Evolution of Delphacidae (Hemiptera: Fulgoroidea): combined‐evidence phylogenetics reveals importance of grass host shifts

The planthopper family Delphacidae is a speciose lineage of phloem‐feeding insects, with many species considered as pests of economic significance on essential world food commodities (including rice, maize, wheat, barley and sugar cane). Despite their economic importance, evolutionary relationships among delphacids, particularly those within the speciose tribe Delphacini, are largely unknown. Presented here are the results of a phylogenetic investigation of Delphacidae based on DNA nucleotide sequence data from four genetic loci (18S rDNA, 28S rDNA, wingless and cytochrome oxidase I) and 132 coded morphological characters. The resulting topologies are used to test the higher classification of Delphacidae and to examine evolutionary patterns in host–plant associations. Our results generally support the higher classifications of Delphacidae proposed by Asche, Emeljanov and Hamilton, and suggest that the rapid diversification of the Delphacini was associated with host shifts to, and within, Poaceae, and specifically from C3 to C4 grasses.     

The effects of different blend ratios and temperature on the active space of the Oriental fruit moth sex pheromone

Abstract The wing-fanning activation response of male Oriental fruit moths (OFM), Grapholita molesta (Busck), in the field to the three-component pheromone containing the female-produced ratio of components (Z8-12:OAc + 6% E8-12:OAc + 3% Z8-12:OH) was compared with the response to blends containing 2,10 and 20% E with 3% OH, and the 6% E blend containing 30 and 100% OH. Comparisons were made over three temperature ranges: 15–17, 20–21 and 26–28^oC. Both the maximum response distance and male response specificity were significantly altered by changes in odour quality as well as temperature. For blends containing different Z/E ratios the maximum response distance increased significantly with temperature. Response specificity was most pronounced at the 20–21^oC range, with males displaying a lower threshold for the natural 6% E ratio, evidenced by the fact that fewer males responded and at closer distances to the source with off-ratios. At 26–28^oC response specificity for the Z/E ratios was much reduced, primarily due to more males activating to off-ratios. With blends containing different proportions of Z8-12:OH in the 6% E blend, increasing temperature increased the maximum response distance for all treatments, but in addition increasing the proportion of OH alone from 3% to 30% significantly increased the maximum response distance over the three temperature ranges tested. This increase occurred without affecting the proportion of responders or the distribution of response distances around the mean value. However, with 100% OH added to the blend, whereas male response was high at 20–21^oC, the distribution of response distances was significantly more variable than with 3% or 30%, and male response was eliminated or very low at 15–17^oC and 26–28^oC. Our results support previous studies showing that peak response levels in this species are dependent on male perception of the natural blend of components, and that males have a high degree of specificity for the qualitative properties of the pheromone. However, the present results also extend those of previous flight tunnel tests in which response specificity was most pronounced in the upwind flight phase of the sequence, by showing that male OFM also display a     

The Ascidian Sperm Reaction

SYNOPSIS. Ascidian sperm are simplified by omission of the midpieceand proximal centriole with the single mitochondrion locatednext to the nucleus in the head. Small acrosome- like vesiclesappear in some species but their distribution is unclear. Spermstructure correlates well with the location of fertilization;members of the orders Phlebobranchiata and Stolidobranchiatawith external fertilization have sperm with short heads andlong tails, while sperm from the exclusively internally fertilizingAplousobranchiata have relatively longer heads and shorter tails. The mitochondrion swells when the sperm contacts the chorion,then translocates along the tail as it enters the chorion tobe discarded when the tail disappears inside. Structural changesalso occur in the anterior sperm head that have been interpretedas an acrosome reaction. Proteolytic enzymes are involved inpenetration of the chorion. The mitochondrial transformationis under control of intracellular pH and Ca²⁺ levels with thesperm releasing H⁺ and taking up Ca²⁺ during the sperm reaction.Acid release is from inactivation of a Na⁺ requiring acidificationsystem and triggering of a Cl^– releasing HCO₃ requiringacid release system. An increase in intracellular pH increasesthe permeability to Ca²⁺, resulting in increased intracellularCa²⁺, the proximal trigger to the mitochondrial reaction.     

Evidence for Follicle Wall Involvement in Ovulation and Progesterone Production by Frog (Rana pipiens) Follicles in vitro

Involvement of different cellular investments of the amphibian ovarian follicle wall in the ovulatory process, progesterone production, and oocyte maturation was investigated. Following microdissection, to selectively remove one or more layers (surface epithelium, theca, follicle cells) of the follicle wall, dissected and undirected ovarian follicles were treated with frog pituitary homogenate (FPH) or progesterone. Intact follicles ovulated in response to pituitary homogenate and this was associated with contractions of the follicle wall. Ovulation and follicular contractions were not observed following removal of the surface epithelium without removing the thecal layer. Oocyte maturation occured in response to FPH following removal of the surface epithelium alone or together with the theca, but not in the absence of the follicle cells. Intact follicles were most responsive to FPH with respect to progesterone production, and removal of all somatic cells from oocytes obliterated FPH stimulated progesterone production. Oocytes, regardless of wether any or all follicular wall layers were removed, matured but did not ovulate following exposure to progesterone. The results suggest that the surface epithelium, but not the theca, is required for FPH-induced extrusion (ovulation) of the oocyte from ovarian follicle wall. Additionally, the somatic tissue rather than the oocyte appears to be the cells producing progesterone following FPH treatment. The results indicate that separate cellular layers (individually and/or as a result of interactions) of the follicle wall carry out different functions during follicular differentiation and mediation of ovulation. Data provide functional evidence for a role of the surface epithelium in controlling the process of ovulation and follicular contraction.