Novel trophobiotic interactions in lantern bugs (Insecta: Auchenorrhyncha: Fulgoridae)

When Cockroaches Replace Ants in Trophobiosis: A New Major Life-Trait Pattern of Hemiptera Planthoppers Behaviour Disclosed When Synthesizing Photographic Data

The mutualistic interspecific relationships of trophobiosis between trophobiont planthoppers (Hemiptera, Fulgoromorpha) providing food to the host called xenobiont, are reviewed. The degree of interspecific relationships between these symbionts varies from occasional or short time duration (a few hours to a few days) to longer ones, with trophobionts left free to escape (optobiotic type) by the xenobiont, or maintained enclosed in nests or ant shelters (cryptobiotic type). Of 267 collected cases, 126 are new illustrated observations. Occasional trophobiosis is documented in 13 families of planthoppers and appears to be quite general in Fulgoromorpha, although it is reported for the first time for Dictyopharidae, Eurybrachidae, and Nogodinidae. Xenobionts associated with planthoppers are reported from ants and other Hymenoptera, Lepidoptera, and Blattodea, but also from Mollusca and even small gekkonid vertebrates. Tettigometridae appear to be exclusively tended by ants, while Fulgoridae significantly more often by cockroaches (40%) than by ants (27%). Long-time trophobiosis occurs always with ants, cryptobiotic ones reported in Cixiidae, Delphacidae, Tettigometridae, Meenoplidae, Flatidae and Hypochthonellidae, while optobiotic ones remain restricted to tettigometrids. A particular focus on Tettigometridae attended by ants is provided with new etho-ecological observations. of 92 currently described tettigometrids species, 32 different species (35%) are now known to be able to be ant-attended. In Bulgaria, where fourteen species occur, trophobiosis occurs with at least five species of them (36%). In tettigometrids, subsociality, sessility, and underground life appear to be key factors allowing more complex relationships with ants. However, the planthopper size and thus the amount of food (drops of honeydew) is probably also an important factor. This might explain many new observations in large-sized and often isolated fulgorids with cockroaches. Tapping of trophobiont forewings by cockroaches, moths, or of the bark subtrate by geckos has been observed, but antennal palpation behaviours by ants are the most commonly observed with tettigometrids, although not with larger planthoppers. In tettigometrids, specific tegumentary glands secretions (allomones) of the abdomen pleurites might also mediate their long-term mutualistic associations, even possibly completing honeydew kairomones actions mediating planthopper trophobiosis in general.

Looking beyond the flowers: associations of stingless bees with sap-sucking insects

The main sources of food for stingless bees are the nectar and pollen harvested from flowers, whereas one important kind of nesting material (i.e. wax) is produced by their own abdominal glands. Stingless bees can, nonetheless, obtain alternative resources of food and wax from exudates released by sap-sucking insects as honeydew and waxy cover, respectively. To date, there are no comprehensive studies investigating how diversified and structured the network interactions between stingless bees and sap-sucking insects are. Here, we conducted a survey of the data on relationship between stingless bees and sap-sucking insects to evaluate: (1) which resources are collected by which stingless bee species; (2) how diverse the interaction network is, using species degree and specialisation index as a proxy; and if (3) there would be any phylogenetic signal in the species degree and specialisation indices. Our findings demonstrate that approximately 21 stingless bee species like Trigona spp. and Oxytrigona spp. have been observed interacting with 11 sap-sucking species, among which Aethalion reticulatum is the main partner. From ca. 50 records, Brazil is the country with most observations (n = 38) of this type of ecological interaction. We found also that stingless bees harvest fivefold more honeydew than waxy covers on sap-sucking insects. However, we did not find any phylogenetic signal for the occurrence of this interaction, considering species degree and specialisation indices, suggesting that both traits apparently evolved independently among stingless bee species. We suggest that specific ecological demands may drive this opportunistic behaviour exhibited by stingless bees, because major sources of food are obtained from flowers and these bees produce their own wax.

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.