The Colorado potato beetle (CPB) is a major insect pest that is controlled mainly through the use of pesticides. Development of potato clones with multiple forms of host plant resistance may provide a stable alternative or supplemental form of CPB control. Tetraploid hybrids were developed by somatic fusion of diploid interspecific Solanum clones with different forms of resistance to CPB. Hybrids were created between a clone containing leptine glycoalkaloids and four clones producing glandular trichomes. One fusion produced vigorous hybrids that were analyzed for CPB resistance traits. Somaclonal variation among hybrids was detected for trichome density and resistance to feeding by adult and larval beetles. Somatic hybrids were less resistant than the parents in adult feeding preference trials, but several were more resistant than either parent in larval feeding trials. Future studies are needed to determine whether clones producing both glandular trichomes and leptines express resistance that is more stable than that of clones with only one resistance factor.
Shelley Jansky, Sandra Austin-Phillips, and Corine McCarthy
Harry Bottenberg, John Masiunas, Catherine Eastman, and Darin Eastburn
Field studies were conducted to determine insect and plant pathogen management effects on weed competitiveness and crop yield and to evaluate weed management impacts on insect pests, diseases, and crop yield. At similar densities, redroot pigweed (Amaranthus retroflexus L.) reduced snapbean (Phaseolus vulgaris L.) and cabbage (Brassica oleracea L. var capitata) yield more than that of common purslane (Portulaca oleracea L.), a low growing weed. In 1995, diamondback moth [Plutella xylostella (L.)] was greater on cabbage growing in plots with purslane than in plots of cabbage growing without weeds. Imported cabbageworm [Pieris rapae (L.)] was greater on cabbage growing in plots with either purslane or pigweed than when growing alone. However, the amount of feeding damage to cabbage was similar across treatments. Disease incidence was low, but fungicide treatments made redroot pigweed more competitive with snapbean, reducing yield in 1995.
Rosalía Servín, Jos L. Martínez, E. Troyo-Diguez, and A. Ortega
The sweetpotato whitefly [Bemisia tabaci (Gennadius)] has become a high-risk insect pest in Mexico as well as in other countries, causing serious damage to several crops. Control of whitefly in Baja California Sur, ,Mexico, is usually done by intense insecticides applications, either alone or in mixtures of several kinds. The aim in this work was to determine its susceptibility to cypermethrin, endosulfan, methamidophos, and methyl-parathion. LC50 was obtained to identify the resistant and susceptible populations. A group of 20 whiteflies were introduced in a 20-ml scintillation vial coated in the inner surface with a known concentration of the insecticide. Mortality readings were obtained 3 h after exposing the insects to the residual activity at five concentrations. Five replications and control were run in different consecutive days for each bioassay. Results indicated that cypermethrin was the most toxic to B. tabaci and metamidophos the least. Data will be considered for further evaluations.
Brian K. Hogendorp and Raymond A. Cloyd
Sanitation, which includes removing plant and growing medium debris, is an important component of any greenhouse or nursery pest management program. However, there is minimal quantitative information on how sanitation practices can reduce pest problems. In this study, conducted from May through Nov. 2005, we evaluated plant and growing medium debris as a source of insect pests from four greenhouses located in central Illinois. Two 32-gal refuse containers were placed in each greenhouse with a 3 × 5-inch yellow sticky card attached to the underside of each refuse container lid. Each week, yellow sticky cards and plastic refuse bags were collected from the containers and insects captured on the yellow sticky cards were identified. Insects captured on the yellow sticky cards were consistent across the four greenhouses with western flower thrips (Frankliniella occidentalis), fungus gnats (Bradysia spp.), and whiteflies (Bemisia spp.) the primary insects present each week. Insect numbers, in order of prevalence on the yellow sticky cards, varied across the four locations, which may be related to the type of plant debris discarded. For example, extremely high numbers of adult whiteflies (range = 702 to 1930) were captured on yellow sticky cards in one greenhouse each month from August through November. This was due to the presence of yellow sage (Lantana camera), bee balm (Monarda didyma), garden verbena (Verbena × hybrida), common zinnia (Zinnia elegans), sage (Salvia spp.) and fuchsia (Fuschia spp.) debris that was heavily-infested with the egg, nymph, pupa, and adult stages of whiteflies. High western flower thrips adult numbers in the greenhouses were generally associated with plant types such as marguerite daisy (Dendranthema frutescens) and pot marigold (Calendula officinalis) disposed while in bloom with opened yellow flowers, which contained adult western flower thrips. Based on the results of this study, it is important that greenhouse producers timely remove plant and growing medium debris from greenhouses or place debris into refuse containers with tight-sealing lids to prevent insect pests from escaping.
Joseph J. Coombs, David S. Douches, Susannah G. Cooper, Edward J. Grafius, Walter L. Pett, and Dale D. Moyer
Colorado potato beetle (Leptinotarsa decemlineata Say) is the leading insect pest of potato (Solanum tuberosum L.) in northern latitudes. Host plant resistance is an important tool in an integrated pest management program for controlling insect pests. Field studies were conducted to compare natural host plant resistance mechanisms (glandular trichomes and Solanum chacoense Bitter-derived resistance), engineered [Bacillus thuringiensis (Bt) Berliner Bt-cry3A], and combined (glandular trichomes + Bt-cry3A and S. chacoense-derived resistance + Bt-cry3A transgenic potato lines) sources of resistance for control of colorado potato beetle. Six different potato clones representing five different host plant resistance mechanisms were evaluated for 2 years in a field situation under natural colorado potato beetle pressure in Michigan and New York, and in a no-choice field cage study in Michigan. In the field studies, the S. chacoense-derived resistance line, Bt-cry3A transgenic, and combined resistance lines were effective in controlling defoliation by colorado potato beetle adults and larvae. Effectively no feeding was observed in the Bt-cry3A transgenic lines. The glandular trichome line suffered less defoliation than the susceptible control, but had greater defoliation than the Bt-cry3A transgenic lines and the S. chacoense-derived resistance line. In the no-choice cage study, the Bt-cry3A transgenic lines and the combined resistance lines were effective in controlling feeding by colorado potato beetle adults and larvae with no defoliation observed. The S. chacoense-derived resistance line and the glandular trichome line suffered less defoliation than the susceptible control. Based on the results of the field trials and no-choice field cage studies, these host plant resistance mechanisms could be used to develop potato varieties for use in a resistance management program for control of colorado potato beetle.
Raymond A. Cloyd
.00). Hardcover, ISBN: 978-0-470-65913-7. To manage insect pests effectively in agricultural cropping systems, whether it is implementing the use of cultural, chemical, or biological approaches, it is essential to understand the biology and life cycle of the
Joe R. Williamson and Donn T. Johnson
Agricultural monocultures with intensive pest management practices reduce diversity and create instability in agricultural ecosystems, thereby increasing reliance upon pesticides. This study compares the influence of three insect pest management programs in vineyards on arthropod diversity as well as parasitism and control of grape berry moth (Endopiza viteana), the key pest of grapes (Vitis labrusca) in eastern North America. Vineyards in Bald Knob, Hindsville, Judsonia, Lowell, and Searcy, Ark., were managed with a range of intensity of insecticide use, a reduced insecticide program with Exosex-GBM dispensers for mating disruption, or no pesticide use in abandoned vineyards. Arthropod diversity and carabid (Carabidae) density in each vineyard was sampled with pitfall traps. Grape berry moth flight was monitored by pheromone traps. Grape berry moth–infested grapes were collected from the field and reared in the lab until parasites or moths emerged. There were significant differences in arthropod diversity between vineyard sites, with Shannon diversity index values generally higher in woods and managed vineyards with conventional sprays and/or mating disruption than in abandoned sites. Shannon index values for arthropod diversity were significantly lower at the vineyard edge in Searcy (recently abandoned), vineyard center and edge in Bald Knob (abandoned), and the vineyard edge in Hindsville (conventional sprays). In 2003, carabid density was significantly highest in the edge and center of the Hindsville vineyard (high insecticide usage) and the abandoned Bald Knob vineyard had significantly lowest carabid density. Apparently, insecticide sprays resulted in more food on the vineyard floor for carabids. The vineyard floor management was too variable among vineyards to deduce its effect on carabid density. With some exceptions, low-spray and no-spray vineyards generally showed greater diversity and parasitism of grape berry moth than high-spray vineyards. Parasitism was higher in some high-spray vineyards than in low-spray with mating disruption vineyards. Grape berry moth flight and berry damage were more dependent on spray timing than intensity. This study demonstrates that insect pest management programs impact arthropod diversity and parasitism. Further testing is needed to determine why parasitism of grape berry moth decreased in the vineyards using the mating disruption tactic.
Brent A. Holtz
Pistachio (Pistacia vera) was successfully introduced into California and initially touted as a tree nut crop with no disease or insect pests. Unfortunately, these expectations were dashed as a number of diseases and pests followed commercial plantings, making plant protection practices integral to production. Verticillium wilt (Verticillium dahliae) devastated early plantings but is now controlled with the use of resistant rootstocks. Botryosphaeria blight (Botryosphaeria dothidea) and alternaria late blight (Alternaria alternata) are recently arrived foliar fungal diseases that blight fruit clusters and defoliate trees, respectively, and multiple fungicide applications are needed for control. The conversion to low volume irrigation systems, specifically to drip or buried drip, has reduced disease. Pruning out botryosphaeria blight infections has reduced overwintering inoculum and disease, while current research aims at accurately predicting infection events to increase fungicide efficacy. A number of hemipteran insect pests have been associated with epicarp lesion: spring treatments have been replaced with dormant carbaryl and oil applications which are less toxic to beneficial insects while controlling phytocoris (Phytocoris californicus and P. relativus) and soft scale pests. Early season insect damage can be tolerated because trees compensate by maturing a higher percentage of remaining fruit kernels. Some mirid (Calocoris spp.) pests can be effectively reduced by eliminating alternate hosts in an effective weed control program. If lygus (Lygus hesperus) populations are present, weeds should not be disturbed from bloom until shell hardening to prevent movement by insects into the trees where feeding can result in epicarp lesion. Stink bugs (Pentatomidae) and leaffooted bugs (Leptoglossus clypealis and L. occidentalis) can penetrate the hardened shell and cause internal nut necrosis along with epicarp lesion. Trap crops are used to monitor pest populations in order to develop treatment thresholds. Degree-day based timing of treatments increase insecticide efficacy for the control of navel orangeworm (Amyelois transitella) and obliquebanded leafroller (Choristonuera rosaceana), but navel orangeworm populations are more effectively managed by destroying unharvested over wintering fruit. Bacillus thuriengiensis sprays, liquid-lime-sulfur, and biological control show promise in controlling obliquebanded leafroller.
Raul Leonel Grijalva-Contreras*, Ruben Macias-Duarte, Manuel de Jesus Valenzuela-Ruiz, and Fabian Robles-Contreras
Production of high value crops in greenhouse in the Northwest of Mexico is an efficient way to achieve high yield, and high quality and the some time vegetables with less pesticide residue. The objective of this experiment was to evaluate the effects of three different plant densities (1.89, 2.50, and 3.78 plants/m2) on yield and fruit quality on tomatoes. This experiment was carried out in the Experimental Station (INIFAP-CIRNO) inside polyethylene greenhouse. In this Trial we used soil medium and the variety used was `Matrix'. The date seedling establishment was on 26 Jan. 2003. Plant density did have an effect on yield, but did not affect the fruit size. Yield per square meter had a linear response a plant density. The yield obtained were 21.8, 16.1 and 14.7 kg/m2 using 3.78, 2.50 and 1.89 plants/m2, respectively. Weight fruit varied from 200.4 to 247.6 g/fruit for all densities. Also the density not affected the fruit color. None of the treatments evaluated had problems of insect pest and disease.
Raul Leonel Grijalva-Contreras*, Ruben Macias-Duarte, Manuel de Jesus Valenzuela-Ruiz, and Fabian Robles-Contreras
The production of vegetables in Mexico under greenhouse conditions has been increased notably during the last years. Actually the area is about 1,250 ha. Tomatoes is the vegetables more important with 70%. The objective of this experiment was to evaluate ten beef tomatoes varieties growing on soil medium and to choice those with high yield, fruit quality and disease resistant. The experiment was carried out on the Experimental Station (INIFAP-CIRNO) inside Polyethylene greenhouse. The soil characteristics are clay loam texture, electrical conductivity (1.22 ds·m-1 and Ph 7.96). The date seedling establishment on 25 Oct. 2003 (28 days after sow seed). The plant density used was of 3.78 plants per square meter. The harvest period occurred from 20 feb. Feb. 20 to 27 May and they were carried out an average of sixteen cutting. There were nonsignificant differences in yield and weight fruit among varieties. Yield varied from 26.2 and 19.2 kg·m-2. The varieties with more yield were Clarion, GC-29125, Attention, Thomas and Charleston with 26.2, 24.7, 24.4, 24.2 and 21.5 kg·m-2, respectively. Fruit weight varied from 96.5 to 174.0 grams per fruit. The important insect pests in this year were Leaf Miner (Lyriomyza sp.); Army worm (Heliothis op.) and white fly (Bemissia sp.) however, we have not recorded any important disease during this trial.