Luis A. Lara-Pérez

The male ejaculate as inhibitor of female remating in two tephritid flies

The inhibition of female receptivity after copulation is usually related to the quality of the first mating. Males are able to modulate female receptivity through various mechanisms. Among these is the transfer of the ejaculate composed mainly by sperm and accessory gland proteins (AGPs). Here we used the South American fruit fly Anastrepha fraterculus (where AGP injections inhibit female receptivity) and the Mexican fruit fly Anastrepha ludens (where injection of AGPs failed to inhibit receptivity) as study organisms to test which mechanisms are used by males to prevent remating. In both species, neither the act of copulation without ejaculate transfer nor sperm stored inhibited female receptivity. Moreover, using multiply mated sterile and wild males in Mex flies we showed that the number of sperm stored by females varied according to male fertility status and number of previous matings, while female remating did not. We suggest female receptivity in both flies is inhibited by the mechanical and/or physiological effect of the full ejaculate. This finding brings us closer to understanding the mechanisms through which female receptivity can be modulated.

Diversity and colonization of arbuscular mycorrhizal fungi in the tree fern Alsophila firma in rainy and dry season

Alsophila firma is a deciduous tree fern considered as an emblematic species of Mexican tropical montane cloud forest (TMCF). We studied spores diversity, structure and colonization by arbuscular mycorrhizal fungi (AMF) within the roots of the Alsophila firma in rainy and dry season. Eighteen species of the genera Acaulospora (5), Gigaspora (4), Glomus (4), Funneliformis (2), Sclerocystis (2) and Scutellospora (1) were identified. The species F. constrictum, F. geosporum, Gigaspora albida, G. decipiens, Glomus microaggregatum and Sclerocystis coremioides are reported for the first time in TMCF. The dominant genera were Funneliformis and Acaulospora. In rainy season, a higher richness (H′ t0.005(2)9 = 4.78) and evenness (E) of AMF spores was recorded, compared to the dry season. However, the degree of colonization was statistically significant higher in the dry season. This study is the first to estimate the species richness of AMF associated with the rhizosphere of a fern in Mexico as well as for A. firma.