Ovarian development and analysis of mating effects on ovary maturation of Diaphorina citri Kuwayama (Hemiptera: Psyllidae)

As many other insects with a restricted diet, the citrus psyllid Diaphorina citri Kuwayama, which vector the causing agent of the Huanglongbing, the bacteria Candidatus Liberibacter spp., is intimately associated with symbiotic microorganisms. These mutualist symbionts play a key role on their host nutritional ecology, and are vertically transmitted to the progeny. However, despite the role symbionts play on host development and reproduction, and the growing opportunities of exploitation of the association insect-symbiont to control insect vectored-pathogens, there are very few studies on the host reproductive biology and on the symbiont transovarial transmission. Therefore, we aimed at analyzing the ovary development during D. citri adulthood, and at verifying for the mating requirement as a trigger to initiate ovary development. Newly-emerged D. citri females were grouped as virgin or mated and ovary development was observed during adulthood. Newly-emerged females have immature ovaries, and ovaries remain without any mature eggs until females mate. Once female mates, the vitellogenesis synthesis and uptake are estimulated, and oocytes are quickly developed. Oocytes maturation in ovarioles is metachronic, with only one oocyte developing at a time in each oogenic cycle. Morphological observations of the reproductive system including the ovaries and spermatheca, after the first cluster of eggs is laid, indicated D. citri is polyandrous, and may require multiple mating to develop additional oogenic maturation cycles.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

External morphology of Cotesia flavipes (Hymenoptera: Braconidae) during larval development

Cotesia flavipes (Cameron, 1891) (Hymenoptera) is a gregarious endoparasitoid used in applied biological control against Diatraea saccharalis (Fabricius, 1794) (Lepidoptera). In this study, we characterize the larval external morphology and the number of instars of C. flavipes. Parasitized larvae of D. saccharalis were sampled from the 1st to the 10th day after parasitism and dissected in an anticoagulant buffer for collection of C. flavipes immatures. Immatures were processed for scanning electron microscopy. Larvae of C. flavipes were prepared in NaOH solution and slide mounted to allow for mandible size measurements. Analysis of measurements of the parasitoid larval mandible size indicated that C. flavipes has three instars. Newly hatched larvae are caudate-mandibulate, assuming a hymenopteriform shape later in their development. The anal vesicle began to expand in the first instar and, once expanded, remained unchanged up to the beginning of the third instar. At the third instar, the anal vesicle decreased in volume. Herein we report the development and possible functions of the larval external structures modified during the development of C. flavipes, as for example their role in aiding newly-eclosed larvae to avoid the host immune response and to move within the host. To summarize the morphological changes during parasitoid growth, we should mention that the modifications in the anal vesicle were correlated with the feeding activity, and the maintenance of the anal vesicle indicates that this structure remained functional, probably playing a role in nutrient absorption and host regulation. On the other hand, the mandibles of early stage larvae are probably used to assist the parasitoid larvae during eclosion.FAPES

Effects of adult feeding on the reproduction and longevity of Noctuidae, Crambidae, Tortricidae and Elachistidae species

This research evaluates the effect of the adult diet on the reproduction of Anticarsia gemmatalis Hübner, Heliothis virescens (Fabr.), Spodoptera frugiperda (J. E. Smith) (Noctuidae), Diatraea saccharalis (Fabr.) (Crambidae), Gymnandrosoma aurantianum Lima (Tortricidae) and Stenoma catenifer Walsingham (Elachistidae). Adults of all species were fed either water or a 10% honey solution. The egg viability for the 1st and 2nd egg masses, adult fecundity, longevity, number of mating and the ovigeny index (OI) (degree of ovarian maturation) were evaluated. Fecundity of A. gemmatalis and H. virescens was drastically reduced when females were fed only on water. Egg viability from both 1st and 2nd egg masses was variable between treatments. Females of A. gemmatalis, H. virescens and S. frugiperda, and males of some species had a reduced longevity when fed only on water. The number of matings was higher for A. gemmatalis and D. saccharalis when fed on water only. The OI was < 1.0 for all species evaluated indicating that all females may develop new oocytes as they age. Based on the OI and the reduced fecundity of A. gemmatalis and H. virescens, one observes that adult feeding is important for the reproduction of both species, and the IO is not a good parameter to indicate such condition. Spodoptera frugiperda, G. aurantianum, D. saccharalis and S. catenifer do not require any source of carbohydrates as adults to sustain their reproduction.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

Exploitation of mitochondrial nad6 as a complementary marker for studying population variability in Lepidoptera

The applicability of mitochondrial nad6 sequences to studies of DNA and population variability in Lepidoptera was tested in four species of economically important moths and one of wild butterflies. The genetic information so obtained was compared to that of cox1 sequences for two species of Lepidoptera. nad6 primers appropriately amplified all the tested DNA targets, the generated data proving to be as informative and suitable in recovering population structures as that of cox1. The proposal is that, to obtain more robust results, this mitochondrial region can be complementarily used with other molecular sequences in studies of low level phylogeny and population genetics in Lepidoptera

The genetic structure of an invasive pest, the Asian citrus psyllid Diaphorina citri (Hemiptera: Liviidae).

The Asian citrus psyllid Diaphorina citri is currently the major threat to the citrus industry as it is the vector of Candidatus Liberibacter, the causal agent of huanglongbing disease (HLB). D. citri is native to Asia and now colonizes the Americas. Although it has been known in some countries for a long time, invasion routes remain undetermined. There are no efficient control methods for the HLB despite the intensive management tools currently in use. We investigated the genetic variability and structure of populations of D. citri to aid in the decision making processes toward sustainable management of this species/disease. We employed different methods to quantify and compare the genetic diversity and structure of D. citri populations among 36 localities in Brazil, using an almost complete sequence of the cytochrome oxidase I (COI) gene. Our analyses led to the identification of two geographically and genetically structured groups. The indices of molecular diversity pointed to a recent population expansion, and we discuss the role of multiple invasion events in this scenario. We also argue that such genetic diversity and population structure may have implications for the best management strategies to be adopted for controlling this psyllid and/or the disease it vectors in Brazil

The gastric caeca of pentatomids as a house for actinomycetes

Abstract Background Microbes are extensively associated with insects, playing key roles in insect defense, nutrition and reproduction. Most of the associations reported involve Proteobacteria. Despite the fact that Actinobacteria associated with insects were shown to produce antibiotic barriers against pathogens to the hosts or to their food and nutrients, there are few studies focusing on their association with insects. Thus, we surveyed the Actinobacteria diversity on a specific region of the midgut of seven species of stinkbugs (Hemiptera: Pentatomidae) known to carry a diversity of symbiotically-associated Proteobacteria. Results A total of 34 phylotypes were placed in 11 different Actinobacteria families. Dichelops melacanthus held the highest diversity with six actinobacteria families represented by nine phylotypes. Thyanta perditor (n = 7), Edessa meditabunda (n = 5), Loxa deducta (n = 4) and Pellaea stictica (n = 3) were all associated with three families. Piezodorus guildini (n = 3) and Nezara viridula (n = 3) had the lowest diversity, being associated with two (Propionibacteriaceae and Mycobacteriaceae) and one (Streptomyceataceae) families, respectively. Corynebacteriaceae and Mycobacteriaceae were the most common families with phylotypes from three different insect species each one. Conclusions Many phylotypes shared a low 16S rRNA gene similarity with their closest type strains and formed new phyletic lines on the periphery of several genera. This is a strong indicative that stinkbug caeca can harbor new species of actinobacteria, which might be derived from specific associations with the species of stinkbugs studied. Although the well-known role of actinobacteria as a source of biomolecules, the ecological features of these symbionts on the stinkbugs biology remain unknown

Geometric morphometry and molecular analysis clarified the identity of Opius

The aim of this study was to clarify the identity of specimens designated as Opius sp. aff. bellus using geometric morphometry and analysis of the ITS2 region of the ribosomal DNA (rDNA) and region D2 of the 28S rDNA. Opius bellus Gahan is a koinobiont endoparasitoid of fruit fly larvae (Diptera: Tephritidae) exclusively found in the Neotropical region, but widely distributed from Mexico to Argentina. Opius sp. aff. bellus is morphologically similar to Opius bellus but exhibits yellowish, instead of dark-brown, posterior tibiae. Twenty anatomical landmarks on the wings from these two taxa sampled from three Brazilian states were analyzed. Multivariate morphometric analysis showed a large amount of morphological similarity between the specimens, indicating they are the same species. Sequence analysis of the ITS2 showed that intrapopulation variability was similar to interpopulation variability and that the morphotypes were also highly similar. In addition, the D2 region of the 28S rDNA displayed high similarity between sequences. Therefore, based on morphometric and molecular analyses, specimens thought to be Opius sp. aff. bellus actually belong to O. bellus. Key words: Chromatic variations, geographic variation, molecular taxonom

Temperature effects on the mating frequency of Anticarsia gemmatalis Hüebner and Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

Este trabalho estudou a influência da temperatura na freqüência de cópula de Anticarsia gemmatalis Hübner e Spodoptera frugiperda J. E. Smith, que empregam diferentes estratégias de alocação, e a utilização de nutrientes para suas atividades reprodutivas. Os insetos foram criados em dieta artificial a 25ºC, sendo a influência da temperatura na freqüência de cópula, fecundidade, fertilidade e longevidade de adultos avaliada em cinco temperaturas (15, 20, 25, 30 e 35ºC). A temperatura afetou a freqüência de cópula de ambas as espécies, sendo o seu efeito mais evidente nas temperaturas extremas estudadas (15ºC e 35ºC), principalmente, para A. gemmatalis, que apresentou redução drástica em sua atividade de cópula. Temperaturas intermediárias (20ºC a 30ºC) permitiram o maior número de cópulas, com S. frugiperda apresentando (até oito cópulas) atividade de cópula muito superior à de A. gemmatalis (até duas cópulas). Mesmo com a variação encontrada na atividade de cópula nas diferentes temperaturas, não foi verificada correlação entre o número de cópulas e os demais parâmetros biológicos observados (fecundidade, fertilidade e longevidade), com exceção da fecundidade de S. frugiperda a 25ºC, que apresentou correlação positiva com a atividade de cópula nessa temperatura (r = 0,589; P = 0,003), indicando que as alterações na atividade reprodutiva desse inseto foram decorrentes, basicamente, de sua resposta à temperatura. Fêmeas de S. frugiperda foram mais fecundas nas temperaturas entre 20ºC e 30ºC e as de A. gemmatalis a 25ºC. A longevidade de ambos os sexos decresceu com o aumento da temperatura para as duas espécies estudadas.This paper deals with the influence of temperature on the mating frequency of two lepidopterans, Anticarsia gemmatalis Hübner and Spodoptera frugiperda (J.E. Smith), which use different strategies of allocation, and with the utilization of nutrients for their reproductive activities. The insects were reared on artificial diets at 25ºC, and the adults were exposed to five temperatures (15, 20, 25, 30, and 35ºC) to observe the influence of each temperature on their mating frequency, fecundity, fertility and longevity. The temperature affectedthe mating frequency of both species, being more evident at 15ºC and 35ºC, mainly for A. gemmatalis, which presented a drastic reduction on mating activities. The highest number of matings were observed from 20ºC to 30ºC, with S. frugiperda presenting mating activity (0-8) much higher than that of A. gemmatalis (0-2), but no correlation was observed among the number of matings and all other biological parameters evaluated (fecundity, fertility and longevity). However, S. frugiperda showed a positive correlation between fecundity and mating activity of females (r = 0.589; P = 0.003) at 25ºC. The highest fecundities were observed at temperatures from 20ºC to 30ºC for S. frugiperda and at 25ºC for A. gemmatalis. For both species, the longevity of males and females decreased as temperature increased

Mismatch curves of <i>Diaphorina citri</i> from the whole sample (a), and from group I (b) and II (c) independently.

<p>Mismatch curves of <i>Diaphorina citri</i> from the whole sample (a), and from group I (b) and II (c) independently.</p