimuli, more specific communication channels may exist for the different Phyllotreta spp. Both Ph. cruciferae and Ph. vittula rank among the most important pest flea beetles in Europe.

An examination of leaf beetle specimens (Coleoptera: Chrysomelidae) in the largest beetle collections in Kentucky, recent inventory work in state nature preserves and other protected areas, and a review of the literature revealed eighty-four species of the tribe Alticini (Subfamily Galerucinae) present in Kentucky, forty-five of which are unreported previously for the state. Distribution maps and label data are presented for the eighty-four Kentucky species including spatial (state and Kentucky county records), temporal (years and months of collection in Kentucky), and plant association information. The following species are reported from Kentucky for the first time: Blepharida rhois (Forster), Luperaltica senilis (Say), Phyllotreta cruciferae (Goeze), Ceraltica insolita (Melsheimer), Glyptina brunnea Horn, Glyptina cyanipennis (Crotch), Glyptina spuria LeConte, Longitarsus acutipennis Blatchley, Longitarsus arenaceus Blatchley, Longitarsus melanurus (Melsheimer), Longitarsus pratensis (Panzer), ...

Greenhouse studies were conducted in 2003 and 2004 to quantify and compare plant growth and yield of canola in response to simulated and crucifer flea beetle, Phyllotreta cruciferae (Goeze), feeding injury. Seedlings of 2 canola varieties, 357 RR a hybrid and Raider RR an open pollinated, were subjected to simulated and actual crucifer flea beetle feeding injury. Canola growth responses were determined for growth rate, seed yield and percent oil of seed at 10, 30, 50 and 70% injury levels. In both years, differences in canola growth rate responses were significant between the injury types and ranged from 2.6–14.9% across injury levels. Differences in growth responses for yield (i.e., seed yield and percent oil content) were significant between simulated and insect injury and ranged from 3.1–33.5% in 2003, and 1.3–67.9% in 2004 across injury levels. Both canola varieties generally showed a greater response in growth rate and yield parameters in response to simulated than crucifer flea beetle feeding injury. Simulated feeding injury tested in this study did not adequately mimic actual P. cruciferae feeding injury. Therefore, until an appropriate technique is found, mechanical injury cannot be relied on to substitute for P. cruciferae feeding injury.

Remarkable differences have been found in host-plant related chemical communication between Phyllotreta cruciferae Goeze and Ph. vittula Redtenbacher (Coleoptera, Chrysomelidae). In preliminary screenings sizeable catches of Ph. vittula were recorded in traps baited with either 3-butenyl isothiocyanate, or a quternary mixture of 2-butenyl-, phenethyl-, 3-butenyl-and butyl isothiocyanates. Later studies revealed that Ph. vittula responded better to the above isothiocyanate mixture, than to allyl isothiocyanate, while Ph. cruciferae catches were always greater in allyl isothiocyanate baited traps. Of the four isothiocyanates in the mixture, 3-butenyl isothiocyanate may predominantly be responsible for attractivity of the mixture towards Ph. vittula .As such differences in isothiocyanate preference may occur also in other flea beetle species, for practical applications more efficient, selective and sensitive baits and traps may be developed in the future based on improved knowledge of the chemical communicat...

A bioassay arena and a laboratory screening protocol were developed for assessing lines of Arabidopsis thaliana L. (Heynh.) for feeding damage by the adult crucifer flea beetle, Phyllotreta cruciferae (Goeze). The arena consists of a 96-well microtitre plate with a modified top to contain flea beetles and allow ventilation. Eight lines of A. thaliana, arranged in an 8 × 8 Latin square design, were screened simultaneously in each arena using 50 starved flea beetles. Two cotyledons and the first pair of true leaves per plant were rated visually under a dissecting microscope using a visual damage rating scale. The protocol was used to screen 29 wild ecotypes, eight mutant lines and a single transgenic line of A. thaliana. Discrimination between both cotyledon and leaf tissue was apparent for young beetles that were both non-reproductive or reproductive, but not for old reproductive beetles. Differences were observed between Asian and European ecotypes of A. thaliana, suggesting that geographic origin may play a role in susceptibility of Arabidopsis ecotypes to flea beetle feeding. The transparent testa regulatory gene mutants (lines 82, 111, 164) were most susceptible to flea beetle feeding, possibly indicating a role for anthocyanins and/or flavonoids in governing flea beetle susceptibility. Significant variation in damage levels indicates that expression of flea beetle resistance in the A rabidopsis genome is plastic, and that potential exists to use the wide array of publicly available Arabidopsis germplasm as tools in the transfer of resistance to agronomically important host plants. Key words: Seedling bioassay, Arabidopsis thaliana, wild ecotypes and mutants, crucifer flea beetle, Phyllotreta cruciferae, host plant resistance

An enantiospecific first total synthesis of (+)-trans-α-himachalene, one of the eight male specific sesquiterpenes isolated from the crucifer flea beetle Phyllotreta cruciferae, starting from the readily and abundantly available monoterpene, (R)-carvone, is described.

Both the (1S,2R) and (1R,2S) isomers of 2,6,6-trimethylbicyclo[5.4.0]undec-7-en-9-one (1) were synthesized by starting from (S)- and (R)-citronellal (5), respectively. The stereochemistry of (1R,2S)-(−)-1 was established by an X-ray analysis; it exhibits a CD spectrum similar to that of cholest-4-en-3-one, in agreement with its absolute configuration. The ketones (1S,2R)- and (1R,2S)-1 were converted into the enantiomers of three other himachalene hydrocarbons, 2,2,6-trimethyl-10-methylenebicyclo[5.4.0]undec-1(11)-ene (2), 1,1,5,8-tetramethyl-1,2,3,4,5,6,5a-heptahydrobenzo[1,2-a][7]annulene (3), and 1,1,5,8-tetramethyl-1,2,3,4,5-pentahydrobenzo[a][7]annulene (ar-himachalene, 4). The stereochemistry of these himachalene-type sesquiterpenes isolated from flea beetles such as Aphthona flava and Phyllotreta cruciferae as their male-pheromone components was revised to (1S,2R)-1, (6R,7S)-2, (5R,5aS)-3, and (R)-4. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

This research investigated the phenology of the striped flea beetle (Phyllotreta striolata (Fabricius) (SFB) and crucifer flea beetle (Phyllotreta cruciferae (Goeze)) (CFB), and examined the efficacy and the persistence of biological activity of the reduced-risk insecticides cyantraniliprole, clothianidin, and thiamethoxam applied as seed treatments to spring canola. Yellow sticky cards were placed around field perimeters in order to assess if CFB and SFB have synchronous phenology. It was found that CFB and SFB have largely asynchronous populations in southern Ontario. In laboratory bioassays, while flea beetle control with cyantraniliprole was comparable to that provided by thiamethoxam or clothianidin at the cotyledon stage, control did not persist through the 1st and 2nd leaf stages. Thiamethoxam and clothianidin both provided moderate control of flea beetles in both 1st and 2nd leaves. Field studies suggested that cyantraniliprole may offer control of flea beetles comparable to that provided by thiamethoxam and clothianidin. E.I. DuPont Canada Co.

Laboratory experiments were conducted to determine the effect of wounding the cotyledons of Sinapis alba L. cv. Ochre, Brassica napus L. cv. Westar, B. rapa L. cv. Tobin, and C8711, a selection from Tobin, on subsequent feeding damage by the flea beetle, Phyllotreta cruciferae (Goeze). Cotyledons of 7-day-old seedlings were wounded either by puncturing them with needles (mechanical wounding) or by exposing them to flea beetles. One, 2, or 9 days following wounding, the wounded and unwounded seedlings were exposed to flea beetles and the feeding damage was estimated as a measure of antixenosis. Mechanical wounding of one of the cotyledons with 96 needle punctures induced a significant reduction in the damage of the unwounded cotyledons of S. alba, 1 or 2 days following wounding. True leaves of the wounded seedlings also showed consistently less damage than unwounded controls, 9 days following wounding. In S. alba, all three levels of mechanical wounding (i.e. 6, 24, or 96 punctures per cotyledon) reduced subsequent flea beetle damage to a similar extent. Wrapping a cotyledon of S. alba with a plastic film produced an effect similar to wounding it with needles. As with mechanical wounding, flea beetle wounding also reduced subsequent flea beetle damage in S. alba. Other plant species (B. napus and B. rapa) tested showed no measurable induced effects on subsequent feeding damage.

Five cycles of single-plant and progeny-row selection in lines derived from Brassica rapa L. "Tobin" were used to identify plants with incomplete resistance to flea beetles, Phyllotreta cruciferae (Goeze). This line, called C8711, had higher survival, grew larger, and yielded more seed than Tobin when the two lines were compared in field plots at Glenlea, Manitoba, unprotected by insecticide. C8711 without insecticide yielded more seed than Tobin treated with a lindane seed dressing, but less than Tobin treated with carbofuran granules. With carbofuran, which prevents most flea beetle damage, the yield of C8711 was 35% higher than for Tobin. At Saskatoon, Saskatchewan, the differences between C8711 and Tobin were not statistically significant, although the trends were similar to those at Glenlea. C8711 was late maturing, produced small seed, and was not of canola quality. The resistance in C8711 is attributed to a low level of antixenosis, rapid growth at the cotyledon stage, and tolerance to damage during the first 3–4 weeks of growth.

The flea beetle Phyllotreta cruciferae (Goeze) is selective of its host plants, both between cultivars and between plants of different ages within cultivars. Previous work has associated these preferences with chemical differences between plants. Factors suspected of affecting P. cruciferae behavior, including host plant chemistry and morphology, were isolated and examined in laboratory assays. P. cruciferae fed equally well on collard and kale cotyledons in both choice and no-choice assays. During 15-min observation periods, flea beetles spent more time on cotyledons than on older leaves of either cultivar. Injured collard and kale cotyledons were fed upon more than uninjured cotyledons in both choice and no-choice assays, and this preference is associated with release of chemical cues from the host. Leaf morphology, however, also affected flea beetle behavior. During 15-min observation periods, P. cruciferae spent more time on 6-wk-old collard leaves than on 6-wk-old kale leaves, and on collard leaf models than on kale leaf models treated with identical leaf extracts. Laboratory results indicate that P. cruciferae host preference is associated with chemical and morphological differences and help explain the spatial patterns in population density observed in the field.

Crop brassicas with waxy leaves (> 1000 mg kg−1) were fed upon by flea beetles, Phyllotreta cruciferae (Goeze) (Coleoptera: Chrysomelidae), at a low rate, and feeding occurred predominantly at the edges of leaves. Species with non-waxy leaves (−1) were fed upon at a high rate, and feeding occurred randomly throughout the leaf. The regression of feeding rate upon amount of epicuticular wax had an R2 = 0.64, indicating that 64% of the feeding variation of flea beetles on diverse species and cultivars of Brassicaceae was explained by a single factor regression. Feeding studies on low-wax (eceriferum, cer) Brassica mutants confirmed that leaf epicuticular wax is an important antixenotic factor that affects the rate and pattern of feeding of flea beetles. The CC genome of B. oleraceae was identified as the source of the waxy-leaf character that gives rise to the low feeding rate and edge-feeding pattern of flea beetles. The digenomic amphidiploid B. napus (AACC genome), derived from the monogenomic diploids B. oleraceae (CC genome) and B. rapa (AA genome), and the digenomic amphidiploid B. carinata (BBCC genome), derived from monogenomic diploids B. oleraceae and B. nigra (BB genome), had waxy leaves and an edge-feeding pattern and rate similar to members of the B. oleraceae group. All other monogenomic diploids (AA, BB, DD, SS, RR) and digenomic amphidiploids (AABB) not possessing the CC genome had non-waxy leaves, a high rate of feeding and a random feeding pattern by flea beetles.Key words: Brassica, epicuticular wax, feeding, resistance, Phyllotreta cruciferae

Two distinctive leaf feeding patterns, termed "edge" and "random", by flea beetles, Phyllotreta cruciferae (Goeze) were identified in 38 Brassicaceae belonging to nine groups of known genomic composition. Edge feeding occurred in the monogenomic diploid Brassica oleracea group (cc genome) and the digenomic amphidiploid B. napus group (aacc genome). All other genomic groups were fed upon randomly. Experimental manipulation of the plant (by leaf edge removal and new edge creation) and the insect (by antennectomy) and paired feeding tests with plants selected for type of feeding pattern revealed some of the salient features of pattern feeding by P. cruciferae. Leaf edge feeding was correlated with a feeding rate one-tenth of that observed for random feeding, suggesting that edge feeding may be determined by physical and/or chemical factors that render the leaf unpalatable or difficult to feed upon or both.Key words: Insecta, Phyllotreta cruciferae, Brassicaceae, feeding pattern, feeding rate

Antixenosis (nonpreference) and tolerance were identified as two mechanisms of resistance in seedlings of mustard, Sinapis alba 'Ochre', that likely account for the high level of resistance that this plant shows to flea beetles, Phyllotreta cruciferae Goeze, in the field. Sinapis alba showed antixenosis in no-choice and choice feeding tests with a susceptible species, Brassica napus 'Westar'. The beetles consumed about twice as much of the B. napus foliage as compared with S. alba. The highest level of antixenosis occurred in younger seedlings, indicating that S. alba puts forth an optimum defense when it is most vulnerable to flea beetle herbivory. Seedlings of S. alba were tolerant of low levels of flea beetle feeding damage to their cotyledons and continued to grow at almost the same rate as undamaged seedlings, whereas the growth of B. napus declined continuously with the level of feeding damage. The level of tolerance shown by S. alba combined with antixenosis probably accounts for the resistance reported for this crop in the field. In comparison with S. alba, B. napus seedlings, which show no tolerance and are preferred hosts, succumb rapidly to flea beetle attack unless protected with an insecticide. Key words: Insect resistance, mechanism, flea beetle, seedling, mustard, Sinapis alba

In field tests in Hungary, Slovenia and Bulgaria, in allyl isothiocyanate-baited traps significantly more beetles of Phyllotreta cruciferae, Ph. vittula, Ph. undulata, Ph. nigripes, Ph. nodicornis, Ph. balcanica, Ph. atra, Ph. procera, Ph. ochripes, Ph. diademata and Psylliodes chrysocephalus (Coleoptera, Chrysomelidae, Halticinae) were captured than in unbaited control traps. With the exception of Ph. cruciferae, this is the first report on significant field attraction by allyl isothiocyanate for these species. The species spectrum captured included six important agricultural pests. At all sites a great portion of the catch (ranging from ca 30 to 98%) was Ph. cruciferae, irrespective of the plant culture. The second most abundant species present at most sites was Ph. vittula. The present results are very promising from the point of view of applicability of allyl isothiocyanate in Europe as a bait in cabbage flea beetle traps for detection and monitoring.

Four himachalene sesquiterpenes and (+)-gamma-cadinene, previously identified as possible pheromone components from males of a North American population of Phyllotreta cruciferae Goeze (Coleoptera, Chrysomelidae), were tested for attractiveness in field trapping experiments in Hungary. A mixture of the four synthetic racemic himachalene derivatives and (+)-gamma-cadinene from a botanical source was slightly attractive to beetles, but much more attractive when blended with the known host-plant-derived attractant allyl isothiocyanate. This result was consistent with a previous study in North America. In tests with optically pure synthetic compounds, a blend of the same himachalene enantiomers found from male beetles was equivalent to the corresponding blend of racemic compounds, whereas a blend of the opposite enantiomers was not active. Through subtraction tests, it was found that the single compound, (6R,7S)-2,2,6,10-tetramethylbicyclo[5.4.0.]undeca-9,11-diene [compound (+)-A in this study], was as active as the whole mixture, suggesting that this compound is the key pheromone component of the European population of P. cruciferae. During field trials, several congeneric species, including P. vittula, P. nemorum, P. nodicornis, and P. ochripes, also were caught, suggesting that the same compound(s) may be relatively widespread as pheromone components in this genus.

The biochemical systematics of 6 closely related species: Phyllotreta aerea Allard, 1859, P. astrachanica Lopatin, 1977, P. atra (F., 1775), P. consobrina (Curtis, 1837), P. cruciferae (Goeze, 1777) and P. nigripes (F., 1775) were studied. This study is on the genetics and biochemical systematics of these 6 economically harmful species, including several populations of each species. Material from 27 populations divided over 6 species (>3,500 specimens) was used for allozyme electrophoresis. An allozyme-based determination key was constructed. Genetic variability measures for the different populations were calculated; Rogers modified distances and Cavalli-Sforza and Edwards arc distances between each pair of populations are presented. Unweighted pair-group method with arithmetic average and distance Wagner trees based on Rogers and Cavalli-Sforza and Edwards arc distances show slightly different topologies. Two major clusters ( P. aerea / P. consobrina and P. atra / P. cruciferae ) are found in all dendrograms, but the positions of P. astrachanica and P. nigripes leave some room for discussion.