Western Spotted Cucumber Beetle Research Articles

Field and Vegetable Crops as Hosts of Larval Western Spotted Cucumber Beetle (Coleoptera: Chrysomelidae)

The western spotted cucumber beetle, Diabrotica undecimpunctata undecimpunctata Mannerheim, is an important pest of melons (Cucurmis melo L.) in northern California. Recent observations indicate that adults are using alfalfa (Medicago sativa L.) as a feeding host and larvae may be developing on the roots. Greenhouse studies were conducted during the winters of 2009 and 2010 in which larval development was compared on the roots of six field and vegetable crops commonly grown in the southern Sacramento Valley. The growth parameters used to evaluate the hosts were larval and pupal head capsule width, body width, and body length as well as total survival percentage and survival percentage to the third instar. According to larval growth and survivorship in 2009, maize (Zea mays L.) was the best host, followed by alfalfa and tomato (Solanum lycopersicum L.) that were roughly equivalent to one another. Melon was a slightly weaker host than alfalfa and tomato; sunflower (Helianthus annuus L.) was a completely incompatible host and thus dropped from the 2010 study. In 2010, melon was the weakest host for larval development. Maize was the superior host again followed closely by alfalfa that performed slightly better than tomato and lima bean (Phaseolus lunatus L.). Data suggest that larval western spotted cucumber beetles may primarily develop outside of melon fields and the adults emigrate to melons.

Aggregation Behavior of Western Spotted Cucumber Beetle (Coleoptera: Chrysomelidae) in Vegetable Cropping Systems

Aggregation behavior of adult western spotted cucumber beetles (Diabrotica undecimpunctata undecimpunctata Mannerheim) (Coleoptera: Chrysomelidae) was examined in six snap bean (Phaseolus vulgaris) fields adjacent to corn fields in western Oregon in 2004-2006. In the 2004 and 2005 studies, sweep net sampling was used to estimate beetle numbers along transect lines running perpendicular to the edges of the bean fields next to sweet corn fields. Beetles were collected from the fields and dissected to determine sex and egg development. Beetles were highly aggregated along the edge of the snap bean field next to the sweet corn, with the highest number of beetles occurring within the first meter next to the edge. Beetles in the aggregation areas were mostly females (average female to male ratio of 8.4 to 1), whereas beetles in the field section away from the edges were mostly male (female to male ratio of 0.6 to 1). Of the females collected in the aggregation areas, an average of 53% contained developing or fully developed eggs. In the 2006 study, beetle densities in the field edges were compared with densities within the fields in 40 bean fields with adjacent corn fields. Linear regression analysis showed that, across fields, nearly two times as many beetles were found in the field borders as in the rest of the field. These data suggest modifying traditional field scouting protocol to include field margins when a bean field is adjacent to or near a sweet corn field. A pest management strategy of only spraying the edges of bean fields containing beetle aggregations shows potential for significant pesticide reduction, as well as reducing risk of economic loss from crops harvested from the highly aggregated areas.

Diabrotica virgifera

<i>Diabrotica virgifera</i>

Field Tests with Kairomone–Baited Traps for Cucumber Beetles and Corn Rootworms in Cucurbits

Sticky traps with and without the attractant TIC (1,2,4-trimethoxybenzene, indole, and tralls-cinnamaldehyde) were evaluated in cucurbits for capture of striped cucumber beetle, Acalymma trivittaum (F.), spotted cucumber beetle, Diabrotica undecimpunctata howardi Barber, western corn rootworm, Diabrotica virgifera virgifera LeConte, and northern corn rootworm, D. barberi Smith & Lawrence, in New York and western striped cucumber beetle, Acalymma trivittatum (Mannerheim), and western spotted cucumber beetle, Diabrotica undecimpunctata undecimpunctata Mannerheim, in California. Traps with TIC lures captured more beetles than un baited traps for all species except for western spotted cucumber beetle in 1 of 2 California trials. Yellow traps captured more striped cucumber beetle and western spotted cucumber beetle than did white traps but did not increase capture of spotted cucumber beetle or western striped cucumber beetle. The response of the western corn rootworm and northern corn rootworm to TIC varied by time of day, the greatest response occurring around midday. Increases in TIC per trap resulted in increases in capture of western spotted cucumber beetle, western striped cucumber beetle, western com rootworm, and striped cucumber beetle, but not for northern corn rootworm or spotted cucumber beetle. For cucurbits with short plant canopies, traps were most effective when placed close to the ground. In pumpkins with taller canopies, traps at canopy and midcanopy height captured the most beetles. The effect of trap height varied by time of day for spotted cucumber beetle, western corn rootworm, and northern corn rootworm, and the pattern varied for the species. Sex ratio of captured beetles varied among species and time of day. Overall, western corn rootworm and northern corn rootworm were captured in greatest numbers during the middle of the day, whereas the greatest captures of striped cucumber beetle occurred between 1800 and 0600 hours EST. Significantly greater numbers of striped cucumber beetle, western corn rootworm, and northern corn rootworm were captured on the downwind side of traps. Traps replaced 2 times per day had greater captures than traps replaced 1 time per day or 1 time every 2 d.

Combination of Two Entomopathogenic Nematode Species for Suppression of an Insect Pest

Laboratory and greenhouse studies were conducted to determine whether combining 2 entomopathogenic nematode species would result in synergistic, additive, or antagonistic effect against 2nd-stage larvae of the western spotted cucumber beetle, Diabrotica undecimpunctata undecimpunctata Mannerheim. After an initial screening of 12 nematode species/strains, the most efficacious Steinernema and Heterorhabditis and 2 Steinernema species that were intermediate in effectiveness were selected for further evaluations. In laboratory soil bioassays, tile lethal concentration resulting in 50% mortality (LC50) for the most virulent nematode, Steinernema carpocapsae (Weiser) All strain, was 14.5 infective juveniles followed by 18.4 infective juveniles for Heterorhabditis bacteriophora Poinar NCI strain, 48.1 infective juveniles for S. riobravis Cabanillas, Poinar and Raulston Texas strain, and 98.6 IJs for Steinernema sp. Hanrim strain. Combining 2 of the 4 nematode species at the LC25 values always resulted in an additive effect, regardless of the effectiveness of the individual nematode species. In the greenhouse, application of S. carpocapsae, S. riobravis, Steinernema sp., or H. bacteriophora was made alone or in paired combinations at the rates of 1 × 108 and 2.5 × 108 infective juveniles/ha against western spotted cucumber beetle larvae. At both rates, the most efficacious single nematode species against the larvae was S. carpocapsae . The combination of 2 nematode species showed variable results. Its efficacy ranged between as high as the better of the 2 combined species alone and as low as the less effective of the 2 species alone. In addition, the combined nematode treatments were always less effective than the most efficacious single nematode species, S. carpocapsae . We conclude that no advantage was gained by combining 2 entomopathogenic nematode species against western spotted cucumber beetle larvae.

Control of the Western Spotted Cucumber Beetle Using a Predaceous Nematode

Control of the Western Spotted Cucumber Beetle Using a Predaceous Nematode

Sweep-Net Sampling for Western Spotted Cucumber Beetle (Coleoptera: Chrysomelidae) in Snap Beans: Spatial Distribution, Economic Injury Level, and Sequential Sampling Plans

Sweep-net and absolute density samples for adult western spotted cucumber beetle (WSCB), Diabrotica undecimpunctata undecimpunctata Mannerheim (Coleoptera: Chrysomelidae), in snap beans, Phaseolus vulgaris L., were analyzed using Iwao’s patchiness regression and Taylor’s power law. Iwao’s patchiness regression described sweep-net and absolute density samples better than Taylor’s power law. The equation that described the patchiness regression of sweep sampling data was m * = 0.10 + 1.07m. Linear regression analysis of the relationship between WSCB relative density and snap bean pod damage provided the basis for estimating the economic injury level for WSCB in snap beans at a daily average of 4.1 beetles per 10 sweeps (corrected) during the 14 d preceding harvest. An average of 3.0 beetles per 10 sweeps (corrected) was proposed as the economic threshold. Thresholds adjusted to compensate for circadian variation in sweep sampling efficiency ranged from 1.2 to 3.3 beetles per 10 sweeps (uncorrected). Adjusted thresholds were used with α and β values from the sweep-net patchiness regression to construct critical-density sequential sampling plans modified for specific sampling times. Sequential sampling plans for fixed-precision population density estimates also were constructed.

Sweep-net Sampling for Western Spotted Cucumber Beetle (Coleoptera: Chrysomelidae) in Snap Beans: Daily Fluctuations in Beetle Counts and Correlation Between Relative and Absolute Density Estimates

Sweep-net sampling was evaluated as a method of sampling populations of adult western spotted cucumber beetles (WSCB), Dtabrotica undecimpunctata undecimpunctata Mannerheim, in snap beans, Phaseolus vulgaris L. Each of 18 fields was sampled initially between 0800 and 1000 hours; 1–6 subsequent sets of samples were collected later on the same date. Field means of beetle counts in sweep-net samples collected after the initial sampling episode (subsequent means) were significantly lower than the field mean of initial samples collected in the same field (initial mean) in 16 of 42 comparisons. Subsequent mean/initial mean ratios were negatively correlated ( R 2 = 0.72) with the amount of increase in solar radiation intensity between initial and subsequent sampling episodes. When fluctuations in beetle counts in sweep samples were described in relation to an average daily radiation curve, estimated counts were lowest for sampling conducted at 1300 hours. Time based correction factors used as multipliers to stabilize relative density estimates according to a standard (0900 hours) sampling time ranged from 0.9 for 1800 hours to 2.5 for 1300 hours. The linear relationship between corrected counts of WSCB in sweep-net samples and measures of WSCB absolute density (beetles per meter of row) was described by the equation: y = 0.44 + 2.55 x ( R 2 = 0.69), where x = number of WSCB per meter of row and y = corrected number of WSCB per 10 sweeps.

Identification of a female-produced sex pheromone from the southern corn rootworm,Diabrotica undecimpunctata howardi Barber

A sex pheromone has been isolated and identified from virgin females of the southern corn rootworm (SCR),Diabrotica undecimpunctata howardi Barber. The synthesized compound, 10-methyl-2-tridecanone was shown to be attractive to males of the SCR, and also to males ofD. u. undecimpunctata Mannerheim, the western spotted cucumber beetle (WSCB), and ofD. u. duodecimnotata in Mexico. Males of both the SCR and the WSCB strongly preferred theR over theS enantiomer. The resolved enantiomers were not tested againstD. u. duodecimnotata.

Laboratory Bioassay to Assess Toxicity of Insecticides to Diabrotica Larvae1

A laboratory soil bioassay was developed to simulate field control of corn rootworm larvae. Eggs of the western spotted cucumber beetle, Diabrotica undecimpunctata undecimpunctata Mannerheim, were placed in insecticide-treated soil along with corn seeds. Seed germination and plant development preceded eclosion, which ensured a readily available food source for larvae. Assays were completed in 7 to 9 days when root damage and population reduction were assessed. Tests with 11 acutely toxic insecticides demonstrated the feasibility of the test.

Susceptibility in ‘Deserta Naja’ Casaba Melon to a Cucumber Beetle1

Abstract Greenhouse and field tests showed casaba melon, (Cucumis melo L. cv. Deserta Naja) to be highly susceptible to the western spotted cucumber beetle (Diabrotica undecimpunctata ssp. undecimpunctata Mannerheim). F1 and F2 progenies derived from a cross between ‘Deserta Naja’ and a comparatively resistant melon aphid-resistant breeding line ‘Top-Mark’ were nearly as susceptible as ‘Deserta Naja’, indicating a dominance of susceptibility. The mean damage to the progeny was significantly different from that of ‘Deserta Naja’; however, this indicated that dominance was incomplete. Greater numbers of the beetles on ‘Deserta Naja’ than on other entries in a field trial indicated that preference is associated with its high susceptibility. Differential damage to ‘Top-Mark’ in free-choice and no-choice tests supported the theory that resistance includes non-preference.

Transmission of Muskmelon Necrotic Spot Virus in Muskmelons by Cucumber Beetles123

Muskmelon necrotic spot virus, a new disease of greenhouse-grown melons, was transmitted to 13 and 8% of muskmelon test plants by the western spotted cucumber beetle, Diabrotica undecimpunctata undecimpunctata Mannerheim, and the banded cucumber beetle, Diabrotica balteata LeConte, respectively. The virus also was recovered from extracts from these beetles. This demonstration of insect transmission of the virus means that dissemination of this seed-borne virus in commercially grown melons is a definite possibility.

Mass Rearing of the Western Spotted Cucumber Beetle

In 1960 the development of resistance to chlorinated insecticides in the western corn rootworm, Diabrotica virgifera LeConte, required the evaluation of other insecticides with different modes of action. Although several workers, including Robinson and Arant (1931) and Searls (1928), have reared Diabrotica species for life-history studies, none of their methods is suitable for mass rearing. To provide insects for laboratory evaluation of newer insecticides, a method was developed in this laboratory in 1960 for mass rearing of the western spotted cucumber beetle, D. undecimpunctata undeimpuctata Mannerheim, which is closely related to the corn rootworm and is locally available. A continuous culture of this species has been maintained successfully since 1960. This report describes its life history, development, and mass-rearing method.

2-Imidazolidinone as an Insect Growth Inhibitor and Chemosterilant

2-Imidazolidinone has been found to possess some unique properties affecting insect growth and development. Drosophila melanogaster Meigen larvae develop normally in media treated with 50 to 100 ppm of 2-imidazolidinone, but adults fail to emerge from the pupae. This compound affected growth and development of the immature stages of the house fly, Musca domustica. L.; the large milkweed bug, Oncopeltus fasciatus (Dallas); the corn earworm, Heliothis zea (Boddie); the mosquito Anopheles albimanus Wiedemann; the stable fly, Stomoxys calcitrans (L.); and the western spotted cucumber beetle, Diabrotica undecimpunctata Mannerheim. 2-Imidazolidinone was found also to be a house fly sterilant when flies were fed either liquid or solid treated bait. Unlike the house fly, both sexes of the large milkweed bug are sterilized when nymphs are fed solutions of 2-imidazolidinone for several days. However, it was ineffective as a chemosterilant when insects were exposed to treated surfaces. 2-Imidazolidinone inhibits house fly development in the excrement of poultry fed 500 ppm either in the drinking water or in the solid ration. At this level. 12 ppm of the toxicant were found in the egg; it was also distributed uniformly in various tissues.

The Development and Behavior of Populations of Diabrotica 11-Punctata in Foothill Areas of California

The western spotted cucumber beetle, Diabrotica 11-punctata Mannerheim, is at times a serious local pest of deciduous stone fruits (Michelbacher el al. , 1941, 1943). An attempt is made here to delimit the factors influencing the population fluctuations of this species in relation to infestations in deciduous fruit orchards. The problem of infestations in field and vegetable crops is not comparable to this situation.

The Western Spotted Cucumber Beetle as a Pest of Forage Crops in the Pacific Northwest

The Western Spotted Cucumber Beetle as a Pest of Forage Crops in the Pacific Northwest