Three species of Mesodanis flies that attack the developing seeds of Chrysanthemoides monilifera in South Africa are being assessed for their potential as biological control agents of C. monilifera in Australia. Surveys in South Africa indicated that M. polana Munro is restricted to C, m. rotundata along the subtropical northern coast, M. magnipalpis Bezzi and M. dubia Walker occur on all three subspecies sampled (C. m. rotundata, C. m. monilifera, C. m. pisifera), although M. dubia is less abundant and has a more restricted distribution than M. magnipalpis. Mesodanis eggs are laid into a wide range of flowerhead stages of C. m. rotundata over a period of approximately 12-14 days, from very small flowerheads with involucral bracts still completely closed, to flowerheads with the laminae of ray florets (petals) starting to elongate. Levels of oviposition by M. magnipalpis into C. m. pisifera are low in very young flowerheads, possibly as a consequence of a heavy layer of indumentum on young C. m. pisifera flowerheads. The pattern and location of feeding and pupation within flowerheads differs slightly for the three Mesodanis species, but none of the species is associated with the formation of gall tissue. The effect of Mesodanis activity on ovule development was assessed on four occasions. Mesodanis destroyed all the ovules in some capitula, and the maximum level of ovule destruction recorded for a site was 64%.
This field guide to introduced dung beetles covers all species found in Australia, including two newly introduced species. It will enable farmers, Landcare workers and the interested public to identify and learn about the basic biology of these beetles found in cattle dung.
Nine insect species endemic to tropical America have been released into the Northern Territory as biological control agents for Mimosa pigra L. (Mimosaceae). To date, few studies have been published that quantify the abundance of these agents post‐release. Hence, populations of adult agents in three stands of M. pigra were monitored using Malaise traps. Trap catches frequently contained the lepidopteran agents Carmenta mimosa Eichlin and Passoa and Neurostrota gunniella (Busck). Neurostrota gunniella, which was first released in 1989, was the most abundant of all the agents caught, irrespective of the stand of M. pigra where trapping was conducted. The three coleopteran agents (namely Acanthoscelides Schönherr spp., Chlamisus mimosae Karren and Coelocephalapion Wagner spp.) were caught less frequently. Two recently released beetles, Chalcodermus serripes Fåhraeus and Sibinia fastigiata Clark, were not caught. Trap catches of Acanthoscelides spp. were greatest during the late dry season with smaller catches during the mid‐ to late wet season. Chlamisus mimosae was most abundant during the dry to dry–wet transition. Neurostrota gunniella was generally most abundant during the dry season. The abundances of Ca. mimosa and Coelocephalapion spp. exhibited little seasonality. Malaise trapping is recommended as part of a long‐term monitoring program to quantify agent populations and their impact upon M. pigra.
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