The Diet and Reproductive Schedules of Leptonycteris curasoae curasoae and Glossophaga longirostris elongata (Chiroptera: Glossophaginae) on Curaçao

Two bat species, Leptonyrteris curasoae and Glossophaga longirostris, are the principal pollinators of at least two of the three species of columnar cacti that grow on the semiarid island of Curaçao, Netherlands Antilles. I examined the importance of the cacti in the diets of the bats and found that 85–91 percent of their diet samples contained cactus pollen and seeds. At least 43 percent of the samples from each species contained cactus pollen andlor seeds exclusively. Leptonycteris curasoae consumes nectar and pollen of Ceiba pentandra and Agave spp. at the beginning of the dry season and G. longirostris also consumes a few other plant products in the wet season, but both bat species depend nutritionally on cacti. Female bats give birth to one pup per year, and the periods of parturition and lactation in each species correspond to peaks in the reproductive phenology of the two most abundant columnar cactus species. From personal observations and a review of the literature, I determined that bats were unlikely to fly to the mainland to feed, although L. curasoae may do so. I conclude that the interdependence of bats and cacti is suggestive of coevolution, and that columnar cacti are critical for the survival and persistence of nectar-feeding bats on Curaçao.     

The mating chances of small males of the cerambycid beetleTrachyderes mandibularis differ in different environments (Coleoptera: Cerambycidae)

Some males of the cerambycid beetle Trachyderes (Dendrobias) mandibularisgained access to mates by defending a patchily distributed food resource, the fruits of saguaro cactus (Cereus giganteus).Male beetles differed greatly in fighting ability because of extreme variation in body size and a striking dimorphism in mandibular weaponry. As is typical in resource defense mating systems, larger males had an advantage in combat. Major males with their large pincer jaws invariably defeated minor males with small cutting jaws, and larger majors usually defeated smaller majors. However, although minor males were at a competitive disadvantage on saguaro fruits, they did not suffer a great penalty in terms of mating probability. In contrast, minor males have a considerably lower probability of mating at desert broom (Baccharis sarothroides)where sap ooze sites are few in number and effectively monopolized by major males (Goldsmith, S. K., Behav. Ecol. Sociobiol.20,111–115, 1987). On saguaros, minor males successfully obtained mates through scramble competition while avoiding direct physical competition with larger, territorial major males. Smaller males of either morph may have succeeded in acquiring mates in part because there were many more ripe saguaro fruits than beetles, which made it impossible for larger major males to monopolize females effectively under these conditions.     

Yeast communities of the cactusPilosocereus arrabidae as resources for larval and adult stages ofDrosophila serido

The feeding behavior ofDrosophila serido on the yeast communities of necrotic stem tissue ofPilosocereus arrabidae were studied in a sand dune ecosystem of Rio de Janeiro, Brazil. The prevalence of cactophilic yeasts includingPichia barkeri, Candida sonorensis andGeotrichum sp. in the crops and external surfaces ofD. serido reflected its association with the cactus habitat. The effective number of yeasts vectored on the surface of flies was higher than that in the crops. Also overlap between the yeasts from stems and from crops was partial suggesting selective feeding by the flies in the substrates visited. The females had a higher effective number of yeast species and a lower similarity than males with the yeast community ofP. arrabidae. This was probably related to the search for oviposition sites by females. The presence ofPichia thermotolerans-like andPichia amethionina varpachycereana in the flies, but not inP. arrabidae stems, indicated thatD. serido was not limited to this cactus species. The larvae and adults lived in different patches with the adults feeding in patches with higher yeast species richness. The larvae had a narrower feeding niche and higher overlap withP. arrabidae, and preferredP. barkeri andPichia cactophila as food. Adult flies fed on patches with the most frequent yeasts except forP. cactophila. Pichia caribaea was found in higher frequency in the adult crops than in the stems. Our data suggested that there was food selection and diet partitioning between adult and larval stages ofD. serido.     

Pereskiophaga brasiliensis,a natural enemy of the invasive alien cactus Pereskia aculeata,is not suitably host specific for biological control in South Africa

The stem-mining weevil, Pereskiophaga brasiliensis, was a candidate biological control agent for the invasive cactus Pereskia aculeata in South Africa. In host specificity trials, it developed on two indigenous test plant species under choice and no-choice conditions. Pereskiophaga brasiliensis is therefore not suitably host specific for release in South Africa.     

Stem tilting,pseudocephalium orientation,and stem allometry in <Emphasis Type="Italic">Cephalocereus columna-trajani</Emphasis> along a short latitudinal gradient

Cephalocereus columna-trajani is a giant columnar cactus endemic of the Tehuacán-Cuicatlán Valley in Central Mexico. Stem tilting and northward pseudocephalium azimuth in C.␣columna-trajani have functional advantages in terms of interception of direct solar radiation at the northernmost portions of its range. Since the success of both characters strongly depends on the apparent position of the sun during the growing season, in this paper we test the hypothesis that the occurrence of such columnar morphology is restricted geographically and imposes mechanical restrictions that limit column height. Following a latitudinal gradient along the Tehuacán-Cuicatlán Valley, we selected five populations, recorded tilting angle and pseudocephalium azimuth, and carried out allometric and biomechanical analyses of height–diameter relationships. Northern populations showed higher tilting angles. Pseudocephalium azimuth significantly differed among populations, and pseudocephalium orientation was consistently North-Northwestern. Stem allometry showed that the stems of the southern populations increased in height at a far greater rate with respect to diameter than the northern populations. The southernmost population showed the lowest safety factor. These results support the hypothesis that stem tilting in C.␣columna-trajani is functionally advantageous in a restricted geographical range, and imposes mechanical restrictions to column height.     

Cactus-independent nuclear translocation of Drosophila RELISH

Insects can effectively and rapidly clear microbial infections by a variety of innate immune responses including the production of antimicrobial peptides. Induction of these antimicrobial peptides in Drosophila has been well established to involve NF-kappaB elements. We present evidence here for a molecular mechanism of Lipopolysaccharide (LPS)-induced signaling involving Drosophila NF-kappaB, RELISH, in Drosophila S2 cells. We demonstrate that LPS induces a rapid processing event within the RELISH protein releasing the C-terminal ankyrin-repeats from the N-terminal Rel homology domain (RHD). Examination of the cellular localization of RELISH reveals that the timing of this processing coincides with the nuclear translocation of the RHD and the retention of the ankyrin-repeats within the cytoplasm. Both the processing and the nuclear translocation immediately precede the expression of antibacterial peptide genes cecropin A1, attacin, and diptericin. Over-expression of the RHD but not full-length RELISH results in an increase in the promoter activity of the cecropin A1 gene in the absence of LPS. Furthermore, the LPS-induced expression of these antibacterial peptides is greatly reduced when RELISH expression is depleted via RNA-mediated interference. In addition, loss of cactus expression via RNAi revealed that RELISH activation and nuclear translocation is not dependent on the presence of cactus. Taken together, these results suggest that this signaling mechanism involving the processing of RELISH followed by nuclear translocation of the RHD is central to the induction of at least part of the antimicrobial response in Drosophila, and is largely independent of cactus regulation.     

Comparative toxicity of different chemical and biological insecticides against the scale insect Dactylopius opuntiae and their side effects on the predator Cryptolaemus montrouzieri

The contact toxicity of various chemical and biological pesticides for the first and second instar nymphs and adults of the Opuntia cochineal scale insect Dactylopius opuntiae and the predator ladybird Cryptolaemus montrouzieri was determined under Morocco semi field conditions. d-limonene (60?g/l) at 100 and 150?cc/hl, mineral oil (780?g/l) at 2400?cc/hl and malathion (500?g/l) at 300?cc/hl caused the highest mortality (99–100%) among first instar nymphs of D. opuntiae 24?h after treatment. d-limonene (60?g/l) at 150?cc/hl caused greatest mortality (99%) in second instar nymphs. The highest mortality (99%) among adult female D. opuntiae was observed 120?h after treatment with d-limonene (60?g/l) at 150?cc/hl and mineral oil (780?g/l) at 2400?cc/hl. For the predator C. montrouzieri the highest mortality (92–97%) among adults 24?h after treatment was caused by malathion (500?g/l) at 100, 200 and 300?cc/hl and alpha-cypermethrin (100?g/l) at 75, 150 and 225?cc/hl. The most harmful pesticides to C. montrouzieri larvae 24?h after treatment were malathion and alpha-cypermethrin with mortality rates of 89–95%. Mortality in larvae ranged from 87 to 100% 120?h after treatment with chlorpyriphos-methyl (480?g/l) at 75, 150 and 225?cc/hl and spinosad (480?g/l) at 100, 200 and 300?cc/hl. d-limonene (60?g/l) at 50?cc/hl and mineral oil (780?g/l) at 1000?cc/hl had the least impact on C. montrouzieri adults and larvae, causing mortality of 11 and 15%, respectively, 120?h after treatment. d-limonene (60?g/l) and mineral oil (780?g/l) may therefore be viable alternatives to others high-risk chemical pesticides. These two biological insecticides are effective in controlling the Opuntia cochineal scale insect but have little adverse impact on the predator C. montrouzieri.     

Development and characterization of microsatellite loci in endangered Astrophytum asterias (Cactaceae)

We report the development of polymorphic microsatellite markers for the endangered North American cactus Astrophytum asterias (Cactaceae). Six loci, averaging 8.5 alleles per locus, were found to amplify genomic DNA consistently in 94 individuals from four geographically defined demes in South Texas. These markers will permit the generation of appropriate data for estimating population genetic parameters, population structure and the degree of inbreeding in the small, fragmented populations of A. asterias that currently exist. These are the first microsatellites reported for the genus Astrophytum and for the tribe Cacteae.