Honeydew-producing Hemipterans Research Articles

Fight and rescue or give up and flee? Behavioural responses of different ant species tending the mutualist walnut aphid Panaphis juglandis to native and exotic lady beetles.

Mutualism between ants and honeydew-producing hemipterans is a highly successful evolutionary innovation that attains the status of ecological keystone across many terrestrial ecosystems, involving a multitude of actors through direct or cascading effects. In these relationships, ants often protect their hemipteran partners against their arthropod natural enemies, sometimes interfering with the biological control of pest species. However, the dynamics of these interactions are highly variable based on the specific identity of all the actors involved, and baseline data remain scarce. We performed a field experiment exposing colonies of the walnut aphid Panaphis juglandis attended by five European ant species (Camponotus piceus, Ca. vagus, Crematogaster scutellaris, Dolichoderus quadripunctatus, Lasius emarginatus) to a native and an exotic lady beetle (Adalia bipunctata and Harmonia axyridis), documenting the behavioural interactions between these insects and the performance of ants in the protection of the aphids. Our results reveal a significant behavioural diversity among the ant species involved, with D. quadripunctatus and L. emarginatus being the most aggressive and having the best performance as aphid defenders, and Ca. piceus being least effective and often fleeing away. Cr. scutellaris displayed a rare rescue behaviour attempting to pull away the aphids that the lady beetles grabbed. On the other hand, behavioural responses to A. bipunctata and H. axyridis were similar. Further investigations are needed to understand the eco-ethological implications of these differences, while a better understanding of ant behavioural diversity may help refine biological control strategies.

Toward sustainable management of ant-hemipteran mutualism in agricultural settings: a comparison of different approaches

Mutualistic associations between ants and honeydew-producing hemipterans have a great ecological and evolutionary significance across terrestrial habitats but can also cause pest outbreaks in agroecosystems. At the same time, ants are often effective predators of several agricultural pests, can improve soil quality, and can control some plant pathogens. Neither ant attendance of hemipteran pests alone, nor a positive correlation between the abundance of ants and hemipterans automatically imply that ants are a worthy target or a key element in hemipteran management strategies. The main tactics in the management of ant-hemipteran associations in agroecosystems include the use of sticky or insecticidal barriers, low-toxicity baits, alternative sugary sources, or ant-adapted biocontrol agents. Barriers can quickly seal ground-nesting ants from the canopy of perennial plants but are unselective towards other arthropods and costly in terms of maintenance. Low-toxicity baits have been particularly tested against invasive and supercolonial ant species and yet are worth considering only when the complete elimination of ant colonies can be desirable. More recently developed and not yet widely available methods based on the provision of alternative sugary sources to manipulate ant behavior can allow to retain or even enhance the contribution of ants to the control of other phytophagous insects or plant pathogens while effective disrupting their mutualism with hemipteran pests. Finally, many parasitoids and predators possess specific adaptations to bypass attending ants, but the existence of species-specific factors complicatesthese networks. Further basic research and longer-term studies are needed to refine and improve the development of sustainable management strategies.

A low-toxicity baiting program precipitates collapse of Argentine ant and ant-associated hemipteran pest populations in commercial citrus

The Argentine ant, Linepithema humile Mayr (Hymenoptera: Formicidae), disrupts biological control agents which induces population outbreaks of honeydew-producing hemipteran pests infesting agroecosystems. A multi-season liquid baiting program was evaluated for control of L. humile and ant-associated hemipteran pests in six commercial citrus orchards in southern California. Ant activity in treated trees fell by 96% within three months of treatment and was, on average, 95% lower in treated plots than untreated plots across the 18-month study period. Ant control resulted in the near elimination of hemipteran pest populations on trees in treated plots. Pre- and post-treatment estimates indicated that hemipteran pest infestation of twigs, flush, and fruit decreased by 97, 84, and 99% one year after treatment, respectively. Furthermore, cumulative infestation frequency was 10 times lower and cumulative colony size was 5 times lower on treated trees than control trees across the final year of study. Examining individual hemipteran pest species, the mean infestation rate by Diaphorina citri Kuwayama (Hemiptera: Liviidae) was 75% lower, Coccus hesperidum L. (Hemiptera: Coccidae) 95% lower, Planococcus citri Risso (Hemiptera: Pseudococcidae) 98% – 100% lower, and Aonidiella aurantii Maskell (Hemiptera: Diaspidae) 70 – 80% lower in treated trees relative to untreated trees. A surge in generalist predator activity and parasitism following ant bait deployment appear to be the driving forces behind the marked decrease in pest infestation observed in treated trees. Results underscore the importance of L. humile control for integrated pest management programs targeting ant-associated hemipteran pests in commercial citrus.

A new ant-butterfly symbiosis in the forest canopy fills an evolutionary gap

Myrmecophilous butterflies can establish complex symbiotic relationships with ants. A caterpillar wandering among the brood of the aggressive ponerine ant Neoponera villosa was found inside the core of a nest built in the myrmecophytic bromeliad Aechmea bracteata. This is the first caterpillar found living inside a ponerine ant nest. Its DNA barcode was sequenced, and an integrative approach was used to identify it as Pseudonymphidia agave, a poorly known member of the subtribe Pachythonina in the riodinid tribe Nymphidiini. The cuticle of the tank-like caterpillar lacks projections or tubercles and is covered dorsally by specialized flat setae that form an armor of small plates. Ant-organs potentially related to caterpillar-ant signaling, such as perforated cupola organs and tentacle nectary organs, are present. These morphological traits, together with evidence of social integration (direct contact with host brood, protective morphology, slow movement, no host aggressiveness), suggest that P. agave is a symbiotic, social parasite of N. villosa, preying on its host brood. However, several knowledge gaps remain, including oviposition site, dependence on bromeliad association, steps to colony integration, and larval diet through development. Carnivory has been reported in all known members of the subtribe Pachythonina (caterpillars prey on honeydew-producing hemipterans) suggesting a shift to myrmecophagy inside the ant nests as a possible evolutionary transition.

Chemical communication in ant-hemipteran mutualism: potential implications for ant invasions.

Ant-hemipteran mutualism is one of the most frequently observed food-for-protection associations in nature, and is recently found to contribute to the invasions of several of the most destructive invasive ants. Chemical communication underlies establishment and maintenance of such associations, in which a multitude of semiochemicals, such as pheromones, cuticular hydrocarbons, honeydew sugars and bacteria-produced honeydew volatiles mediate location, recognition, selection, learning of mutualistic partners. Here, we review what is known about the chemical communication between ants and honeydew-producing hemipterans, and discuss how invasive ants can rapidly recognize and establish a mutualistic relationship with the hemipterans with which they have never coevolved. We also highlight some future directions for a clearer understanding of the chemical communication in ant-hemipteran mutualism and its role in ant invasions.

The first known riodinid ‘cuckoo’ butterfly reveals deep-time convergence and parallelism in ant social parasites

Abstract Mutualistic interactions between butterflies and ants can evolve into complex social parasitism. ‘Cuckoo’ caterpillars, known only in the Lycaenidae, use multimodal mimetic traits to achieve social integration into ant societies. Here, we present the first known ‘cuckoo’ butterfly in the family Riodinidae. Aricoris arenarum remained in taxonomic limbo for > 80 years, relegated to nomen dubium and misidentified as Aricoris gauchoana. We located lost type material, designated lectotypes and documented the morphology and natural history of the immature stages. The multifaceted life cycle of A. arenarum can be summarized in three phases: (1) females lay eggs close to honeydew-producing hemipterans tended by specific Camponotus ants; (2) free-living caterpillars feed on liquids (honeydew and ant regurgitations); and (3) from the third instar onward, the caterpillars are fed and tended by ants as ‘cuckoos’ inside the ant nest. This life cycle is remarkably similar to that of the Asian lycaenid Niphanda fusca, despite divergence 90 Mya. Comparable eco-evolutionary pathways resulted in a suite of ecomorphological homoplasies through the ontogeny. This study shows that convergent interactions can be more important than phylogenetic proximity in shaping functional traits of social parasites.

Mutualistic ants (Hymenoptera: Formicidae) associated with Paracoccus ficus in fig orchards of Fars province, Iran.

Introduction: Ants are the most ubiquitous insects on the earth with more than 12000 species which are classified into 21 subfamilies. Until now, more than 170 ant species have recorded in Iran. Mutualistic relationship between ants and scale insects have been reported in Iran. Such relationships between ants and insects are known as trophobiosis which is due to attraction of ants to honeydew of scale insects. Honeydew is a sugar-rich sticky liquid, secreted by aphids and some scale insects as they feed on plant sap. Ants provide protection from predators and parasitoids by building shelters around scale insect colonies. Such a relationship is mostly facultative and only a few taxa of mostly tropical or subtropical scale insects have obligate mutualism with ants. The coccoids with obligate mutualism display obvious behavioral and morphological adaptations for living with ants. Ants are also able to establish antagonistic interaction with honeydew-producing hemipterans and contribute positively to biological control by the suppression of pests. Materials and Methods: In a study during 2013-2014, colonies of the mealybug Paracoccus ficus Moghaddam, 2014 were investigated for mutualistic ants feeding on honeydew of the mealybug in fig orchards of Neyriz, Estahban and Shiraz cities of Fars province, South Iran. Samples were collected by hand, forceps and soft brush. The specimens were preserved in 75% alcohol in small glass vials and were transferred to the laboratory. The morphological keys were used for identification. Specimens were deposited in Insect and Mite Collection of Ahvaz, at Department of Plant Protection, Shahid Chamran University of Ahvaz. Results and Discussion: Totally, 6 species belonging to 3 subfamilies of ants were identified as follows: Myrmicinae: Monomorium abeillei Andre, 1881; Tetramorium sp.; Pheidole pallidula Nylander, 1849; Crematogaster antaris Forel, 1894; Formicinae: Cataglyphis lividus Andre, 1881; Dolichoderinae: Tapinoma simrothi Krausse, 1911. Among collected species, T. simrothi and P. pallidula were more frequent. T. simrothi has also recorded as most frequent mutualistic ants with aphids in Central Iran. Natural enemies exploit hemipterans which receive ant protection for their benefit. For example, some parasitoid wasps soliciting honeydew directly from aphids by antennation and mimicking ants during foraging in host patches. Researchers believe that preventing ants from colonies of Pseudococcidae scale insects is necessary for success in biological control of such pests. However, not all of ants have negative effects in biological control of pests. Predatory ants are less attracted to the honeydew and mostly feed on egg, larvae and adult insects. Moreover, some ants are important in pollination, soil improvement, and nutrient cycling. Conclusion: Behavioral and ecological should be carried on ants in pest management programs, and only if they have a negative influence on biological control of scale insects, then perform control measures for ants.

Parasitism disruption by ants of Anagyrus lopezi (Hymenoptera: Encyrtidae), parasitoid of cassava mealybug

Abstract. Fanani MZ, Rauf A, Maryana N, Nurmansyah A, Hindayana D. 2020. Parasitism disruption by ants of Anagyrus lopezi (Hymenoptera: Encyrtidae), parasitoid of cassava mealybug. Biodiversitas 21: 2337-2343. Parasitoid, Anagyrus lopezi (De Santis) (Hymenoptera: Encyrtidae) was introduced into Indonesia in 2014 to control the invasive cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae). Among ants associated with honeydew-producing hemipterans, there are three common species in Indonesia i.e., Anoplolepis gracilipes (Smith), Dolichoderus thoracicus (Smith), and Oecophylla smaragdina (Fabricius) (Hymenoptera: Formicidae). The objective of this research was to investigate the relative influence of the three ant species on the parasitism of A. lopezi under laboratory conditions. Experiments were carried out by allowing a number of ants and parasitoids to forage on mealybugs-infested waterleaf (Talinum triangulare (Jaqc.) Willd.). The average time spent by individual parasitoid foraging was significantly longer (27.39 minutes) on ant-excluded plants compared to ant-attended plants (2.47- 4.68 minutes). Accordingly, parasitoid spent less time in finding hosts on ant-excluded plants, while spent a longer time in handling hosts. More oviposition activities by parasitoids on mealybug were occurred on ant-excluded plants compared to those on ant-attended plants. As a result, the percentage of parasitism and the number of wasps that emerged from the hosts on ant-excluded plants were almost 2 - 3 folds higher than those on ant-attended plants.

The impact of ant mutualistic and antagonistic interactions on the population dynamics of sap-sucking hemipterans in pear orchards.

Ants are known to establish antagonistic and mutualistic interactions with honeydew-producing hemipterans, depending on the species involved and the ecological context. The aim of this work was to infer the role that such interactions play in the population dynamics of psyllids and aphids in pear orchards. Interactions were inferred from field data and periodical sampling along a 4-year study, and from interaction assays performed under controlled conditions. A decline in the abundance of the pear psyllid (Cacopsylla pyri L.), parallel to an increase in the abundance of aphids, was registered over 4 years. Ants were the dominant species, representing about 90% of the predators, followed by spiders and predatory hemipterans (namely Pilophorus gallicus Remane). Ant abundance increased over the 4 years, matching the population dynamics of aphids. Evidence of mutualistic and antagonistic interactions were found for ant-aphid and ant-psyllid, respectively: (i) ant-aphid abundances on pear trees were positively correlated, and ants reduced predation on aphids by generalist predators, and (ii) ant-psyllid abundances were negatively correlated, ants have a negative effect on the psyllid population growth rates, and ants were found to prey on the psyllid. Because of their high abundance in comparison with other predators and the mutualistic-antagonistic relationships with aphids-psyllids, ants are considered to be the principal force behind the decline of pear psyllid populations and the increase in aphid numbers. In summary, ants contribute positively to biological control by the suppresion of pests (i.e. the psyllid) which are more damaging than those they protect (i.e. aphids). © 2019 Society of Chemical Industry.

Ant-mealybug mutualism modulates the performance of co-occurring herbivores

Mutualism between ants and honeydew producing hemipterans has been extensively studied. However, little is known on how ant-hemipteran mutualism impacts the co-occurring herbivores, which in turn affect the mutual relationship in ecosystems. Herein, we investigated the effect of ant-mealybug mutualism on the oviposition preference and spatial distribution of cotton leaf roller Sylepta derogata, a polyphagous herbivore, and in Apantetes derogatae performance, a larvae parasitoid of S. derogata. Leaf rollers constructed shelters for mealybugs to prevent them from enemy attack and preferred to lay eggs on plants with ant-mealybug mutualism. Egg abundance on mutualism-present plants was higher than on mutualism-absent plants. Leaf roller parasitoid A. derogatae showed higher parasitism on mutualism-absent plants. No obvious change in leaf roller egg abundance was observed when A. derogatae was excluded, suggesting that the parasitic pressure can also regulate the oviposition behavior of S. derogate. Apantetes derogatae showed higher aggressiveness in parasitizing leaf roller larvae at the absence of the mutualism. There was a definite correlation between leaf roller egg abundance and the number of patrolling ants on plants. Without ant-mealybug mutualism, S. derogata eggs showed a significantly aggregated distribution pattern, but a uniform distribution pattern was observed when the mutualism was present. Ant workers showed a consistently uniform distribution on plants. The results reveal a novel mediation effect of ant-mealybug association on the composition and structure of food webs in cotton field, which may contribute to a better understanding of the cascading effects of ant-hemipteran mutualism on other niche-related species in ecosystem.

Effect of Soil Treatments for Cottony Cushion Scale (Hemiptera: Monophlebidae) Control on Nylanderia fulva (Hymenoptera: Formidicae) Survival and Trailing Activity

Nylanderia fulva (Mayr) (Hymenoptera: Formicidae), or tawny crazy ant, is an invasive ant from South America that is spreading in the southern US. Extremely large populations of this ant can inundate urban and natural landscapes, and efficient control methods are lacking. This study was conducted to determine if activity of N. fulva would decline after controlling the hemipteran honeydew-producers they were tending. Potted plants infested with cottony cushion scale (Icerya purchasi Maskell) (Hemiptera: Monophlebidae) were treated with 2 imidacloprid insecticide formulations, and changes in N. fulva survival and foraging behavior were monitored. There were fewer ant trails, lower trailing intensity, less foraging, and less nesting in potted plants treated with either product than in the control pots. The use of low application rates of systemic insecticide to reduce honeydewproducing hemipterans, such as cottony cushion scale, could be an important component of the integrated pest management of N. fulva.

Development and testing of a standardized method to estimate honeydew production

Honeydew production by Hemiptera is an ecologically important process that facilitates mutualisms and increases nutrient cycling. Accurate estimates of the amount of honeydew available in a system are essential for quantifying food web dynamics, energy flow, and the potential growth of sooty mould that inhibits plant growth. Despite the importance of honeydew, there is no standardized method to estimate its production when intensive laboratory testing is not feasible. We developed two new models to predict honeydew production, one based on insect body mass and taxonomic family, and one based on body mass and life stage. We tested the accuracy of both models’ predictions for a diverse range of honeydew-producing hemipteran families (Aphididae, Pseudococcidae, Coccidae, Psyllidae, Aleyrodidae, Delphacidae, Cicadellidae). The method based on body mass and family provided more accurate estimates of honeydew production, due to large variation in honeydew production among families. We apply our methodology to a case study, the recalculation of honeydew available to invasive red imported fire ant (Solenopsis invicta) in the United States. We find that the amount of honeydew may be an order of magnitude lower than that previously estimated (2.16 versus 21.6 grams of honeydew per day) and discuss possible reasons for the difference. We anticipate that being able to estimate honeydew production based on minimal biological information will have applications to agriculture, invasion biology, forestry, and carbon farming.

Effects of different ant species on the attendance of neighbouring hemipteran colonies and the outcomes for the host plant

ABSTRACTAnts commonly participate simultaneously in mutualisms with honeydew-producing hemipterans and extrafloral nectar-bearing host plants. These interactions are based on the exchange of resources (honeydew and extrafloral nectar) for ant protection against natural enemies. The benefits may vary according to the species of ant interacting, and the outcomes for the host plant and hemipteran will depend on the results of the ant-plant-hemipteran relationship as a whole. We studied a plant-mealybug association with Camponotus crassus Mayr (Formicinae) and Ectatomma tuberculatum Olivier (Ectatomminae) in a Brazilian tropical savanna. We aimed to elucidate whether the frequency of visitation by different species of ants can be affected by neighbouring colonies of mealybugs, and whether these ant species influence the number of hemipterans in a different way. Furthermore, we intended to find out whether the interaction between ant and hemipteran has any effect on the proportion of fruit production or on the abundance of trophobiont and non-trophobiont herbivores, also influenced by the ant species. Our results show that neighbouring aggregations of mealybugs influenced the frequency of ant visitation and the ants affected the number of nymphs over time, with both positive results only for C. crassus. We also detected an indirect negative effect on proportion of fruit production and an increase in abundance of trophobiont and non-trophobiont herbivores in the presence of C. crassus-mealybug interaction. Thus, we provide further evidence that colonies of hemipterans interacting with ants can be beneficial for these herbivorous insects, but they are quite harmful to the host plant. Nevertheless, the outcomes can be highly conditional in relation to ant species.

Temperature warming strengthens the mutualism between ghost ants and invasive mealybugs

Although the exogenous forces that directly affect the mutualisms between ants and honeydew-producing hemipterans have been well documented, few studies have been focused on the impacts of environmental warming on ant-hemipteran interactions. Here, we investigated how temperature warming affects the mutualism between ghost ant Tapinoma melanocephalum and invasive mealybug Phenacoccus solenopsis by experimental manipulation of temperature. We found that higher temperatures have significant direct effects on the growth rate of mealybug colony, and the positive effect of ant tending on mealybug colony growth is temperature-dependent. Honeydew excretion by mealybugs was affected by ant tending and temperature warming, and was significantly increased under higher temperature. The effect of ant tending on percentage parasitism was also influenced by temperature warming. Ant performance including tending level, aggression, activity, and honeydew consumption was enhanced by temperature warming, which may provide superior protection to the mealybugs. Our results show that ghost ant-mealybug mutualism is strengthened in a warmer environment. These findings may facilitate the prediction of how each partner in the ant-hemipteran-enemy interactions responds to increasing temperature.

Whiteflies Provide Honeydew to Camponotus ants Without Receiving Reciprocal Favor

The notion that tending ants provide protection to honeydew-producing hemipterans is widely accepted. Nevertheless, there have been debates about whether or not this protection can always disrupt the biological control of hemipterans. Although various hemipteran species interact with tending ants, most studies have focused on the mutualism between ants and aphids. Woolly whitefly Aleurothrixus floccosus (Maskell) is an important pest of citrus whose nymphs are frequently tended by ants such as Camponotus. However, it is unknown whether or not ants in this genus can disrupt biological control of woolly whitefly by protecting this pest’s nymphs from natural enemies. We investigated the impact of Camponotus ants on the biological control of woolly whitefly in the field by excluding or allowing the access of ants to whitefly nymph colonies in different tangerine trees. Furthermore, in a laboratory study we also assessed the behavior of Camponotus ants in response to woolly whitefly’s common predator cues (visual and scent). In summary, this field-laboratory study suggests that there is no mutualism between tending Camponotus ants and the whitefly A. floccosus; rather it indicates commensalism as an alternative interaction. Interactions as this may provide more benefits for the host plant, whereby Camponotus ants can reduce sooty mold by removing honeydew from the leaves and favor pest biological control by leaving the whiteflies unprotected.

Foliage-dwelling ants in a neotropical savanna: effects of plant and insect exudates on ant communities

Ant dominance in tropical ecosystems can be explained by a capacity to exploit liquid foods such as extrafloral nectaries (EFNs) and secretions from honeydew-producing hemipterans (HPHs). Such nutritious exudates may determine ant distribution in space and shape specialization in ant–plant interactions. We provide a first assessment of how EFNs and HPHs mediate the structure of ant assemblages, ant visitation intensity, and characteristics of ant–plant interaction networks across space in Brazilian “cerrado” savanna. We used arboreal pitfall traps to sample visiting ants in four cerrado localities and recorded the presence of lepidopteran larvae to determine their possible response to ant visitation. Ant species composition and richness did not differ regardless of the presence of liquid rewards on plants, and most network patterns did not show consistent differences. However, in two of the four sites, ant densities were higher on plants with HPHs or EFNs due to increased activity by Camponotus and Pseudomyrmex ants. At these two sites, plants with liquid food sources had a more specific ant assemblage (higher specialization d′) than did plants without resources, and caterpillars were more frequently found on plants with fewer workers of Camponotus and Pseudomyrmex. Plants with HPHs had increased ant visitation and accumulated more ant species than did plants with EFNs or without liquid foods. Ant response to such food sources may thus depend on local conditions and identity of ant species, and may determine how ant assemblages are structured. Results highlight how different patterns of ant visitation to liquid resources can produce distinctive effects on herbivore infestation.

How plants and honeydew-producing hemipterans affect ant species richness and structure in a tropical forest zone

Extrafloral nectaries (EFNs) and hemipteran honeydew are often discussed as two alternative mechanisms encouraging ant visitation in mutualistic ant–plant relationships, but little is known about the processes that generate distribution pattern in species-rich insect communities. A case study on the interaction between ants, EFN-bearing plants and hemipterans was investigated along a gradient of increasing disturbance from regenerated forest to mixed crop field. Ants, EFN-bearing plants and hemipterans sampling was conducted in these vegetations during the wet and the dry seasons in five locations. Results showed that partitioning of ant species between season and vegetation was significantly different from random. High specialization index was observed in hemipterans/plants and ant/hemipterans interactions. Low specialization index was observed between ants and EFN-bearing plants mainly in the mixed crop field. Ant species were mostly found in non-aggressive co-occurrence at nectar sources. At the species level, specialization index was high for Anoplolepis tenella (0.86 ± 0.06) and also for its associated hemipterans Stictococcus vayssierei (0.97 ± 0.02). This association is detrimental to food crop especially cassava. These results outline the effect of vegetation and food source on the structure of the ant assemblage and interaction in tropical forest zone.

Synthetic pheromones as a management technique - dispensers reduce Linepithema humile activity in a commercial vineyard.

Invasive ants, such as the Argentine ant, have often been reported to facilitate honeydew-producing hemipteran pests such as mealybugs, which can be vectors of plant pathogens. Synthetic pheromones may offer a target-specific method to control such ants and consequently lower the abundance of honeydew-producing pests. Here we report the results of a trial to suppress Argentine ants in grapevines using ant pheromone dispensers. Compared with untreated controls, we observed a significant drop in Argentine ant activity on the ground, irrespective of whether pheromone dispensers were placed at ground level, within the canopy or in both locations. Ant counts in the canopy confirmed that Argentine ant abundance was reduced under the influence of the pheromone dispenser placed at ground level compared with untreated controls. However, placing dispensers only in the canopy did not reduce the numbers of ants within the canopy compared with untreated controls. Our results showed that pheromone dispensers can significantly reduce Argentine ant foraging in grapevines if they are positioned appropriately. This technique could potentially reduce the abundance of associated mealybugs and potentially attendant virus vectoring areawide.

Mutualism Between Fire Ants and Mealybugs Reduces Lady Beetle Predation.

Solenopsis invicta Buren is an important invasive pest that has a negative impact on biodiversity. However, current knowledge regarding the ecological effects of its interaction with honeydew-producing hemipteran insects is inadequate. To partially address this problem, we assessed whether the interaction between the two invasive species S. invicta and Phenacoccus solenopsis Tinsley mediated predation of P. solenopsis by Propylaea japonica Thunbery lady beetles using field investigations and indoor experiments. S. invicta tending significantly reduced predation by the Pr. japonica lady beetle, and this response was more pronounced for lady beetle larvae than for adults. A field investigation showed that the species richness and quantity of lady beetle species in plots with fire ants were much lower than in those without fire ants. In an olfaction bioassay, lady beetles preferred to move toward untended rather than tended mealybugs. Overall, these results suggest that mutualism between S. invicta and P. solenopsis may have a serious impact on predation of P. solenopsis by lady beetles, which could promote growth of P. solenopsis populations.

Interactions between Ghost Ants and Invasive Mealybugs: The Case ofTapinoma melanocephalum(Hymenoptera: Formicidae) andPhenacoccus solenopsis(Hemiptera: Pseudococcidae)

Abstract Mutualism between ants and honeydew-producing hemipterans is a common phenomenon in ecosystems, and interactions between ants and hemipterans have been extensively studied. The invasive solenopsis mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), and the ghost ant, Tapinoma melanocephalum (F.) (Hymenoptera: Formicidae), are widely distributed in China. Previous studies showed that the ghost ant can promote the fitness of the invasive mealybug when natural enemies of the mealybug are excluded. In this study, we investigated the interactions between the ghost ant and the invasive solenopsis mealybug when the mealybug's natural enemies were included. Our results indicated that the honeydew produced by mealybugs facilitated colony growth of the ghost ant significantly more than by allowing them to feed on the mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae). Tending by the ghost ant increased mealybug survival on the plants when six-spotted zigzag lady beetle larvae, Chei...