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KEYWORDS: RNA interference, tyrosine hydroxylase, double-stranded RNA, Plutella xylostella, pest Management, interferencia de ARN, tirosina hidroxilasa, ARN de doble cadena, control de plagas
Cruciferous vegetables are severely damaged by infestation of the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae). Successful utilization of RNA interference (RNAi) in insect pest management programs depends on various factors, such as target gene, mode of double-stranded RNA (dsRNA) delivery, frequency of application, and development stage of the target insect. Among these factors, selection of the target gene is crucial to the success of RNAi-based programs. In the present investigation, an attempt was made to assess the potential of tyrosine hydroxylase (TH) as a target gene, which is a key regulator in the biosynthesis of 3,4-dihydroxyphenylalanine (DOPA). DOPA is a precursor for agents that function in neurotransmission, melanization, sclerotization of the cuticle, and immune responses in insects. Here, we provided to diamondback moth larvae 3 concentrations (1.04, 2.08, and 3.12 μg/cm2) of cognate dsRNA coated on discs of cabbage leaf, the natural diet for the larvae. We recorded the influence of the dietary dsRNA on TH transcript levels, larval growth, and larval survival rate. The dietary dsRNA led to reduced target gene transcript level and larval feeding level, and caused larval mortality in a concentration-dependent manner. These results demonstrate that the TH gene has potential as a target gene for RNAi-mediated management of P. xylostella.
Pedro Figueroa-Castro, Héctor González-Hernández, José Luis Carrillo-Sánchez, Juan Fernando Solís-Aguilar, José Ignacio del Real-Laborde, Ramón Rubio-Cortés, Julio C. Rojas
The weevil Scyphophorus acupunctatus Gyllenhal (Coleoptera: Cuculionidae) is the most important insect pest of wild and cultivated agaves worldwide. This weevil causes direct damage while feeding and egg laying on host plants, and indirect damage due to the wounds on agave tissue that may serve as an entry for plant pathogens. Sampling and control of this weevil is complicated because of its cryptic habits. Thus, the use of synthetic aggregation pheromone-baited traps may be a useful tool for monitoring or control of this pest. The attraction of agave weevil to pheromone traps is synergized by the presence of host plant tissue. In this study, we evaluated the effect of the amount of fresh agave tissue and bagging of the plant tissue on the capture of S. acupunctatus with pheromone-baited traps in a blue agave crop. The highest captures of weevils were obtained in traps baited with the synthetic pheromone plus 400 g of agave tissue. Weevil capture rate was increased when the food bait was placed into a plastic bag or plastic container with holes as compared with unbagged food bait.
Phytoplasmas are wall-less bacteria, unculturable in vitro, and transmitted primarily by leafhoppers (Cicadellidae). Maize bushy stunt disease has been linked to phytoplasmas belonging to the16SrI-B subgroup and vectored by leafhoppers in the genus Dalbulus spp. (Hemiptera: Cicadellidae). The recent detection of maize bushy stunt affecting native corn, maize, in the southeast highlands of Mexico motivated the survey to determine which leafhoppers were associated with this crop during the 2013-2014 growing season. We detected 7 leafhopper genera in native corn cultivated 2,400 meters above sea level (masl), with 4 of these genera reported for the first time in corn. Based on external morphology and male genitalia, we identified Idiodonus wickhami (Ball) (Hemiptera: Cicadellidae), Amblysellus grex (Oman) (Hemiptera: Cicadellidae), Empoasca fabae (Harris) (Hemiptera: Cicadellidae), Macrosteles quadrilineatus (Forbes) (Hemiptera: Cicadellidae), and Dalbulus elimatus (Ball) (Hemiptera: Cicadellidae). We were not able to identify the leafhopper genera Graphocephala (Hemiptera: Cicadellidae) and Erythridula (Hemiptera: Cicadellidae) to species because of a lack of male leafhoppers. Nymphal stages of I. wickhami also were identified using taxonomic and molecular tools. The presence of adults and nymphs of I. wickhami in the crop suggest that native corn grown in the southeast highlands of Mexico is a feeding and reproductive host for I. wickhami. Moreover, I. wickhami was found infected with 16SrI-B strain maize bushy stunt-Ver while D. elimatus, a well-known maize bushy stunt phytoplasma vector, was found infected with the 16SrI-B strain maize bushy stunt-Pueb.
Paulo Roberto Ribeiro Mesquita, Jairo Torres Magalhães-Junior, Maiara Alexandre Cruz, Hugo Oliveira Novais, Jânio Rodrigo Jesus Santos, Sergio Lemos Carvalho, Frederico de Medeiros Rodrigues, Cristiane de Jesus Barbosa, Iara Sordi Joachim Bravo, Antonio Souza Nascimento
The West Indian fruit fly, Anastrepha obliqua Macquart (Diptera: Tephritidae), is an economically important fruit pest in the Americas. Food attractants are used as bait in traps for monitoring the population of flies in orchards, but their effectiveness differs with location, fruit fly variety, and the type of trap deployed. In this work, we tested the effectiveness of a hydrolyzed protein, BioAnastrepha®, and a yeast extract, Bionis YE MF®, under field conditions and in a laboratory bioassay and identified the main volatile compounds emitted from such mixtures. Hydrolyzed protein and yeast extract were attractive in a wind tunnel, but in the field, hydrolyzed protein was not attractive and only pure yeast extract and yeast extract with sugar were attractive for A. obliqua. Sugar alone was not attractive to the flies in either experiment. Yeast extract itself is a good attractant for A. obliqua. The addition of sugar, however, will stimulate feeding, which could be useful in insecticide-bait sprays.
KEYWORDS: artificial diet, larval development, old world bollworm, standardization of breeding, molecular characterization, dieta artificial, desenvolvimento larval, padronização de criação, caracterização molecular
We performed molecular and biological characterizations of immature stages of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) using insects from different states in Brazil, and different host plants. Three laboratory colonies of H. armigera were established with insects from the states of São Paulo, Bahia, and Distrito Federal, that were collected from citrus, cotton, and corn, respectively. For each colony, microsatellites were used to assess genetic similarity among insects. The biology of the immature stages from each colony also was compared under laboratory conditions (25 ± 1 °C, 70 ± 10% RH, 14:10 h [L:D] photoperiod). Microsatellite analysis revealed genetic variability in sampled specimens and that the grouping of individuals was independent of the geographic origin. The utility of an artificial diet was validated during the comparative biology experiment, and the ingredients of the artificial diet were analyzed for purity, particle size, and the presence and quantity of aggregates. The mean development times of the larvae and pre-pupae from the 3 locations were similar, and mean total development time (egg to adult) was not significantly different.
The stingless bees of tribe Meliponini are efficient pollinators playing a key role in ecosystem services. Frieseomelitta Friese (Hymenoptera: Apidae: Meliponini) includes 16 Neotropical species, of which 6 are found in the state of Bahia, northeastern Brazil. In order to provide a refined cytotaxonomic analysis, we characterized the heterochromatin composition and variation among 6 Frieseomelitta species. All species shared a diploid number (2n) of 30 chromosomes. Frieseomelitta dispar Moure, Frieseomelitta francoi Moure, and Frieseomelitta meadewaldoi Cockerell (Hymenoptera: Apidae), presented GC-rich heterochromatic regions while Frieseomelitta sp.n., Frieseomelitta varia Lepelitier, and Frieseomelitta doederleini Friese (Hymenoptera: Apidae) were characterized by homogenous heterochromatin, without evidence of AT or GC-rich sites. The number and location of microsatellite repeats mapped by fluorescence in situ hybridization revealed interspecific variation. These data were useful to identify each species based on chromosomal markers, and represent important tools for clarifying the interspecific differentiation among Frieseomelitta species and for understanding the genome evolution in bees as a whole.
Robson José Esteves Peluzio, Bárbara Monteiro de Castro e Castro, Bruno Pandelo Brügger, Angelica Plata-Rueda, Flávio Lemes Fernandes, Ricardo Henrique Silva Santos, Carlos Frederico Wilcken, José Cola Zanuncio
Podisus nigrispinus Dallas (Hemiptera: Pentatomidae) is reared in the laboratory and released for biological control programs. The objective of this study was to evaluate, using life tables, P. nigrispinus development when fed on Anticarsia gemmatalis Hübner (Lepidoptera: Erebidae) reared on different diets, or with the alternative prey Tenebrio molitor L. (Coleoptera: Tenebrionidae). Podisus nigrispinus was reared with soybean plants supplemented with A. gemmatalis caterpillars fed an artificial diet (T1), with soybean plants supplemented with caterpillars fed soybean leaves (T2), with soybean plants supplemented with T. molitor pupae (T3), or with soybean plants supplemented with A. gemmatalis pupae from caterpillars fed soybean leaves (T4). The duration of instar V and of the total nymph period of this predator were longer when preying caterpillars fed soybean plants (T2). The survival of the nymph stage was greater when fed on soybean plants with T. molitor pupae (T3), with A. gemmatalis caterpillars fed on soybean plants (T2), and with A. gemmatalis caterpillars fed an artificial diet (T1), relative to A. gemmatalis pupae from caterpillars fed soybean leaves (T4). The weights of instar V nymphs and of adult male and female P. nigrispinus were greater when fed with T. molitor pupae (T3). Life table parameters showed population growth for this predator in all treatments except when fed with A. gemmatalis pupae (T4). The net reproductive rate (Ro), the duration of a generation (DG), and time to double the population (TD) of P. nigrispinus displayed higher values when fed with caterpillars cultured on soybean (T2) and with T. molitor pupae (T3). The rates of increase (λ and rm) value were positive in all treatments. Anticarsia gemmatalis pupae from caterpillars fed soybean leaves (T4) are inadequate prey for P. nigrispinus. Anticarsia gemmatalis caterpillars fed soybean leaves (T2) or T. molitor pupae (T3) are a more suitable food for rearing this predator than A. gemmatalis caterpillars fed an artificial diet (T1).
Diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is the dominant insect pest of cruciferous crops around the world, and is resistant to many chemical insecticides. In this study, we measured the chemical composition and bioactivity of Artemisia lavandulaefolia DC (Asteraceae) essential oil on P. xylostella. The essential oil was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry. A total of 35 constituents were identified. The principal compounds were: eucalyptol (35.60%), (R)-4-methyl-1-(1-methylethyl)-3-cyclohexen-1-ol (16.25%), π-trimethyl-3-cyclohexene-1-methanol (6.83%), 3-methyl-6-(1-methylethyl)-2-cyclohexen-1-one (6.63%), and (1S)-1,7,7-trimethyl-bicyclo[2.2.1] heptan-2-one (4.72%). The LD50 contact toxicity of the essential oil to immature P. xylostella was estimated at 0.045 μL per larva. Artemisia lavandulaefolia oil exhibited fumigant toxicity against P. xylostella adults with an LC50 of 0.113 mg per L after 12 h and also provided 80 to 100% repellency at a 1% v/v concentration.
The brown marmorated stinkbug, Halyomorpha halys, is an invasive insect pest in North America and Europe that attacks crop species and causes substantial economic damage. To evaluate the genetic diversities and distributions of different H. halys populations in East Asia, North America, and Europe, COI sequences obtained from 79 new specimens from Korea and 10 from the USA were compared with 725 existing COI sequences. In total, 45 haplotypes were detected in populations from 10 countries. Sixteen haplotypes from Korea (H34–H49) and 2 from the USA (H50 and H51) were novel. Korean populations exhibited the 2nd highest diversity among the 10 countries, with only Greece exhibiting higher diversity. Haplotype H22 was prominent in Korea, H1 was prominent in China, Greece, Hungary, Italy, Canada, and USA, and H3 was prominent in France and Switzerland. Of the 18 haplotypes found in Korea, 1 was shared with China (H2) and 1 with Greece (H22). Haplotype diversity patterns showed that Korean populations were genetically distinct from populations in China, Europe, and North America. This suggested that populations in Europe and North America arose through multiple invasions from China and that (with the exception of Greece), Korean populations did not spread to other countries. This study represents a comprehensive analysis of H. halys populations in Korea and places these populations in a global context that includes other native populations in East Asia and invasive populations in Europe and North America.
The tropical fire ant, Solenopsis geminata (F.) (Hymenoptera: Formicidae), is an invasive pest throughout most of the tropics, especially on islands in the Pacific. Natural enemies such as the fire ant decapitating fly, Pseudacteon bifidus Brown and Morrison (Diptera: Phoridae), offer the potential for use as self-sustaining biological control agents provided they are host specific and do not cause other unintended problems. This paper provides details of sequential field and laboratory choice tests with host and non-host ants, as well as tests with a variety of potential food items to which adult flies may be attracted. Results of these tests showed that P. bifidus flies are highly host specific to tropical fire ants and that they are not attracted to ants in other genera. Even other species of fire ants are unlikely to be parasitized by this fly in the field. Furthermore, tests with a variety of food items demonstrated that P. bifidus is not likely to be a nuisance to humans because it is not attracted to carrion, feces, fruits, or various kinds of human food items. In short, P. bifidus would not likely cause unintended problems if it were used as a self-sustaining biological control agent of invasive tropical fire ants.
A study was conducted in 4 plots within a newly established olive grove in Florida to assess surveillance methods for insects present around the period of olive bloom. Over 99% of thrips collected were Frankliniella bispinosa (Morgan) (Thysanoptera: Thripidae), with occasional collections of predacious Leptothrips pini (Watson) (Thysanoptera: Phlaeothripidae). Collections of thrips using sticky traps or in tap or brush samples were high at the time of bloom, with low numbers before bloom and very low numbers after bloom. No differences in collections were seen among plots for thrips numbers when sampled using sticky cards. However, one plot had higher thrips numbers when sampled using tap and brush samples. Overall, and especially during bloom, blue sticky traps were most attractive, followed by yellow and then white sticky traps. Clear (color-free) traps collected the fewest thrips. Using tap samples, more thrips were collected on the edges than in the middle of the grove. Highly localized high densities of thrips were detected by the tap samples. Although sticky traps were highly effective for collecting thrips, only tap samples detected the localized hot spots.
In this study we assessed the effect of pre-exposure to host sex pheromones and plant volatiles on the response of virgin males and mated females of Copitarsia decolora (Guenée) (Lepidoptera: Noctuidae), by using glandular extracts of virgin females and host volatile extracts in bioassays conducted in a wind tunnel. Four-day-old insects, either virgin males pre-exposed to glandular extracts of the sex pheromone or mated females pre-exposed to host volatiles, were evaluated 2, 24, and 48 h after pre-exposure. In both sexes, pre-exposure and a subsequent attraction response at 2 h resulted in an inhibitory effect on the olfactory response. Recovery in the olfactory response was observed at 24 and 48 h; however, it took males a shorter activation time when compared with control insects. A brief pre-exposure of insects provoked a short-term (2 h) inhibition of the response to the olfactory stimulus. Consequently, as an integral part of strategies for the management of this pest species, the study of the ecological implications of such inhibition should be considered.
Hydrilla, Hydrilla verticillata (L.f.) Royle (Hydrocharitaceae), is an invasive aquatic macrophyte found in fresh water. The introduction of hydrilla by the aquarium plant trade has led to its invasion throughout much of the southern US and its current listing as a federal noxious weed. Hydrilla employs many pathways of reproduction and once established can rapidly fill the water column, impeding recreation and negatively affecting the environment. Waterways infested with hydrilla typically experience matting of vegetation at the surface that results in less light penetration, and changes in dissolved oxygen levels, which disturb native species richness and diversity. Efforts to minimize hydrilla populations include using biological control agents such as the hydrilla tip mining midge, Cricotopus lebetis Sublette (Diptera: Chironomidae). The larvae of C. lebetis feed on the apical meristem of hydrilla tips, disabling further vertical growth and forcing growth into a branched horizontal direction. Currently, a colony of C. lebetis is being mass-reared to augment midge populations throughout hydrilla-infested waters. In order to maintain colony viability for effective releases, midge eggs must be collected and placed on hydrilla before larvae exhaust endogenous nutrient reserves. To understand the effects of larval starvation on survival and subsequent development to adult eclosion, neonates at 0, 1, 2, and 3 d post-hatch were studied with and without access to food. Midge survival and adult eclosion decreased significantly after continued starvation post-hatch. Larvae starved for 2 d post-hatch did not eclose. Highest survival to adult eclosion occurred when midge larvae were placed on hydrilla as soon as they hatched (48 h post-oviposition). This study highlights fundamental information necessary for efficient midge rearing for effective biological control of hydrilla.
In addition to being a structural pest, the Asian subterranean termite, Coptotermes gestroi (Wasmann) (Blattodea [Isoptera]: Rhinotermitidae), appears to be a serious pest of the native urban tree canopy of southeastern Florida. Asian subterranean termite colonies have the ability to cause feeding damage to a wide range of trees comprising the urban canopy, some potentially to a lethal level. Slash pine, Pinus elliottii Engelm. (Pinaceae), appears to be particularly susceptible to C. gestroi feeding damage, as the termites feed primarily on the outer layers of the wood, immediately beneath the bark, wounding live tissues and ultimately girdling the tree. In comparison, hardwood trees such as live oak, Quercus virginiana Mill. (Fagaceae), sustain damage to the heartwood at the center of the tree, resulting in a central cavity, but leaving the live tissue intact. Our results suggest that C. gestroi has the potential to kill pine trees within the local urban canopy, which may irreversibly alter the urban forest composition. In addition, many large trees in our survey have been consumed partially by mature C. gestroi colonies, potentially compromising their structural integrity. Some large oak trees that were extensively hollowed out by C. gestroi collapsed in 2017 during hurricane Irma. We discuss different potential approaches for protecting susceptible trees, as a comprehensive IPM strategy is needed for this invasive termite pest species, especially in the complex and extensive urban forest of southeastern Florida.
Monthly parasitism rates and oviposition behavior of tachinid flies parasitizing Dichelops furcatus (F.) (Hemiptera: Pentatomidae) adults were determined. Weekly surveys, with duration of 2 hr each, were performed during 1 yr at the National Wheat Research Center in Passo Fundo, Rio Grande do Sul, Brazil. Stink bugs were collected from different plants and from crop residues, and taken to the laboratory to examine whether or not they were parasitized (presence of fly eggs). Number and egg allocation (dorsal and ventral surfaces) on stink bug bodies were determined. Stink bugs were kept inside plastic boxes to collect the parasitoid pupae and to identify the flies after emergence. Four tachinid (Diptera: Tachinidae) species were obtained as follows: Ectophasiopsis gradata (Wiedemann), Cylindromyia sp., and Gymnoclytia sp. 1 and sp. 2. The parasitism rate ranged from 2.5 to 7.0% (during Apr–Aug), and from 12 to 59% (Sep–Mar). Eggs were laid preferably on the dorsal surface (82%), and the majority of them (42%) under the wings. The number of fly eggs per parasitized stink bug ranged from 1.0 to 2.0.
The Puyehue Cordon Caulle volcanic outbreak from 2011 affected the Patagonian Region of Argentina. The insecticidal effect of volcanic ash, as well as other inert dusts, has been proven to occur by contact exposure, disturbing the water balance in insects. However, little has been studied on sublethal effects of volcanic ash or inert dusts on coleopterans through chronic dietary intake. The aim of this study was to gain further understanding on the impact of volcanism on tenebrionid larvae by studying the chronic dietary exposure of volcanic ash in laboratory bioassays. For this purpose, Tenebrio molitor L. (Coleoptera: Tenebrionidae), an insect pest of stored grain, was used as an experimental model organism. Larvae were fed with flour discs prepared with volcanic ash at 500, 1,000, 5,000, 30,000, and 50,000 ppm. Chronic dietary intake of volcanic ash was dose-dependent, with effects visible after long-term exposure (15 and 27 d). Mortality was observed at the two highest concentrations tested (30,000 and 50,000 ppm). At the lower concentrations (500, 1,000, and 5,000 ppm), sub-lethal effects were observed, including larval size decrease, weight loss, and reduction in the number of molts. Thus, chronic dietary intake of volcanic ash causes adverse effects on T. molitor larvae that leads to mortality at high concentrations and decrease of larval size at sub-lethal concentrations.
Flower thrips (mainly Frankliniella spp.) (Thysanoptera: Thripidae) are common in Florida strawberries, causing bronzed fruit and reduced yields. As control relies on just a few insecticides, there is a need to evaluate novel management options and insecticides. The entomopathogenic nematode Steinernema feltiae (Filipjev) (Rhabditida: Steinernematidae) has been shown to be effective on flower thrips larvae in other plants, and the new insecticide sulfoxaflor has been effective on thrips in other crops. In winter 2016, S. feltiae was evaluated at 2 foliar application rates (2.47 and 4.94 billion infective juveniles per ha) in combination with and without the insecticide spinetoram by counting thrips in strawberry flowers and assessing numbers of damaged fruits. A second experiment was conducted to compare sulfoxaflor, spinetoram, and S. feltiae applications based on flower thrips thresholds. High and low S. feltiae rates did not reduce or suppress thrips and did not reduce fruit damage. Sulfoxaflor reduced thrips by 60 to 70% compared to the reduction caused by spinetoram. Hot, dry conditions likely limited the survival and effectiveness of S. feltiae. Sulfoxaflor appears to be a promising insecticide for flower thrips, and may reduce reliance on spinetoram by strawberry producers.
The field cockroach, Blattella vaga Hebard (Blattodea: Ectobiidae), is native to central Asia including Afghanistan, India, Iran, Pakistan, and Sri Lanka. It was described first in 1935; however, from specimens collected in Arizona and California. Since then, the distribution of B. vaga has slowly increased along the southern United States and Mexican border, apparently following major interstate highways. We report the first record of B. vaga from Mobile, Alabama, and suggest that this species will spread to Florida and possibly northward into Georgia and South Carolina. The identification was confirmed using morphological, chemical, and molecular methods. We suggest that when possible, multiple independent methods should be used to confirm species identifications.
Horticulture crops are economically important in the state of Guerrero, México. However, fruit flies (Diptera: Tephritidae) are the most important limiting factor due to the direct damage they cause to fruit crops such as mango (Mangifera indica Lour. [Anacardiaceae]), sweet citrus, guava (Psidium guajava L. [Myrtaceae]), and some Sapotaceae species. The aim of this study was to define fruit fly species diversity and population dynamics in the municipalities of Tetipac and Atoyac de Alvarez, Guerrero. Fruit flies were obtained from the official trapping system of the National Campaign against Fruit Flies (NCFF) of the National Directorate for the Protection Plan, SENASICA, SAGARPA, in the state of Guerrero. Eleven fruit fly species were detected: Anastrepha ludens (Loew), A. striata Schiner, A. obliqua (Macquart), A. serpentina (Wiedemann), A. spatulata Stone, A. bicolor (Stone), A. dentata (Stone), A. chiclayae Greene, Toxotrypana curvicauda Gerstaecker, Rhagoletis ramosae Hernandez-Ortiz, and Zonosemata cocoyoc Bush (all Diptera: Tephritidae). In Tetipac, we recorded the greatest abundance of fruit flies (S = 10) and also the highest values for the Shannon-Wiener (H′) diversity index and Simpson (λ) index (H′ = 1.30; λ = 0.68). Total fruit fly abundance was 1,546 individuals (Tetipac 1,085; Atoyac de Alvarez 461). The main peak populations of fruit flies were recorded from Feb to Oct, coinciding with the phenological stages of fruiting, ripening, and harvesting of fruits of each area. The host range of the most predominant fruit fly species was confirmed by recording flies emerging from fruit. Anastrepha obliqua was detected in mango and jobo (Anacardiaceae) collected in Tetipac and mango from Atoyac de Alvarez. The fruit fly parasitoid Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae) was recorded only in Tetipac emerging from fruit flies infesting mango, guava and jobo.
Chemical inducers have relevant roles in activating the defense responses of plants to insects. The present research examines the defense mechanisms of Brachiaria (Poaceae) grasses and sugarcane cultivars exposed to exogenous of chemical inducers with and without injury due to Mahanarva spectabilis (Distant) (Hemiptera: Cercopidae). Plants were subjected to herbivory by spittlebug nymphs and to 3 chemical inducers: salicylic acid, silicic acid, and nitric oxide. Dry matter was calculated at 15 d after induction, and extraction and quantification of phenolic compounds were performed. The phenolic content and percentage of dry matter of the plants was evaluated by analysis of variance, and means were compared by the Scott-Knott test (P < 0.005). Changes in dry matter were assessed with regard to interactions between inducers and Brachiaria roots and sugarcane shoots. Salicylic acid, silicic acid, and nitric oxide, as well as attack by M. spectabilis, triggered alterations in phenolic contents. The highest and lowest concentrations of phenolic compounds were found in the standard cultivar susceptible (cv. Basilik) and resistant to the insect pest (cv. Marandu), respectively. However, the results showed that inducers failed to impact the defense mechanism of Brachiaria cultivars and that assessment of total phenolic compounds is not the most adequate approach for measuring resistance in these cultivars. In sugarcane, inducers did not appear to act on defense mechanisms, though the resistant cultivar did exhibit a greater phenolic content. Hence, the use of the above chemical inducers is not useful for triggering resistance in Bracharia and sugarcane.
The mole crickets Neoscapteriscus borellii (Giglio-Tos) and Neoscapteriscus tenuis (Scudder) (Orthoptera: Gryllotalpidae) are recorded for the first time in Bahia State, Brazil in tobacco (Nicotiana tabacum L. [Solanaceae]) plantations. Insects were collected using pitfall traps in tobacco plantations in the municipalities of Cruz das Almas, Governador Mangabeira, and Muritiba, Bahia, Brazil. The presence of nymphs and adults of these species suggests that mole crickets may threaten tobacco productivity due to the root damage caused by excavation and/or feeding by these subterraneous insects.
Claubert Wagner Guimarães de Menezes, Sollano Rabelo Braga, Sebastião Lourenço de Assis Júnior, Marcus Alvarenga Soares, Wiane Meloni Silva, Wagner de Souza Tavares, José Cola Zanuncio
Abarema villosa Iganci & M. P. Morim (Fabales: Fabaceae) is a medicinal and ornamental plant in the Cerrado biome of Brazil. Poekilloptera phalaenoides L. (Hemiptera: Flatidae) is a polyphagous pest that imbibes plant sap. This insect was observed on A. villosa plants in Diamantina, Minas Gerais State, Brazil. Poekilloptera phalaenoides uses A. villosa plants as a site for shelter, feeding, and reproduction. This is the first report of A. villosa as a host of P. phalaenoides.
Adding plant-based nutritional resources to a landscape may help to recruit and retain predaceous and parasitic arthropods. As a first step in determining whether the addition of nectary plants can increase the abundance and diversity of biocontrol agents of Diaphorina citri and psyllid suppression in urban and unmanaged landscapes in southern Florida, the occurrence of coccinellids was recorded on a native poinsettia, Euphorbia heterophylla (L.) and partridge pea, Chamaecrista fasciculata (Michx.) Greene, a native legume. Thirteen coccinellid species consisting of a total of 663 specimens were collected over the course of the 8-mo long sampling period. A total of 464 specimens comprising 12 species were collected from E. heterophylla from Jun to Oct, with 3 species, Coelophora inequalis, Cryptolaemus montrouzieri, Harmonia axyridis, comprising the majority of species collected. A total of 199 specimens comprising 6 species were collected from C. fasciculata from Sep to Feb. Nearly 80% of the specimens collected from C. fasciculata were C. montrouzieri.
KEYWORDS: plant-insect interactions, toxic compounds, weed biocontrol, sex-biased herbivory, Interacciones planta-insecto, compuestos tóxicos, control biológico de malezas, herbivoría sesgada por el sexo
Brazilian peppertree, Schinus terebinthifolia Raddi (Sapindales: Anacardiaceae), is an ornamental dioecious shrub introduced from South America that has become one of the major invasive weeds in Florida. Anecdotal evidence from the literature suggests that crushed leaves from female plants produce a more pungent aroma, indicating these plants may be better defended chemically than their male counterparts. To test this hypothesis, we compared the performance (adult feeding and survival) of the South American stem boring weevil Apocnemidophorus piptzi (Faust) (Coleoptera: Curculionidae) by caging insects on foliage collected from both male and female Brazilian peppertree plants. Results showed that weevils consumed significantly less leaf tissue from female plants compared to male plants. Furthermore, the LT50 (average time required to cause 50% mortality of the weevils) was significantly shorter when weevils fed exclusively on female leaf tissue. Our findings confirmed male-biased plant herbivory on Brazilian peppertree by one of its folivorous natural enemies.
Plagiolepis alluaudi, of Madagascar origin, is an invasive ant species in many tropical localities around the world. Here we report the first record of an established population of P. alluaudi in the continental Americas. This established population is thriving in a neighborhood of Fort Lauderdale, Florida, USA, and it raises concerns that this new invader may become another pest in the crowded landscape of Florida's invasive ant fauna. Taking into account the local densities of this ant in the area, it is possible that it was established for several years before being detected. It has the potential to be a household nuisance, and may also have an impact on urban ecosystems of southeastern Florida. It is expected that its own movement and human activity will further spread P. alluaudi beyond its current range.
Euplatypus parallelus (Coleoptera: Curculionidae) is a neotropical ambrosia beetle that that is rapidly spreading around the world. It has been recorded from over 80 host trees and is implicated as a primary pest attacking rubber trees and rosewood. Here, we report the first country record and successful establishment of the species in Hainan, China. Currently, E. parallelus does not appear to act as a destructive forest pest in Hainan.
Food baits are a key component in trapping programs to detect infestations of pest species of tephritid fruit flies (Diptera: Tephritidae). Traditionally, a torula yeast-borax slurry has been used most frequently, but the recently developed food bait CeraTrap, consisting of hydrolyzed animal protein, has proven more attractive to certain tephritids. This study compared field captures of melon flies, Zeugodacus cucurbitae (Coquillett), and oriental fruit flies, Bactrocera dorsalis (Hendel), in traps baited with torula yeast-borax or CeraTrap in an agricultural setting in Hawaii. Data show that melon flies were captured in significantly greater numbers in traps baited with torula yeast-borax than CeraTrap, while no difference in captures was noted for the oriental fruit fly between traps baited with the 2 food types.
For the first time in Tajikistan, South American tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) was detected in greenhouses and open field environments in Khatlon region and the region of Republican Subordination. Leaf damage, although lower at the beginning of the season, gradually rose to 15–30% in surveyed sites. Fruit damage also gradually increased during the season. Fruit damage was as high as 20% in the locations surveyed, with the exception of Guliston and Ghayrat Jamoats, which had very low fruit damage. Tuta absoluta is becoming established in Tajikistan. Suitable integrated pest management strategies are needed to reduce the incidence of this invasive pest species.
Giant African land snail, Lissachatina fulica (Bowdich), is currently found in 2 counties in Florida in the continental USA. Five years after their initial sightings, eradication efforts are still underway. A study was conducted to determine the upper and lower temperatures that giant African land snail can tolerate and survive. We observed 100% mortality at 2 °C and at 42 °C. Another study was conducted to ensure that dead snails and eggs collected during the eradication program will be buried at an appropriate depth with no risk of neonate emergence. We observed that hatching snails could dig through at least 81 cm of soil, but the maximum depth of soil from which they could emerge was not successfully determined.
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