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Simple Summary: Giant pine scale, Marchalina hellenica Gennadius (Hemiptera, Marchalinidae), is a sap sucking insect native to the Eastern Mediterranean Basin. In 2014, giant pine scale was detected for the first time in Victoria, Australia, feeding on a new host, Pinus radiata. We studied the life cycle and feeding activity of giant pine scale in Victoria over 32 months, with the aim of drawing comparisons between exotic and native populations. Australian life stages of this pest emerged during similar months to Greek seasonal equivalents, although the timing of Australian life stages differed between years. Insect density and feeding activity on infested trees differed among locations and between generations. Strong evidence was found in support of density and feeding intensity being explained by climatic conditions. The value of Pinus radiata as a food source for this insect may fluctuate with climate conditions. Our findings aim to inform future management efforts for this scale insect, including surveillance strategies and optimal seasons for release of biocontrol agents. Our findings also suggest that the impact of this pest in Australia may be exacerbated by climate change. Invasive insects pose an increasing risk to global agriculture, environmental stability, and public health. Giant pine scale (GPS), Marchalina hellenica Gennadius (Hemiptera: Marchalinidae), is a phloem feeding scale insect endemic to the Eastern Mediterranean Basin, where it primarily feeds on Pinus halepensis and other Pinaceae. In 2014, GPS was detected in the southeast of Melbourne, Victoria, Australia, infesting the novel host Pinus radiata. An eradication program was unsuccessful, and with this insect now established within the state, containment and management efforts are underway to stop its spread; however, there remains a need to understand the insect's phenology and behaviour in Australia to better inform control efforts. We documented the annual life cycle and seasonal fluctuations in activity of GPS in Australia over a 32 month period at two contrasting field sites. Onset and duration of life stages were comparable to seasons in Mediterranean conspecifics, although the results imply the timing of GPS life stage progression is broadening or accelerating. GPS density was higher in Australia compared to Mediterranean reports, possibly due to the absence of key natural predators, such as the silver fly, Neoleucopis kartliana Tanasijtshuk (Diptera, Chamaemyiidae). Insect density and honeydew production in the Australian GPS population studied varied among locations and between generations. Although insect activity was well explained by climate, conditions recorded inside infested bark fissures often provided the weakest explanation of GPS activity. Our findings suggest that GPS activity is strongly influenced by climate, and this may in part be related to changes in host quality. An improved understanding of how our changing climate is influencing the phenology of phloem feeding insects such as GPS will help with predictions as to where these insects are likely to flourish and assist with management programs for pest species. [ABSTRACT FROM AUTHOR]

We report the discovery of the invasive aphid Aphis lugentis for the first time in Australia. This aphid specialises on Compositae, particularly on Senecio species. Aphids were tended by several ant species at a site on Kangaroo Island, South Australia, which is unlikely to be the location of the original introduction. We recommend the investigation of the distribution of A. lugentis in Australia and its impacts on plant hosts including threatened species and associated native ant and aphid community structures. [ABSTRACT FROM AUTHOR]

Ants in the genus Iridomyrmex cause extensive problems for citrus producers in southern Australia by disrupting the biological control of honeydew-producing Hemiptera. We used baited pitfall traps to survey ant communities in 20 commercial citrus groves and test the hypothesis that populations of Iridomyrmex rufoniger gp spp. and Iridomyrmex purpureus can be reduced by conserving volunteer inter-row vegetation. Nine groves (five in the Murrumbidgee Irrigation Area, New South Wales, and four in the Sunraysia area, Victoria) were classified as ‘bare’ groves, where inter-row vegetation was routinely eliminated using herbicides and cultivation. The remaining ‘grassed’ groves (five in the MIA, six in Sunraysia) had inter-row vegetation controlled only by intermittent mowing. All groves had been managed consistently for between 9 and 22 years. MIA groves were trapped on three occasions (October 1997, January 1998 and April 1998), and Sunraysia groves once (March 1999). Over 190 000 ants were recovered, with I. rufoniger gp spp. accounting for 74% of overall captures and dominating collections in both ‘bare’ and ‘grassed’ groves. A linear mixed model analysis showed that ground cover management history had no significant effect (P > 0.05) on captures of I. rufoniger gp spp., I. purpureus, other Dolichoderinae, Ponerinae, Formicinae or Myrmicinae. High variability between ant populations in groves under the same management regime in each region suggests that aspects of grove management may be affecting ant community composition, however, our results indicate that suppression of pest Iridomyrmex species cannot be reliably achieved simply by altering the management of volunteer inter-row vegetation. [ABSTRACT FROM AUTHOR]

Ants (Hymenoptera: Formicidae) consume a broad spectrum of liquid food sources including nectar and honeydew, which play a key role in their diet especially in tropical forests. This study compares carbohydrates and amino acids from a representative spectrum of liquid sources used by ants in the canopy and understorey of a tropical rainforest in northern Queensland, Australia. Eighteen floral nectars, 16 extrafloral nectars, two wound sap and four homopteran honeydew sources were analysed using high performance liquid chromatography. Wounds comprised flower abscission scars on Normanbya normanbyi L. H. Bailey and bitemarks on Cardwellia sublimis F. Muell. where ants were actively involved in wounding. Discriminant analysis was performed to model differences between food sources in sugar and amino acid concentration and composition. All characteristics varied significantly among plant species. Honeydew contained a broader spectrum of sugars (including melezitose, raffinose, melibiose, lactose and maltose) than nectar (sucrose, glucose, fructose), but certain extrafloral nectars had similar amino acid profiles and, like honeydew sources, were often monopolized by ants. Most common amino acids across the sources were proline, alanine and threonine among 17 α-amino acids identified. Interspecific variability concealed characteristic differences in sugar and amino acid parameters between nectar, honeydew and wound sap across all plants, but these types differed significantly when found on the same plant. Among all sources studied, only a few flower nectars were naturally not consumed by ants and they were significantly less attended than sugar controls in feeding trials. These nectars did not differ in sugars and amino acids from ant-attended flower nectars, suggesting the activity of repellents. Apart from these exceptions, variability in amino acids and carbohydrates is proposed to play a key role in ant preferences and nutrition. [ABSTRACT FROM AUTHOR]

Complex distribution patterns of species-rich insect communities in tropical rainforests have been intensively studied, and yet we know very little about processes that generate these patterns. We provide evidence for the key role of homopteran honeydew and plant nectar in structuring ant communities in an Australian tropical rainforest canopy and understorey. We also test the ant visitation of these resources against predictions derived from the ‘ant-mosaic’ hypothesis. Two ant species were highly dominant in terms of territorial behaviour and abundance: Oecophylla smaragdina and Anonychomyrma gilberti. Both dominant ant species monopolised large aggregations of honeydew-producing homopterans. Attended homopteran species were highly segregated between these two ant species. For the use of extrafloral and floral nectar (involving 43 ant species on 48 plant species), partitioning of ant species among plant species and between canopy and understorey was also significant, but less pronounced. In contrast to trophobioses, simultaneous co-occurrence of different nectar foraging ant species on the same plant individuals was frequent (23% of all surveys). While both dominant ant species were mutually exclusive on honeydew and nectar sources, co-occurrence with non-dominant ant species on nectaries was common. The proportion of visits with co-occurrences was low for dominant ants and high for many sub-ordinate species. These findings support the ant mosaic theory. The differential role of honeydew (as a specialised resource for dominant ants) and nectar (as an opportunistic resource for all ants including the co-occurring non-dominant species) provides a plausible structuring mechanism for the Australian canopy ant community studied. [ABSTRACT FROM AUTHOR]