Norma Flores-Estévez

Insecticidal activity of raw ethanolic extracts from Magnolia dealbata Zucc on a tephritid pest

Ethanolic extracts from Magnolia dealbata (Zucc.) (Magnoliaceae); leaves, bark, seeds, sarcotesta and flowers were evaluated for insecticidal activity against adults of the Mexican fruit fly, Anastrepha ludens (Loew) (Diptera: Tephritidae). Using feeding bioassays composed from sugar-extract mixtures, only the extract from sarcotesta indicated insecticidal activity against the flies. The extracts from the other four plant tissues (leaves, bark, seeds and flowers) did not manifest any biological activity. The most effective extract was obtained from oven-dried sarcotesta, whereas extracts from fresh sarcotesta were inactive. Our results suggest that M. dealbata sarcotesta contains secondary metabolites with insecticidal activity against A. ludens adults. These metabolites are as potent as natural pyrethins and represent a potential substance for controlling this type of pest.

Male age and strain affect ejaculate quality in the Mexican fruit fly: Age and strain affect Mexican fly ejaculates

Aging in all organisms is inevitable. Male age can have profound effects on mating success and female reproduction, yet relatively little is known on the effects of male age on different components of the ejaculate. Furthermore, in mass‐reared insects used for the Sterile Insect Technique, there are often behavioral differences between mass‐reared and wild males, while differences in the ejaculate have been less studied. The ejaculate in insects is composed mainly of sperm and accessory gland proteins. Here, we studied how male age and strain affected (i) protein quantity of testes and accessory glands, (ii) the biological activity of accessory gland products injected into females, (iii) sperm viability, and (iv) sperm quantity stored by females in wild and mass‐reared Anastrepha ludens (Diptera: Tephritidae). We found lower protein content in testes of old wild males and lower sperm viability in females mated with old wild males. Females stored more sperm when mated to young wild males than with young mass‐reared males. Accessory gland injections of old or young males did not inhibit female remating. Knowledge of how male age affects different ejaculate components will aid our understanding on investment of the ejaculate and possible postcopulatory consequences on female behavior.

Variation and Genetic Structure in Platanus mexicana (Platanaceae) along Riparian Altitudinal Gradient

Platanus mexicana is a dominant arboreal species of riparian ecosystems. These ecosystems are associated with altitudinal gradients that can generate genetic differences in the species, especially in the extremes of the distribution. However, studies on the altitudinal effect on genetic variation to riparian species are scarce. In Mexico, the population of P. mexicana along the Colipa River (Veracruz State) grows below its reported minimum altitude range, possibly the lowest where this tree grows. This suggests that altitude might be an important factor in population genetics differentiation. We examined the genetic variation and population structuring at four sites with different altitudes (70, 200, 600 and 1700 m a.s.l.) using ten inter-simple sequence repeats (ISSR) markers. The highest value for Shannon index and Nei’s gene diversity was obtained at 1700 m a.s.l. (He = 0.27, Ne = 1.47, I = 0.42) and polymorphism reached the top value at the middle altitude (% p = 88.57). Analysis of molecular variance (AMOVA) and STRUCTURE analysis indicated intrapopulation genetic differentiation. The arithmetic average (UPGMA) dendrogram identified 70 m a.s.l. as the most genetically distant site. The genetic structuring resulted from limited gene flow and genetic drift. This is the first report of genetic variation in populations of P. mexicana in Mexico. This research highlights its importance as a dominant species, and its ecological and evolutionary implications in altitudinal gradients of riparian ecosystems.

Influence of season and organ on antibacterial activity ofMagnolia dealbataZucc. against two phytopathogenic bacteria

As an alternative to reduce the use of agrochemicals, plant extracts can be a better choice in the control of phytopathogens. In this study, we tested the effects of Magnolia dealbata Zucc. crude extracts on the bacterial growth of Pectobacterium carotovorum and Pseudomonas cichorii, both micro-organisms of phytopathogenic relevance. In addition, our other aim was to explain the influence of the seasons and source organs at different maturing stages in the bioactivity of the extracts. Several ethyl acetate and ethanol crude extracts obtained from leaves, bark, flowers, polyfollicles and seeds were tested using the disk-diffusion method. The ethyl acetate extract of M. dealbata polyfollicle collected in summer inhibited the development of P. carotovorum and P. cichorii to the same extent as the tetracycline positive control (Z=1.0690, p=.285 and Z=1.278, p=.201, respectively) while the ethyl acetate seed extract inhibited the growth of P. carotovorum, but did not equal the effect of tetracycline (Z=2.022, p=.043). It can be concluded that the extracts obtained during summer showed the highest inhibition of these bacteria.