Stem CO2 efflux of Cycas micronesica is reduced by chronic non-native insect herbivory.

Carbon dioxide efflux (Es) from the base of Cycas micronesica K.D. Hill stems was quantified in four locations containing healthy populations and in one location with populations threatened by non-native insect herbivores in order to determine the influence of reduced plant health on Es. Minimal variation of Es occurred among the four locations with healthy plants, and Es ranged from 1.68 to 1.79 µmol·m-2·s-1. The threatened in situ populations were on the island of Guam, where recent invasions of non-native insects have caused epidemic plant mortality, and the Es was 0.59 µmol·m-2·s-1. This is the first known report of Es for any cycad species, and the values for the unique pachycaulous stem form fit in the lower half of the range of published Es for woody trees. The results illuminate the potential for using Es to screen in situ C. micronesica populations to identify the individual trees with the greatest likelihood of surviving conservation measures.

Chilades pandava mothers discriminate among Cycas species during oviposition choice tests, but only in an endemic naïve population.

Host and non-host plant species communicate with insect herbivores to influence oviposition decisions. We studied if Chilades pandava female adults expressed oviposition preferences among host Cycas species in 2 choice tests, counting 39,420 eggs among assays from 4 butterfly populations. A naïve butterfly population from Cycas nongnoochiae habitat oviposited 2.2-fold more eggs on leaves of Cycas species that are susceptible to butterfly herbivory than on leaves of its native host Cycas nongnoochiae. In contrast, Chilades pandava populations experienced with novel Cycas species in Thailand, Philippines, and Guam exhibited no preference in choice tests between leaves of susceptible versus leaves of minimally damaged Cycas species. The results indicated that oviposition deterrents and/or stimulants partly mediate the sustainable relationship between an endemic Cycas species and the naïve Chilades pandava population from its habitat. Alternatively, differences in infochemicals among Cycas species do not enable discrimination in oviposition choices for Chilades pandava populations that have experienced Cycas species exhibiting no evolutionary history with Chilades pandava.

Information-based or resource-based systems may mediate Cycas-herbivore interactions.

Invasive arthropod herbivores comprise one of the greatest threats to cycad conservation both in situ and ex situ. We discuss two mechanisms, not necessarily mutually exclusive, that may underlie the disparity in Chilades pandava damage among Cycas species. In an information-based system, plant infochemicals may differentially influence oviposition behavior of Ch. pandava adults or host finding behavior of this butterfly's natural enemies. Alternatively, heterogeneity in damage may be mediated by a resource-based system whereby plant substrate is more palatable to larvae for susceptible species or more defended by less damaged species.

Infestation of peridomestic Attalea phalerata palms by Rhodnius stali, a vector of Trypanosoma cruzi in the Alto Beni, Bolivia.

OBJECTIVES: To determine (i) whether peridomestic Attalea phalerata palms in fragmented human-occupied areas of the Alto Beni, Bolivia, are infested by triatomines; (ii) the specific status of triatomines captured in the area; and (iii) the rate of natural Trypanosoma cruzi infection among those triatomines. METHODS: One hundred and twenty-five live-bait traps were used to sample 47 A. phalerata palms in three Alto Beni localities. Active search for vectors was also performed in 10 chicken coops and three rice storage units. Only Rhodnius specimens were found. As nymphs of closely related Rhodnius species are morphologically undistinguishable, and because of controversy in the literature regarding which Rhodnius species occur in Bolivia, collected insects were identified through molecular taxonomy. Phylogenetic analyses of DNA sequences obtained for a fragment of the mitochondrial cytochrome b gene and for the nuclear ITS-2 ribosomal region were used as molecular markers. Natural infection rates were determined using a pair of primers that PCR-amplify a 330-bp fragment of the parasite's kDNA. RESULTS: Twelve nymphs were captured in five A. phalerata palms (from two of the three localities studied), and an adult was collected from a chicken coop in Iniqua (and morphologically identified as Rhodnius stali). All nymphs (as well as the adult) were molecularly identified as R. stali based on the two molecular markers used. A single nymph was found to be infected with T. cruzi. CONCLUSIONS: Attalea phalerata palms represent an important sylvatic ecotope occupied by R. stali in the Alto Beni region of Bolivia, where there are signs of T. cruzi transmission to humans, despite the preliminary indication of low level of natural infection of the vectors.

Efficacy of five volatile oils and their mixtures against the soft scale insect, Saissetia coffeae (Walker) (Hemiptera: Coccidae) infesting the Sago palm, Cycas revoluta in Alexandria, Egypt.

Five tested plant volatile oils and their mixtures were evaluated for controlling the coccid, Saissetia coffeae (Walker) on growing Sago palms Cycas revoluta in Antoniades public gardens, Alexandria, Egypt. The tested volatile oils at concentration rates of 0.5, 1 and 1.5% (v/v) were: Camphor 20%, Dill 20%, Rose 30%, Peppermint 20% and Clove 30% (v/v). Their mixtures were : Camphor/Peppermint, Camphor/Rose at a rate of 1:1, Camphor/Rose/Peppermint at 1:1:2 rate and Camphor/Rose/Dill at 2:1:1 rate. The results, as a general mean of residual reduction percent for the whole inspection intervals of the test lasted 2 days up to 9 days post treatment, indicated that the superior volatile oils in reducing the insect were both Camphor and Rose, followed by Dill, Peppermint and the least efficient one was the Clove oil. The evaluated mixtures of the volatile oils showed that each of Camphor/Rose/Peppermint, Camphor/Rose and Camphor/Peppermint mixtures attained a higher rank of efficiency against that of the assigned soft scale insect.

Efficacy of five volatile oils and their mixtures against the mealybug, Icerya seychellarum seychellarum (Westw.) infesting Sago palm, Cycas revoluta in Alexandria, Egypt.

Five tested plant volatile oils and their mixtures were evaluated for controlling the Margarodid, Icerya seychellarum seychellarum (Westw.) on growing Sago palms in Antoniades public gardens, Alexandria, Egypt. The tested volatile oils at concentration rates of 0.5, 1 and 1.5 % (v/v) were as follows: Camphor 20%; Dill 20%; Rose 30%; Peppermint 20% and Clove 30% (v/v). Their mixtures were Camphor/Peppermint; Camphor/Rose; at a rate of 1:1 Camphor/Rose/ Peppermint at 1:1:2 and Camphor/Rose/Dill at 2:1:1. The calculated results as general mean of residual reduction percent for the whole inspection periods of the test indicated that the superior volatile oils in reducing mealybugs were both Camphor and Rose, followed by Dill, Peppermint and the least efficient was Clove volatile oil. The evaluated volatile oils mixtures showed that each of Camphor/Rose/Peppermint, Camphor/Rose, and Camphor/Peppermint mixtures occupied a higher rank of efficiency against the treated mealybugs.

Integrated crop management of the lesser date moth Batrachedra amydraula Meyr. (Lepidoptera: Cosmopteridae) infesting some date-palm varieties in Egypt.

The present study was conducted during the two subsequent seasons of 2001 and 2002 in El-Beheira Governorate, Egypt, to evaluate the efficiency of some agricultural practices on the incidence of the lesser date-moth, Batrachedra amydraula Meyr. (Lepidoptera: Cosmopteridae) on some date-palm varieties, i.e. Sammany, Hayany and Halawy. The studied agricultural practices, were: covering clusters of flowers with paper craft, covering date bunches with porous plastic cloth, thinning of bunches and/or diverging strands of bunches using special metal rings. The infestation percentages of the lesser date moth for each of the evaluated varieties indicated that Sammany had the lowest value (22.68) as compared with Hayany (37.42) and Halawy (53.16), successively. So, Sammany variety was more tolerable to the infestation than the other two varieties. In an attempt to explain such variations in the infestation by Batrachedra amydraula, determination of wax contents as well as the histological studies of the green fruits of each variety were conducted. Results revealed that tolerance of Sammany to the infestation was due to relatively higher wax content (0.420 g/10 fruits) than that of either Hayany (0.220 g/10 fruits) or Halawy (0.320/10 fruits), respectively. Moreover, the lowest infestation percentage in Sammany variety was attributed to the structure of the outer and inner layers of fruits tissues, which could be considered as natural barriers against the insect pest, causing a considerable reduction in its infestation. To know the effect of the studied agricultural practices on the quality of dates, the physical parameters of ripened fruits (length, diameter, thickness and weight), in addition to the chemical properties of the same fruits (P.H, T.S.S, T.S. and E.C.) were also determined. There is a correlation between the studied chemicals, morphological and histological characteristics of the fruits on one hand and the calculated infestation rates on the other one. The tested varieties showed that Sammany variety had the lowest value of T.S.S (20.40) in comparison to Halawy (30.2) and Hayany (35.6). Also, the estimated sugar values were 23.60, 28.10 and 30.40 for the Sammany, Halawy and Hayany, consecutively.