Intraspecific and interspecific interaction and fitness cost of stink bugs Euschistus heros, Diceraeus melacanthus, and Piezodorus guildinii in soybean.

BACKGROUND: The most common pentatomid species in soybean crops are Euschistus heros (F.), Piezodorus guildinii (W.), and Diceraeus melacanthus (D.), causing a significant reduction in yield. It is known that these stink bugs inhabit the reproductive structures of soybeans simultaneously; however, there are few studies addressing their intraguild interactions, as well as aspects of possible competition between them in plants. Thus, the interspecific and intraspecific interactions of these stink bugs were evaluated in laboratory and field conditions, throughout the duration of the instars and adulthood, including longevity, mortality, and the number of eggs per female. RESULTS: Euschistus heros had a higher competitive capacity in the interaction with D. melacanthus and P. guildinii, negatively interfering in the abundance or development (duration of instar, fertility, and mortality) of these stink bugs in soybean crops. This interference may act on the natural balance of these insect pests. Mortality of adults in interactions containing E. heros as a competitor or not showed that this species was not affected by the other species under field conditions. In the scenario where D. melacanthus was evaluated, it was observed that the presence of other species caused higher mortality in D. melacanthus. Additionally, higher P. guildiniii mortality was observed in interspecific interactions. CONCLUSION: Our results suggest that E. heros has a greater competitive ability in the soybean crop, followed by D. melacanthus and P. guildinii. Therefore, the results found justified the greater abundance of E. heros and helped to explain the increasing occurrence of D. melacanthus in soybean crops, contributing to new directions for understanding the interaction of the soybean stink bug complex. © 2023 Society of Chemical Industry.

Beneath the blooms: Unearthing the effect of rhizospheric bacteria on floral signals and pollinator preferences.

The relationship between plants and pollinators is known to be influenced by ecological interactions with other community members. While most research has focused on aboveground communities affecting plant-pollinator interactions, it is increasingly recognized that soil-dwelling organisms can directly or indirectly impact these interactions. Although studies have examined the effects of arbuscular mycorrhizal fungi on floral traits, there is a gap in research regarding similar effects associated with plant growth-promoting rhizobacteria (PGPR), particularly concerning floral scent. Our study aimed to investigate the influence of the PGPR Bacillus amyloliquefaciens on the floral traits of wild (Solanum habrochaites, Solanum pimpinellifolium and Solanum peruvianum) and cultivated tomato (Solanum lycopersicum), as well as the impact of microbially-driven changes in floral scent on the foraging behaviour of the stingless bee Melipona quadrifasciata. Our findings revealed that inoculating tomatoes with PGPR led to an increased number of flowers and enhanced overall floral volatile emission. Additionally, we observed higher flower biomass and pollen levels in all species, except S. peruvianum. Importantly, these changes in volatile emissions influenced the foraging behaviour of M. quadrifasciata significantly. Our results highlight the impact of beneficial soil microbes on plant-pollinator interactions, shedding light on the multiple effects that plant-microbial interactions can have on aboveground organisms.

Differential defensive and nutritional traits among cultivated tomato and its wild relatives shape their interactions with a specialist herbivore.

MAIN CONCLUSION: Cultivated tomato presented lower constitutive volatiles, reduced morphological and chemical defenses, and increased leaf nutritional quality that affect its resistance against the specialist herbivore Tuta absoluta compared to its wild relatives. Plant domestication process has selected desirable agronomic attributes that can both intentionally and unintentionally compromise other important traits, such as plant defense and nutritional value. However, the effect of domestication on defensive and nutritional traits of plant organs not exposed to selection and the consequent interactions with specialist herbivores are only partly known. Here, we hypothesized that the modern cultivated tomato has reduced levels of constitutive defense and increased levels of nutritional value compared with its wild relatives, and such differences affect the preference and performance of the South American tomato pinworm, Tuta absoluta-an insect pest that co-evolved with tomato. To test this hypothesis, we compared plant volatile emissions, leaf defensive (glandular and non-glandular trichome density, and total phenolic content), and nutritional traits (nitrogen content) among the cultivated tomato Solanum lycopersicum and its wild relatives S. pennellii and S. habrochaites. We also determined the attraction and ovipositional preference of female moths and larval performance on cultivated and wild tomatoes. Volatile emissions were qualitatively and quantitatively different among the cultivated and wild species. Glandular trichomes density and total phenolics were lower in S. lycopersicum. In contrast, this species had a greater non-glandular trichome density and leaf nitrogen content. Female moths were more attracted and consistently laid more eggs on the cultivated S. lycopersicum. Larvae fed on S. lycopersicum leaves had a better performance reaching shorter larval developmental times and increasing the pupal weight compared to those fed on wild tomatoes. Overall, our study documents that agronomic selection for increased yields has altered the defensive and nutritional traits in tomato plants, affecting their resistance to T. absoluta.

Leaf metabolic profiles of two soybean genotypes differentially affect the survival and the digestibility of Anticarsia gemmatalis caterpillars.

Insect pests such as Anticarsia gemmatalis cause defoliation and yield losses. Soybean breeding has obtained resistant genotypes, however the mechanism remains unknown. Studies indicated the presence of deterrents compounds in the resistant genotype IAC17, and their leaf metabolite profiles were compared to the susceptible genotype UFV105, which was elicited or not by caterpillar infestation. Cluster analysis indicated a significative distinction between these profiles as well as differences in plant defense pathways. Methylquercetins were constitutively present in the largest concentrations, specifically in the IAC17. Relationship between the resistance and the levels of phytohormones jasmonic acid, abscisic acid and salicylic acid was not observed. However, 1-aminocyclopropane -1carboxylic acid levels indicated that the ethylene may be involved in the constitutive biosynthesis of bioactive compounds. Extracts were added to the diets at three different concentrations to evaluate the effect on caterpillar survival. Lowest survival rates were observed when extracts from the resistant IAC 17 were used, at the lowest concentrations. Survival rates were not higher when IAC 17 infested by caterpillars were used. On the other hand, when extracts from the susceptible were used, the survival reductions were only observed in the highest extract concentrations. These supplementations of the diet reduced the digestive capacity, agreeing with the proteolytic activities, whereas malformations of the intestinal cells were dose dependent. The inhibitory effects persisted in higher dilutions only for the IAC17. Constitutive resistance was also explained by higher levels of protease inhibition. These results can be useful to elucidate the genes and cascades controlling the resistance.

Variable Levels of Resistance of Soybean Genotypes on the Performance of Euschistus heros (Hemiptera: Pentatomidae).

The Neotropical brown stink bug Euschistus heros (Fabr.) (Hemiptera: Pentatomidae) is one of the major soybean pests in South America. This species is responsible for high levels of infestation, causes critical damage to seeds, it is associated with leaf retention on plants, and it is extremely difficult to manage. Host plant resistance is a notable technique to assist in reducing the stink bug population in soybean crops. The antibiosis resistance of soybean genotypes to E. heros was evaluated in laboratory. Genotypes L1-1-01, 'IAC 100', 'IAC 23', and 'Coodetec 208' increased the length of nymphal developmental time. PI 274453 and PI 227687 reduced egg viability and also adult body weight. PI 274454, 'IAC 19', PI 227687, and PI 229358 led to low nymphal viability. These results suggest that these genotypes may be useful in soybean breeding programs that focus on the development of genotypes resistant to E. heros.

Biochemical responses of Anticarsia gemmatalis (Lepidoptera: Noctuidae) in soybean cultivars sprayed with the protease inhibitor berenil.

The damage caused by Anticarsia gemmatalis motivates this study on the adaptive mechanisms of the insect to soybean. The lipoxygenase pathway produces and releases jasmonic acid, involved in the regulation of the plant defense genes, which encodes protease inhibitor (PI) production. Three soybean cultivars IAC-18, IAC-24, and Foscarin-31 were sprayed with water and berenil, a synthetic inhibitor, at 0.60 and 1.0% (w/v) and then infested with A. gemmatalis larvae. The lipoxygenase (LOX) activity increased in the leaves of Foscarin-31, IAC-18, and IAC-24 by 87, 81, and 78%, respectively, after 24 h of A. gemmatalis damage. IAC-18 revealed the lowest increase in PI when compared to the other cultivars. Protease, amidase, and esterase activities in soybean larvae dropped drastically after berenil application. PIs may be included in the control strategies of A. gemmatalis in soybean by lowering the digestive enzyme activity in the larval midgut, thus affecting insect growth and development.

Soybean toxin (SBTX) impairs fungal growth by interfering with molecular transport, carbohydrate/amino acid metabolism and drug/stress responses.

Soybean toxin (SBTX) is an antifungal protein from soybeans with broad inhibitory activity against the growth and filamentation of many fungi, including human and plant pathogenic species such as Candida albicans, Candida parapsilosis, Aspergillus niger, Penicillium herquei, Cercospora sojina and Cercospora kikuchii. Understanding the mechanism by which SBTX acts on fungi and yeasts may contribute to the design of novel antifungal drugs and/or the development of transgenic plants resistant to pathogens. To this end, the polymorphic yeast C. albicans was chosen as a model organism and changes in the gene expression profile of strain SC5314 upon exposure to SBTX were examined. Genes that were differentially regulated in the presence of SBTX were involved in glucose transport and starvation-associated stress responses as well as in the control of both the induction and repression of C. albicans hyphal formation. Transmission electron microscopy showed that C. albicans cells exposed to SBTX displayed severe signs of starvation and were heavily granulated. Our data were indicative of C. albicans cell starvation despite sufficient nutrient availability in the medium; therefore, it can be speculated that SBTX blocks nutrient uptake systems. Because neither the starvation signal nor the alkaline response pathway lead to the induction of hyphae, we hypothesise that conflicting signals are transmitted to the complex regulatory network controlling morphogenesis, eventually preventing the filamentation signal from reaching a significant threshold.

[Molecular characterization and genetic divergence of Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) on different crops and growing areas]. / Caracterização molecular e divergência genética de Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) em diferentes culturas e locais de cultivo.

Knowledge on the genetic variation of populations of Bemisia tabaci (Genn.) can improve the understanding of genetic diversity found in their biotypes and, consequently, offer guidelines for its management. In this study, the molecular characterization was performed and genetic diversity data were obtained for this insect from three regions of Brazil on different crops [cotton and soybean (Mato Grosso - MT); cabbage (Distrito Federal - DF); soybean and potato (São Paulo - SP)], using RAPD markers. RAPD analysis indicated 80.6% polymorphic loci and the average genetic similarity obtained by the Jaccard coefficient was 0.67. The whitefly populations collected on potato (SP) and soybean (MT) had higher genetic diversity values (0.75 and 0.72, respectively). Shannon's index (Ho) showed higher values for potato and soybean (SP e MT), and a smaller value for cabbage (DF). A high genetic divergence within and among the collected populations occurred, structured according to the regions of collection. Moreover, the great genetic similarity observed between potato (SP) and soybean (SP) populations suggested that both belong to the same biotype B and reinforces the polyphagous behavior of the species.

[Yield of soybean genotypes under infestation of the velvetbean caterpillar and stink bugs]. / Produtividade de genótipos de soja sob infestação da lagarta-da-soja e de percevejos.

Three soybean experiments, one for each maturation group (early, semi-early, and medium), were installed in the field in Assis, State of São Paulo, during the 2003/2004 growing season to evaluate damage caused by Anticarsia gemmatalis (Hubn.) and by the soybean stink bug complex, Euschistus heros (F.), Piezodorus guildinii (West.), and Nezara viridula (L.). The experiments were installed again in 2004/2005, with the exception of the early cycle group. Defoliation caused by A. gemmatalis was evaluated by the percentage estimate of leaf area cut in the first year only, due to low caterpillar infestations in 2004/2005. All three stink bug species were present in both growing seasons. In 2003/2004, E. heros was predominant over the other two; in the following year, all three species occurred in similar numbers. The productivity criterion was adopted to evaluate stink bug damage. Based on both growing seasons and mainly considering productivity, a few lines could be selected within each maturation group for new field studies or for hybridizations in breeding programs. Among the early germplasm varieties, lines IAC 98-4540, IAC 98-4576, and IAC 98-3123 can be highlighted as promising; the latter also showed little defoliation by A. gemmatalis; in the semi-early group, IAC 98-4017, IAC 98-2663, and IAC 98-4250 were prominent, with steady productivity in both years; in the medium group, IAC 98-4136, the most productive, as well as IAC 98-4140 and IAC 98-4133, all with little defoliation, can be pointed out as promising.

Caracterização molecular e divergência genética de Bemisia tabaci (Genn. ) (Hemiptera: Aleyrodidae) em diferentes culturas e locais de cultivo / Molecular characterization and genetic divergence of Bemisia tabaci (Genn. ) (Hemiptera: Aleyrodidae) on different crops and growing areas

Knowledge on the genetic variation of populations of Bemisia tabaci (Genn.) can improve the understanding of genetic diversity found in their biotypes and, consequently, offer guidelines for its management. In this study, the molecular characterization was performed and genetic diversity data were obtained for this insect from three regions of Brazil on different crops [cotton and soybean (Mato Grosso - MT); cabbage (Distrito Federal - DF); soybean and potato (São Paulo - SP)], using RAPD markers. RAPD analysis indicated 80.6 percent polymorphic loci and the average genetic similarity obtained by the Jaccard coefficient was 0.67. The whitefly populations collected on potato (SP) and soybean (MT) had higher genetic diversity values (0.75 and 0.72, respectively). Shannon's index (Ho) showed higher values for potato and soybean (SP e MT), and a smaller value for cabbage (DF). A high genetic divergence within and among the collected populations occurred, structured according to the regions of collection. Moreover, the great genetic similarity observed between potato (SP) and soybean (SP) populations suggested that both belong to the same biotype B and reinforces the polyphagous behavior of the species.

Produtividade de genótipos de soja sob infestação da lagarta-da-soja e de percevejos / Yield of soybean genotypes under infestation of the velvetbean caterpillar and stink bugs

Three soybean experiments, one for each maturation group (early, semi-early, and medium), were installed in the field in Assis, State of São Paulo, during the 2003/2004 growing season to evaluate damage caused by Anticarsia gemmatalis (Hubn.) and by the soybean stink bug complex, Euschistus heros (F.), Piezodorus guildinii (West.), and Nezara viridula (L.). The experiments were installed again in 2004/2005, with the exception of the early cycle group. Defoliation caused by A. gemmatalis was evaluated by the percentage estimate of leaf area cut in the first year only, due to low caterpillar infestations in 2004/2005. All three stink bug species were present in both growing seasons. In 2003/2004, E. heros was predominant over the other two; in the following year, all three species occurred in similar numbers. The productivity criterion was adopted to evaluate stink bug damage. Based on both growing seasons and mainly considering productivity, a few lines could be selected within each maturation group for new field studies or for hybridizations in breeding programs. Among the early germplasm varieties, lines IAC 98-4540, IAC 98-4576, and IAC 98-3123 can be highlighted as promising; the latter also showed little defoliation by A. gemmatalis; in the semi-early group, IAC 98-4017, IAC 98-2663, and IAC 98-4250 were prominent, with steady productivity in both years; in the medium group, IAC 98-4136, the most productive, as well as IAC 98-4140 and IAC 98-4133, all with little defoliation, can be pointed out as promising.

[Biology of the citrus blackfloy, Aleurocanthus woglumi Ashby (Hemiptera: Aleyrodidae), in three host plants]. / Biologia da mosca-megra-dos-citros, Aleurocanthus woglumi Ashby(Hemiptera: Aleyrodidae), em três plantas hospedeiras.

The citrus blackfloy, Aleurocanthus woglumi Ashby, was detected in Brazil in 2001. The aim of this research was to evaluate the biology, biometry and host preference of A. woglumi in sweet orange, acid lime Tahiti and mango. Experiments were set in laboratory conditions with insects collected in rangpur lime plants in Manaus, State of Amazonas, from January to June of 2006. The following parameters were evaluated: number of spirals (ovopositions) and eggs per plant, number of eggs by spiral per plant, survival of the immatures (eggs, 1st, 2nd, 3rd and 4th instars), and length and survival of the immature stage. The mean embrionary period was 15 days for the three hosts. The 4th nymph (puparium) was the longest during nymph development. Second and third instars had the highest survival. The mean length of the egg-adult cycle was 70 days for the three hosts evaluated. The eggs were laid in a spiral shape on the adaxial leaf surface. The 1st instars moved to short distances from the spiral, while the 2nd, 3rd and 4th are sessile and have bristles on the whole body. Based on the highest oviposition and the highest survival of the immature stage of the citrus blackfloy in acid lime Tahiti, this plant can be considered the most suitable host to A. woglumi.

Biologia da mosca-megra-dos-citros, Aleurocanthus woglumi Ashby(Hemiptera: Aleyrodidae), em três plantas hospedeiras / Biology of the citrus blackfloy, Aleurocanthus woglumi Ashby (Hemiptera: Aleyrodidae), in three host plants

A mosca-negra-dos-citros, Aleurocanthus woglumi Ashby, foi detectada no Brasil em 2001. O objetivo deste estudo foi avaliar a biologia, a biometria e a preferência hospedeira de A. woglumi em três plantas hospedeiras (laranja doce, lima ácida Tahiti e manga). Para isso, foram montados experimentos em laboratório, de janeiro a junho de 2006, com insetos coletados em plantas de limão-cravo, C. limonia na área de produção da Faculdade de Ciências Agrárias - UFAM. No estudo da preferência hospedeira, foram avaliados: número de espirais (posturas) e de ovos por planta, número de ovos por espiral por planta, sobrevivência dos imaturos (ovos, ninfas de 1º, 2º, 3º e 4º estádios), enquanto no experimento de biologia foram avaliadas a duração e sobrevivência da fase imatura. O período embrionário foi de 15 dias em média para os três hospedeiros. O estádio de ninfa 4 (pupário) foi o mais longo quando comparado com as outras fases de desenvolvimento. A sobrevivência foi maior nas fases de ninfa 3, ovo e ninfa 2. A duração média do ciclo ovo-adulto foi de 70 dias para os três hospedeiros avaliados. Os ovos são colocados em forma de espiral na face inferior das folhas. As ninfas de 1º estádio locomovem-se a pequenas distâncias da espiral, enquanto as de 2º, 3º e 4º são sésseis e têm cerdas em todo o corpo. Com base na maior oviposição e sobrevivência da fase imatura da mosca-negra em lima ácida Tahiti, esta planta pode ser considerada o hospedeiro mais favorável para A. woglumi.

The citrus blackfloy, Aleurocanthus woglumi Ashby, was detected in Brazil in 2001. The aim of this research was to evaluate the biology, biometry and host preference of A. woglumi in sweet orange, acid lime Tahiti and mango. Experiments were set in laboratory conditions with insects collected in rangpur lime plants in Manaus, State of Amazonas, from January to June of 2006. The following parameters were evaluated: number of spirals (ovopositions) and eggs per plant, number of eggs by spiral per plant, survival of the immatures (eggs, 1st, 2nd, 3rd and 4th instars), and length and survival of the immature stage. The mean embrionary period was 15 days for the three hosts. The 4th nymph (puparium) was the longest during nymph development. Second and third instars had the highest survival. The mean length of the egg-adult cycle was 70 days for the three hosts evaluated. The eggs were laid in a spiral shape on the adaxial leaf surface. The 1st instars moved to short distances from the spiral, while the 2nd, 3rd and 4th are sessile and have bristles on the whole body. Based on the highest oviposition and the highest survival of the immature stage of the citrus blackfloy in acid lime Tahiti, this plant can be considered the most suitable host to A. woglumi.

First report and differential colonization of Passiflora Species by the B biotype of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) in Brazil / Primeiro relato e colonização diferencial de espécies de Passiflora pelo biótipo B de Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) no Brasil

This note is the first report of Bemisia tabaci (Gennadius) biotype B colonizing passionvine in Brazil. We examined the colonization of nine Passiflora species by a wild B type population under greenhouse conditions. P. amethystina Mikan was the most preferred species for oviposition and colonization, whereas P. suberosa L., P. coriacea Juss. and two commercially cultivated species, P. alata Curtis and P. edulis Sims f. flavicarpa Degener, were mostly uncolonised. P. morifolia Mast., P. cincinnata Mast., P. foetida L. and P. caerulea L. showed intermediate levels of colonization. Such differential colonization might suggest some degree of resistance by certain Passiflora species or oviposition preference by B. tabaci.

Esse trabalho descreve pela primeira vez a ocorrência do aleirodídeo Bemisia tabaci (Gennadius) biótipo B colonizando maracujazeiros no Brasil. Também foi examinada a colonização de nove espécies de Passiflora pelo inseto em condições de telado. P. amethystina Mikan foi a espécie de maior preferência para oviposição e colonização, enquanto P. suberosa L., P. coriacea Juss. e duas espécies cultivadas comercialmente, P. alata Curtis e P. edulis Sims f. flavicarpa Degener, foram pouco colonizadas pelo aleirodídeo. P. morifolia Mast., P. cincinnata Mast., P. foetida L. e P. caerulea L. exibiram níveis intermediários de colonização. Esses resultados sugerem que certas espécies de Passiflora exibem diferentes graus de resistência à colonização ou preferência para oviposição de B. tabaci biótipo B.

Outbreaks of Trialeurodes vaporariorum (West.) (Hemiptera: Aleyrodidae) under field conditions in the State of São Paulo, Brazil.

Trialeurodes vaporariorum (West.) is a pest of greenhouse vegetables and ornamentals and infests crops in Europe and in the American continent. In Brazil, just a few cases are known on economic crops, being all restricted to greenhouse crops. In 2003, in Itatiba and neighboring localities of State of São Paulo, Brazil, field infestations of T. vaporariorum were observed, mainly on tomato and green bean. So far, whitefly infestation in this area expanded to squash and kale also. Field studies are needed for determining interactions of T. vaporariorum with plants and natural enemies, injury levels, and methods of control.

Outbreaks of Trialeurodes vaporariorum (West.) (Hemiptera: Aleyrodidae) under field conditions in the State of São Paulo, Brazil

Trialeurodes vaporariorum (West.) is a pest of greenhouse vegetables and ornamentals and infests crops in Europe and in the American continent. In Brazil, just a few cases are known on economic crops, being all restricted to greenhouse crops. In 2003, in Itatiba and neighboring localities of State of São Paulo, Brazil, field infestations of T. vaporariorum were observed, mainly on tomato and green bean. So far, whitefly infestation in this area expanded to squash and kale also. Field studies are needed for determining interactions of T. vaporariorum with plants and natural enemies, injury levels, and methods of control.

Trialeurodes vaporariorum (West.) é praga de hortaliças e ornamentais em cultivo protegido e infesta diversas culturas na Europa e nas Américas. No Brasil, as informações sobre sua ocorrência restringem-se a estudos em casa de vegetação. Em 2003, em Itatiba e cidades adjacentes (SP), observaram-se infestações de T. vaporariorum em hortaliças e ornamentais em campo, com maiores níveis populacionais em tomateiro e feijão-vagem. Nos anos seguintes, as infestações se mantiveram, atingindo cultivos de couve e de aboboreiras. São necessários estudos em campo para conhecer as interações dessa mosca-branca com plantas e inimigos naturais, níveis de dano e avaliação de métodos de controle.

First report and differential colonization of Passiflora species by the B biotype of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) in Brazil.

This note is the first report of Bemisia tabaci (Gennadius) biotype B colonizing passionvine in Brazil. We examined the colonization of nine Passiflora species by a wild B type population under greenhouse conditions. P. amethystina Mikan was the most preferred species for oviposition and colonization, whereas P. suberosa L., P. coriacea Juss. and two commercially cultivated species, P. alata Curtis and P. edulis Sims f. flavicarpa Degener, were mostly uncolonised. P. morifolia Mast., P. cincinnata Mast., P. foetida L. and P. caerulea L. showed intermediate levels of colonization. Such differential colonization might suggest some degree of resistance by certain Passiflora species or oviposition preference by B. tabaci.

[Parasitism in Trialeurodes variabilis (Quaintance) (Hemiptera: Aleyrodidae) by Encarsia hispida De Santis (Hymenoptera: Aphelinidae), in papaya, in Brazil]. / Parasitismo em Trialeurodes variabilis (Quaintance) (Hemiptera: Aleyrodidae) por Encarsia hispida De Santis (Hymenoptera: Aphelinidae), em mamoeiro, no Brasil.

Infestation of Trialeurodes variabilis (Quaintance) was observed in October 2004, in papaya plants of cultivar Sunrise Solo, under screenhouse conditions, in Cruz das Almas, State of Bahia, Brazil. In infested leaves, around 20% of parasitism on nymphs was verified. Leaves with parasitized nymphs were kept in laboratory until emergence of the parasitoid, identified as Encarsia hispida De Santis. This is the first time that this parasitoid was detected on T. variabilis nymphs in Brazil.

Parasitismo em Trialeurodes variabilis (Quaintance) (Hemiptera: Aleyrodidae) por Encarsia hispida De Santis (Hymenoptera: Aphelinidae), em mamoeiro, no Brasil / Parasitism in Trialeurodes variabilis (Quaintance) (Hemiptera: Aleyrodidae) by Encarsia hispida De Santis (Hymenoptera: Aphelinidae), in papaya, in Brazil

Em Cruz das Almas, BA, em outubro de 2004, foi verificada infestação de Trialeurodes variabilis (Quaintance) em mamoeiros 'Sunrise Solo', mantidos em telado. Nas folhas infestadas, detectaram-se níveis de parasitismo em ninfas da mosca-branca da ordem de 20 por cento. Folhas com ninfas parasitadas foram mantidas em laboratório até emergência dos parasitóides, identificados como Encarsia hispida De Santis. Trata-se do primeiro registro de parasitismo de ninfas de T. variabilis por essa espécie de Encarsia no Brasil.

Infestation of Trialeurodes variabilis (Quaintance) was observed in October 2004, in papaya plants of cultivar Sunrise Solo, under screenhouse conditions, in Cruz das Almas, State of Bahia, Brazil. In infested leaves, around 20 percent of parasitism on nymphs was verified. Leaves with parasitized nymphs were kept in laboratory until emergence of the parasitoid, identified as Encarsia hispida De Santis. This is the first time that this parasitoid was detected on T. variabilis nymphs in Brazil.

Resistência de genótipos de aboboreira a Bemisia tabaci (Genn) biótipo B (Hemiptera: Aleyrodidae) / Resistance of squash genotypes to Bemisia tabaci (Genn) biotype B (Hemiptera: Aleyrodidae)

O uso de cultivares resistentes para controle de mosca-branca integra-se de forma harmônica em programas de manejo integrado. Cultivares e linhagens de aboboreira com diferentes genealogias e características têm sido desenvolvidas e liberadas aos produtores por instituições privadas e oficiais. Pouco se sabe sobre a resistência ou suscetibilidade desse germoplasma a insetos. Assim, avaliaram-se em condições de casa de vegetação dezesseis genótipos de aboboreiras (Cucurbita spp.) disponíveis no mercado brasileiro em relação a Bemisia tabaci (Genn.) biótipo B. O híbrido Golden Delight foi o mais atrativo aos adultos enquanto 'Menina Brasileira', 'Bárbara' e 'Atlas' apresentaram os menores números de adultos na superfície inferior das folhas. A oviposição foi avaliada em experimentos com e sem chance de escolha. 'Novita', 'Exposição' e 'Caserta' foram as cultivares com menor número de ovos, apresentando não preferência para oviposição como mecanismo de resistência. O ciclo de ovo a adulto foi avaliado em seis genótipos, incluindo-se os de melhor desempenho nos testes anteriores mais uma testemunha suscetível. Em 'Golden Delight', a duração desse ciclo foi a mais curta (24,9 dias) e a porcentagem de emergência de adultos a mais elevada (93,8 por cento), indicando ser um genótipo adequado ao desenvolvimento do inseto. Já 'Exposição' e 'Menina Brasileira' prolongaram esse ciclo (35,8 e 33,5 dias, respectivamente) e reduziram a emergência de adultos (46,3 e 58,1 por cento), mostrando-se resistentes.

Whitefly control using resistant cultivars can be considered the ideal option in integrated pest management programs. Squash cultivars and lines with different genealogies have been developed and released by private and public research institutions. However, little information is available about the resistance or susceptibility of those genotypes to insects. The main squash (Cucurbita spp.) cultivars available in the Brazilian market were evaluated as to Bemisia tabaci biotype B resistance, under greenhouse conditions. The cultivar 'Golden Delight' was the most attractive to adults, while 'Menina Brasileira', 'Bárbara' and 'Atlas' presented the lowest numbers of adults on the abaxial leaf surfaces. Oviposition was evaluated in free-choice and no-choice tests. 'Novita', 'Exposição' and 'Caserta' behaved as resistant and showed oviposition nonpreference as the resistance mechanism. The cycle from egg to adult emergence was determined in six genotypes. In 'Golden Delight', the duration of this cycle was the shortest one (24.9 days), and the percentage of adult emergence, the highest one (93.8 percent), thus indicating that this cultivar is suitable to the insect. On the other hand, 'Exposição' and 'Menina Brasileira' prolonged this cycle (35.8 and 33.5 days, respectively) and reduced the adult emergence (46.3 and 58.1 percent), showing to be resistant.