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A sugar cane pest in Mexico, Scolecocampa mochisa (Schaus) (new combination), was originally described in the monotypic genus SaccharophagosSchaus (1923), which is considered a new synonym of Scolecocampa Guenée (1852). The adult and larva are illustrated. The genitalia, egg, and pupa are described and illustrated. The closely related species, Scolecocampa stygialis (Smith), is a new combination.
The tribe Dacini (Diptera: Tephritidae: Trypetinae) currently consists of ≈40 genera and 1,000 described species. Among others, it includes the genera Bactrocera, Ceratitis, and Dacus, all of which are pests of agricultural importance because they oviposit in ripening fruit. Although previous studies, based on morphological and molecular data, suggested that the members of Dacini are monophyletic, no extensive molecular phylogenetic studies have been published on Bactrocera, Ceratitis, or Dacus. Therefore, we undertook a phylogenetic analysis of 34 tephritid taxa, including 16 species of the tribe Dacini, utilizing 1,391 bp from the mitochondrial 16S rRNA, 12S rRNA, and cytochrome oxidase II tRNALys tRNAAsp genes. Combined maximum parsimony analysis suggested the following with strong quantitative support: (1) the subfamilies Tephritinae and Trypetinae are monophyletic, (2) Dacini is monophyletic, and (3) members of the subtribe Dacina are monophyletic. In addition, Ceratitidina Gastrozonina are basal to Dacina. Within Dacina, Dacus and Bactrocera were each monophyletic. The results obtained here are generally congruent with those based on morphology.
Wood cockroaches (Blattaria: Blattellidae) are important prey of the red-cockaded woodpecker, Picoides borealis Wilson (Piciformes: Picidae), an endangered species inhabiting pine (Pinus spp.) forests in the southern United States. These woodpeckers forage on the boles of live pine trees, but their prey consists of a high proportion of wood cockroaches, Parcoblatta spp., that are more commonly associated with dead plant material. Consequently, we sampled large woody debris, logs and standing dead trees (snags), in a South Carolina pine forest to determine densities of wood cockroaches in these habitats. Nearly 80% of the 662 wood cockroaches we collected from woody debris were found in snags. However, when we estimated the number of wood cockroaches per hectare, we found that the two habitats contained approximately equal numbers because logs are more abundant than snags. The broad wood cockroach, Parcoblatta lata Brunner, was the most common cockroach on live pine boles constituting 46% of the wood cockroaches. Males were present from late April to late July in field studies suggesting that P. lata has only one generation per year, which is consistent with laboratory studies in which males lived an average of 91.3 d. Female P. lata lived almost twice as long (158.2 d) and produced an average of 12.6 oothecae/female (SE = 3.4) or ≈517 offspring/female. Although P. lata were common on boles of live trees, our results show that snags and logs also are important habitats of these wood cockroaches in pine forests.
To study the relationship of Mediterranean fruit fly or medfly, Ceratitis capitata (Wiedemann), to native plant hosts in an area within its original home range, fruits were sampled in diverse areas of Kenya from 1999 to 2001. Sampling effort was concentrated in and around forested areas in coastal, central highland, and western highland habitats. Medflies were reared from fruits of 55 species of plants, 51 of them indigenous; 46 of these species represent previously unknown hosts in Africa. Fruits infested by C. capitata were collected in all study sites, east and west of the Gregory Rift Valley, in xeric habitats between the coast and the central highlands, and at altitudes from sea level to 2,164 m above sea level. The conditions for year-round breeding of medfly in indigenous fruits are present at the coast, and possibly in highland areas as well. Infestation indices were comparable to those reported elsewhere from cultivated fruits. Although polyphagous in its home range, C. capitata was not distributed uniformly among species within two important host-plant families, Sapotaceae and Rubiaceae.
As is the case with many egg parasitoids, parasitism rates in Trichogramma spp. vary markedly among individuals. Here we test whether this individual variability in Trichogramma carverae (Oatman and Pinto) is associated with trade-offs between early and late reproduction and between early reproduction and life span. We also consider a recently postulated trade-off between an index of pro-ovigeny and life span. Early and late reproduction were positively correlated. To further test for a trade-off, wasps were subdivided into groups depending on their total reproductive output because any correlations among traits might have been masked when wasps produced only a few eggs. This led to correlations between early and late reproductive output becoming negative. However, arbitrary subdivision in this manner is expected to result in artifactual negative correlations, and correlations between early and late reproduction were no longer evident once this confounding factor had been removed. There was no evidence that early reproduction influenced life span; even wasps that failed to parasitize any host eggs had the same mean life span as wasps that reproduced. There was a negative correlation between an index of pro-ovigeny and life span; however, this negative association is likely to be an artifact of the greater opportunity wasps have to parasitize eggs when they are long-lived. Patterns of reproduction and life span therefore appear unconstrained in Trichogramma spp.
The diurnal and seasonal activity patterns of the western cherry fruit fly, Rhagoletis indifferens Curran, were determined on three sweet cherry trees, Prunus avium (L.), from 0700 to 1900 hours during June and July 2001 in Yakima County, WA. There were significant effects of time of day and season on numbers of flies seen on fruit relative to leaves, indicating that presence on or attraction to these substrates for feeding, mating, or oviposition, whether caused by visual or chemical cues, was greatly modified by temperature. When temperatures were 15–16°C at 0700 hours in early June, flies of both sexes were seen mostly on leaves, but when the temperature reached 20°C, more flies of both sexes moved onto fruit. Peak fly sightings occurred at 25–35°C, usually after 1000 hours. At >35°C, most flies vanished from view, and those seen were less active. Over the entire season, males were seen four times more often than females and spent more time on fruit than on leaves. Females were seen equally on and spent equal time on fruit and leaves when temperatures were 20–35°C. Mating was initiated on fruit but was completed on fruit and leaves. Overall fly sightings and daily temperatures were positively correlated early in the season when it was cooler, uncorrelated in the middle of the season, and negatively correlated in late season when it was warmest. The results show that R. indifferens presence and times spent on fruit and leaves are greatly altered by daily and seasonal changes in temperature, but they also suggest that at 20–35°C substrate-seeking behaviors of each sex do not change with time of day or season.
Whiteflies (suborder Sternorrhyncha, family Aleyrodidae) are known to harbor prokaryotic symbionts, some of which are vital and provide specific nutritional needs, while others are transient or nonessential, that can either be beneficial or deleterious in the long-term. However, the extent to which diverse bacterial symbionts are associated with populations of the same species of whitefly that colonize herbaceous plants in diverse habitats, and their particular influence on the evolution of the whitefly host, are not well studied. Here, the composition and diversity of prokaryotic symbionts associated with biotypes or haplotypes of the whitefly Bemisia tabaci Gennadius were examined for collections from representative host plants and different geographical locations worldwide. The eubacterial 16S ribosomal DNA (rDNA) and Wolbachia-specific 16S rDNA genes for endosymbionts were obtained by polymerase chain reaction (PCR) amplification. Amplification and comparison of 16S rDNA sequences revealed that a primary-like symbiont was associated with all whitefly collections examined. However, the endosymbiont 16S rDNA phylogeny was not strictly concordant with the phylogeographically informative cytochrome oxidase I tree for the respective whitefly host. Secondary symbiont sequences for 13 of 20 whitefly populations clustered with Arsenophonus spp. and aphid T-type bacteria, which both belong to the Enterobacteriaceae. PCR and sequencing of Wolbachia-specific 16S rDNA revealed that at least 33% of B. tabaci populations harbored Wolbachia.
Tobacco thrips, Frankliniella fusca Hinds, are a major pest of many southeastern crops; however, very little information is available on the internal microflora of these insects. Pantoea ananatis (Serrano) Mergaert and Pantoea agglomerans (Beijerinck) Mergaert were each isolated from 9.6% of the 73 thrips tested from our laboratory colony. These bacteria were isolated from the same individual only once; in all remaing bacteria-infected thrips, only one bacterium was found. Tobacco thrips from our laboratory colony contained between 3.7 × 103 and 1.1 × 105 colony forming units (CFU)/ml/thrips of P. ananatis and between 1.2 × 103 and 2.5 × 105 CFU of P. agglomerans. Between 2.0 × 103 and 3.2 × 107 CFU of P. ananatis were isolated from leaflets exposed to thrips harboring P. ananatis. Leaflets on which thrips harboring P. agglomerans fed contained between 9.6 × 104 and 3.0 × 106 CFU of P. agglomerans. Field populations of tobacco thrips collected from onion plants harbored an average of 1.3 × 104 CFU/ml/thrips of P. ananatis, whereas those collected from peanut plants harbored an average 4.3 × 103 CFU of this bacterium. P. agglomerans was not isolated from field-collected thrips. Our data support a strong relationship between thrips feeding and the presence of these bacteria on the leaf surface. The fact that tobacco thrips are so strongly associated with P. ananatis, a known plant pathogen, is of particular importance. The leaf disk assay provided a consistently reliable method of detecting bacteria within the thrips body. Bacteria were not recovered from leaves unless the corresponding thrips also contained bacteria. This correlation suggests that this assay can be used to detect P. ananatis and P. agglomerans within the body of an individual thrips without homogenizing and plating the individual insect.
The seed beetle Stator limbatus adjusts egg size in response to the quality of the oviposition host, laying small eggs on the high quality host, Acacia greggii seeds, and larger eggs on the poor quality host, Cercidium floridum seeds. We examined various proximate mechanisms of this egg-size plasticity. Once exposed to a new host, it takes 24 to 48 h for females to change the size eggs they lay. Beetles that came into direct contact with seeds adjusted egg size to a much greater extent than beetles that only came in contact with the fruits or were physically separated from the seeds. Egg size was not affected by size of the seed. Both the host seed in which the larvae were reared as well as the host to which adults were subsequently exposed influenced egg size. The default egg size in the absence of a suitable host is slightly larger than the size egg laid on A. greggii. Thus, beetles increase egg size in response to C. floridum seeds and slightly decrease egg size in response to A. greggii seeds.
An eradication project has been initiated in the southwestern island of Japan to contain the West Indian sweetpotato weevil, Euscepes postfasciatus (Fairmaire) using the sterile insect technique (SIT). We report here about rearing this insect for >14 successive generations on an artificial diet, an element required for successful use of SIT. The fecundity of reared weevils increased with each generation. Egg hatch (85–95%) and adult yield (30–60%) were consistently high throughout the test period. Comparisons of fecundity and preoviposition periods indicated that females from the artificially reared strain at generation 14 oviposited more and earlier in life than those from the base stock. These differences resulted from an increase in frequency (100%) of females that laid eggs without standard oviposition substrates in the artificially reared strain. Adaptation to an artificial diet is discussed in relation to the oviposition behavior of E. postfasciatus and the success of SIT against this weevil.
Twenty-six field populations and five laboratory strains of Lutzomyia longipalpis (Lutz & Neiva), the sand fly vector of Leishmania chagasi in the Americas, were analyzed for genetic variation at 15 enzyme loci. The goal was to describe the genetic structure of natural populations, to evaluate the notion that this taxon is composed of a number of sibling species, and to delimit the boundaries among putative species within the complex. Allele frequencies for three loci, Gpi, Aat-1, and Pgm, permitted discrimination of three discrete population groups (Colombia, Central America, and Brazil) with a probability of correctly assigning an individual to one of the groups >99%. Overall FST was high (0.489) and estimated Nem for all 26 populations was 0.23, indicating genetic substructuring and restricted gene flow among populations. More than 90% of the variance in allele frequencies was attributed to differences among the three regions. Levels of gene flow (Nem) among populations within species (2.41) were 8.3 times higher than between species (0.29). Cluster analysis of Nei’s genetic distance coefficients grouped populations into three well-defined clades (Brazil, Central America, and Colombia). Nei’s genetic distance (D) among putative species varied from 0.15 to 0.19 and was consistent with values previously published for species within the genus Lutzomyia. These results are consistent with Lu. longipalpis being a complex of at least three sibling species.
DNA sequencing analysis of the mitochondrial DNA cytochrome oxidase II (COII) region was used to examine genetic variation in the termite genus Reticulitermes Holmgren. We examined 21 species and subspecies from three continents. Sequencing of a 677-bp region of a 780-bp amplicon from 41 individuals and from 17 sequences obtained from GenBank revealed 221 polymorphic sites within the genus. Tajima-Nei distances from species ranged from 0.9 to 12.7%, and parsimony and maximum likelihood analysis revealed several clades within the genus. Reticulitermes flavipes (Kollar) formed a distinct clade along with R. santonensis De Feytaud. European R. lucifugus (Rossi) formed a distinct clade with R. banyulensis (Béziers). Turkish R. lucifugus was distinct relative to European R. lucifugus, and along with R. clypeatus Lash from Israel formed a sister group with R. balkanensis Clément from Greece. This study provides support for the separation of Turkish R. lucifugus from European members of the species. This mitochondrial DNA marker was also able to identify several Reticulitermes specimens from Oklahoma, Texas, Missouri, and South Korea to R. flavipes, R. hageni Banks, R. virginicus (Banks), and R. speratus Shimizu.
We examined the pollen foraging responses of Africanized and European honey bee colonies to hexane extractable compounds of Africanized and European larvae (brood pheromone). Brood pheromone was presented to broodless Africanized and European colonies equalized for numbers of bees, food stores and, empty comb space. The pheromone significantly increased the ratio of pollen to nonpollen foragers returning to colonies. There was no differential pollen foraging response to pheromone racial origin. European colonies in this study had a significantly higher proportion of pollen to nonpollen foragers entering colonies than did Africanized colonies for pheromone and control treatments. The proboscis extension response to sucrose was used to test the sensitivity to sucrose of eight Africanized (most similar to Apis mellifera scutellata Lepeletier) and six European colonies (most similar to Apis mellifera ligustica L.). Individual sensitivity to sucrose has been demonstrated as a neuro-sensory correlate of foraging behavior in European bees such that individuals that forage for pollen have lower response thresholds to sucrose than bees that forage for nectar. Africanized bees were significantly more likely to respond to lower concentrations of sucrose than European bees. We concluded that sucrose response threshold was a poor predictor for comparative foraging behavior of these races because the neuro-sensory systems of the two races may be differentially “tuned” by thresholds to defensive cues.
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