Western Com Research Articles

Child Mortality and Child-Abuse-Related Deaths in Albania, Bulgaria, Croatia, Cuba, Czech Republic, Estonia, FRY Macedonia, Hungary, Latvia, Lithuania, Moldova, Poland, Romania, Russia, Serbia, Slovakia and Slovenia Compared to Western Comparators the USA and the UK (1988–90 to 2012–14)

Child-abuse-related deaths (CARD) and child mortality rates (CMR) are important issues in every culture. This paper examines both CARD and CMR in seventeen former communist countries (FCCs) since the end of the Russian hegemony, with two Western comparator countries: the USA and the UK. World Health Organisation CARD and CMR data (birth to four years) between 1988–90 and 2012–14 have been extrapo- lated. Chi-square tests compare each FCC mortality outcome with the Western com- parators over the period. To avoid under-reporting of CARD, undetermined deaths are also analysed and combined with confirmed CARD to provide a maximum esti- mate of abuse-related deaths. Combined CARD fell substantially in all FCCs, on aver- age by 66 per cent. Russia had the least successful reduction (–25 per cent). Combined CARD fell significantly more in sixteen FCCs than in the USA. CMR in FCCs fell on aver- age by 66 per cent over the period. Moldova, Russia and FRY Macedonia have the highest current CMR. Thirteen FCCs had significantly greater CMR reductions than the Western comparators. All but one FCCs met the UN millennium 2 per cent per annum reduction target for CMR but not the USA and Bulgaria. Most FCCs have made sub- stantial improvements in reducing CARD and CMR. Country-specific research is required to investigate the major differences between FCCs and Western comparator outcomes.

Genetic Relationships between Cultivated and Wild Olive Trees (Olea Europaea L. Var. Europaea and Var. Sylvestris) Based on Nuclear and Chloroplast SSR Markers

The olive is widely cropped in Tunisia where also oleaster trees thrive all around orchards and in natural sites. Little is known on the genetic relationships between the olive crop and oleaster trees in Tunisia. Fifty-two oleaster trees and fifteen cultivars were sampled from Tunisia. SSR genotyping was performed in polyacrylamide gels after fluorescent labeling. We used seven nuclear and two chloroplast SSR markers. AFC analyses showed close genetic relationships between cultivated and oleaster trees. Genetic relationships were also displayed in a dendrogram based on Unweighted Pair Group Method (UPGMA). Five clusters were defined mixing cultivar and oleaster trees suggesting close relationship between some cultivar and some oleaster trees. One oleaster is single in a cluster. The chlorotype SSR markers show probably three olive origins. Some cultivars have the CE chlorotype originates from the East of the Mediterranean basin, the CCK haplotype originates from Maghreb and the COM chlorotype originates from West Mediterranean. The cultivars were 1) introduced from the East; 2) selected in the West; 3) or selected in the North Africa region. The Tunisian oleaster trees carry eastern and western Mediterranean chlorotype CCK, COM and CE.

Cultivation and Planting-Time Insecticide Treatments for Control of Corn Rootworms in South Dakota, 1997

Abstract Cornfields located near New Holland and Garretson in central and eastern South Dakota, respectively, were chosen for this study. The experiment was conducted to evaluate insecticide efficacy using ground-driven Noble metering and electronic Smartbox metering units with band or in-furrow insecticide placement methods for control of northern and/or western com rootworm larvae. Treatment plots (15.2-m-long rows spaced 0.96 m apart) were arranged in a RCB design with four replications. Noble and Smartbox metering units were calibrated on the planter prior to insecticide applications. Banded treatments were applied in an 18-cm swath in front of the furrow-closing wheels, and incorporated by the wheels and drag chains. In-furrow applications consisted of directing granules immediately between double-disk furrow openers. Pioneer IR-3751 (100-day) com seed was planted at approximately 23,000 kernels per acre at each location. Five roots per replicate were dug, washed, examined for feeding damage, and rated using the Iowa 1 to 6 scale. Data were analyzed with the ANOVA procedure and means were compared using LSD.

A New Species of Albizia Durazzini (Leguminosae Mimosoideae) from Madagascar

A new species of Albizia, A. mainaea, is described from western Madagascar and com- pared with previously known species. R. Capuron (1970) indicated the presence of Al- bizia gummifera (J. F. Gmelin) C. A. Smith from all phytogeographic domains of Madagascar. Upon ex- amination of gatherings of this species complex from Madagascar, three species were encountered: Albizia adianthifolia (Schumacher) W. Wight from moist forests, Albizia gummifera from montane and submontane forests, and a new species from prin- cipally tropophyllous forests, which is here de- scribed and compared with species previously known in the Albizia gummifera complex sensu Brenan (1952).

Effect of Manure on Maize Tolerance to Western Corn Rootworm (Coleoptera: Chrysomelidae)

This study evaluated the potential of manure and maize tolerance to serve as alternative management strategies for reducing yield losses in maize, Zea mays (L.), by the western com rootworm, Diabrotica virgifera virgifera (LeConte). The interactions between manure and 2 maize hybrids and their subsequent effects on the growth and development of maize infested with western com rootworm were investigated in 1992 and 1993. Treatment combinations included 2 maize hybrids (Pioneer hybrid 3733 and Cornell 281), 4 manure rates (0, 45, 90, and 135 MT/ha), and 3 western com rootworm egg densities (1992: 0, 500, 700 eggs per 30.5-cm row; 1993: 0, 400, 800 eggs per 30.5-cm row). All plots received adequate nutrients (supplied by manure, inorganic fertilizer, or both) to satisfy or exceed soil test recommendations. Manure increased plant height, root recovery, and overall silage and grain yields, and decreased early feeding injury and lodging in 1 or both years of the study. However, manure had no effect on final root injury or on silage quality. Effects of manure were seemingly more pronounced in a wetter than average year. Pioneer 3733 had lower root injury ratings at the low western com rootworm density in 1993, equal root recovery, less lodging, and higher silage and grain yields with less loss to western com rootworm than Cornell 281. In both hybrids, manure produced an environmentally induced tolerance by increasing root recovery and in some cases reducing yield losses.

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.

Western Corn Rootworm (Coleoptera: Chrysomelidae) Larval Injury to Corn Grown for Seed Production Following Soybeans Grown for Seed Production

In late June 1987, severe western com rootworm, Diabrotica virgifera virgifera LeConte, larval injury to com grown for seed production (inbred com) was observed within a 3-km 2 area near Piper City (Ford County), IL. The rootworm injury occurred in 6 fields that in the prior year had been planted to weed-free soybeans grown for seed production. The severe rootworm injury problem reoccurred in 1st-yr seed com in the same area in 1988 and to varying degrees in the years since (through 1994). Laboratory and field studies were initiated in 1987 to investigate several possible causes of the problem. Under simulated field soil temperature conditions, western com rootworm eggs from the Piper City population did not show evidence of the prolonged diapause trait. Although higher than expected oviposition took place in Piper City soybean fields, a large field study with staggered plantings of soybeans at Urbana, IL, <75 km away, confirmed earlier studies that few western com rootworm eggs are laid in weed-free soybean fields. Pyrethroid insecticides are routinely used in seed corn for com earworm, Helicoverpa zea (Baddie), control. In laboratory bioassays, the pyrethroid insecticide, permethrin, repelled western com rootworm female beetles from treated com to lay eggs in untreated soybeans and demonstrated that western com rootworm damage to 1st-yr seed com could have been caused by pyrethroid use the previous summer in adjacent cornfields.

Field Performance of Entomopathogenic Nematodes for Suppression of Western Corn Rootworm (Coleoptera: Chrysomelidae)

Entomopathogenic nematodes, Steinemema carpocapsae (Weiser) (Mexican and All strains) and Heterorhabditis bactetiophora Poinar (Lewiston strain), and terbufos were evaluated as control agents for the western com root worm, Diabrotica virgifera virgifera LeConte. Several application methods for the nematodes were tested: a subsurface knife (planting or after planting) or soil surface (single or multiple applications after planting). Terbufos was applied in a band to the soil surface at planting. Tests were conducted with artificially infested populations of the western com root worm. S. carpocapsae (Mexican strain) and H. bactetiophora (Lewiston strain) as a single soil surface, after planting treatment of 200,000 nematodes per plant significantly reduced root damage below that of the control and reduced adult emergence equivalent to terbufos. These treatments reduced root damage below the threshold for potential economic loss and adult emergence by 66-98%. Three soil surface, after planting applications with a total of 600,000 nematodes per plant did not decrease root damage or adult emergence as compared with that of a single application at 200,000 nematodes. The All strain of S. carpocapsae as a knifed or soil surface, after planting treatment was ineffective. Studies are needed to evaluate thee efficacy of additional nematode species and strains on natural root worm populations under a set of soil and crop management condition that are representative for maize production.

Sex Ratio and Sexual Dimorphism in Western Corn Rootworm (Coleoptera: Chrysomelidae) Adults on Yellow Sticky Traps in Corn

Field studies were conducted in 1993 to investigate a possible sexual dimorphism in the elytra coloration pattern of western com rootworm, Diabrotica virgifera virgifera LeConte, adults, and to compare the sex ratio of adults captured on 2 types (Olson and Pherocon AM) of commercial yellow sticky traps with those obtained by aspiration. Striped and solid variationsin elytra pattern were found in both sexes. Of the western corn rootworm adults that exhibited the solid elytra pattern, >99% captured on yellow stickytraps and 97% collected by aspiration were male. In contrast, of those adults which exhibited the striped elytra pattern, 79% captured on yellow stickytraps and 42% collected by aspiration were male. Sex ratio of adults varied significantly over time and among sampling methods. Sticky traps captured a significantly greater proportion of males compared with aspiration. No significant difference in sex ratio was found between the 2 types of sticky traps; however,the Olson trap captured significantly more com rootworm adults overall than the modified Pherocon AM trap.

Field Evaluations of Hydroxamic Acids as Antibiosis Factors in Elite Maize Inbreds to the Western Corn Root worm (Coleoptera: Chrysomelidae)

The relationship between total hydroxamic acid content in roots of 9 inbreds of maize, Zea mays L., and root damage by western com root worm, Diabrotica virgifera virgifera LeConte, larvae was investigated. Measurements of root damage made just before adult root worm emergence revealed a significant negative correlation between root damage rating and the logarithm of total hydroxamic acid content detected by high-pressure liquid chromatography. However, no correlation was found between these variables at the end of the growing season. Plant morphological factors, plant height, and total leaf count were not affected by infestation with western com root worm larvae and are therefore insensitive as measurements of plant damage. Generally, relative number of days to silk of susceptible inbreds was significantly increased with increasing infestation with western com root worm larvae, but remained unaffected in resistant inbreds. lnbreds containing high levels of root hydroxamaters had significantly lower reductions in seed yield than inbreds containing low levels of root hydroxamates. It appears that resistance, in the form of antibiosis, is present in midwhorl maize inbreds to the western com root worm larvae and that root hydroxamic acid content may be contributing to this resistance.

Germinating Corn Extracts and 6-Methoxy-2-Benzoxazolinone: Western Corn Root worm (Coleoptera: Chrysomelidae) Larval Attractants Evaluated with Soil Insecticides

6-Methoxy-2-benzoxazolinone (MBOA), a host-location semiochemical for western com root worm, Diabrotica virgifera virgifera LeConte, larvae, was tested as an attractant with the experimental insecticide chlorethoxyphos in laboratory and field experiments. Crude dichloromethane extracts of germinating com seedlings were tested as an additional attractant for incorporation in soil insecticides (chlorethoxyphos and carbofuran) in laboratory experiments. Significantly more western corn root worm larvae were recovered in the core portion of the bioassay apparatus (the portion where the attractant was located) in laboratory experiments when MBOA or a crude dichloromethane extract of germinating corn seedlings was present with insecticide than in the other three treatments (attractant alone, insecticide alone, and control), indicating that MBOA or a crude dichloromethane extract of germinating com seedlings are behaviorally active to western com root worm larvae at ambient carbon dioxide levels. In these same experiments, significantly more larvae died in the core portion of the bioassay when insecticide was present with an attractant than when insecticide alone or attractant alone were present, or in the control, indicating that either MBOA or crude dichloromethane extract of germinating corn seedlings can be used to increase insecticide efficacy in laboratory bioassays. Naturally infested and artificially infested field experiments were conducted in 1991 and 1992. Most of the MBOA/chlorethoxyphos combinations did not significantly lower com root worm damage when compared to the same level of chlorethoxyph phos without MBOA. The only MBOA/chlorethoxyphos combination that provided significantly reduced corn root worm damage was the 1992 naturally infested field experiments in Akron, CO. Treatments with granules containing both 2.5% chlorethoxyphos and 3 mg/g MBOA had significantly less com root worm damage (lower root ratings) than treatments with 2.5% chlorethoxyphos without MBOA. Western com root worm larvae are very sensitive to MBGA levels. The single attractant MBGA, though promising in laboratory studies, did not consistently increase the efficacy of chlorethoxyphos under the variable conditions of field studies.

Copulation and Its Duration Affects Female Weight, Oviposition, Hatching Patterns, and Ovarian Development in the Western Corn Rootworm (Coleoptera: Chrysomelidae)

To understand the relationship between copulation and ovarian development in the western com rootworm, Diabrotica virgifera virgifera LeConte, newly emerged virgin beetles were used to establish female groups of various copulatory durations. The results demonstrate that a mating of ≥1 h stimulates an increase in weight, egg-laying, and ovarian development. This stimulation in females mated for 1 h (none contained sperm in the spermatheca at the time of dissection) was transitory and lasted 1-2 wk. Females that mated for 2 h (contained sperm in the spermatheca at the time of dissection) were indistinguishable in weight, egg-laying, and ovarian development from females mated until natural completion; they were stimulated to a sustained mature ovarian state and were capable of laying eggs for at least 4-5 wk after mating. Unmated females of similar ages underwent limited ovarian development and rarely laid eggs.

Vegetative and Reproductive Biomass Accumulation in Field Com: Response to Root Injury by Western Com Rootworm (Coleoptera: Chrysomelidae)

A 2-yr field study was conducted to evaluate the effects of larval injury by western corn rootworm, Diabrotica virgifera virgifera LeConte, on vegetative and reproductive biomass accumulation of field corn, Zea mays L. Studies in 1989 were conducted in irrigated, silty clay loam soil, whereas in 1990, the possible interacting effects of soil texture (silty clay loam, loam, and sandy loam) and soil moisture (furrow-irrigated and dryland) were examined. In both years, during the early phases of injury (feeding by first and second instars), the vegetative biomass was detrimentally affected. Larval infestations reduced leaf area and leaf wet weight by up to 17.4%. However, during the period of peak injury by third instars and during the postinjury period, the plant biomass accumulation response differed slightly between the 2 yr. Overcompensatory and exact compensatory responses were noted in 1989 and 1990, respectively. In 1989, dry weights of injured plants were greater than the uninjured plants at ≈2 wk following pupation and in 1990, plants from the two treatments had similar biomass. The reason for the differing response was probably related to the plant development stage at the time of peak injury. In 1989, plants were in the V15 stage, averaging 8,350 cm2 leaf area, whereas in 1990, plants were in the V8-V10 stage with 4,761.3 cm2 leaf area. The greater amount of photosynthetically active tissue in 1989 compared with 1990 may have allowed the plants to respond better to the injury. In addition, rootworrn-injured plants were unable to utilize, for the production of vegetative biomass, the supplemental soil moisture through irrigation compared with uninjured plants. The root injury apparently inhibited the plants from utilizing the soil moisture. Plant response to stress was generally similar in all three soil textures. The compensation and maintenance of unaltered levels of vegetative tissue biomass appeared to be at the sacrifice of reproductive tissue biomass. Western com rootworrn larval injury consistently reduced com grain yield by up to 15.0% in 1989 and by 40.7% in 1990.

Affects of Larval Injury by Western Com Rootworm (Coleoptera: Chrysomelidae) on Gas Exchange Parameters of Field Corn

The effect of larval-induced root injury by western corn rootworm, Diabrotica virgifera virgifera LeConte, on plant physiological parameters of field corn ( Zea mays L.) was examined in a 2-yr field study. Controlled infestations of 200,500, and 1,000 eggs per 30.5 row-cm were established in an irrigated, silty clay loam soil in 1989 and in silty clay loam, loam, and sandy loam soil textures with irrigated and dryland treatments in 1990. Infestations were made 16 d after planting and at planting in 1989 and 1990, respectively. Gas exchange parameters were examined before egg hatch, during the injury period, and ≈2 wk following the cessation of the injury. During both years, corn photosynthetic rates at full sunlight were reduced by an average of 7.9% coinciding with the initial period of larval injury; i.e., feeding by primarily first and second instars. During the periods of maximum injury and postinjury, western corn rootworm injury to corn roots resulted in either no significant effect on photosynthetic rate (1990) or in an apparent stimulatory effect (by up to 11.2%) on photosynthetic rate (1989). The photosynthesis effects were not consistently related to changes in stomatal conductance or intercellular CO2 concentration. Plant response to root injury was similar in all three soil textures and in differing soil moisture levels (occurring during postinjury period only) in 1990; however, soil texture and soil moisture did have significant direct effects on plant physiology. Plant developmental stage at the time of injury may be an important factor in determining the plant response to injury. Peak injury occurred in the VI2-V15 and V9-Vl 1 stages of development in 1989 and 1990, respectively. The increased amount of photosynthetically active biomass (i.e., leaf tissue) may have enhanced the plants’ compensatory response in 1989.

Efficacy and Persistence of Steinernema carpocapsae (Rhabditida: Steinemematidae) Applied through a Center-Pivot Irrigation System Against Larval Com Rootworms (Coleoptera: Chrysomelidae)

We evaluated control of natural and artificially infested populations of larval com rootworms (Diabrotica virgifera virgifera LeConte and D. barberi Smith & Lawrence) in corn ( Zea mays L.) treated with entomopathogenic nematodes, Steinernema carpocapsae (Weiser); All strain, applied after planting through a center-pivot irrigation system at 2.5 and 1.2 x 109 infective juvenile nematodes per hectare. We compared control achieved with nematodes with that achieved with planting time applications of terbufos (Counter 15G [granular]; 9.9 kg [AI]/ha) and chlorpyrifos (Lorsban 4E [emulsion]; 1.12 kg [AI]/ha) applied after planting through an irrigation system, and with an untreated (water only) control. In 1989 studies with natural rootworm populations, chlorpyrifos and both nematode rates provided significantly lower root damage ratings than terbufos and the untreated control. Chlorpyrifos was significantly more effective than the low nematode rate. In 1990 studies with a natural rootworm infestation, the high nematode rate, terbufos, and chlorpyrifos provided Significantly lower root damage ratings than the untreated control. Effectiveness of the low rate of nematodes was not significantly different from that of the untreated control. In both years, all treatments were generally less effective under higher rootworm pressure in artificially infested plots. In 1989, the high rate of nematodes significantly reduced adult western corn rootworm emergence compared with terbufos, the low rate of nematodes, and the untreated control. In 1990, all treatments significantly reduced western com rootworm adult emergence compared with the untreated control. In 1989, viable nematodes were commonly found 1-3 d after application and at low levels 28 d after application. However, in 1990, no viable nematodes were found >7 dafter application.

Spatial Analysis of Counts of Western Com Rootworm (Coleoptera: Chrysomelidae) Adults on Yellow Sticky Traps in Corn: Geostatistics and Dispersion Indices

Studies were conducted in 1990 and 1991 to investigate the spatial distribution of counts of western corn rootworm, Diabrotica virgifera virgifera LeConte, adults on yellow sticky traps in field corn. Samples were collected over 3 consecutive wk in July of each year using modified Pherocon A. M. traps placed in a 7 by 7 grid covering 0.84 ha in each of 24 cornfields. Dispersion indices indicated that counts of western corn rootworms on traps were aggregated. Geostatistic analyses, which are based on the relative position of samples, revealed that counts were nonrandomly distributed at least half the time at all population densities. Correlograms showed significant spatial relation in 46 of 72 trap-weeks (63%). Semivariograms, constructed from those 46 trap-weeks, were linear 55% of the time, suggesting the presence of gradients within the sampled portion of each field. The presence and type of spatial pattern was not correlated with mean density. Traps should be placed >30 m apart to obtain counts that are spatially independent.

Variation of Hydroxamic Acid Content in Maize Roots in Relation to Geographic Origin of Maize Germ Plasm and Resistance to Western Corn Rootworm (Coleoptera: Chrysomelidae)

Thirty-three lines of maize, Zea mays L., from different latitudinal geographical regions were surveyed for concentrations of hydroxamic acids. All root extracts were found to contain four major hydroxamic acids: 2,4-dihydroxy-7-methoxy-I,4-benzoxazin-3-(4H)-one (DIM BOA), 2,4-dihydroxy-7,8-dimethoxy-l,4-benzoxazin-3(4H)-one (DIM2BOA), 2-hydroxy-7-methoxy-l,4-benzoxazin-3(4H)-one (HMBOA), and 6-methoxy-benzoxazolinone (MBOA). The range in hydroxamic acid levels between various maize lines was >30-fold, which may provide the variation necessary for selection of lines with high levels ofhydroxamic acids in breeding programs. There was a trend showing that differences in concentrations of hydroxamic acids were associated with the different geographical groups, and that the intermediate temperate region (ITR) group had higher levels of all individual compounds, especially DIM BOA equivalents. Several maize lines commonly used in resistance studies of western corn rootworm, Diabrotica virgifera virgifera LeConte, were analyzed for hydroxamic acid levels. Corn rootworm-resistant inbreds such as SD-10 had both a larger root system and a higher hydroxamic acid concentration. A positive though weak correlation between concentration of DIM BOA in maize roots and in maize leaves was found. Seven maize lines with various hydroxamic acid levels were grown and infested by western com rootwoml larvae under controlled environmental conditions. Larval development parameters, including survival, weight, and head capsule width, were significantly and negatively correlated with hydroxamic acid levels in maize roots. These results suggest that hydroxamic acids may in some instances contribute to the resistance of maize to western corn rootworm larvae, and that hydroxamic acids may be useful as a phytochemical indicator of resistance in screening programs.

Planting Time Application of Soil Insecticides and Western Corn Rootworm (Coleoptera: Chrysomelidae) Emergence: Implications for Long-Term Management Programs

A 3-yr study assessed the influence of three commonly used planting-time soil insecticides (carbofuran, chlorpyrifos, and terbufos) on emergence of western corn rootworm, Diabrotica virgifera virgifera LeConte, from different tillage systems located near Champaign (1983 and 1984) and Monmouth (1985), III. The potential interaction of insecticides and tillage systems was not significant in any of the 3 yr with regard to beetle emergence. In 1983, significantly fewer (P > F = 0.0107) western com rootworm beetles emerged from control plots than from insecticide-treated plots. Conversely, beetle emergence in 1984 was greater from the control plots than from the insecticide-treated plots (P > F = 0.0001). In 1985, the main effect of insecticide application on beetle emergence was not significant. Total precipitation during the peak larval feeding period in June was distinctly different each year of the study (1983, 23.2 em; 1984, 3.1 cm; 1985, 8.0 cm) and may have influenced the dynamics of soil insecticide and beetle emergence interactions. In 1983 and 1984, beetle emergence among the insecticide-treated plots was greatest in plots treated with carbofuran, the most water-soluble of the compounds examined. The effect of tillage on root damage was not significant; whereas, the insecticides provided satisfactory root protection compared with the control. Results suggest that producers who use planting-time soil insecticides to protect corn roots from damage are not actually managing rootworm populations (i.e., reducing the population level) in some seasons. Although applying an insecticide in a band is intended only to protect the root system, greater beetle emergence from insecticide-treated areas in some years implies that the long-term severity of western corn rootworm infestations may be exacerbated.

Semiochemical attractants ofDiabrotica undecimpunctata howardi barber, southern corn rootworm, andDiabrotica virgifera virgifera leconte, the western corn rootworm (Coleoptera: Chrysomelidae)

During the summers of 1984 and 1985, a variety of structurally related benzenoid compounds was evaluated in sweet corn plots as attractants for adult southern corn rootworms (SCR), western com rootworms (WCR), and northern corn rootworms (NCR). Field response to the volatiles was measured by beetle counts on baited cylindrical sticky traps placed inside the corn plots at a height of l m above ground level. SCR adults were attracted late in the season (last week of August through September, 1984 and 1985) to numerous aromatic compounds, including phenylacetaldehyde, benzyl acetone, phenethyl alcohol, phenyl acetate, indole, veratrole, methyl eugenol, methyl isoeugenol, eugenol, and isoeugenol. Although many compounds attracted SCR adults late in the season, only veratrole, phenylacetaldehyde, and chavicol were significantly active in early and middle August 1985. WCR adults were attracted to a different group of compounds, namely estragole,trans-anethole, and indole. Estragole (4-methoxy-1-allylbenzene) was an effective WCR attractant from corn tasseling in early August 1985, until the end of the trapping period in late September and early October 1985. Indole andtrans-anethole (4-methoxy-1-propenylbenzene) were less effective attractants than estragole and were most active at the beginning and/or end of the corn season. Traps baited with 100 mg of estragole caught an average of 20 times more WCR adults than unbaited control traps, and the females outnumbered the males in the baited traps. Estragole dosage tests were conducted in three sweet corn plots on different dates in 1985 and the minimum effective dose ranged between 5 and 30 mg/trap. Field tests with structural analogs revealed the importance of the site of unsaturation in the allylic side chain of estragole and the effect of different ring substituents on WCR response. The phenylpropanoids, eugenol and isoeugenol, significantly attracted NCR adults, even though these beetles were in low abundance in the test corn plots. Field tests indicate there is no cross-species response by WCR and NCR adults to their related phenylpropanoid attractants. However, in late August, SCR adults do respond to some WCR and NCR attractants (indole and several eugenol analogs). Electroantennographic analysis of SCR males revealed they can perceive peripherally a wide range of benzenoid compounds.