We used polymerase chain reaction to determine whether Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) DNA was present in the guts of larvae and adult males and females of the generalist predator Coleomegilla maculata De Geer (Coleoptera: Coccinellidae). The predators were fed Ostrinia nubilalis egg masses and allowed to digest at either 20 degrees C or 27 degrees C for time spans ranging from 0 to 12 h. Four primer pairs, specific for O. nubilalis were developed, using a nuclear ribosomal RNA sequence including part of the 18S gene, the complete internal transcribed spacer (ITS-1) region and part of the 5.8S gene. These primers amplified four sequences that were 492, 369, 256 and 150 base pairs long. We found a significant negative effect of time since feeding on the number of bands that could be detected. The shortest fragment was detected for the longest time after feeding (up to 12 h). We found no effect of predator weight, sex, developmental stage, or meal size on the time course over which bands of varying lengths could be detected.
We examine the effects of fecundity-limited attack rates and resistance of hosts to parasitism on the dynamics of two-host-one-parasitoid systems. We focus primarily on the situation where one parasitoid species attacks two host species that differ in their suitability for parasitism. While all eggs allocated to suitable hosts develop into adult parasitoids, some of the eggs allocated to marginal host do not develop. Marginal hosts can therefore act as a sink for parasitoid eggs. Three-species coexistence is favoured by low levels of parasitoid fecundity and by low levels of suitability of the marginal host. Our model also produces an indirect (+, )) interaction in which the suitable host can benefit from the presence of the marginal host, but the marginal host suffers from the presence of the suitable host. The mechanism driving the indirect (+, )) interaction is egg limitation of parasitoids incurred by allocating eggs to marginal hosts.
The PowerPlex(®) Fusion 6C System is a 27-locus, six-dye, multiplex that includes all markers in the expanded CODIS core loci and increases overlap with STR database standards throughout the world. Additionally, it contains two, rapidly mutating, Y-STRs and is capable of both casework and database workflows, including direct amplification. A multi-laboratory developmental validation study was performed on the PowerPlex(®) Fusion 6C System. Here, we report the results of that study which followed SWGDAM guidelines and includes data for: species specificity, sensitivity, stability, precision, reproducibility and repeatability, case-type samples, concordance, stutter, DNA mixtures, and PCR-based procedures. Where appropriate we report data from both extracted DNA samples and direct amplification samples from various substrates and collection devices. Samples from all studies were separated on both Applied Biosystems 3500 series and 6-dye capable 3130 series Genetic Analyzers and data is reported for each. Together, the data validate the design and demonstrate the performance of the PowerPlex(®) Fusion 6C System.
We conducted field-cage studies on the direct interactions between a coccinellid species native to North America, Coleomegilla maculata De Geer, and a species introduced from Asia, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae). We compared the mortality and weight gain of larvae of both species in field cages that enclosed one or both species with corn plants containing high or low aphid numbers. We did not find a significant effect of the presence of H. axyridis on the survival or weight gain of C. maculata , but H. axyridis larvae weighed more when kept with C. maculata for 5 days than when kept with equal numbers of conspecifics. This suggests that intraspecific competition was stronger for H. axyridis than the interspecific competition with C. maculata . The spatial distribution of C. maculata over the plants differed between single-species and two-species treatments in a manner that suggested that this species avoided interactions with H. axyridis .
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