Dori Edson Nava

Biology of Diaphorina citri (Hem., Psyllidae) on different hosts and at different temperatures

Abstract:  The objective of this work was to study the effect of different hosts and temperatures on Diaphorina citri Kuwayama (Hem., Psyllidae) biology. Citrus limonia (Rangpur lime), Murraya paniculata (orange jessamine) and Citrus sunki (Sunki mandarin) were used as hosts. Measurements included duration and viability of the egg and nymphal stages, sex ratio, fecundity and longevity. In order to verify the effect of temperature on D. citri biology, the duration and viability of its developmental stages and biological cycle were compared at seven different temperature conditions. Durations of the embryonic and nymphal stages were similar for Rangpur lime, orange jessamine and mandarin. However, the nymphal viability obtained on mandarin was lower than the values obtained on the other hosts. Fecundity was higher on orange jessamine and, in all instances, females had greater longevity than males. A fixed number of instars (five) was obtained on the three hosts. Rangpur lime and orange jessamine provided better D. citri development when compared with mandarin. Duration of the egg and nymphal stages varied from 2.6 to 7.7 and from 9.4 to 35.8 days, respectively, at temperatures from 18 to 32°C. Egg viability was higher than 81.6% at the temperature range studied (18–32°C); nymphal viability was higher than 70% at the 18–30°C range, differing from viability at 32°C, which was dramatically reduced. The D. citri lower temperature development threshold (TT) and thermal constant (K) values for the egg, nymphal and biological cycle (egg–adult) stages were 12.0°C and 52.6 Degree‐Day (DD); 13.9°C and 156.9 DD; and 13.5°C and 210.9 DD respectively.

Biology and ecology of the vector Diaphorina citri and transmission of bacteria associated with huanglongbing.

Com a descoberta do huanglongbing (HLB, ex-greening) no Brasil, em 2004, o psilideoasiatico-dos-citros, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), assumiu o status de praga-chave na citricultura pela sua capacidade de transmitir bacterias do genero Candidatus Liberibacter spp., associadas a esta enfermidade. Por ser uma especie exotica e de importância recente, ha poucas informacoes sobre a biologia e ecologia desse psilideo nas condicoes do Brasil, as quais sao necessarias para o seu manejo. Portanto, este artigo busca compilar dados disponiveis sobre danos, dinâmica populacional e biologia de D. citri, com enfase na influencia de plantas hospedeiras, temperatura e umidade relativa do ar no seu desenvolvimento (duracao e viabilidade dos estagios de ovo e ninfal), razao sexual e fecundidade. Sao descritos metodos alternativos de controle D. citri, com destaque para o controle biologico e a utilizacao do ectoparasitoide Tamarixia radiata (Waterston). Com base nas exigencias termicas deste parasitoide e de D. citri, elaborou-se o zoneamento ecologico para prever o numero de geracoes anuais de ambas as especies no estado de Sao Paulo. Finalmente, sao discutidos os mecanismos de transmissao de Ca. Liberibacter spp. por D. citri, baseando-se nas informacoes disponiveis sobre a interacao patogeno-vetor.

Effects of azadirachtin on Tetranychus urticae (Acari: Tetranychidae) and its compatibility with predatory mites (Acari: Phytoseiidae) on strawberry

BACKGROUND The spider mite, Tetranychus urticae, is the major strawberry pest in Brazil. The main strategies for its control comprise synthetic acaricides and predatory mites. The recent register of a commercial formula of azadirachtin (Azamax(®) 12 g L(-1) ) can be viable for control of T. urticae. In this work, the effects of azadirachtin on T. urticae and its compatibility with predatory mites Neoseiulus californicus and Phytoseiulus macropilis in the strawberry crop were evaluated. RESULTS Azadirachtin was efficient against T. urticae, with a mortality rate similar to that of abamectin. In addition, the azadirachtin showed lower biological persistence (7 days) than abamectin (21 days). Azadirachtin did not cause significant mortality of adult predatory mites (N. californicus and P. macropilis), but it did reduce fecundity by 50%. However, egg viability of the azadirachtin treatments was similar to that of the control (>80% viability). The use of azadirachtin and predatory mites is a valuable tool for controlling T. urticae in strawberry crop. CONCLUSIONS Azadirachtin provided effective control of T. urticae and is compatible with the predatory mites N. californicus and P. macropilis. It is an excellent tool to be incorporated into integrated pest management for strawberry crop in Brazil.

Moscas frugívoras e seus parasitoides nos municípios de Pelotas e Capão do Leão, Rio Grande do Sul, Brasil

Frugivorous flies (Tephritoidea) are the main pests in temperate-zone fruit crop in Brazil. The objective of this research is to evaluate the infestation of these flies and the incidence of their parasitoids in fruit trees from 2007/08 and 2008/9 crops in Pelotas and in Capao do Leao, located in the south of Rio Grande do Sul. Fruits were collected from yellow guava and red guava (Psidium cattleianum Sabine, 1821), pindo palm [Butia capitata (Mart.) Becc., 1916], persimmon (Diospyros kaki Linnaeus, 1753), wild cherry (Eugenia involucrata DC., 1828), guava [Psidium guajava (Linnaeus, 1753)], feijoa tree [Acca sellowiana (Berg.) Burret, 1941], medlar [Eriobotrya japonica (Thunb.) Lindley, 1822], peach [Prunus persicae (L.) Batsch, 1801], surinam cherry (Eugenia uniflora Linnaeus,1753) and (Eugenia pyriformis Cambessedes, 1832). The fruit was collected and transported to the laboratory, where the following parameters were individually determined: fly infestation rate, parasitism rate, and its frequency per parasitoid specie. It was found two species of Tephritidae, Anastrepha fraterculus (Wiedemann, 1830) (90.5%) and Ceratitis capitata (Wiedemann, 1824) (9.5%) and two of Lonchaeidae, Neosilba zadolicha McAlpine & Steyskal, 1982 (87.8%) and a species not yet described, called Neosilba n. sp. 3 (12.2%). Anastrepha fraterculus is the most abundant species in the two cities and it was detected in most fruit crops collected. The persimmon and the guava were the hosts that showed the highest index of C. capitata infestation. Regarding to the species of Neosilba, the highest infestation occurred in fruits of feijoa tree. From the emerged parasitoids, it was identified three species two of Braconidae, Doryctobracon areolatus (Szepligeti, 1911) (52.6%) and Opius bellus (Gahan, 1930) (27.5%) and a species of Figitidae, Aganaspis pelleranoi (Brethes, 1924) (20.0%). Doryctobracon areolatus was the most frequent parasitoid in most sampled fruit trees, except for surinam cherry and wild cherry, where O. bellus was predominant and for peach, A. pelleranoi.

Efficacy of indigenous entomopathogenic nematodes (Rhabditida: Heterorhabditidae, Steinernematidae), from Rio Grande do Sul Brazil, against Anastrepha fraterculus (Wied.) (Diptera: Tephritidae) in peach orchards.

Laboratory, greenhouse, and field experiments were performed with the objective of selecting efficient indigenous strains of entomopathogenic nematodes (EPNs) from Rio Grande do Sul (RS) state, Brazil, for controlling the South American fruit fly, Anastrepha fraterculus (Wied.). Laboratory experiments were conducted in 24 well-plates filled with sterile sand and one insect per well. In greenhouse experiments, plastic trays filled with soil collected from the field were used, while in field experiments, holes were made in soil under the edge of peach tree canopies. Among 19 EPN strains tested, Heterorhabditis bacteriophora Poinar RS88 and Steinernema riobrave Cabanillas, Poinar, & Raulston RS59 resulted in higher A. fraterculus larval (pre-pupal) and pupal mortality, with LD(90) of 1630, 457 and 2851, 423 infective juveniles (IJs)/cm(2), respectively. Greenhouse experiments showed no differences in pupal mortality at 250 and 500IJs/cm(2) of either nematode. In the field, H. bacteriophora RS88 and S. riobravae RS59 sprayed individually over natural and artificially infested fruit (250IJs/cm(2)) resulted in A. fraterculus larval mortality of 51.3%, 28.1% and 20%, 24.3%, respectively. There was no significant difference in A. fraterculus pupal mortality sprayed with an aqueous suspension of either nematode; however, when using infected insect cadavers, H. bacteriophora RS88 was more efficient than S. riobrave RS59. Our results showed that H. bacteriophora RS88 was more virulent to insect larvae, with an efficient host search inside the infested fruit and control of pupae in the soil after being applied by aqueous suspension or infected cadavers.

BIOLOGY, THERMAL REQUIREMENTS, AND ESTIMATION OF THE NUMBER OF GENERATIONS OF ZAPRIONUS INDIANUS (DIPTERA: DROSOPHILIDAE) FOR THE MAIN FIG PRODUCING REGIONS OF BRAZIL

Abstract The African fig fly, Zaprionus indianus, was first recorded in fig orchards in Brazil in 1999, at the Valinhos region, in the State of São Paulo. In view of the scarcity of biological data on this insect in Brazil, the objective of this research was to study the biology, temperature requirements, and to estimate the number of Z. indianus annual generations for the main fig producing regions of Brazil, aimed at controlling the pest. The insects were reared on artificial diet at constant temperatures of 18, 20, 22, 25, 28, 30, and 32°C, relative humidity 80 ± 10%, and 14-h photophase. Duration of the development stages was variable with temperature, being longer at the lower temperatures. Temperature also influenced viability during the larval and pupal stages and the egg-adult biological cycle, with significant differences between 32°C and the other temperature conditions. The lower temperature development threshold (TT) and thermal constant (K) values for the egg, larval, and pupal stages were 9.7 and 10.5; 9.2 and 148.6, and 10.7°C and 66.25 DD, respectively, for a total thermal constant of 262.2 DD for the egg-adult biological cycle. Based on a lower temperature development threshold of 7.9°C., Z. indianus may have up to 16.6, 12.4, and 12.7 annual generations in the regions of Valinhos-SP, Pelotas-RS, and São Sebastião do Paraíso-MG, respectively, which are traditionally known as fig producing regions in the country.

Isca tóxica e disrupção sexual no controle da mosca-da-fruta sul-americana e da mariposa-oriental em pessegueiro

The objective of this work was to evaluate the simultaneous use of toxic bait and mating disruption technique using sexual pheromone for Anastrepha fraterculus and Grapholita molesta control, in commercial peach orchards. Three 0.5-ha orchards were used, with the following treatments: orchad 1, toxic bait (Biofruit 3% + Malathion 500 CE, 200 mL in 100 L) and mating disruption using sexual pheromone (Splat Grafo) in 1,000 points ha-1; orchad 2, conventional management, using contact insecticides 2 to 3 times a year; orchad 3, no pest control. Adult populations of both species, and sprout and fruit damages were monitored during the 2007/2008 and 2008/2009 crop seasons. Simultaneous use of toxic bait and mating disruption technique decreased the captures of A. fraterculus and G. molesta in more than 90%. In the two crop seasons, the damages on sprouts decreased 62-85%, and 98-99% on fruit, compared to the untreated orchard.

Population dynamics of Stenoma catenifer (Lepidoptera: Elachistidae) and related larval parasitoids in Minas Gerais, Brazil

Abstract The avocado seed moth Stenoma catenifer Walsingham (Lepidoptera: Elachistidae) can cause total production losses and is considered a key pest of avocado in Brazil. This research aimed to evaluate the larval dynamics of S. catenifer and its associated parasitoids in an avocado growing region throughout two consecutive agricultural seasons. The highest percentage of fruits attacked by S. catenifer was found in the period near harvest, starting in June. The percentage of infested fruits in the first agricultural season was approximately 60%, near 11% above that of the second season. Five undetermined braconids within five genera (Dolichogenidea sp., Hypomicrogaster sp., Apanteles sp., Chelonus sp., and Hymenochaonia sp.) and two ichneumonids (Eudeleboea sp. and Pristomerus sp.) were found. Dolichogenidea sp. and Apanteles sp. were the most abundant, and therefore are the species with the highest potential as S. catenifer population regulators. In both seasons, the emergence peak of parasitoids occurred at the end of the winter (August), when at least 30 and 40% total larval parasitism was observed.

Biology and fertility life table of the green aphid Chaetosiphon fragaefolli on strawberry cultivars.

Abstract Our objective was to study the biology and develop a fertility life table for the aphid Chaetosiphon fragaefolli (Cockerell) (Hemiptera: Aphididae) on leaves of strawberry, Fragaria × ananassa, Duchesne ex Rozier (Rosales: Rosaceae), of the cultivars Albion, Aromas, Camarosa, Camino Real, Diamante, Earlibrite, and Saborosa. This study was conducted under controlled conditions: 25 ± 1 °C, 70 ± 10% RH, and 12:12 L:D . Arenas were set up consisting of leaves inside Petri dishes containing 3% agar. Female aphids obtained after the last nymphal ecdysis were individually placed in arenas for 24 hours. The following biological parameters were evaluated: duration and survival of the nymph stage and of the life cycle (nymph-nymph), daily and total fecundity, and adult longevity. The aphids completed their biological cycle on all of the cultivars. The shortest durations (in days) of the nymphal stage were on the cultivars Camino Real and Camarosa (8.67 and 8.74 days, respectively), and the longest was on Aromas (11.12 days). The lowest survival was on cultivar Aromas (51%) and the highest on Saborosa (96%). When the time to development to the adult stage was compared, the aphids developed fastest (14.63 days) and survival was highest (96%) on cultivar Saborosa. Aphids reared on cultivar Aromas leaves had the longest pre—reproductive period (8.74 days), the greatest longevity (26.88 days), and the longest duration of the life cycle (19.76 days). Based on the fertility life table, cultivars Camarosa and Saborosa were the most favorable for development of C. fragaefolli, while Albion and Aromas were the most inadequate for aphid development.

Linhagens de Trichogramma e Trichogrammatoidea para controle de Stenoma catenifer

The objective of this work was to select Trichogramma and Trichogrammatoidea species and strains with potential to control the avocado fruit borer Stenoma catenifer, considered the main avocado (Persea americana Mill.) pest. Laboratory experiments were carried out with the following strains and species, which comprised eight Trichogramma pretiosum; one Trichogramma atopovirilia; two Trichogramma bruni; and one Trichogrammatoidea annulata. The number of parasitoids to be released per S. catenifer egg under semi-field conditions was studied. Biological parameters evaluated in laboratory were egg-adult development time, survivorship, parasitism, sex ratio, number of parasitoids emerged per S. catenifer egg, and adult longevity. In semi-field experiment, the number of parasitized eggs was evaluated. The species Trichogrammatoidea annulata, Trichogramma atopovirilia and their strains were selected for the largest number of S. catenifer eggs parasitized. Under semi-field conditions, the highest parasitism was achieved with an estimated ratio of 28 and 30 parasitoids per pest egg, respectively, for Trichogrammatoidea annulata and Trichogramma atopovirilia.