Isolation and identification of indigenous Arbuscular Mycorrhizal Fungi (AMF) of forest clove rhizosphere from Maluku, Indonesia

Mahulette AS, Alfian A, Kilkoda KA, Lawalata IJ, Marasabessy DA, Tanasale VL, Makaruku MH. 2021. Isolation and identification of indigenous Arbuscular Mycorrhizal Fungi (AMF) of forest clove rhizosphere from Maluku, Indonesia. Biodiversitas 22: 3613-3619. Forest clove is classified as wild-type and endemic to the Maluku (Moluccas) Islands, Indonesia. The different condition of growing areas causes various types of Arbuscular Mycorrhizal Fungi (AMF) associated with forest clove. The study aimed to identify and obtain indigenous AMF inoculums from the forest clove rhizosphere from two distribution areas in Maluku. The results of AMF identification found two types of spores from the genus Glomus in the rhizosphere of forest cloves from Ambon Island with a spore density of 35/50 g of soil. In comparison, three spores were found in Seram Island, two from the genus Scutellospora and one from the Acaulospora. With an overall spore density of 5/50 g of soil. After culture trapping, there was a change in type and an increase in spore density in soil samples from the rhizosphere of the two forest clove distribution areas. Soil samples from Ambon after trapping culture obtained two new types of spores from the genus Acaulospora with a total spore number of 57/50 g soil while in soil samples from Seram found three new types of spores from the genus Glomus with a total spore count of 104/50 g of soil.

Anopheles coluzzii infection by the microsporidian, Vavraia culicis: the effect of host age

Host age at infection has important implications for disease development. In mosquitoes, infections with microsporidia and later concurrent infections with malaria parasites, leads to a suppression in the development of malaria parasites. Host age at infection with microsporidia could have implications for disease outcomes when infection occurs subsequently with malaria parasites. Mosquito larvae can take between five to seven days or more depending on the temperature to reach the adult stage, giving the microsporidian Vavraia culicis, a theoretical head start in establishing and developing within larvae and possibly resulting in different levels of infection in emergent adult mosquitoes. To determine the effects of early or late infection with V. culicis, equal numbers of Anopheles coluzzii larvae were infected individually with a high or low dose of V. culicis, at different ages post hatching.Significantly fewer spores were produced from mosquitoes infected later, than ones infected earlier with microsporidia and there was an initial delay in the production of spores from later infected mosquitoes. In early infected larvae, there was no such initial delay and spore production took off unchecked. The infectious dose of V. culicis did not affect the total spore count per mosquito. Male mosquitoes produced fewer spores than females. Daily mosquito longevity and pupation was not affected significantly by infection, the infectious dose of V. culicis given or by the sex of the mosquito. Considering hourly deaths, early infected hosts died 17 to 18 hours earlier than later infected larvae. The number of V. culicis spores rose with increasing duration of infection. When equal duration of infection was considered, the findings remained the same. Host age at infection influences disease outcomes and virulence.

Influence of Environment on Atmospheric Concentrations of Peronospora antirrhini Sporangia in Field-Grown Snapdragon

Hourly concentrations of airborne sporangia of Peronospora antirrhini at a commercial snapdragon farm were investigated over three growing seasons to determine the influence of the environment on their occurrence and concentration. Hourly concentrations of sporangia of P. antirrhini were estimated using a Burkard volumetric spore sampler. Atmospheric sporangial concentrations followed a diurnal pattern and were greatest during 0500 to 1200 h. Minimum daily temperatures <10.0°C appeared to have a moderate limiting effect on atmospheric sporangial concentrations, whereas temperatures <6.0°C had more severe limiting effects. Maximum daily temperatures ≥30.0°C limited concentrations of atmospheric sporangia. Long dew periods (≥6 h) were associated with relatively large sporangia releases. On 69 days (1999 to 2001), the total number of sporangia trapped was >100/m3/day, and the average length of leaf wetness duration prior to these releases was 11 h. Consecutive days with short leaf wetness periods were associated with low atmospheric sporangial concentrations. Significant positive correlations (P = 0.0502 and P = 0.0174) were found between total rainfall and total spore count for both research plots in 2000. Information gained from this study will contribute to the development of a disease management program that utilizes environmental cues to prompt fungicide applications, thus increasing the efficiency of fungicide programs and delaying the development of pathogen resistance.

A survey of sources of heat-resistant bacteria in milk with particular reference to psychrotrophic spore-forming bacteria

SummarySamples of winter bedding and summer pasture, rinses of teats and milking equipment, and milk samples from bulk tanks from 4 farms were analysed bacteriologically for total count (TC), thermoduric count, total spore count (TSC) and psychrotrophic spore count (PSC).In bedding and pasture samples the TSC comprised the main component of the thermoduric flora but was less than 0·1 % of the TC. The PSC formed ∼ 1 % of the TSC in winter bedding and ∼23 % of the TSC in pasture. For pasture, the PSC: TSC ratio was highest for the upper layer of soil and lower for the grass and deeper layer of soil. The TSC formed 5% of the thermoduric flora in rinses of milking equipment and only a very low PSC was obtained. The TSC of farm bulk tank milks was higher in the winter than the summer but the PSC was similar in both seasons. This was due to an increase of ∼9 times in the PSC:TSC ratio for milks in summer compared with winter. The PSC in raw and commercially pasteurized milks from a local creamery showed a similar seasonal trend.