Elliptic Fourier Analysis in the Study of the Male Genitalia to Discriminate Three Macrolophus Species (Hemiptera: Miridae).

Within the genus Macrolophus (Heteroptera: Miridae), the species M. costalis (Fieber), M. melanotoma (Costa) and M. pygmaeus (Rambur) are present in the Mediterranean region on a wide variety of plant species. While M. costalis can easily be separated from the other two by the black tip at the scutellum, M. pygmaeus and M. melanotoma are cryptic species, extremely similar to one another in external traits, which has resulted in misidentifications. M. pygmaeus is an efficient biological control agent, both in greenhouse and field crops. The misidentification of these cryptic species could limit the effectiveness of biological control programs. Although the morphology of the left paramere of the male genitalia has been used as a character for identification of these two cryptic species, there is controversy surrounding the reliability of this character as a taxonomic tool for these species. Using geometric morphometric techniques, which are a powerful approach in detecting slight shape variations, the left parameres from these three Macrolophus species were compared. The paramere of M. costalis was larger and had a different shape to that of M. melanotoma and M. pygmaeus; however, no differences in size or shape were found between the left paramere of M. melanotoma and that of M. pygmaeus. Therefore, our results confirm that this character is too similar and it cannot be used to discriminate between these two cryptic species.

Infection capacities in the orange-pathogen relationship: compatible (Penicillium digitatum) and incompatible (Penicillium expansum) interactions.

Penicillium digitatum and Penicillium expansum are the most devastating pathogens of citrus and pome fruits, respectively. Whereas P. digitatum is a very specific pathogen that only infects Citrus fruits, P. expansum has a broader host range but has not been reported to be infectious in Citrus. To determine the responses of fruits and the infection capacities of both moulds, two varieties of oranges at different maturity stages, different inoculum concentrations and two different storage temperatures were studied. In compatible interactions, no significant differences in rot dynamics among harvests were found with a 10(7) conidia mL(-1) inoculum concentration at both temperatures tested (20 °C and 4 °C). However, at other inoculum concentrations, significant differences in rot dynamics were found, especially in immature fruits. Incompatible interactions showed that P. expansum could infect oranges at commercial maturity in both tested varieties. Decay incidence and severity were higher at 4 °C than at 20 °C. In addition to infection capacity studies, histochemical tests were performed to detect wound-healing compounds for both pathogens. A positive reaction for lignin was detected for both pathogens in immature oranges over a short period (48 h). In all cases, no reactions were found in control samples. Our results indicate that pathogen concentration, host maturity and storage temperature can play important roles in the defence mechanisms of fruit. Furthermore, to our knowledge, this is the first work that demonstrates that P. expansum can infect oranges under favourable conditions.

Monogamy and polygamy in two species of mirid bugs: a functional-based approach.

Multiple mating in females is widespread among insects in spite of the risk of predation, disease acquisition and/or physical injury that may occur. One common consequence of female polyandry is competition among sperm from two or more males within the female to fertilize the ova. This competition is an evolutionary driving force that determines a series of adaptations in both males and females. In this work, we examine some behavioral, morphological and physiological characteristics of males and females of two Heteropteran species that are related to their monoandrous/polyandrous mating behavior. Females of Macrolophus pygmaeus (Het. Miridae), the monoandrous species, were coy about accepting a male partner, spent a short time in copula, and received only a small volume of ejaculate. Even so, with only one mating event, they received enough sperm to fertilize most of their ova (21 days after mating all females were still fertile). In contrast, females of Nesidiocoris tenuis (Het. Miridae), the polyandrous species, readily accepted any mating partner, spent a long time in copula and received a large volume of ejaculate. However, these latter females soon ran out of sperm and needed to mate periodically in order to maintain a sufficient sperm supply to fertilize their eggs. As predicted, based on current theory (Simmons, 2001b), an increased investment in spermatogenesis was detected in N. tenuis with relation to M. pygmaeus. The males of the polyandrous species had larger accessory reproductive glands, seminal vesicles, testes and sperm cells than those of the monoandrous species.