Biology, ecology and demography of the tropical treehopper Ennya maculicornis (Hemiptera: Membracidae): relationships between female fitness, maternal care and oviposition sites

Abstract

1. Treehoppers (Hemiptera: Membracidae) exhibit a wide range of social behaviours related to maternal care and nymphal aggregation. Maternal care represents an investment in terms of time and energy leading to trade-offs which bear a strong relationship with parity and can thus affect population dynamics. These trade-offs can be modulated by biotic and abiotic features of the oviposition site.2. Preliminary observations on Ennya maculicornis (Membracidae: Similinae: Polyglyptini) show that females generally lay a single egg mass, and occasionally two or three egg masses, and that maternal care is a plastic trait because some females abandoned their egg mass before it hatched while other females remained with their offspring after egg hatching. These features make this species an interesting model to study the relationship between female fitness, maternal care and ecological factors such as oviposition site.3. The biology and natural history of E. maculicornis are described and the relationships in question analysed using demographic parameters estimated by matrix models. Ennya maculicornis showed sexual dimorphism and a longer developmental period than other species of the same tribe. Females exhibited maternal care that increased offspring survival, and preferred mature over young host leaves for oviposition. Finite rate of increase ( ) values were lower than 1, suggesting a tendency towards population decrease.4. The results represent the first detailed description of the life history and ecology for a species of this genus. Additionally, new hypotheses for treehopper sexual dimorphism, oviposition site choice and the ecological effects on population dynamics are proposed.

Mate searching inEnnya maculicornis(Membracidae: Polyglyptini) initiated by females: behavioural and acoustic descriptions

“…6. A study of the biology and ecology of the same population of E. maculicornis indicated the presence of a higher proportion of females (Caceres-Sanchez et al, 2017), which is an attribute that can also promote the development of female strategies to initiate attraction towards males through competition to find a mate (Kvarnemo & Simmons, 1999;Clutton-Brock, 2009). Numbers above arrows denote the frequency with which an event occurred.…”

“…Flowchart with the mate searching process. A reversal in terms of the sex that starts the search for a mating partner can also be related to the reproductive strategy of females of this species who, within a short time interval, can oviposit up to three clutches of eggs: they abandon the first clutches and look for new mating events, thus maximising their fitness, which is a strategy followed by some polyandrous females (Lloyd, 1966;Claridge, 1985;Bailey, 2003;Bailey & Hammond, 2003;Clutton-Brock, 2007;Caceres-Sanchez et al, 2017). invest more energy in their offspring (Magrath & Komdeur, 2003;Campbella et al, 2009); however, this is not the case in E. maculicornis because males do not provide parental care.…”

“…The lifestyles of E. maculicornis and E. chrysura share many similarities: both live on the same plant species, sometimes oviposit together or with other Ennya species, females abandon their nymphs and sometimes even their eggs, and the nymphs and adults live in groups (Godoy et al, 2006;Caceres-Sanchez et al, 2017). On the other hand, mate searching behaviour is distinctly different in these two species: (i) in E. chrysura (Miranda, 2006), males start mate searching by calling the females, whereas the opposite occurs in E. maculicornis, and (ii) after the initial call signal, two vibrational signals are necessary for mating to occur in E. chrysura (one emitted by the female after the male call and another emitted by the male after the duet is formed), whereas, in E. maculicornis, there are three such signals (M-1, M-2 and F-2), as discussed above.…”

“…Adults show sexual dimorphism in both size (females are usually larger than males) and the colour of their pronotum (black in males and green in females but turning to yellow as females age) (Caceres-Sanchez et al, 2017). Adults show sexual dimorphism in both size (females are usually larger than males) and the colour of their pronotum (black in males and green in females but turning to yellow as females age) (Caceres-Sanchez et al, 2017).…”

“…Adults show sexual dimorphism in both size (females are usually larger than males) and the colour of their pronotum (black in males and green in females but turning to yellow as females age) (Caceres-Sanchez et al, 2017). Females may oviposit more than once, sometimes side by side with females of Ennya chrysura Fairmaire (Membracidae), in which case nymphs form mixed-species aggregations (Caceres-Sanchez et al, 2017). Females may oviposit more than once, sometimes side by side with females of Ennya chrysura Fairmaire (Membracidae), in which case nymphs form mixed-species aggregations (Caceres-Sanchez et al, 2017).…”