Pyrethroid-resistant malaria vectors have become a serious threat for malaria control, and bed nets that reduce the development of resistance are urgently needed. Here, we tested the effects of bed nets treated with the insect growth regulator pyriproxyfen against adult female Anopheles gambiae Giles (Diptera: Culicidae) under laboratory conditions. Noninsecticidal nets made of 195 denier monofilament polyethylene with a mesh size of 75 holes per square inch (equivalent to the Olyset Net) were dipped in a 0.1, 0.01, or 0.001% (wt:vol) alcohol solution of pyriproxyfen and dried overnight. Adult females of an insecticide-susceptible An. gambiae strain were exposed to treated and untreated nets before and after a bloodmeal. Bioassays showed that females were completely sterilized after exposure to 0.1% (35 mg [AI]/m2) and 0.01% pyriproxyfen-treated nets both before and after a bloodmeal. In addition, adult longevity decreased after exposure to the pyriproxyfen-treated nets in a concentration-dependent manner. The sterilizing and life-shortening effects of pyriproxyfen on the vector mosquito indicate that the combined use of pyriproxyfen and pyrethroids on bed nets has the potential to provide better malaria control and prevent the further development of pyrethroid resistance in malaria vectors.

An insect growth regulator, pyriproxyfen, has been used for the control of a range of pest insects, including mosquitoes. Pyriproxyfen is effective in inhibiting adult emergence and sterilizing adult females. The Asian tiger mosquito, Aedes albopictus (Skuse), is an important vector of dengue and chikungunya, and is expanding its distribution throughout Europe and the Americas. In the present study, we evaluated the impact of pyriproxyfen-treated bed nets on population growth of Ae. albopictus under semi-field conditions, using 6 small microcosms. We created microcosms containing breeding sites to simulate the natural ecosystem of vector mosquito and installing miniature bed net treated with 350 mg/m2 pyriproxyfen in Experiment I and 35 mg/m2 in Experiment II. For each experiment, we also established microcosms installing untreated polyethylene net (untreated control). The installing nets were provided with artificially torn holes, to simulate damage and allow mosquitoes to penetrate. We released 100 pairs of Ae. albopictus into each microcosm, and allowed them to feed on a mouse under the bed nets at approximately 1-week intervals. In comparison with the untreated control microcosms, the number of eggs laid by the released adults in the pyriproxyfen-treated microcosms was significantly lower in both Experiment I and II. Moreover, egg hatchability was significantly suppressed and pupal mortality was increased. Our results indicate that tarsal contact with pyriproxyfen has been shown to suppress egg production and hatchability in adult females and the auto-dissemination of pyriproxyfen into larval breeding sites by adult mosquitoes, through contact with pyriproxyfen-treated polyethylene bed nets, may suppress the mosquito population density.

The effect of a tomato (Lycopersicon esculentum) mutation, diageotropica (dgt), on the accumulation of mRNA corresponding to tomato homologs of three auxin-regulated genes, LeAux, LeSAUR, and Lepar, was examined. The dgt mutation inhibited the induction of LeAux and LeSAUR mRNA accumulation by naphthalene acetic acid (NAA) but had no effect on NAA-induced Lepar mRNA accumulation. The effect of two synthetic auxins, NAA and 3,7-dichloro-8-quinoline carboxylic acid (quinclorac), on the accumulation of LeAux, LeSAUR, and Lepar mRNA was also examined. Quinclorac induced the expression of each of the auxin-regulated genes, confirming its proposed mode of herbicidal action as an auxin-type herbicide. Concentrations of quinclorac at least 100-fold higher than NAA were required to induce LeAux and LeSAUR mRNA accumulation to similar levels, whereas Lepar mRNA accumulation was induced by similar concentrations of NAA and quinclorac. Collectively, these data suggest the presence of two auxin-dependent signal transduction pathways: one that regulates LeSAUR and LeAux mRNA accumulation and is interrupted by the dgt mutation and a second that regulates Lepar mRNA accumulation and is not defective in dgt tomato hypocotyls. These two auxin-regulated signal transduction pathways can be further discriminated by the action of two synthetic auxins, NAA and quinclorac.

l h e plant plasma membrane H+-ATPase energizes the secondary uptake of nutrients and may facilitate cell expansion by acidifying the cell wall. In yeast, Clc stimulates the accumulation of H+-ATPase mRNA, and the growth rate supported by various sugars is correlated with H+-ATPase protein abundance. Expression of three H+-ATPase genes, LHAI, LHA2, and LHA4, was previously detected in tomato (Lycopersicon esculentum). We have characterized the sequence of the LHA4 gene and examined the expression of these three tomato H+-ATPase genes in growing tissues and i n response to exogenous sugars. LHA4 is a member of the H+-ATPase subfamily, including the Arabidopsis fhaliana genes AHAl, AHA2, and AHA3. l h e 5' untranslated region of the deduced LHA4 cDNA contains a short, open reading frame very similar to that in the Nicofiana plumbaginifolia gene PMAl . LHA4 transcript abundance in seedlings is correlated with cell growth, being 2.5 times greater in hypocotyls of dark-versus light-grown plants. The accumulation of both LHA4 and LHA2 mRNAs is induced by the addition of exogenous sugars and this induction appears to be dependent on sugar uptake and metabolism, because mannitol and 3-Omethylglucose do not stimulate mRNA accumulation. These results suggest that the induction of expression of H+-ATPase genes by metabolizable sugars may be part of a generalized cellular response to increased cell growth and metabolism promoted by the availability of an abundant carbon source.H+-ATPases in the PM plays a critica1 role in the physiology of plants at both the cellular and organismal levels. They establish an electrical potential and pH gradient across the PM, which provides the force for the secondary transport of anions, cations, amino acids, and sugars (Serrano, 1989;Sussman and Harper, 1989). These secondary transport systems control physiological processes such as nutrient uptake by roots, phloem transport, and stomatal function. H+-ATPase in the PM may have other physiological roles, because the enzyme is subjected to control by physiological effectors such as hormones, light, and pathogens (Serrano, 1989;Sussman and Harper, 1989 control of the cell cycle by the regulation of cytosolic pH (Pichon and Desbiez, 1994) and by driving the auxin-induced cell expansion by cell-wall acidification (Rayle and Cleland, 1992). Total H+-ATPase levels in the PM may be directly correlated with growth. Hager et al. (1991) demonstrated by immunodetection that H+-ATPase levels in the PM increased 2-fold during auxin-induced maize coleoptile elongation. Rao et al. (1993) showed that the growth rate of liquid cultures of yeast supported by different sugars is closely correlated with PM H+-ATPase activity. Furthermore, the expression of the primary yeast PM H+-ATPase isoform PMAl was shown to be induced by the addition of growth-inducing exogenous sugars.Considerable progress has recently been made in the understanding of the molecular biology of plant PM H+-ATPases. Multiple genes encoding PM H+-ATPases have been cloned in tomato (Lycopers...

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