Ephutomorpha tyla Hearn, Williams, and Parslow, 2019

Hearn, Lucas R., Stevens, Mark I., Schwarz, Michael P. & Parslow, Ben A., 2021, Parasitoids of the uniquely social colletid bee Amphylaeus morosus (Hymenoptera: Colletidae) in Victoria, Memoirs of Museum Victoria 80, pp. 183-191 : 188-189

Ephutomorpha tyla Hearn, Williams, and Parslow, 2019

(fig. 3b). The host association for Ephutomorpha tyla has already been described by Hearn et al. (2019). Here, we present additional details based on new data. In two nests, a single adult female E. tyla was observed trying to break through the most proximal cell in the nest, while in a further 21 instances, adult females were observed waiting in the nest entrance. Ephutomorpha tyla does not appear to specifically target certain nest types, attacking nests with up to 14 brood cells or nests with only four brood cells interspersed with vestibules. A total of 29 nests contained either parasitised immatures, an adult female E. tyla in the entrance, or both. No adult female A. morosus were present in 69% (20/29) of these nests.

Parasitised brood cells consisted of brown papery cocoons that occupied the entirety of the brood cell. As the E. tyla immatures developed, the brood cells became darker and increasingly difficult to open. In nine affected nests, all brood cells were parasitised by E. tyla , with damaged partitions between cells. The body sizes of male and female E. tyla were generally consistent. However, in some cases there were marked differences in body size within each sex.

Ephutomorpha aff. varipes ( André, 1895) (fig. 3c). Larvae of Ephutomorpha aff. varipes were observed as external parasitoids of the mature larvae, prepupae and pupae of A. morosus and were observed feeding on young pupae (fig. 3e). Larvae of E. aff. varipes remained on their host until mature before producing a light-brown silk-like cocoon and eclosing as an adult. The ectoparasitoid larva of E. aff. varipes were observed on multiple consecutive A. morosus immatures in one nest. The first three brood cells of the parasitised nest contained fully healthy A. morosus immatures, whereas the next eight brood cells were occupied by parasitised larvae, all of which eclosed as males. Ephutomorpha aff. varipes was observed parasitising several species that occupy excised Cyathea australis fronds, including another mass provisioning bee, Hylaeus sp. , and a crabronid wasp, Pison sp. While, on numerous occasions, females were observed in the nest entrance of the allodapine bee, Exoneura robusta Cockrell, 1922 , no parasitic association has been confirmed.

Other enemies

Of the 243 potentially viable A. morosus nests collected, 34.2% (83/243) contained no A. morosus adults or brood cells and had been superseded or temporarily occupied by other insect species. Twenty-four of these nests were occupied by Pison sp. ( Hymenoptera : Crabronidae ), two nests were occupied by the pteromalid wasp of the genus Eupelmophotismus ( Hymenoptera : Pteromalidae ), while one nest contained recently eclosed encyrtid wasps from the genus Coelopencyrtus ( Hymenoptera : Encyrtidae ). Five nests contained clerid beetle larvae ( Coleoptera : Cleridae ), including two instances of nests with A. morosus immatures and adults that contained beetle larvae in the nest entrance.