Diabrotica Undecimpunctata Research Articles

Feasibility of Delaying Removal of Row Covers to Suppress Bacterial Wilt of Muskmelon (Cucumis melo).

Bacterial wilt, caused by Erwinia tracheiphila, is a major disease of cucurbit crops in the United States. Management of the disease relies on controlling two vector species, striped (Acalymma vittatum) and spotted (Diabrotica undecimpunctata) cucumber beetles. Six field trials were conducted at Iowa State University research farms during 2007, 2008, and 2009 to assess the efficacy of delayed removal of spunbond polypropylene row covers to control bacterial wilt on muskmelon (Cucumis melo). Treatments were (i) row cover removed at anthesis (conventional timing of removal), (ii) covers removed 10 days after row cover ends were opened at anthesis, (iii) covers removed 10 days after bumble bee hives were inserted under row covers at anthesis, and (iv) a noncovered control. In two field trials during 2007 and 2008, the delayed-removal row-cover treatments significantly suppressed bacterial wilt throughout the growing season and enhanced yield compared with the noncovered and removal-at-anthesis controls. In Gilbert in 2008, however, bacterial wilt suppression was equivalent among all three row-cover treatments. No bacterial wilt was observed during three trials in 2009, and there was minimal difference in marketable yield among treatments. Net returns were compared using partial budget and sensitivity analyses. Melon prices and occurrence of bacterial wilt had a strong impact on net returns. Using row covers increased production costs by 45%. In site years in which bacterial wilt occurred, delaying removal of row covers resulted in the highest returns. When bacterial wilt was absent, however, the delayed-removal row-cover treatments had the lowest returns. Results of the sensitivity analysis indicated that delaying removal of row covers for 10 days could be a cost-effective component of an integrated bacterial wilt suppression strategy for muskmelon where bacterial wilt occurs ≥50% of production seasons.

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.

Belowground Resistance to Western Corn Rootworm in Lepidopteran-Resistant Maize Genotypes

Several maize, Zea mays L., inbred lines developed from an Antiguan maize population have been shown to exhibit resistance to numerous aboveground lepidopteran pests. This study shows that these genotypes are able to significantly reduce the survival of two root feeding pests, western corn rootworm, Diabrotica virgifera virgifera LeConte, and southern corn rootworm, Diabrotica undecimpunctata howardi Barber. The results also demonstrated that feeding by the aboveground herbivore fall armyworm, Spodoptera frugiperda (J. E. Smith), before infestation by western corn rootworm reduced survivorship of western corn rootworm in the root tissues of some, but not all, genotypes. Likewise, the presence of western corn rootworm in the soil seemed to increase resistance to fall armyworm in the whorl in several genotypes. However, genotypes derived from the Antiguan germplasm with genetic resistance to lepidopterans were still more resistant to the fall armyworm and both rootworm species than the susceptible genotypes even after defense induction. These results suggest that there may be intraplant communication that alters plant responses to aboveground and belowground herbivores.

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ChemInform Abstract: A Novel Polyfunctional Chiral Building Block Derived from (S)-Ethyl Lactate. Application to the Synthesis of the Sex Pheromone of the Southern Corn Rootworm (Diabrotica undecimpunctata howardi).

Highly enantiomerically pure (4S, 5E)-4-bromomethylhept-5-enenitrile was prepared from (S)-ethyl lactate by a six-step procedure involving a rearrangement of chiral cyclopropylcarbinol. This product was used for the synthesis of the sex pheromone of the southern corn rootworm (Diabrotica undecimpunctata howardi), (10R)-10-methyltridecan-2-one.

ChemInform Abstract: Stereoselective Synthesis of (R)‐10‐Methyltridecan‐2‐one, the Sex Pheromone of the Southern Corn Rootworm, Using (4S)‐Benzylthiazolidinethione as a Chiral Auxiliary.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Capsid protein of cowpea chlorotic mottle virus is a determinant for vector transmission by a beetle

Cowpea chlorotic mottle virus (CCMV) is a bromovirus transmitted by species of chrysomelid beetles, including the spotted cucumber beetle, Diabrotica undecimpunctata howardii Barber. An experimental system was set up to identify the viral determinant(s) of the beetle transmission of CCMV. Nicotiana clevelandii was selected as an experimental plant host because it supports the replication and accumulation of both CCMV and a second member of the family Bromoviridae, cucumber mosaic virus (CMV). Using a reverse genetic system for CMV, a cDNA copy of the CCMV capsid protein (CP) gene was substituted for that of the CMV CP gene. The resulting 'CMV-hybrid' consisted of wild-type CMV RNA1, RNA2, and a chimeric CMV RNA3 expressing the CCMV structural protein. The CMV-hybrid replicated and formed virions in N. clevelandii; in electron micrographs the hybrid virus was indistinguishable from CCMV. In beetle feeding assays, both CCMV and the CMV-hybrid were transmitted by D. undecimpunctata, while beetle transmission of CMV was not observed. Conversely, only CMV was observed to be transmitted by the aphid Myzus persicae. Surprisingly, the CMV-hybrid was transmitted more efficiently than the parental CCMV, and a virus-induced alteration in beetle feeding behaviour is proposed to account for the difference. These results indicate that the CCMV CP is a viral determinant for beetle vector transmission.

Stereoselective synthesis of ( R)-10-methyltridecan-2-one, the sex pheromone of the southern corn rootworm, using (4 S)-benzylthiazolidinethione as a chiral auxiliary

The stereoselective synthesis of ( R)-10-methyltridecan-2-one, the sex pheromone of the southern corn rootworm, was carried out in 20.7% overall yield based on (4 S)-benzylthiazolidinethione (five steps). In the crucial step, the stereogenic center was generated by an asymmetric Michael addition using enantiomerically pure (4 S)-benzylthiazolidinethione as a chiral auxiliary.

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.

Enhancement of Bacillus thuringiensis Cry3Aa and Cry3Bb toxicities to coleopteran larvae by a toxin-binding fragment of an insect cadherin.

The Cry3Aa and Cry3Bb insecticidal proteins of Bacillus thuringiensis are used in biopesticides and transgenic crops to control larvae of leaf-feeding beetles and rootworms. Cadherins localized in the midgut epithelium are identified as receptors for Cry toxins in lepidopteran and dipteran larvae. Previously, we discovered that a peptide of a toxin-binding cadherin expressed in Escherichia coli functions as a synergist for Cry1A toxicity against lepidopteran larvae and Cry4 toxicity against dipteran larvae. Here we report that the fragment containing the three most C-terminal cadherin repeats (CR) from the cadherin of the western corn rootworm binds toxin and enhances Cry3 toxicity to larvae of naturally susceptible species. The cadherin fragment (CR8 to CR10 [CR8-10]) of western corn rootworm Diabrotica virgifera virgifera was expressed in E. coli as an inclusion body. By an enzyme-linked immunosorbent microplate assay, we demonstrated that the CR8-10 peptide binds alpha-chymotrypsin-treated Cry3Aa and Cry3Bb toxins at high affinity (11.8 nM and 1.4 nM, respectively). Coleopteran larvae ingesting CR8-10 inclusions had increased susceptibility to Cry3Aa or Cry3Bb toxin. The Cry3 toxin-enhancing effect of CR8-10 was demonstrated for Colorado potato beetle Leptinotarsa decemlineata, southern corn rootworm Diabrotica undecimpunctata howardi, and western corn rootworm. The extent of Cry3 toxin enhancement, which ranged from 3- to 13-fold, may have practical applications for insect control. Cry3-containing biopesticides that include a cadherin fragment could be more efficacious. And Bt corn (i.e., corn treated with B. thuringiensis to make it resistant to pests) coexpressing Cry3Bb and CR8-10 could increase the functional dose level of the insect toxic activity, reducing the overall resistance risk.

Polymorphic microsatellite loci from northern and Mexican corn rootworms (Insecta: Coleoptera: Chrysomelidae) and cross‐amplification with other Diabrotica spp.

The northern corn rootworm (Diabrotica barberi) and Mexican corn rootworm (Diabrotica virgifera zeae) are significant agricultural pests. For the northern corn rootworm, and to a lesser extent, the Mexican corn rootworm, high resolution molecular markers are needed. Here we present 14 polymorphic microsatellite loci isolated from libraries constructed using pooled northern and Mexican corn rootworm genomic DNA. Polymorphism in other Diabrotica, including the banded cucumber beetle, southern corn rootworm and western corn rootworm, is described.

Interactions of Chlorpyrifos and Herbicides Applied to Peanut (Arachis hypogaea L.)

Abstract Experiments were conducted from 2004 through 2006 in North Carolina to determine peanut injury, pod scarring, pod yield, and percentages of extra large kernels (%ELK), fancy pods (%FP), and total sound mature kernels (%TSMK) following chlorpyrifos applied as a granular at pegging or as emulsifiable concentrate applied preplant incorporated (PPI) in mixture with pendimethalin. In one experiment, preemergence (PRE) herbicides consisted of S-metalochlor, S-metalochlor plus diclosulam, and S-metalochlor plus flumioxazin following chlorpyrifos. In a separate experiment, the postemergence (POST) herbicides acifluorfen, acifluorfen plus bentazon, imazapic, and paraquat plus bentazon were applied when peanut diameter was 10 to 15 cm. Chlorpyrifos did not interact with diclosulam or flumioxazin applied PRE or with the POST herbicides acifluorfen, acifluorfen plus bentazon, imazapic, or paraquat plus bentazon with respect to visual injury and pod yield. Applying chlorpyrifos at pegging was more effective than PPI applications in reducing pod scarification caused by southern corn rootworm (Diabrotica undecimpunctata Howardi) feeding. Although PRE and POST herbicides injured peanut in a manner consistent with standard application of these herbicides, pod yield, %ELK and %TSMK were not affected by early season injury. However, pod yield was lower in the experiment with POST herbicides when chlorpyrifos was applied PPI compared with granular application at pegging. No differences in pod yield, %ELK, %FP, and %TSMK were noted when comparing PPI and pegging applications of chlorpyrifos in the PRE herbicide experiment.

Organic Management of Cucumber Beetles in Watermelon and Muskmelon Production

Organic methods for managing striped cucumber beetles (Acalymma vittatum) and spotted (Diabrotica undecimpunctata) cucumber beetles were examined in the production of watermelon (Citrullus lanatus) and muskmelon (Cucumis melo) using sticky traps to monitor beetle populations. In 2002, the numbers of trapped striped and total (striped + spotted) cucumber beetles were significantly (P ≤ 0.05) reduced by the combined use of three companion plants thought to repel cucumber beetles [radish (Raphanus sativus), tansy (Tanacetum vulgare), and nasturtium (Tropaeolum spp.)] or by the combined use of three companion plants known to attract beneficial insects [buckwheat (Fagopyrum esculentum), cowpeas (Vigna unguiculata), and sweetclover (Melilotus officinalis)]. In 2003 and 2004, the single companion plant treatment consisted of the combined use of radish and buckwheat. In 2003, use of aluminum-coated plastic mulch (Al-plastic) or companion plants significantly increased muskmelon yields and vine cover, while significantly reducing numbers of trapped striped, spotted, and total cucumber beetles. The use of pyrethrin insecticide did not significantly affect muskmelon yields or vine cover. In 2004, the beneficial effects of companion plant and Al-plastic treatments on muskmelon yields and vine cover were also significant and similar to those in 2003; however, these treatments only affected early season numbers of trapped beetles. The use of rowcovers significantly increased muskmelon yields and vine cover in 2003 and 2004 and did not affect beetle populations after rowcover removal. It was concluded that use of companion plants and Al-plastic increased muskmelon yields and vine cover while reducing populations of cucumber beetles, particularly striped cucumber beetles. The use of rowcovers also increased muskmelon yields and vine cover.

‘Marketmore 97’: A Monoecious Slicing Cucumber Inbred with Multiple Disease and Insect Resistances

‘Marketmore 97’ is the most recent addition to a series of disease-resistant slicing cucumbers developed in the Cornell University Department of Plant Breeding. The fruit have green skin with white spines and an average length and diameter of 18.8 cm and 4.8 cm, respectively. Broad resistance to a number of destructive diseases and insects makes this cultivar well-suited to low-input agricultural systems at the scale of the home gardener or the commercial grower. In addition to the cucumber mosaic virus (CMV), cucumber scab (Cladosporium cucumerinum Ell. &amp; Arth.), downy mildew (Pseudoperonospora cubensis Berk &amp; Curtis), and powdery mildew (Sphaerotheca fuliginea Schl. ex Fr.) resistances of ‘Marketmore 76’, ‘Marketmore 97’ contains resistance to alternaria leaf spot [Alternaria alternata (Fr.) Keis.], Ulocladium leaf spot (Ulocladium cucurbitae Let. &amp; Roum.), target leaf spot (Corynespora cassiicola Berk. &amp; Curt.), watermelon mosaic virus, papaya ringspot virus, and zucchini yellow mosaic virus. Furthermore, the bitterfree character of this cultivar is responsible for nonpreference of the striped cucumber beetle (Acalymma vittatum Fab.) and spotted cucumber beetle (Diabrotica undecimpunctata howardi Barber). Finally, a near isogenic line of ‘Marketmore 97’ is available that is gynoecious. A replicated trial of ‘Marketmore 97’ conducted in New York in 2006 confirmed comparable yield and quality to other Marketmore cultivars.

Toxicity of &lt;I&gt;Chromobacterium subtsugae&lt;/I&gt; to Southern Green Stink Bug (Heteroptera: Pentatomidae) and Corn Rootworm (Coleoptera: Chrysomelidae)

Diabrotica spp. (Coleoptera: Chrysomelidae) beetles and southern green stink bugs, Nezara viridula (L.) (Heteroptera: Pentatomidae), are pests on corn, Zea mays L., and soybean, Glycine max (L.) Merr., as well as on cucurbits. Control of these insects has depended on chemicals. An alternative to chemical control is the use of biologicals. Use of bacteria, fungi, viruses, pheromones, and metabolites to control these insects can potentially improve resistance management and reduce pesticide use. Other than Bacillus thuringiensis Berliner, few bacteria have been discovered that are lethal to either of these pests. Chromobacterium subtsugae Martin et al., a newly described bacterium that is known to be toxic to Colorado potato beetle, Leptinotarsa decemlineata (Say), larvae, was found to be toxic to both diabroticite adult beetles and southern green stink bug adults. In laboratory assays, toxins produced by these bacteria kill 80-100% of the adults of two species of diabroticite beetles, Diabrotica undecimpunctata howardi Barber and Diabrotica virgifera virgifera LeConte, and 100% of southern green stink bug adults within 6 d. For green stink bug, live bacteria were not needed for toxicity.

Utility of Morphological and Molecular Techniques for Determination of Paternity in Two Subspecies of Diabrotica undecimpunctata (Coleoptera: Chrysomelidae)

An experiment was conducted to determine the paternity of F1 progeny using morphological and molecular methods in Diabrotica (Coleoptera: Chrysomelidae) subspecies: Diabrotica undecimpunctata howardi Barber, also known as spotted cucumber beetle, and D. undecimpunctata undecimpunctata Mannerheim, also known as western cucumber spotted beetle. Results from crosses that involved the females of D. u. howardi and the males of D. u. undecimpunctata had all F1 progeny with phenotypes as the male parent. Similarly, in all the crosses that involved the females of D. u. undecimpunctata and the males of the D. u. howardi, all the F1 progeny had phenotypes as the male parent. DNA from females and males were amplified using two primers to confirm the paternity of F1 progeny. The study on the inheritance of body color in these two subspecies appeared to be governed by one dominant gene (monogenic), and it is the male that determines the body color of progeny in both subspecies.

Resistance of Sweetpotato Genotypes to Adult Diabrotica Beetles

Production of sweetpotatoes, Ipomoea batatas (L.) Lam. (Convolvulaceae), is limited by several insect pests, including Diabrotica spp. (Coleoptera: Chrysomelidae), and new integrated pest management (IPM) techniques for this crop are needed. Host plant resistance is one attractive approach that fits well into IPM programs. A host plant resistance research program typically depends on reliable bioassay procedures to streamline evaluation of germplasm. Thus, a bioassay technique was developed for evaluating sweetpotato germplasm by using adults of the banded cucumber beetle, Diabrotica balteata LeConte, and spotted cucumber beetle, Diabrotica undecimpunctata howardi Barber. A single beetle was placed on a piece of sweetpotato peel (periderm and cortex with stele removed) that was embedded periderm-side up in plaster in a petri dish. Feeding and longevity of insects on 30 sweetpotato genotypes were evaluated in two experiments by using this procedure. Adult longevity ranged from 7 to 11 d for starved individuals to 211 d for beetles fed a dry artificial diet. Longevity of banded cucumber beetles that fed on sweetpotato peels ranged from 12 d for the most-resistant genotype to 123 d for SC1149-19, a susceptible control cultivar. Longevity of spotted cucumber beetles was slightly shorter than longevity of banded cucumber beetles. For the most resistant sweetpotato genotypes, both Diabrotica species exhibited a significant delay in initiation of feeding, and more beetles died on these genotypes before they had fed. Both antibiosis and nonpreference (antixenosis) are important mechanisms of resistance in sweetpotato genotypes. This bioassay was consistent with field results, indicating that this technique could be useful for evaluating resistance to Diabrotica spp. in sweetpotato genotypes.

Resistance of Sweetpotato Genotypes to Adult &lt;I&gt;Diabrotica&lt;/I&gt; Beetles

Production of sweetpotatoes, Ipomoea batatas (L.) Lam. (Convolvulaceae), is limited by several insect pests, including Diabrotica spp. (Coleoptera: Chrysomelidae), and new integrated pest management (IPM) techniques for this crop are needed. Host plant resistance is one attractive approach that fits well into IPM programs. A host plant resistance research program typically depends on reliable bioassay procedures to streamline evaluation of germplasm. Thus, a bioassay technique was developed for evaluating sweetpotato germplasm by using adults of the banded cucumber beetle, Diabrotica balteata LeConte, and spotted cucumber beetle, Diabrotica undecimpunctata howardi Barber. A single beetle was placed on a piece of sweetpotato peel (periderm and cortex with stele removed) that was embedded periderm-side up in plaster in a petri dish. Feeding and longevity of insects on 30 sweetpotato genotypes were evaluated in two experiments by using this procedure. Adult longevity ranged from 7 to 11 d for starved individuals to 211 d for beetles fed a dry artificial diet. Longevity of banded cucumber beetles that fed on sweetpotato peels ranged from 12 d for the most-resistant genotype to 123 d for SC1149-19, a susceptible control cultivar. Longevity of spotted cucumber beetles was slightly shorter than longevity of banded cucumber beetles. For the most resistant sweetpotato genotypes, both Diabrotica species exhibited a significant delay in initiation of feeding, and more beetles died on these genotypes before they had fed. Both antibiosis and nonpreference (antixenosis) are important mechanisms of resistance in sweetpotato genotypes. This bioassay was consistent with field results, indicating that this technique could be useful for evaluating resistance to Diabrotica spp. in sweetpotato genotypes.

Discovery and characterization of Sip1A: a novel secreted protein from Bacillus thuringiensis with activity against coleopteran larvae

Bioassay screening of Bacillus thuringiensis culture supernatants identified strain EG2158 as having larvicidal activity against Colorado potato beetle (Leptinotarsa decemlineata) larvae. Ion-exchange fractionation of the EG2158 culture supernatant resulted in the identification of a protein designated Sip1A (secreted insecticidal protein) of approximately 38 kDa having activity against Colorado potato beetle (CPB). An oligonucleotide probe based on the N-terminal sequence of the purified Sip1A protein was used to isolate the sip1A gene. The sequence of the Sip1A protein, as deduced from the sequence of the cloned sip1A gene, contained 367 residues (41,492 Da). Recombinant B. thuringiensis and Escherichia coli harboring cloned sip1A produced Sip1A protein which had insecticidal activity against larvae of CPB, southern corn rootworm (Diabrotica undecimpunctata howardi), and western corn rootworm (Diabrotica virgifera virgifera).

Female Choice by Scent Recognition in the Spotted Cucumber Beetle

AbstractIn species that demonstrate female choice, geographically distinct populations can vary in their signal‐response behaviors as a result of environmental differences or genetic drift. Observing whether or not females discriminate against males from allopatric populations can establish such signal deviations. Here we compare mating success within and between populations of the spotted cucumber beetle (Diabrotica undecimpunctata howardi) collected from Delaware, Tennessee, Missouri, and New Mexico, USA. A no‐choice cross‐mating experiment was employed to measure female preference for sympatric and allopatric males. While only two of the populations (Tennessee and Missouri) demonstrated statistically significant female preference for sympatric males, this trend was observed in all populations tested. Further, we show that (i) males from Tennessee, Missouri, and New Mexico differ in their scent, (ii) females may use population‐specific scents to discriminate among males, and (iii) females whose antennae have been surgically removed are unable to recognize acceptable mates. New Mexico males, which were never accepted by either Tennessee or Missouri females, became acceptable mates when crowded with Tennessee or Missouri males prior to copulation. We infer that male odor may be an important factor in determining cucumber beetle mating success.