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Chapter 15 of the Vegetable Production Handbook.

Chapter 17 of the Vegetable Production Handbook.

Chapter 10 of the Vegetable Production Handbook.

Chapter 9 of the Vegetable Production Handbook.

Sweetpotato weevil (SPW), Cylas formicarius elegantulus (Summers), is the most damaging root-feeding insect of sweetpotato, Ipomoea batatas (L.) Poir., worldwide. Larval feeding on storage roots reduces yield and induces terpene production, rendering roots inedible. Selection of sweetpotato cultivars with resistance to insect pests has been carried out for over a century but no high yielding, production acceptable varieties are currently available that are resistant to SPW. A cultivar with resistance to SPW oviposition would be a desirable choice for growers since it will reduce the number of larvae and damage level from SPW. Previous studies have compared cultivar effect on the oviposition of SPW but have not considered the effect of previous rearing experience. Hopkins’ host-selection principle (Hopkin’s HSP) states that phytophagous insects have an oviposition preference for the host that they have been reared on. In this study, we tested cultivar effect on oviposition preference of SPW reared on different cultivars for a minimum of two generations. For adults reared on cvs. Beauregard and Evangeline, adult oviposition preference followed their previous living experience. Thus, our results indicate a strong effect of host fidelity, supporting Hopkin’s HSP. Our results also confirm that cv. Murasaki is a resistant cultivar, resulting in reduced oviposition but not oviposition capacity. It is possible that the reduced oviposition is due to the stress-triggered oosorption from the females feeding on cv. Murasaki.

This chapter covers beet, radish, carrot, sweetpotato, cassava, taro, and malanga production.

This chapter covers production of celery, okra, and parsley.

This chapter covers lettuce, endive, escarole, and spinach cultivation.

The sugarcane aphid, Melanaphis sacchari (Zehntner), has emerged as a serious pest of sorghum in the United States. Field trials were conducted in Louisiana and South Carolina in 2016–2018 to investigate its population characteristics and distribution patterns in relation to four sample unit sizes (three circular and one leaf based). Sugarcane aphid populations usually progressed through a phase of rapid rise followed by a phase of rapid decline within a span of 5–6 wk, with peak density determined by sorghum cultivars and climatic conditions. Peak population densities for susceptible cultivars were 1.9–14.9× that for resistant cultivars on a per plant basis. Melanaphis sacchari tended to concentrate on the lower green leaf nodes early in the infestation, with the distribution shifting toward higher green leaf nodes as the infestation progressed. Aphid densities per cm2 at the basal and middle sections were about twice as high as at the distal section of leaves. The proportions of infested sample units were fitted to the Wilson–Room binomial model that incorporates the effect of density on clumping pattern. For a specific sample unit size, clumping patterns were similar across cultivars, years, and leaf positions, but varied across infestation stages. For a fixed aphid density per sample unit, the proportion of infested sample units decreased with increasing sample unit size. For a fixed aphid density per cm2, proportion infested increased with increasing sample unit size, indicating less clumping with a larger sample unit size. Field sampling time and efficiency between samplers were quantified.

Aquatic weeds such as muskgrass (Chara spp.), water hyacinth (Eichhornia crassipes), water lettuce (Pistia stratiotes), hydrilla (Hydrilla verticillate), filamentous algae (Lyngbya wollei), and duckweed (Lemna minor) thrive in farm canals within the Everglades Agricultural Area of South Florida. Their presence, particularly during the summer months is an environmental concern with regards to water quality, in addition to being a nuisance because of their ability to multiply and spread rapidly in open waters causing restricted drainage/irrigation flow and low dissolved oxygen levels. Chemical control is effective but can have undesirable off-target effects, so reduced herbicide use is desirable. Hence, need exists to discover ways in which these weeds could be best managed or utilized. The objective of this research was to evaluate the allelopathic effect of these weeds to determine their use as potential biopesticides. Six aqueous extracts were tested against 100 bacterial strains isolated from plants and soil to evaluate their antimicrobial activity. These extracts were also used to determine their insecticidal and antifeedant effects on fall armyworm (FAW, Spodoptera frugiperda). Both extracts and powder form of the aquatic weeds were tested for their herbicidal activity towards seed germination and growth of three common terrestrial weed species. At a dilution of 1:100 and 1:1,000, none of the aquatic weeds inhibited in-vitro growth of the bacterial strains, with one exception (filamentous algae extract at 1:100 reduced growth of one bacterial isolate by 54%). Water lettuce reduced the survival rate of FAW by 14% while hydrilla and duckweed caused 11% and 9% reduction of FAW growth, respectively. Powdered duckweed inhibited the growth of nutsedge by 41%, whereas filamentous algae powder and extract reduced germination of amaranth by 20% and 28%, respectively. Harvesting these weeds and converting them into useable compounds could not only eliminate the in situ farm canal and water quality problems but also result in development of new soil amendments or biopesticides.

The U.S. Gulf Coast has ideal conditions, including abundant rainfall and a long growing season, for production of dedicated bioenergy crops. Interest in producing bioethanol from high-biomass graminaceous crops including energycanes (Saccharum spp.) and energy sorghums (Sorghum spp. hybrids) in the region has increased. However, insect pests including the sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), will likely adversely affect bioenergy crops. The impact of D. saccharalis infestations on yields of conventional and bioenergy sugarcanes and sorghums was investigated in three separate field studies conducted from 2012 to 2013. These studies compared D. saccharalis injury and crop yield parameters among insecticide-protected and unprotected plots of sugarcanes, energycanes, high biomass sorghums, and sweet sorghum. In unprotected plots, D. saccharalis injury ranged from 2.9 (resistant sugarcane) to 13.6% bored internodes (susceptible sugarcane). A resistant energycane cultivar was among the least injured (3.5% bored internodes) and demonstrated the greatest potential for bioethanol production with an average of >17,000 L/ha. Linear regressions revealed negative relationships between percentage of bored internodes and ethanol yield in all cultivars. At one location, D. saccharalis injury resulted in a 13% reduction in bioethanol production across all years and cultivars. These studies indicate D. saccharalis has potential to substantially reduce yields in bioenergy crops and pest management programs will be needed to maximize ethanol production.

Sugarcane yellow leaf virus (SCYLV), the causal agent of yellow leaf disease, naturally infects at least three plant species in Florida: sugarcane (Saccharum spp.), the weed Columbus grass (Sorghum almum) and cultivated sorghum (S. bicolor). All three hosts are also colonized by the sugarcane aphid (Melanaphis sacchari), the main vector of SCYLV worldwide. To understand the high incidence of SCYLV observed in sugarcane commercial fields and in germplasm collections, we investigated the transmission efficiency of SCYLV from sugarcane and Columbus grass to sugarcane using the sugarcane aphid and a spider mite (Oligonychus grypus) that also tested positive for SCYLV in Florida. Healthy and SCYLV-infected leaf pieces of sugarcane and Columbus grass carrying viruliferous aphids or spider mites were transferred to virus-free plants of the yellow leaf susceptible sugarcane cultivar CP96-1252. Three- and 6-months post inoculation, the 108 aphid-inoculated plants of Columbus grass and the 90 mite-inoculated plants of sugarcane tested negative for SCYLV by tissue blot immunoassay (TBIA) or reverse transcription polymerase chain reaction (RT-PCR). Similar results were obtained for 162 aphid-inoculated plants of sugarcane, except for two plants that tested positive for SCYLV by TBIA and RT-PCR. In two field experiments planted with SCYLV-free and virus-infected sugarcane (cultivar CP96-1252), only 18–28% of healthy plants became infected during a 24- to 28-month period. SCYLV prevalence in these field experiments did not differ between aphicide treated and untreated plots. Incidence of M. sacchari haplotypes in the Everglades agricultural area also indicated that the predominant haplotype that is currently colonizing sugarcane was not a vector of SCYLV in Florida. Lack of virus transmission by the spider mite suggested that this arthropod only acquired the virus when feeding on infected plants but was unable to transmit SCYLV. The current vector of SCYLV in Florida remains to be identified.

A study was conducted in Florida to determine sugarcane borer, Diatraea saccharalis (F.), injury and infestation levels in sugarcane (Saccharum spp. hybrids), D. saccharalis parasitism rates, and ant foraging activity in 32 commercial fields as affected by soil type (shallow organic vs deep organic vs mineral). In 2017 and 2018, each field was sampled four times during the summer for D. saccharalis by inspecting 100 sugarcane stalks and for foraging ants using plastic tubes baited with hot dog at 12 locations. One non-parasitized D. saccharalis larva was collected in 2017 and in 2018 out of 12,100 and 12,600 stalks sampled, respectively. Additional sampling of 50 stalks per field in October showed that 0.6% (2017) and 0.1% (2018) of the sugarcane stalks had bored internodes, and one Cotesia flavipes (Cameron) (Hymenoptera: Braconidae) cocoon mass was observed. Seven ant species foraged in sugarcane fields, including the red imported fire ant, Solenopsis invicta Buren, which was the most abundant ant. Solenopsis invicta was not affected by soil type; however, sugarcane fields on shallow organic soils might represent a more suitable environment. The third most abundant foraging ant, Nylanderia bourbonica (Forel), was more abundant in mineral soil fields than in shallow and deep organic soil fields. Results suggest that D. saccharalis population levels in Florida sugarcane are extremely low under current production conditions regardless of soil type. In addition, the observation of C. flavipes, S. invicta, and six other ant species suggest that biological control contributes to these low D. saccharalis population levels.

The West Indian canefly, Saccharosydne saccharivora (Westwood) (Hemiptera: Delphacidae), is a sporadic pest of sugarcane in Louisiana which has recently emerged as a more consistent threat with outbreaks occurring in 2012, 2016, 2017, and 2019. Surveys of commercial fields in 2016 revealed that S. saccharivora infestations were present throughout Louisiana sugarcane and populations peaked in mid-June before declining. High minimum winter temperatures are generally associated with S. saccharivora outbreaks. Six insecticide evaluations demonstrated effective control with several insecticides including λ-cyhalothrin, flupyradifurone, acetamiprid, and imidacloprid. In five of the six insecticide trials, S. saccharivora infestations had substantially declined by 21 d after treatment. Effects of insecticidal control of S. saccharivora on sugar yields were detected in one of four small plot trials in which yield data were collected. Linear regression revealed S. saccharivora cumulative insect days in a grid sampling study were inversely associated with sugar yields. Results from these collective experiments suggest impacts on sugar yields are influenced by pest density and infestation duration. Differences were detected in numbers of S. saccharivora nymphs and adults as well as sooty mold coverage among commercial sugarcane cultivars with more than twofold increases in the most susceptible compared to resistant cultivars. The research presented herein documents the impact of S. saccharivora to Louisiana sugarcane and provides important ground work for developing effective pest management strategies. Future research efforts should aim to identify ecological factors influencing population dynamics, varietal preferences, and economic thresholds.

The sugarcane borer, Diatraea saccharalis (F.), rice stalk borer, Chilo plejadellus Zincken, and Mexican rice borer, Eoreuma loftini (Dyar), are stem borers (Lepidoptera: Crambidae) that infest rice (Oryza sativa L.) in the southern United States. A 2-yr study was conducted to determine stem borer injury, infestation, and parasitism levels in Florida. Thirty commercial rice fields were selected during the 2017 and 2018 growing seasons throughout the rice production region in southern Florida. Sampling for stem borer injury and infestations was conducted in each field between the milk and early maturation stages by observing plants at 10 locations, with three 1-m2 quadrats per location. In addition, monitoring for E. loftini adults was conducted using one pheromone trap adjacent to each field. In 2017, the number of rice tillers exhibiting stem borer injury averaged 0.024 tillers/m2 and infestation levels averaged 0.008 stem borers/m2, with only D. saccharalis being observed. In 2018, injury and infestation levels averaged 0.062 injured tillers/m2 and 0.023 D. saccharalis larvae or pupae/m2, respectively. The solitary parasitoid Alabagrus stigma Brullé (Hymenoptera: Braconidae) parasitized 33 and 40% of the collected D. saccharalis in 2017 and 2018, respectively. In addition, pheromone traps did not capture E. loftini adults. This study shows that D. saccharalis infests rice in Florida but at relatively low levels not threatening production and that rice fields are habitats for D. saccharalis parasitoids. This study also suggests that C. plejadellus and E. loftini do not occur in southern Florida.

Fulmekiola serrata (Kobus) was observed infesting sugarcane, Saccharum spp. hybrids, in the United States for the first time in January 2017 in Florida. Field studies were conducted to determine F. serrata infestation levels on popular sugarcane cultivars and to determine the efficacy of foliar insecticide treatments that could be used for management. Cultivar evaluations comparing six and five commercial cultivars representing >46% of the sugarcane production area in Florida were conducted in 2017 and 2018, respectively. Fulmekiola serrata infestation levels did not differ among cultivars in 2017. However, infestation levels on CP 00-1101 were greater than on CP 96-1252 grown on organic soils, and infestation levels on CP 96-1252 were greater than on CPCL 97-2730 grown on mineral soils in 2018. Three insecticide evaluations, two in 2017 and one in 2018, were conducted. The pyrethroid lambda-cyhalothrin, which is registered for use on sugarcane, was consistently associated with the greatest decreases in F. serrata infestation levels. The neonicotinoids imidacloprid and thiamethoxam, as well as the butenolide flupyradifurone, decreased infestation levels but to a lesser extent than did lambda-cyhalothrin. The spinosyn spinetoram was associated with the lowest decreases in F. serrata infestation levels. Our results supported short-term F. serrata management recommendations: Popular Florida sugarcane cultivars should be considered equally susceptible to F. serrata until additional evaluations are conducted and F. serrata outbreaks can be treated with lambda-cyhalothrin when infestations stress the crop beyond acceptable levels.

Melanaphis sacchari (Zehntner) is a major pest of sorghum, Sorghum bicolor (L.) Moench, in the United States and neighboring Caribbean countries including Haiti. Laboratory, greenhouse, and field experiments were conducted to determine the effects of biological insecticides on M. sacchari infesting sorghum. Azadirachtin, pyrethrins, Beauveria bassiana strain GHA, Isaria fumosorosea Apopka strain 97, Chromobacterium subtsugae strain PRAA4-1T, Burkholderia spp. strain A396, and vetiver oil were compared to a conventional insecticide, flupyradifurone. In the laboratory, sorghum leaf discs were sprayed with treatment solutions and subsequently infested with M. sacchari nymphs. In the greenhouse, potted sorghum plants were sprayed with treatment solutions before or after infestation with M. sacchari nymphs. In the field, plots exposed to natural M. sacchari infestations were sprayed with treatment solutions. All insecticide treatments except I. fumosorosea and Burkholderia spp. were associated with 58–100% aphid mortality after 72 h in the laboratory, which was greater than the 20% mortality observed in the non-treated control. In the greenhouse, azadirachtin and pyrethrins were the biological insecticides associated with the lowest aphid infestation levels 7 days after treatment. Flupyradifurone was associated with the greatest mortality in the laboratory and the lowest infestation levels in the greenhouse. In the field, decreases in aphid infestation levels relative to the non-treated control were not observed although flupyradifurone was consistently associated with the lowest infestations. Our results suggest that biological insecticides including azadirachtin, pyrethrins, and B. bassiana could potentially control M. sacchari infestations in sorghum if applied under favorable environmental conditions.

Sugarcane (Saccharum interspecific hybrids) is the main source of sugar in the world. It is grown in more than 90 countries in tropical and subtropical regions. Cultivation techniques and production challenges vary by location (Rott 2017; Rott 2018). This 19-page document discusses characteristics of the sugarcane crop and pests affecting its production in Florida, which is the largest producer of sugarcane in the United States. Written by P. Rott, D. C. Odero, J. M. Beuzelin, R. N. Raid, M. VanWeelden, S. Swanson, and M. Mossler, and published by the UF/IFAS Agronomy Department, revised May 2018. https://edis.ifas.ufl.edu/pi207

The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae) is an invasive stem borer of sugarcane, Saccharum spp., and sorghum, Sorghum bicolor (L.), and poses a threat against the production of dedicated bioenergy feedstocks in the U.S. Gulf Coast region. A 2-yr field study was conducted in Jefferson County, TX, to evaluate yield losses associated with E. loftini feeding on bioenergy and conventional cultivars of sugarcane and sorghum under natural and artificially established E. loftini infestations. Bioenergy sugarcane (energycane) 'L 79-1002' and 'Ho 02-113' and sweet sorghum 'M81E' exhibited reduced E. loftini injury; however, these cultivars, along with high-biomass sorghum cultivar 'ES 5140', sustained greater losses in fresh stalk weight. Negative impacts to sucrose concentration from E. loftini injury were greatest in energycane, high-biomass sorghum, and sweet sorghum cultivars. Even under heavy E. loftini infestations, L 79-1002, Ho 02-113, and 'ES 5200' were estimated to produce more ethanol than all other cultivars under suppressed infestations. ES 5200, Ho 02-113, and L 79-1002 hold the greatest potential as dedicated bioenergy crops for production of ethanol in the Gulf Coast region; however, E. loftini management practices will need to be continued to mitigate yield losses.

The Mexican rice borer, Eoreuma loftini (Dyar), is a major pest of sugarcane (hybrids of Saccharum spp.) in Louisiana and Texas. Resistance to E. loftini was evaluated in 51 commercial and experimental cultivars of sugarcane, energycane (hybrids of Saccharum spp.), and sorghum [Sorghum bicolor (L.) Moench and hybrids of Sorghum spp.] in four replicated small plot field experiments from 2009 to 2012. A relative resistance ratio was developed to compare levels of susceptibility among cultivars based on the percentage of bored internodes and survival to adulthood. This index was able to separate cultivars into five resistance categories and provides a new method for comparing levels of resistance among cultivars. E. loftini pest pressure in 2009 was among the highest recorded with injury ranging from 55 to 88% bored internodes. Commercial sugarcane cultivar HoCP 85-845 was identified as resistant in three of four experiments, whereas HoCP 04-838 was identified as susceptible in all experiments. Of the five sugarcane cultivars in commercial production in the Rio Grande Valley of Texas, only TCP 87-3388 was categorized as resistant. Of the cultivars with potential for bioenergy production, all of the energycane cultivars demonstrated higher levels of resistance than high-biomass and sweet sorghum cultivars. Continued evaluation of cultivar resistance to E. loftini is important to development of effective integrated pest management strategies for this pest.

The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), is an invasive pest of sugarcane, Saccharum spp., rice, Oryza sativa L., and other graminaceous crops in the Gulf Coast region of the United States. Traps baited with E. loftini female sex pheromones were used to document establishment and distribution of E. loftini near sugarcane, rice, and noncrop hosts in seven southwest Louisiana parishes from 2009 to 2013. Additional field surveys documented larval infestations in commercial sugarcane and rice. After its initial detection in 2008, no E. loftini were detected in Louisiana in 2009 and only two adults were captured in 2010. Trapping documented range expansion into Cameron, Beauregard, and Jefferson Davis parishes in 2011 and Allen, Acadia, and Vermilion parishes in 2013. During the course of this study, E. loftini expanded its range eastward into Louisiana 120 km from the Texas border (≈22 km/yr). Surveys of larval infestations provided the first record of E. loftini attacking rice and sugarcane in Louisiana. Infestations of E. loftini in rice planted without insecticidal seed treatments in Calcasieu Parish reached damaging levels.

Oviposition preference and host suitability of the Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), on bioenergy and conventional cultivars of sugarcane, Saccharum spp., and sorghum, Sorghum spp., were examined in a series of greenhouse experiments. Two energycane cultivars, two sugarcane cultivars, two high-biomass sorghum cultivars, and one sweet sorghum cultivar were assessed at two phenological stages (immature and mature). Mature plants possessed greater availability of dry leaf material compared with immature plants, and all E. loftini eggs were observed exclusively on dry leaves. Oviposition did not vary among host combinations (cultivar by phenological stage); however, eggs per plant and eggs per oviposition event were numerically greater on mature plants than immature plants. In a no-choice experiment, survival from egg to adult did not vary among host combinations, with

The rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), is the most injurious insect pest in US rice production. Yield losses in excess of 25% can occur from severe infestations. Management demonstrations were conducted in the 2008, 2009, 2010, and 2011 growing seasons to evaluate the use of commercially available insecticides to control L. oryzophilus in commercial rice fields. The demonstration tests, conducted on farms throughout Louisiana, compared the efficacies of recently registered seed treatment insecticides to untreated controls and to foliar applications of pyrethroids. Efficacy was assessed by collecting root/soil core samples three to four weeks after application of permanent flood and counting numbers of larvae and pupae in core samples. Tests were replicated across locations in multiple rice-producing Louisiana parishes. Densities of larvae and pupae in core samples exceeded the larval threshold (three larvae or pupae per core sample) in over 80% of untreated plots/cuts, confirming the ubiquity and severity of this insect as a pest of rice. Use of chlorantraniliprole (Dermacor® X-100, DuPont™ Crop Protection, Wilmington, DE), thiamethoxam (CruiserMaxx® Rice, Syngenta® Crop Protection, Greensboro, NC), and clothianidin (NipsIt Inside®, Valent® USA Corporation, Walnut Creek, CA) seed treatments significantly reduced L. oryzophilus infestation compared to untreated checks. Fewer larvae and pupae were observed in rice treated with chlorantraniliprole than in rice treated with other insecticides.

Phorid flies, Pseudacteon spp. (Diptera: Phoridae), have been released in the United States since 1996 as biological control agents for imported fire ants, Solenopsis invicta Buren, Solenopsis richteri Forel, and their hybrid (Hymenoptera: Formicidae). A statewide survey was conducted in Louisiana during 2009 and 2010 to determine the distribution of Pseudacteon tricuspis Borgmeier and Pseudacteon curvatus Borgmeier, and to quantify the potential spatial association between the two species. Additionally, collected phorid flies were tested for the microsporidium Kneallhazia ( =Thelohania ) solenopsae (Knell, Allen, and Hazard), another natural enemy of fire ants, to establish an account of the pathogen’s distribution and prevalence in phorid fly populations. P. tricuspis and P. curvatus have expanded their range from four and three separate release sites, respectively, in Louisiana. By 2010, P. tricuspis and P. curvatus occupied approximately 86,600 and 111,900 km 2 , respectively. Overall, P. curvatus was more abundant than P. tricuspis , with 41.9 ± 7.3 (SE) and 9.8 ± 1.5 (SE) females, respectively, collected on average per sampling site in 2009. Spatial Analysis by Distance IndicEs (SADIE) suggested aggregation for the two phorid fly species. P. tricuspis collections were positively associated with P. curvatus collections, indicating that gaps and clusters of both species generally overlapped. K. solenopsae was detected in 22 of 64 parishes, and among 124 collection sites tested, 19% yielded positive responses for K. solenopsae . P. tricuspis males and females and P. curvatus females were found to harbor K. solenopsae . This study is the first to detect K. solenopsae in P. tricuspis .

Studies in the field and growth chamber evaluated sorghum, Sorghum bicolor (L.) Moench, hybrids for resistance to sugarcane aphid, Melanaphis sacchari (Zehntner). Hybrids were known resistant ATx2752/RTx2783, known susceptible ATx2752/RTx430, and 14 with suspected resistance. The field study was done during 2015 and 2016 at three locations in Louisiana. The study was a split-plot design with hybrids randomized to main plots and insecticidal protection from aphid infestation (sprayed versus non-sprayed) randomized to sub-plots. Seedlings of the hybrids also were evaluated in a growth chamber. In the field, hybrids that seemed susceptible (demonstrated yield benefit after application of insecticide) were ATx2752/RTx430 and DG M756B39. Hybrids with possible tolerance (many cumulative aphid days but no yield benefit from insecticide) were DG M77GB52, DG 765B, and R94153. Hybrids with possible antibiosis (few cumulative aphid days and no benefit from insecticide) were ATx2752/RTx2783, RS84353, RS9813, SP6929, SP73B12, SP7715, SPX760, SP78M30, 83P17, W-844-E, and DKS37-07. Seedlings of ATx2752/RTx2783, DKS37-07, RS9813, RS84353, SP7715, SPX17414, SPX17514, NKX760, and W-844-E were significantly less damaged by aphids feeding than was ATx2752/RTx430. In addition to field and seedling studies, four hybrids were used to evaluate reproductive potential of sugarcane aphids in a growth chamber. Suspected resistant hybrid DKS37-07, suspected susceptible hybrid M75GB39, and two intermediate hybrids P83P17 and W -844-E were used. DKS3707 was the most resistant hybrid evaluated, with reduced intrinsic rate of increase of sugarcane aphids compared to the other hybrids. M75GB39 seemed the most susceptible of the three hybrids.

The corn wireworm, Melanotus communis (Gyllenhal) (Coleoptera: Elateridae), is an important soil insect pest of Florida sugar cane (Saccharum spp.; Poaceae). The objective of this study was to determine the host plant preference of M. communis adults and larvae to weeds and sugar cane varieties found in Florida sugar cane fields. Three sugar cane varieties, 3 grass weeds, and 3 broadleaf weeds were tested for their attraction to the insects in free choice tests. After a 24 h exposure to whole plant extracts (juices), most adults were found in sugar cane varieties, followed by grass weeds, then broadleaf weeds. After a 48 h exposure to chopped roots in muck soil, most larvae were found in sugar cane varieties, followed by grass weeds, then broadleaf weeds. After a 48 h exposure to chopped roots in sandy soil, most larvae were found in sugar cane varieties, followed by broadleaf weeds, then grass weeds. Our data show that in free choice tests, both M. communis adults and larvae prefer sugar cane over weeds present in Florida sugar cane fields. Resumen El gusano del maiz, Melanotus communis (Gyllenhal) (Coleoptera: Elateridae), es una plaga importante de la cana de azucar (Saccharum spp.; Poaceae) en la Florida. El objetivo de este estudio fue determinar la preferencia de la planta hospedera de los adultos y larvas de M. communis a las malezas y variedades de cana de azucar que se encuentran en los campos de cana de azucar de la Florida. Se probaron tres variedades de cana de azucar, 3 pastos-malezas y 3 malezas de hoja ancha por su atraccion hacia los insectos en pruebas de libre eleccion. Despues de una exposicion de 24 h a extractos de plantas enteras (jugos), la mayoria de los adultos se encontraron en variedades de cana de azucar, seguidos de los pastos-malezas y luego malezas de hoja ancha. Despues de una exposicion de 48 h a las raices cortadas en el suelo de lodo, la mayoria de las larvas se encontraron en variedades de cana de azucar, seguidas de los pastos-malezas y luego las malezas de hoja ancha. Despues de una exposicion de 48 h a las raices picadas en el suelo arenoso, la mayoria de las larvas se encontraron en variedades de cana de azucar, seguidas por los pastos-malezas y luego por las malezas con hojas anchas. Nuestros datos muestran que en las pruebas de libre eleccion, tanto los adultos como las larvas de M. communis prefieren la cana de azucar en lugar de las malezas presentes en los campos de cana de azucar en la Florida. Key Words: wireworms; click beetles; ecology; Saccharum View this article in BioOne https://doi.org/10.1653/024.102.0213

FeedingbehaviorofMelanaphissacchariZehntner(Hemiptera:Aphididae)wasstudiedonsugarcane, Saccharum spp. (Poaceae), cultivars HoCP 91-555 (resistant), LCP 85-384 (moderately resistant), and L 97-128 (susceptible) using the electrical penetration graph (EPG) technique. Constitutive concentrations of total phenolics and available carbohydrates, water potential at the whole-leaf tissue level, and free amino acids (FAAs) in phloem sap extracts, and in honeydew produced by aphids fed on L 97-128 and HoCP 91-555 were determined. Cultivar did not influence time for M. sacchari to access phloem sieve elements. Total time in sieve elements was ca. two-fold greater on L 97-128 than on HoCP 91-555, whereas it did not differ from LCP 85-384 in either cultivar. The mean duration of individual events associated with phloem sap ingestion was ca. 50% shorter on both HoCP 91-555 andLCP85-384thanonL97-128.Althoughcultivareffectswerenotdetectedforlevelsoftotalphenolics, available carbohydrates, and water potential, two free essential amino acids, histidine and arginine, were absent from phloem sap in HoCP 91-555. Two free essential amino acids, leucine and isoleucine,andtwo free non-essential amino acids, tyrosine and proline, were absentfromhoneydew of aphids fed on HoCP 91-555. These results suggest that despite apparent biosynthesis of some FAAs, the absence of important FAAs in the phloem sap of HoCP 91-555 and the inability ofM. sacchari and its endosymbionts (e.g., Buchnera) to derive specific free essential and non-essential amino acids from other ingested molecules, possibly along with other unidentified factors, underlie the pest’sdecreasedphloemsapingestionand consequentlyreducedgrowthpotentialonHoCP 91-555.

BACKGROUND The systemic insecticides chlorantraniliprole (CAP) and thiamethoxam (TMX), applied to rice as seed treatments, may affect multiple life stages of the rice water weevil, Lissorhoptrus oryzophilus. Effects of CAP and TMX on adult survival, egg-laying and first- and late-instar survivals were determined by infesting plants treated as seeds with different rates of insecticides. The biological activity was related to insecticidal concentrations in leaves, shoots and roots. RESULTS CAP did not affect adult survival but decreased egg numbers and reduced the survival of the first and late instars. The greatest reduction in weevil population occurred in late instars feeding on roots. In contrast, TMX reduced adult survival and egg and larval numbers. The high biological activity of CAP on root-feeding stages was consistent with the accumulation of CAP in roots, whereas in TMX-treated plants the high activity on adults correlated with high concentrations of TMX in leaves and stems. CONCLUSIONS The differential activity of insecticides on adults suggests poor inherent potency of CAP as an adulticide and/or its limited systemicity in foliage. The distribution of insecticide in specific plant parts can be attributed to the different physicochemical properties of CAP and TMX. The field implications of this research on management of L. oryzophilus are discussed. © 2013 Society of Chemical Industry

A greenhouse study compared oviposition preference and larval development duration of a stem borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), on rice, Oryza sativa L. cv Cocodrie (Poaceae), and four primary non-crop hosts of Texas Gulf Coast rice agroecosystems. Rice and two perennials, johnsongrass, Sorghum halepense (L.) Pers., and vaseygrass, Paspalum urvillei Steud. (both Poaceae), were assessed at three phenological stages. Two spring annuals, brome, Bromus spec., and ryegrass, Lolium spec. (both Poaceae), were assessed at two phenological stages. Phenological stages represented the diversity of plant development stages E. loftini may encounter. Plant fresh biomass, dry biomass, and sum of tiller heights were used as measures of plant availability. Accounting for plant availability, rice was preferred over non-crop hosts, and intermediate and older plants were preferred over young plants. Johnsongrass and vaseygrass were 32–60% as preferred as rice when considering the most preferred phenological stages of each host. Brome and ryegrass received few or no eggs, respectively. Eoreuma loftini larval development (in degree days above developmental threshold temperatures) was fastest on rice and slowest on johnsongrass and vaseygrass. Development duration was only retarded by plant stage on young rice plants. Foliar and stem free amino acid concentrations were determined to help provide insights on the mechanisms of E. loftini oviposition preference and developmental performance.

Effects of treatment of rice seeds with an anthranilic diamide, chlorantraniliprole, and a neonicotinoid, thiamethoxam, on egg laying and first instar survival in rice water weevil, Lissorhoptrus oryzophilus Kuschel, were examined under greenhouse conditions. Exposure of adult weevils to rice (6-7 leaf stage) grown from seeds treated with chlorantraniliprole and thiamethoxam resulted in reduction in numbers of eggs and first instars. The low egg numbers by adults exposed to chlorantraniliprole-treated plants was confirmed as a sublethal effect on adults: adult survival was not impacted after 4 d of feeding on foliage from chlorantraniliprole-treated plants but the number of eggs laid by these weevils was reduced when released on untreated plants. Furthermore, a comparison of first instar emergence from chlorantraniliprole-treated plants and from untreated plants infested with weevils previously exposed to this chemical suggested that chlorantraniliprole was also reducing egg or first instar survival. In contrast, adults that fed on foliage from thiamethoxam-treated plants showed increased mortality. Possible sublethal effects of thiamethoxam on the number of eggs laid by adults were investigated by infesting untreated plants with weevils that survived exposure to thiamethoxam via foliar feeding (7 microg active ingredient/seed). Prior exposure to thiamethoxam through adult feeding reduced egg numbers. However, potential larvicidal or ovicidal effects of thiamethoxam seed treatments could not be detected in this study because of low first instar emergence from both thiamethoxam-treated plants and from untreated plants infested with weevils previously exposed to this chemical. These experiments revealed that the two seed treatments accomplish weevil control in different ways.

The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), is an invasive pest that was first introduced into southern Texas in 1980 and has been expanding its range eastward along the United States Gulf Coast. The pest attacks rice (Oryza sativa L.), sugarcane (Saccharum spp.), corn (Zea mays L.), and other graminaceous crops, and its establishment in Louisiana is expected to have severe economic impacts on crop production. Range expansion and population distribution of E. loftini were monitored with a network of 77 pheromone traps throughout southwestern Louisiana from 2013 to 2015. Eoreuma loftini was ubiquitous throughout the study region, with male moths captured in every habitat sampled. Spatial analysis revealed the population is characterized by high and low density clusters, with the greatest trap captures occurring in southeastern Calcasieu Parish and southern Jefferson Davis Parish. Trap captures in more northern regions of the study were lower than in southern parishes. Trap captures in areas where the pest has been established for >3 yr were greatest in rice habitats. The weighted mean population center moved eastward at a rate of ∼11 km per year. Human-aided movement of E. loftini was probably not involved in the eastward expansion documented during this study. Seasonal population peaks were detected in March-April, July-August, and October-November. This study indicates this species is continuing its spread eastward along the United States Gulf Coast and will likely become established throughout Louisiana within the next 20 yr.

Field experiments assessed control of the stem borers, Diatraea saccharalis (F.) and Eoreuma loftini (Dyar), in sugarcane (Saccharum spp.) with selected insect growth regulators and diamide insecticides. Tebufenozide, novaluron, chlorantraniliprole, and flubendiamide were evaluated for D. saccharalis control in four field experiments in Louisiana between 2009 and 2014. Aerial application of the same insecticides was evaluated for control of E. loftini in commercial sugarcane fields in southern Texas in 2012 and 2015. Stalk injury from D. saccharalis in nontreated plots ranged from 7.4-28.1% bored internodes across the four experiments. All insecticides reduced D. saccharalis injury compared with nontreated plots (39.1-99.4% reduction). Better control was achieved with novaluron, flubendiamide, and chlorantraniliprole than with tebufenozide. Pheromone trap-assisted scouting for E. loftini in Texas sugarcane helped to time insecticide applications. Reduced E. loftini injury was observed in diamide-treated plots (3.6-4.7% bored internodes) compared with nontreated controls (13.1%), but not in novaluron- (6.0%) or tebufenozide-treated (8.3%) plots in the 2012 experiment. Significant E. loftini injury was present prior to the aerial insecticide application in 2015, and differences in overall injury were not detected among treatments. However, chlorantraniliprole reduced injury to the top portion of sugarcane stalks. None of the insecticides improved sugar yields in 2012 or 2015. Results suggest insect growth regulators and diamide insecticides fit well in D. saccharalis management programs in Louisiana sugarcane. These chemistries also have potential to improve control of E. loftini, but more research into application strategies is needed to achieve consistent efficacy.

The Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), is an invasive pest of sugarcane, Saccharum spp., rice, Oryza sativa L., and other graminaceous crops in the United States. Traps baited with the synthetic female sex pheromone of E. loftini are used for monitoring and management of this invasive pest. However, the active space, or radius of attraction, of these traps is not known. Two field experiments examined the effect of intertrap distance on trap captures with hexagonal arrays of traps deployed in rice stubble habitat in Texas (2011) and Louisiana (2013). Trap capture increased with increasing intertrap distance. Trap interference occurred at intertrap distances ≤50 m in the 2011 experiment. Results from the experiment conducted in 2013 indicate that trap interference occurs at intertrap distances of 50 m, but not at distances ≥100 m. These results suggest that under field conditions, E. loftini pheromone traps attract males from distances of 50–100 m. The active space of pheromone traps also was examined under controlled wind conditions by direct observation of male response to detection of the female sex pheromone. Eoreuma loftini males responded to the pheromone blend by becoming active, fanning their wings, and rapidly walking in circles. The mean distance from the pheromone source at which males responded was 47.6 m. This work provides the first documentation of active space for traps baited with female sex pheromone for a crambid species, and these data will improve pheromone trap deployment strategies for E. loftini monitoring and management.

A three-treatment aerial application insecticide experiment was conducted in five commercial sugarcane, Saccharum spp., fields in south Texas to evaluate the use of pheromone traps for improving chemical control of the Mexican rice borer, Eoreuma loftini (Dyar), in 2009 and 2010. A threshold of 20 moths/trap/wk was used to initiate monitoring for larval infestations. The percentage of stalks with larvae on plant surfaces was directly related to the number of moths trapped. Reductions in borer injury and adult emergence were detected when a threshold of >5% of stalks with larvae present on plant surfaces was used to trigger insecticide applications. Novaluron provided superior control compared with beta-cyfluthrin; novaluron treated plots were associated with a 14% increase in sugar production. A greenhouse experiment investigating establishment and behavior of E. loftini larvae on two phenological stages of stalkborer resistant, HoCP 85-845, and susceptible, HoCP 00-950, sugarcane cultivars determined that more than half of larvae on HoCP 00-950 and > 25% on HoCP 85-845 tunneled inside leaf mid-ribs within 1 d of eclosion, protected therein from biological and chemical control tactics. Exposure time of larvae averaged < 1 wk for all treatments and was shortest on immature HoCP 00-950 and longest on mature HoCP 85-845. This study shows a short window of vulnerability of E. loftini larvae to insecticide applications, and demonstrates the potential utility of pheromone traps for improving insecticide intervention timing such that a single properly timed application may be all that is required.

A 2-year field study in Texas compared infestations of the stem borers Eoreuma loftini (Dyar) and Diatraea saccharalis (F.) in rice, Oryza sativa L., as affected by main crop harvest cutting height and the production of a ratoon crop. Substantial infestations (>5.6 stem borers/m2) remained in rice culms regardless of cutting height (20 vs. 40 cm). However, the 20-cm cutting height reduced E. loftini infestations by 70–81% whereas D. saccharalis infestations were not affected. Plant dissections showed that compared to D. saccharalis larvae and pupae, relatively more E. loftini immatures are located high in rice plants (>20 cm from the base of the culm). In October, the ratoon crop was more infested with stem borers than the unmanaged main crop stubble during the first year of the study. The opposite was observed during the second year. Differences in unmanaged main crop stubble phenology between the two years likely caused these differences in infestation levels. During the post-growing season, infestations in main and ratoon crop stubble decreased over the winter. After favorable winter conditions, infestations in main and ratoon crop stubble did not differ, attaining 3.3 E. loftini/m2 and 0.4 D. saccharalis/m2 by March 2008. In March 2009, rice stubble harbored 0.3 E. loftini/m2 and 0.2 D. saccharalis/m2 regardless of whether only a main crop or a main and ratoon crop had been produced. This study showed that a lower rice harvest cutting height can suppress late season E. loftini populations. Furthermore, rice stubble under favorable conditions represents a substantial overwintering habitat, thus warranting evaluation of pest management tactics targeting overwintering populations.

To assess potential interactions between Bacillus thuringiensis Berliner (Bt) proteins and jasmonic acid (JA)-induced resistance to the fall armyworm, Spodoptera frugiperda Smith & Abbot (Lepidoptera: Noctuidae), three commercial Stoneville cotton cultivars, Gossypium hirsutum L. (Malvaceae) (‘ST 475', a conventional cultivar; ‘ST 4575 BR', a Bollgard® cultivar expressing Cry1Ac protein; and ‘ST 4554B2RF', a Bollgard II® cultivar expressing Cry2Ab2 in addition to Cry1Ac), were treated with JA. Two experiments were conducted with 6-day-old S. frugiperda larvae on three cotton cultivars at two phenological stages. The first experiment was conducted under laboratory conditions and used excised cotton leaves; the second experiment was performed under greenhouse conditions on intact cotton plants. Relative growth rates (RGRs) and leaf area consumed by 6-day-old S. frugiperda larvae were determined for each combination of treatments. Overall, JA treatment and cultivars significantly impacted RGR and leaf area consumption. Significant JA treatment*cultivar interactions were observed for RGR of larvae in the laboratory experiment and for leaf area consumption in the greenhouse experiment. An additional experiment evaluated S. frugiperda neonates on the same JA and cotton cultivar combinations (at a single phenological stage) under laboratory conditions. Neonate survival was determined after 3, 5, and 10 days of feeding, and final larval weight after 10 days of feeding. Overall, JA treatment and cultivars significantly impacted final weight and survival of S. frugiperda. Significant JA treatment*cultivar interactions were observed for final weight and on overall survival of S. frugiperda. Combination of the cotton tissue expressing pyramided Bt proteins with JA treatment demonstrated the greatest negative impact on larval development. Apparent synergism between Bt proteins and JA-induced resistance emphasizes that traditional host plant resistance has a role to play in combination with Bt technology.

The Mexican rice borer, Eoreuma loftini (Dyar), is the key pest of sugarcane, Saccharum hybrids, in south Texas, having largely displaced the sugarcane borer, Diatraea saccharalis (F.), and it is moving into rice- and sugarcane-growing areas of east Texas and Louisiana. While a number of alternative weed and crop hosts have been reported, the extent to which they might support Mexican rice borer populations is unknown. This study involved choice assays that compared oviposition preference for and larval infestations of five mature graminaceous weed species. Levels of infestation between sugarcane and corn, Zea mays L., crop hosts and between corn and sorghum, Sorghum bicolor (L.) Moench, were also assessed. We determined that the average number of larval entry holes in sudangrass stems was ≥2.5-fold more than for any of the other four weed host plants, that corn had ≥5.9-fold more larval entry holes than sorghum and ≥8.2-fold more than sugarcane. Greater oviposition and infestation of one non-crop host over another was not related to numbers of stems per plant, but was associated with the greater stem diameter and abundance of dry leaf tissue found in Sudangrass, Sorghum bicolor (L.) Moench ssp. drummondi (Nees ex Steud.) de Wet & Harlan, johnsongrass, S . halepense (L.) and barnyardgrass, Echinochloa crus-galli (L.) P. Beauv.; relative to the other weed species in this study. In terms of the crop plants, stalk diameter and quantity of dry leaf tissue were not associated with numbers of eggs or larval entry holes in the choice assays between corn and sorghum, and between sugarcane and corn. While corn has been known as a host of the Mexican rice borer for at least 84 yr, its role in area-wide population dynamics and control efforts has likely been greatly underestimated.

Sugarcane (Saccharum L.) in Louisiana is colonized by the sugarcane aphid, Melanaphis sacchari (Zehntner), and the yellow sugarcane aphid, Sipha flava (Forbes). Five commercial sugarcane cultivars, ‘LCP 85-384′, ‘HoCP 91-555′, ‘Ho 95-988′, ‘HoCP 96-540′, and ‘L 97-128′, representing >95% of Louisiana's sugarcane-growing area, were assessed under southern Louisiana field conditions for numbers of the two aphid species. Biweekly sampling during 2007 and 2008 growing seasons indicated cultivar and time effects on aphid frequency. Aphid population peaks occurred during June and July and then crashed. M. sacchari was more abundant than S. flava on almost all cultivars and on all sampling dates during both years of the study. HoCP 91-555 was found to be the most resistant compared with the susceptible Ho 95-988 and L 97-128 cultivars. HoCP 91-555 might be useful in areas of high aphid pressure, and as a source of resistance in cultivar development programs.

A 2-year field cage experiment was conducted in Beaumont, Texas to estimate parasitism of sugarcane borer, Diatraea saccharalis (F.), by Cotesia flavipes (Cameron) on rice. A lab experiment showed that the number of hosts parasitized per female per day reached a maximum (0.961) at 28 °C. Parasitized larvae recovered from the field experiment produced an average of 27.9 ± 19.1 ( x ¯ ± s.d.) parasitoids, with a 2.57:1 (female/male) sex ratio. A cohort-based age-structured model was developed to simulate the population dynamics and economic impact of sugarcane borer and C. flavipes in rice, as affected by overwintering larval density, timing and rate of parasitoid aerial release, and year-to-year climate (temperature and rainfall). The results suggest the cumulative seasonal damaging larval density (3rd or later instars) is negatively correlated with winter temperature, while maximum parasitoid density and maximum proportion parasitized are positively correlated with the cumulative seasonal damaging larval density. C. flavipes was most effective when released 40 or 50 days after rice planting, with simulated yield loss reduced by up to 50.9% when the release rate was 10 females and 4 males m−2. The maximum simulated economic benefit ($59.48 ha−1) is ca. 6.7% of that provided by insecticide-based control, which occurred when the release rate was 1 female and 0.4 males m−2. The inability of C. flavipes to provide economic control in temperate-subtropical areas is due to its high rearing cost, a low effective search rate, a low maximum number of hosts parasitized per female, and failure of the spring emerging parasitoids to find hosts.

On-farm field experiments were conducted in 2004 and 2007 to assess the suitability of novaluron, a chitin synthesis inhibitor, for sugarcane borer, Diatraea saccharalis (F.), management in Louisiana sugarcane (Saccharum spp. hybrids). Aerial insecticide applications reproducing commercial production practices were made when D. saccharalis infestation levels exceeded a recommended action threshold. In addition to decreased D. saccharalis infestations, 6.3 – 14.5-fold reductions in end of season injury, expressed as the percentage of bored sugarcane internodes, were observed in plots treated with novaluron. D. saccharalis control in novaluron plots was equivalent to (P > 0.05) or better (P 0.05) decreases in predaceous and non-predaceous soil-dwelling non-target arthropods were associated with insecticides. However, numerical trends for decreases in immature crickets associated with novaluron and gamma-cyhalothrin were recorded in 2007. Our data suggest that novaluron will fit well in Louisiana sugarcane integrated pest management.

Twelve thousand to 16,000 ha of Louisiana sugarcane (Saccharum spp.) fields were flooded by saltwater from the Hurricane Rita storm surge in September 2005. A four treatment, 12-replication study comparing storm surge flooded and nonflooded plant and ratoon sugarcane fields was conducted during summer 2006 to assess sugarcane borer, Diatraea saccharalis (F.), pest severity, pest control actions, and soil-associated arthropod abundance and diversity. Even with a significant 2.4-fold increase in the average number of insecticide applications used for D. saccharalis management in flooded fields, growers still incurred higher injury. A significant 2.8-fold reduction in the predaceous red imported fire ant, Solenopsis invicta Buren, was associated with the storm surge, whereas no reduction in abundance of other soil-associated arthropods was recorded. Arthropod diversity measured by the Shannon diversity index significantly increased by a factor of 1.3 in sugarcane fields flooded by the storm surge. Increase in D. saccharalis pest severity associated with the storm surge caused an estimated loss in revenue between $1.9 and $2.6 million to the Louisiana sugarcane industry for the 2006 production season.

A field experiment was conducted at the LSU AgCenter Dean Lee Research Station in Alexandria, LA, to evaluate insecticides for management of sweetpotato soil insect pests, including BCB and SCB. In addition to an untreated check, three insecticide treatments were assessed in a RCB design with four blocks and one replicate per block. Plots were three rows wide (38-inch centers) and 35 ft long. A CO2-pressurized backpack sprayer calibrated to …