Missing in action since 1921!

by Stephen Thorpe (stephen_thorpe@yahoo.co.nz)

Research Associate, University of Auckland

In 1921, Scutellista caerulea (Fonscolombe, 1832) (Hymenoptera: Pteromalidae) was imported and released in Nelson for the biological control of pest scale insects (Thorpe, 2013). It was thought to have failed to establish. On 17 April 2013, I captured a specimen on vegetation by the pond on the Tamaki Campus, University of Auckland. Despite looking out for adults, I did not see it again until 21 March 2015, when another single specimen turned up (see photos), once again on the Tamaki Campus, just metres away from building 733, where I am based! I shook it out of a garden box of dense Libertia, by the staff shuttle stop (see photo). The question remains unanswered as to whether these specimens are descendants of the 1921 release in Nelson, or else represent a new incursion. The fact that I have only managed to find two specimens in nearly two full years adds some plausibility to the idea that it could have been present in N.Z., unnoticed, since 1921. The proximity of the dates of capture also suggests that there may be a very narrow window of seasonality for adult activity. The species is extremely distinctive. It is a chunky 2 mm long blue wasp, with an enormously developed shield like scutellum, under which it tucks away its wings. Nothing else is like it! The species is known to be a parasitoid of soft scales of the family Coccidae (Badary & Abd-Rabou, 2011), and it would make an interesting project to try to rear it from coccids in Auckland. The Coccidae of N.Z. have been well documented by Hodgson & Henderson (2000).

Badary, H.; Abd-Rabou, S. 2011: Role of pteromalid parasitoid Scutellista caerulea (Fonscolombe) (Hymenoptera: Pteromalidae) for biological control of the soft scale insects (Hemiptera: Coccidae) in Egypt. Egyptian academic journal of biological sciences, 4(1): 49-58. http://entomology.eajbs.eg.net/pdf/vol4-num1/5.pdf

Hodgson, C.J.; Henderson, R.C. 2000: Coccidae (Insecta: Hemiptera: Coccoidea). Fauna of New Zealand, (41) http://www.landcareresearch.co.nz/publications/books/fauna-of-nz-series/extracts/fnz41

Thorpe, S.E. 2013: Scutellista caerulea (Fonscolombe, 1832) (Hymenoptera: Pteromalidae), new to New Zealand for the second time! Biodiversity data journal, 1: e959. doi: 10.3897/BDJ.1.e959

Scutellista - recently recorded in Auckland after decades of no sightings.

Scutellista – recently recorded in Auckland after decades of no sightings.

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