Emergence,dispersal, and mate finding via a substrate‐borne sex pheromone in the parasitoid Metaphycus luteolus

Metaphycus luteolus Timberlake (Hymenoptera: Encyrtidae) is a facultatively gregarious parasitoid of soft scale insects. We conducted behavioral experiments to better understand the mating structure of this species. Emergence of male and female offspring is synchronized, beginning at the onset of photoperiod. Both sexes are able to disperse, although dispersal of males from natal patches appears to take longer than dispersal of females. We demonstrated the presence of a female‐produced contact pheromone using open arena bioassays and motion tracking software, testing residues deposited by walking females, and extracts of females. Males responded to the females' ‘chemical footprints’ and to acetone and hexane extracts of females by searching and arrestment on the chemical residues. Responses of males were dose dependent and diminished with time since the stimulus was deposited. Our findings support the hypothesis that non‐local mating among wasps emerging from different hosts may be quite common in these parasitoids. The implications of our results for the mating structure and previously documented sex ratio patterns of these parasitoids are described.     

LepChorionDB,a database of Lepidopteran chorion proteins and a set of tools useful for the identification of chorion proteins in Lepidopteran proteomes

Chorion proteins of Lepidoptera have a tripartite structure, which consists of a central domain and two, more variable, flanking arms. The central domain is highly conserved and it is used for the classification of chorion proteins into two major classes, A and B. Annotated and unreviewed Lepidopteran chorion protein sequences are available in various databases. A database, named LepChorionDB, was constructed by searching 5 different protein databases using class A and B central domain-specific profile Hidden Markov Models (pHMMs), developed in this work. A total of 413 Lepidopteran chorion proteins from 9 moths and 1 butterfly species were retrieved. These data were enriched and organised in order to populate LepChorionDB, the first relational database, available on the web, containing Lepidopteran chorion proteins grouped in A and B classes. LepChorionDB may provide insights in future functional and evolutionary studies of Lepidopteran chorion proteins and thus, it will be a useful tool for the Lepidopteran scientific community and Lepidopteran genome annotators, since it also provides access to the two pHMMs developed in this work, which may be used to discriminate A and B class chorion proteins. LepChorionDB is freely available at http://bioinformatics.biol.uoa.gr/LepChorionDB.     

Nesidiocoris tenuis as a pest in Northwest Europe: Intervention threshold and influence of Pepino mosaic virus

The use of Nesidiocoris tenuis (Hemiptera: Miridae) as a biocontrol agent is controversial as it is considered a pest in Northwest European tomato greenhouses, due to its tendency to damage the plant and fruit. Necessary chemical plant protection products to control N. tenuis have toxic side effects on important beneficials like Macrolophus pygmaeus (Hemiptera: Miridae), which jeopardizes the whole IPM programme. In this study, several commercial tomato greenhouses were monitored for mirid populations. The relationship between the number of N. tenuis individuals and plant damage was assessed in function of availability of prey and interaction with M. pygmaeus. These greenhouse data were used to determine a practical density intervention threshold. Next, the hypothesis that a Pepino mosaic virus (PepMV) infection increases plant and fruit damage by N. tenuis (as has been shown for M. pygmaeus) was tested. Plant damage occurred when the average number of predatory bugs in the head of the plant exceeded 16 per ten plants. Plant damage increased in severity at increasing predatory bug densities, independent of the availability of prey and M. pygmaeus presence. Plant and fruit damage were not affected by the presence of PepMV, as was shown for fruit damage in previous studies for M. pygmaeus. Our study provides a practical density intervention threshold for growers in greenhouse crops. Simple monitoring of the number of predatory bugs in the head of the plant can be used to take specific biocontrol actions. It was also shown that only the predatory bug N. tenuis itself causes damage, and there is no interaction with PepMV.     

The study of the E-class SEPALLATA3-like MADS-box genes in wild-type and mutant flowers of cultivated saffron crocus (Crocus sativus L.) and its putative progenitors

To further understand flowering and flower organ formation in the monocot crop saffron crocus (Crocus sativus L.), we cloned four MIKC^c type II MADS-box cDNA sequences of the E-class SEPALLATA3 (SEP3) subfamily designated CsatSEP3a/b/c/c_as as well as the three respective genomic sequences. Sequence analysis showed that cDNA sequences of CsatSEP3 c and c_as are the products of alternative splicing of the CsatSEP3c gene. Bioinformatics analysis with putative orthologous sequences from various plant species suggested that all four cDNA sequences encode for SEP3-like proteins with characteristic motifs and amino acids, and highlighted intriguing sequence features. Phylogenetically, the isolated sequences were closest to the SEP3-like genes from monocots such as Asparagus virgatus, Oryza sativa, Zea mays, and the dicot Arabidopsis SEP3 gene. All four isolated C. sativus sequences were strongly expressed in flowers and in all flower organs: whorl1 tepals, whorl2 tepals, stamens and carpels, but not in leaves. Expression of CsatSEP3a/b/c/c_as cDNAs was compared in wild-type and mutant flowers. Expression of the isolatedCsatSEP3-like genes in whorl1 tepals together with E-class CsatAP1/FUL subfamily and B-class CsatAP3 and CsatPI subfamilies of genes, fits the ABCE “quartet model,” an extended form of the original ABC model proposed to explain the homeotic transformation of whorl1 sepals into whorl1 tepals in Liliales and Asparagales plants such as C. sativus. This conclusion was also supported by the interaction of the CsatSEP3b protein with CsatAP1/FUL and CsatAP3 proteins. In contrast, expression of both B-class CsatAP3 and CsatPI genes and the C-class CsatAGAMOUS genes together with E-class CsatSEP3-like genes in carpels, without any phenotypic effects on carpels, raises questions about the role of these gene classes in carpel formation in this non-grass monocot and requires further experimentation. Finally, taking advantage of the size and sequence differences in amplified genomic sequences of the triploid C. sativus and comparing them with the respective sequences from C. tomasii, C. hadriaticus and C. cartwrightianus, three putative wild-type diploid progenitor species, we examined the origin of CsatSEP3a sequence.     

Effects of Acute and Chronic Cadmium Administration on the Vascular Reactivity of Rat Aorta

The effect of acute and chronic cadmium (Cd) administration on the vascular function of the rat aorta was studied. The rats were randomly divided into four main groups (A: saline controls under chronic administration, B: Cd-treated rats under chronic administration, C: saline controls under acute administration, D: Cd-treated rats under acute administration). After their sacrifice, the aortic rings were divided into rings with endothelium (E+) and without (E−), and suspended in an isolated organ bath with Krebs–Henseleit buffer. Maximal tension (T _max, in g) was measured in response to potassium chloride (KCl) and phenylephrine (PE) in all aortic rings. Relaxation response to acetylcholine (ACh) administration was expressed as percent of maximal tension induced by PE. Chronic administration: A statistically significant increase of the contraction was observed between groups B (i.m. Cd 0.5 mg/kg for 120 days) and A (i.m. 0.9% NaCl for 120 days) in response to KCl (20–60 mM) and the T _max as well (in both the E+ and the E− subgroups). No statistically significant difference was observed in response to PE and ACh exposure. Acute administration: A statistically significant increase was observed between group D(E+) (i.m. Cd 2 mg/kg, 8 h before sacrifice) and group C(E+) (i.m. 0.9% NaCl, 8 h before sacrifice) in response to 10–30 mM of KCl, and a significant decrease between D(E−) and C(E−) in response to 10⁻⁷–10⁻⁶ M of PE, though T _max was increased between D(E−) and C(E−) with PE exposure. The contractile response levels of the E+ aortic rings to PE and ACh showed no statistically significant difference.     

Survey of brown soft scale Coccus hesperidum L. parasitoids in southern California citrus

The parasitoid complex of brown soft scale, Coccus hesperidum L., a multivoltine soft scale, was determined in southern California citrus over the period February 2004–March 2006. The survey was conducted by placing brown soft scale-infested yucca leaves in the canopy of citrus trees and subsequently rearing individually isolated parasitized scales in the laboratory. A total of 14 species parasitized brown soft scale in the field, the most abundant ones belonging to the genus Metaphycus Mercet (75%). The most abundant parasitoid species was Metaphycus angustifrons Compere (38% parasitism), and this is a new record of establishment for this species in California. Coccophagus species accounted for only 11% parasitism. There were important spatio-temporal differences across the parasitoid complex survey locations. We also found that the five most abundant encyrtid parasitoid species showed preferences for scales of different sizes. Our results have implications for biological control of citricola scale, Coccus pseudomagnoliarum (Kuwana), an important pest of citrus in the San Joaquin Valley of central California. Notably, this species is nearly absent in southern California. Brown soft scale is considered to be an alternate host for parasitoids of citricola scale, a univoltine soft scale, at times when the latter species is unavailable for parasitism.