Discrimination of the closely related biocontrol agents Macrolophus melanotoma (Hemiptera: Miridae) and M. pygmaeus using mitochondrial DNA analysis

Abstract

The separation of the closely related predatory species Macrolophus melanotoma Costa (= M. caliginosus Wagner) and Macrolophus pygmaeus (Rambur) based exclusively on the different colour pattern of the first antennal segment (white central band in M. melanotoma and entirely black in M. pygmaeus) is rather precarious and their taxonomic status is still in doubt. In the present study their taxonomic status was evaluated by DNA confirmatory analysis and hybridization experiments between M. pygmaeus and a Macrolophus taxon, resembling M. melanotoma, with a first antennal segment entirely black or with a white central band collected from Dittrichia viscosa (L.) W. Greuter (Asteraceae) in southern Greece. Adult females from Dittrichia plants hybridized with males of M. pygmaeus and vice versa did not produce viable eggs. The Macrolophus species from Dittrichia irrespective of the first antennal segment coloration differed from M. pygmaeusin digestive patterns generated by AseI, XbaI, and MseI on 16S rRNA and in RAPD profiles produced by the primers OPA-18 and OPA-20. These results demonstrate that on Dittrichia plants there is a distinct dimorphic taxon, M. melanotoma, as it is the only species of the genus Macrolophus bearing a first antennal segment with a central white band. Given the limitation of the coloration pattern, the mtDNA genetic markers are the appropriate method for the identification of M. melanotomaand M. pygmaeus.

Selection of Macrolophus melanotoma between its main non-crop host plant (Dittrichia viscosa) and eggplant, pepper and tomato, in choice experiments

“…In these experiments it was revealed that M. melanotoma avoided tomato (Perdikis et al 2008). Moreover, studies on DNA analysis of Macrolophus specimens found on tomato crops showed that they belonged to the species M. pygmaeus (Perdikis et al 2003, Martinez-Cascales et al 2006. Therefore, if considering that M. melanotoma showed a very low selection rate for tomato plants, our data support these of previous studies indicating that M. melanotoma should be considered as a predator most likely not occurring on tomato crops.…”

“…Macrolophus melanotoma occurs at high numbers on the non-cultivated plant Dittrichia viscosa L. (W. Greuter) (Asteraceae) that is very common in the Mediterranean region (Alomar et al 1994, Perdikis et al 2003, Martinez-Cascales et al 2006. It was present throughout the year on D. viscosa with the highest numbers occurring in June and July, when more than 15 individuals per stem, on average, were recorded (Perdikis et al 2007).…”

“…Albajes and Alomar 1999). However, evidence based on crossings and molecular analyses has shown that Macrolophus specimens recorded on tomato in areas of Greece, Spain and Portugal always belonged to Macrolophus pygmaeus (Rambur) (Perdikis et al 2003, Martinez-Cascales et al 2006.…”

Elliptic Fourier Analysis in the Study of the Male Genitalia to Discriminate Three <em>Macrolophus</em> Species (Hemiptera: Miridae)

“…Although the genus Macrolophus has very simple morphological characters compared to other genera of Dicyphinae, the lack of discontinuous characters makes them difficult to identify. In the case of these species, M. costalis can easily be separated from the other two by the black tip at the scutellum, but M. pygmaeus and M. melanotoma are cryptic species, extremely similar to one another in external traits [1], which has resulted in misidentifications [2,3]. Macrolophus pygmaeus is an efficient predator of several key pests of vegetable crops in Europe, and it is produced and widely used as a biological control agent, both in greenhouse and field crops [4,5,6,7].…”

Single-step PCR differentiation ofCotesia sesamiae(Cameron) andCotesia flavipesCameron (Hymenoptera: Braconidae) using polydnavirus markers

“…However the biological control agent is itself an invader in the system, and can be unsafe for the ecosystem also (Holt & Hochberg 2001;Hopper 2001;Waage 2001). In many cases, antagonist species closely related to the introduced agent are present and are diffi cult to distinguish morphologically (Perdikis et al 2003). In order to follow up introductions and better evaluate the eff ect of biological control on the natural endemic fauna of antagonists, it is necessary to develop rapid taxonomic diagnostic tools (Hinz et al 2001).…”