Chemical stability and aggregation activity of assembly pheromone of argasid ticks and its synthetic purine analogues were studied during long-lasting storage at room temperature as the potential components of attractant/acaricide mixtures. Guanine spherules from dry excreta of Omithodoros moubata Murray, 1877 were very stable in their chemical composition and did not suffer from purine degradation. However, an intensive purine conversion into uric acid occurred in samples of the fluid of the excreta of Argas persicus (Oken, 1818) and to a lesser extent also in an artificial mixture of synthetic guanine, xanthine and hypoxanthine in saline. The presence of bacteria Bacillus sp. and the moulds Talaromyces flavus (syn. Pénicillium dangeardii) and Aspergillus carbonarius, isolated from some samples, might explain the enzymic degradation of purines. The suspension of guanine hydrochloride in saline or in saline with ethanol (1 : 1 v/v) as a potential acaricide solvent, and with diatomaceous earth as the pheromone carrier, was very stable and no guanine degradation occurred. This proved to be suitable for potential use mixed with acaricides for tick control. The assembly of A. persicus males, on most of the substrates tested, was very high up to day 77 of experiment but decreased significantly on day 114-119 in samples of synthetic analogue of assembly pheromone variant 1 in which the absolute amount of guanine in solutions strongly decreased or disappeared completely.
The present paper comprises a systematic survey of the chigger mites (Acarina: Leeuwenhoekiidae) collected from bats and bat guano in Cuban caves in 1965-1985. Wagenaaria similis is recorded for the first time in Cuba. The first hosts known for Ischnothrombium diploctenum are noted. Antrohoekia inexpectala, g.n., sp. n., a parasite of bats, is described.
Chimaerula bonai sp. n. is described from the small Intestine of Phimosus infuscatus (Lichtenstein) in Paraguay. The new species differs from the other two species of Chimaerula Bona, 1994, i.e., Chimaerula woodlandi (Prudhoe, 1960) and Chimaerula leonovi (Belogurov et Zueva, 1968), mainly by the intermediate number of rostellar hooks (30-34 compared to 42-46 in the former and 20-22 in the latter), longer rostellar hooks (31-34 pm versus 26 pm and 19-21 pm, respectively), shorter cirrus sac (58-82 pm versus 158-201 pm and 134-183 pm, respectively) and the absence of rosethorn spines in the cirrus armament. Modifications in the generic diagnosis of Chimaerula are proposed in order to conform it with some peculiarities of the new species (i.e., the relatively small and thin cirrus, the absence of rosethom spines in its armament and the small cirrus sac).
Simultaneous measurements of chlorophyll (Chl) fluorescence and photosynthetic O2 evolution {P^ in leaf disks from Vicia faba (cv. Reina Blanca) leaves were doně during the first weeks of growth in order to evaluate the damage caused by methabenzthiazuron (MBT) under field conditions. The plants were treated at preemergence with two doses of MBT (0.25 .and 0,40 g m'^). Measurements were carried out at constant temperature and saturating CO2 concentration. During the first weeks after plant emergence both doses of herbicide were followed by a drop in and in some fluorescence parameters, such as Fy/Fn, and AF/Fn,' ratios, and in photochemical and non-photochemical quenching, qp and q^. At the same time, increases in minimal fluorescence (Fq and Fq') and in maximal (Fj„') and steady-state fluorescence (Fj) were aiso observed on application of saturating pulses. Fluorescence parameters gave a better indication of the damage caused to the photosynthetic systém than the measurements. The linear relationship found between OO2 and the effective quantum yield, AF/Fn,', suggests that the latter is a good measure of the quantum efficiency of photosynthesis in herbicide-treated plants. Moreover, plant tissues detoxified the herbicide and, one month after plant emergence, photosynthesis was fully recovered in herbicide-treated plants; biomass production recovered and even increased at the end of the growth period.
The effect of inorganic (IC) depletion on fluorescence quenching was studied under laboratory conditions using the chlorococcal alga Scenedesmus quadricauda strain Greifswald/15. The absence of IC caused a decrease in photochemical quenching (^p), fluorescence yield and the photosystem 2 photochemical yield (dF/F^), and an increase of non-photochemical quenching {q^). High extemal pH (about 11), which accompanies the IC-depletion, did not háve any remarkable effect on the algae. Fluorescence parameters were reversed by a resupply of CO2. The IC-defícient algae when exposed to high irradiance appeared to be less sensitive to the photoinhibition than the algae supplied with CO2. Increased thermal dissipation of the excitation energy (non-photochemical quenching) in the absence of IC is one of the probable protective mechanisms against photoinhibitory damage.
Primary leaves of barley (Hordeum vulgare L.) plants, growing either in complete (H) oř nitrogen deficient nutrítion (H-N), were subjected to complex chlorophyll (Chl) a fluorescence measurement after an 8 or 14 d cultivation period. Ilie fluorescence spectra of H-N plants exhibited a higher ratio of the two maxima F690/F73S, caused predominantly by drastic decrease in Chl content. The ratio of Chl to carotenoids (a+b/x+c) decreased considerably in H-N leaves. In špite of high Rfd values (ratio of fluorescence decrease) in H-N leaves, indicating high efficiency of photochemical energy conversion, quenching analysis of H-N leaves showed a significantly higher coefiicient of non-photochemicď quenching, qjsip (i.e. higher proportion of heat loss). Fast fluorescence kinetics indicated slower reoxidation of primáty quencher (Q^) in H-N leaves.
In Cistus ladanifer L. the chlorophyll (Chl) concentration differed widely along a latitudinal transect in the Iberian Peninsula [1.15-3.56 g kg-i(d.m.) and 146-655 mg m*2(leaf area)], and Chl a/b ratio and A43o/A^65 showed also a considerable variation (2.79-3.38 and 1.93-3.32, respectively). Chl content on a dry matter basis increased from the top to the base of the plant, especially in individuals with high leaf area index (LAI) values. Young leaves, situated in the periphery of the plant, had lower Chl content per leaf area and higher A43o/A^65 values than mature, more sclerophyllous leaves. Plants ffom higher altitudes, that suffered cold winters, showed generally lower Chl contents than plants from warmer sites. The Chl content and A43o/A^65 index were more sensitive to intemal and environmental changes than the Chl a/b ratio.