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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.

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/).

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)

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.

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.

Morphological and physical characteristics of plants, such as trichomes (pubescence), surface waxes, silication, toughness, sclerotization, colour, and shape may affect herbivory by providing inhospitable surfaces or by eliciting altered host behaviour (review by Noms and Kogan 1980). Even slight variations in the morphological structure of plants may enhance their fitness and form the basis of resistance. Seedlings of the hybrid cabbage, Brassica oleraceae L. cv. Survivor, provide an intriguing opportunity to study within the same plant the influence of radically different cotyledon morphology on the feeding behaviour of the crucifer flea beetle, Phyllotreta cruciferae Goeze, because a high proportion of seedlings of this cultivar (>92%) have one folded cotyledon. The condition arises from a failure of the inner cotyledon of the embryo to open fully and assume a normal horizontal plane after germination. The outer cotyledon is invariably normal and both cotyledons appear to grow at about the same rate (unpublished data). The degree of folding varies from cotyledons that are only a few degrees from horizontal to those that are fully folded and 90° from horizontal. This study reports the distribution and feeding of P. cruciferae on the morphologically different cotyledons of B. oleraceae cv. Survivor.

The three most important flea beetle pests of western Canadian rape crops appear to be selective in choosing their overwintering sites, as the greatest densities of overwintering adults of Phyllotreta cruciferae (Goeze) and Psylliodes punctulata Melsh. were found in leaf litter and turf beneath hedges and(or) shelterbelts, while that of Phyllotreta striolata (F.) was found in these materials beneath groves of native trees. Most beetles overwintered near the surface in leaf litter and turf rather than in the underlying soil. Within a habitat, sample to sample variation for each species was usually large and the overwintering populations appear to have an aggregated distribution pattern. Winter samples over a 6-year period from all five habitat types combined or from parkland groves reflected the continuously low level of the field population of Psylliodes punctulata, and a marked increase in the field population of P. striolata that occurred in one year. Winter samples taken from hedges and(or) shelterbelts provided little information on population sizes or trends except for indicating the general low level of the Psylliodes punctulata population. Winter mortality was low for all three species. The foregoing information will be useful for developing future sampling plans so that overwintering flea beetle populations can be estimated more reliably.

A 5-yr field study to develop a method for assessing the susceptibility of crucifer seedlings to damage by the flea beetles Phyllotreta cruciferae (Goeze) and Phyllotreta striolata (F.) is described. The recommended method consisted of five replicate 5-m rows per cultivar in a randomized complete-block design. Each test was sown three times at weekly intervals, to assure that at least one test received an appropriate level of flea beetle damage. Each test was assessed 4–5 wk after seeding by counting the number of surviving seedlings in each row and by weighing the dried aboveground portion of 10 randomly selected seedlings, although the latter discriminated fewer lines. The damage caused by flea beetles varied spatially, but this source of variation was minor and did not compromise the tests. This method proved adequate for discriminating among crucifer species and agronomically similar cultivars, some of which showed consistent, significant differences in their responses to flea beettle damage.Key words: Crucifer, rapeseed, flea beetle, pest resistance

More than 50% of crucifer-feeding flea beetle (Coleoptera: Chrysomelidae) adults trapped on 1-m column traps in a rutabaga field were taken at less than 20 cm from ground level. The mean length of jump of Phyllotreta cruciferae (Goeze) is 25 cm. Cylindrical traps painted red and coated with Tangletrap were used with statistics of directional data to measure immigration and emigration of adults. There were four immigration episodes and seven emigration episodes during the season.

Phyllotreta cruciferae (Goeze), an abundant pest in the parklands, is moderately abundant on the open prairie, less common in the southern parts of the boreal forest, and absent elsewhere in the forest. Phyllotreta albionica LeC. occurs in low numbers in parkland and prairie, and is rare in the forest. Phyllotreta robusta (LeC) occurs in low numbers in the parkland, is rare on the prairie, and was not found in the forest. Psylliodes punctulata Melsh., which has a moderately low population in the parkland, occurs in similar numbers on the prairie and perhaps also in the forest. P. cruciferae will likely cause problems in any cruciferous crops grown on the open prairie and eventually in cruciferous crops in newly-cleared forest areas.

Numerical trends of flea beetle, Phyllotreta cruciferae (Geoze), populations on collards intercropped with nonhost polyculture vegetables were studied in Chesterfield County, Va., during 1981, 1982, and 1983. No significant differences in the number of beetles between intercropped and monocropped collards existed when collards were intercropped in rows 91 cm apart. Differences in the width of row spacing did not significantly influence beetle colonization on collards for plants intercropped with row spacings of 46, 61, and 76 cm. However, beetle populations were significantly smaller, and collard foliage was damaged significantly less in intercropped collards than in monocropped collards. Also, collard leaf yield was significantly less in intercropped regimes than in monoculture regimes. These data show that although intercropping reduced P. cruciferae populations on collards, the reduced collard leaf yield minimizes the usefulness of intercropping as a cultural method for controlling flea beetles on collards.

The biology of the crucifer flea beetle, Phyllotreta cruciferae (Goeze), was studied in the laboratory, and under field conditions in southwestern Ontario. Field-collected adults, held in a state of induced hibernation were used for some laboratory studies. A rearing procedure was developed and a culture maintained for eight generations provided additional adults for laboratory work. Development and behaviour of the various crucifer flea beetle stages at different temperatures were studied. The mean preoviposition period ranged from 3.8 (32°C) to 22 (20°C) days. Time required for development from egg to adult varied from 24 (30°C) to 54 (20°C) days. For oviposition capability and egg to adult development, developmental thresholds were ca. 17° and 11°C, respectively, and 61 and 456 degree days were required. Crucifer flea beetle adults overwintered in leaf litter and the top 2.5 cm of soil, in windbreaks, fencerows, and cultivated areas. Adults appeared in early spring. Peak adult movement occurred at this time, primarily within 2 m of the ground, and oriented toward crucifer plots. Using heat unit summations calculated from soil temperatures, adult emergence in the field from eggs set out at various times was predicted with an accuracy of ± 3.7 days. Population studies and heat unit accumulations indicated that there was a single generation of crucifer flea beetle in 1974, and two generations in 1975. Adults were restricted primarily to cruciferous crops, with rutabaga and Chinese cabbage being the preferred hosts, among those varieties tested.

Host and parasite life cycles and field incidence are reported for Microctonus vittatae Muesebeck, a parasite on Phyllotreta cruciferae (Goeze) and P. simmermani (Crotch); M. epitricis (Viereck), on Epitrix cucumeris (Harris); M. disonychae Loan, on Disonycha triangularis (Say); M. crepidoderae Loan, on Crepidodera spp.; M. blapstini Loan, on Blapstinus metallicus (F.); and M. muesebecki Loan, on Paria thoracica Melsheimer. Phyllotreta cruciferae , a recent European import destructive to cultivated crucifers, is a new host of M. Vittatae , which is parasitic on the native P. simmermani . Mesochorus phyllotretae Jourdheuil, a secondary ichneumonid new to North America, was reared from Microctonus vittatae .

Insect samples from field plots of plants representing 23 different families indicated that adults of the flea beetle Phyllotreta cruciferae (Goeze) and the striped flea beetle, P. striolata (F.), have a narrow host range, restricted among the plants tested to the families Capparidaceae, Cruciferae, and Tropaeolaceae. This result was confirmed for P. cruciferae adults by laboratory feeding preference tests; of 55 plant species belonging to 31 families, only those plants belonging to the families Capparidaceae, Cruciferae, Tropaeolaceae, and Limnanthaceae were eaten. The coincidence between the preferred plant families and the plant families known to contain mustard oils suggested that these compounds or their glycosides might be acting as chemical attractants for the beetles. Field experiments showed that allyl isothiocyanate is a powerful attractant for adults of both P. cruciferae and P. striolata .

Field studies on the influence of surrounding collards with non host plants revealed that the flea beetle, Phyllotreta cruciferae (Geoze), occurred significantly ( P 0.05) different from the control. Foliage damage in all treatments, including the nonhost companion plantings, was extensive and reduced the marketability of the vegetable. Thus, although companion planting significantly reduced P. Cruciferae populations in some situations, it did not protect the plants from economic damage.

(1985). Evaluation of the potential of the flea beetle Phyllotreta cruciferae to transmit Xanthomonas campestris pv. campestris, causal agent of black rot of crucifers. Canadian Journal of Plant Pathology: Vol. 7, No. 3, pp. 308-310.

In 1982, the synthetic pyrethroid, cypermethrin, was among the insecticides recommended as a spray for control of adult flea beetles attacking canola crops in Saskatchewan (Saskatchewan Agriculture 1982). Growers reported some problems with its effectiveness at the recommended rates of 14–20 g AI/ha, however, and the recommendation for its use against flea beetles was subsequently discontinued. Laboratory spray trials were begun in 1982 to determine if post-treatment temperature affected the contact toxicity of cypermethrin to adults of the major pest species, Phyllotreta cruciferae (Goeze), and if the dosage that had been recommended was adequate as a contact spray.

During a 1981 study on possible insect vectors of a yeast in Saskatchewan mustard crops, several incidental observations of attack by the western damsel bug, Nabis alternatus Parshley, on adults of the flea beetle Phyllotreta cruciferae (Goeze) were made near Oxbow in the southeastern part of the province. This is the fourth record of insect predation on crucifer-feeding flea beetles in the Canadian prairie provinces. Previous records involved the beetle Collops vittatus Say (Gerber and Osgood 1975), a big-eyed bug, Geocoris bullatus (Say) (Burgess 1977), and larvae of the green lacewing, Chrysopa carnea Stephens (Burgess 1980).

Several instances of predation by lacewing larvae on adults of the flea beetle Phyllotreta cruciferae (Goeze) have been observed in Saskatchewan. Other reported insect predators of rapeseed-crop-infesting flea beetles in the Canadian prairie provinces are the beetle Collops vittatus Say (Gerber and Osgood 1975), and one of the big-eyed bugs, Geocoris bullatus (Say) (Burgess 1977).The first observation of an attack on an adult flea beetle by a lacewing larva was in August 1972, when some lacewing larvae, adult flea beetles, diamondback moth larvae (Plutella xylostella (L.)) and unidentified aphids and midges were swept from maturing rapeseed near Aberdeen, Saskatchewan. One of these lacewing larvae attacked an adult of P. cruczferae in a glass collecting-vial and carried the flea beetle around in its jaws. Other lacewing larvae attacked aphids, midges, and diamondback moth larvae. Further evidence for lacewing larvae feeding on adult flea beetles was obtained in August 1979, when a sizeable population of lacewing larvae in a rapeseed crop was encountered near St. Gregor, Saskatchewan. One of the larvae swept from this crop had an adult of P. cruciferae in its jaws when it was first seen in the sweep net. Later the same day, another lacewing larva, swept from a nearby rapeseed field, attacked an adult of P. cruciferae in a collecting vial. In the laboratory both lacewing larvae, still carrying their prey, were quick-frozen, preserved in 70% ethanol and later photographed.

The length of the developmental period from oviposition to adult emergence for nondiapausing individuals of a solitary endophagous braconid, Microctonus vittatae Mues., was usually about 4 wk at 20°C, 70–80% R.H., and a 16h:8h L:D cycle. However, living second and subsequent instar parasite larvae were occasionally found in adults of Phyllotreta cruciferae (Goeze) and Phyllotreta striolata (F.) (Coleoptera: Chrysomelidae) dissected 25–30 days after parasitization. Most of these beetles also contained one or more dead parasite eggs or first-instar larvae, suggesting that superparasitism prolonged development of the single surviving parasite in each host. Therefore, the effect of superparasitism on the parasite's development was investigated by recording the length of the developmental period of M. vittatae in two groups of adult P. cruciferae, one consisting of a majority of superparasitized individuals and the other mostly of hosts with only one immature parasite each.