NC State University Insect Museum

Hymenoptera: Braconidae: Binodoxys carolinensis (Smith)

Introducing another friend of the gardener – Why should gardeners love this little non-descript wasp? Binodoxys carolinensis is in the subfamily Aphidiinae, which are all parasitoids of aphids. Aphids, as many have found, can be a huge problem on the tender new growth of many vegetables and ornamentals.

Aphidiine braconids are all very small wasps, with reduced wing veins as compared to most other braconids. It is a diverse group distributed world wide.

After mating, the female wasp will search for a population of aphids suitable as hosts for her young. She will lay a single egg in an aphid, which will hatch into a larva. The larva develops to adult on that single aphid host. This aspect categorizes these wasps as parasitoids, meaning that all the sustenance needed from egg to adult is taken from a single host. Because of this, parasitoids are some of the most efficient organisms on the planet, converting nearly all of their food to biomass.

Parasitoids such as B. carolinensis are useful to commercial growers as well. Because parasitoids have such a narrow host range, targeting only a few or sometimes just one species, it isn’t too difficult to develop a pest control program that doesn’t have a large impact on other insect fauna. Many ecological studies have been done concerning aphid parasitoids in crop pest systems (Jones 1972, Muller et al. 1997, Macfadyen et al. 2009). Using parasitoids is a method of biological control, which can sometimes be more cost effective and easier than using pesticides.

If you’re wondering if you have this little helper in your garden, look for what are called “aphid mummies” such as in the image below. There is often an emergence hole where the parasitoid has exited the host. If you find some of these “aphid mummies”, you may have B. carolinensis or one of its relatives helping to keep the aphid populations down.

Image credit: Denis Crawford

There are no records of this species in GBIF

Find out more:

Jones, M. G. (1972). “Cerial aphid their parasites and predators caught in cages over oat and winter wheat crops.” Annals of Applied Biology 72(1): 13-25.

Macfadyen, S., R. Gibson, et al. (2009). “Parasitoid control of aphids in organic and conventional farming systems.” Agriculture Ecosystems & Environment 133(1-2): 14-18.

Muller, C. B., W. Voelkl, et al. (1997). “Are behavioural changes in parasitised aphids a protection against hyperparasitism?” European Journal of Entomology 94(2): 221-234.

Hymenoptra: Pelecinidae: Pelecinus polyturator (Drury 1773)

Inspired by the complaints about the low number of Hymenoptera “Insect of the week” blogs (No. 25.) I have decided to write about one of the most interesting and distinct North American Hymenoptera, the pelecinid wasp.  Due to its relatively large body size (5–11mm) and unique morphological characteristics (extremely elongated, telescopic-like female metasoma), the shining black and slow flier pelecinid specimens are easily recognized even with the naked eye while taking our late summer-early fall walks in hardwood NC forests.

Pelecinus polyturator female specimens

The unigeneric family Pelecinidae is usually classified into the superfamily Proctotrupoidea due to the annular, ring like pronotum and retractable ovipositor. Although Proctotrupoidea has never been reported as monophyletic in the most recent higher-level phylogenetic studies of Hymenoptera, Pelecinidae is usually retrieved as sister to Proctotrupidae, Vanhorniidae and Heloridae. Pelecinus, the only genus of the family, contains 3 species, of which, Pelecinus polyturator is the most widely distributed from southern parts of eastern Canada to northern Argentina. The species is the only Neartic representative of the genus.

The size variation of P. polyturator is relatively large (body length varies between 20–90 mm). The wasp is wholly black in the Nearctic region, however, some reddish specimens have been collected in Central America. The fore wing venation is reduced comparing with the usually brownish Neotropic Monomachidae species, that are the only Hymenoptera which pelecinids could be confused with.

The exceptionally elongate telescopic-like, apical female metasomal segments are shared by both taxa and is related to the ovipozition behavior: Pelecinid females are able to parasitize Phyllophaga larvae up to 5 cm under the soil surface!

Although Pelecinus polyturator is relatively large and easily recognizable, surprisingly little is known about its biology.  Specimens of the species have been reared from larvae of Phyllophaga sp. (Coleoptera: Scarabaeidae) with low rates of parasitization (1-3%). Phyllophaga species in the Nearctic region have three larval instars, and the life cycle varies from 1 to 4 years. The incredible size variation of Pelecinus specimens may be the result of either the differing range in size of larvae of different Phyllophaga species (length larvae of North American Phyllophaga species ranges between 7.25 to 25 mm) or may also be related to whether the wasp develops on a second or third instar.

Life cycle of Phyllophaga sp. Image credit: UNL Turfgrass Entomology )

The abundance of males are low in the Nearctic region (4%), whereas the sex ratio is around 36% in Central and South America. Brues has treated the disjunction between the temperate spanandrous (males are only very sparsely found) and subtropical/tropical bisexual population as an example of the geographic parthenogenesis.  Based on Brues theory Pelecinus polyturator populations are thelythokous (females are produced from unfertilized eggs) in temperate zones, whereas arrchenotokous (unfertilized eggs develop into haploid males, and fertilized eggs develop into diploid females) in tropical regions. Parthenogenetic reproduction is favored in marginal areas (temperate zone in the case of Pelecinus polyturator) with lower population density. Mate chance as well as the influence of the biotic factors behind the force of selective pressure for the increased genetic diversity are decreased.

The NCSU Insect Collection encompasses 120 P. polyturator specimens of which 112 females and 1 male have been collected in the USA and 4 males and 3 females from Central America (Costa Rica). The largest specimen is 7.5 cm and the smallest is 3.4 cm long.

Find out more:

http://data.gbif.org/search/polyturator

Bennett AMR (2003) Host location behavior of Pelecinus polyturator (Hymenoptera, Pelecinidae). Journal of the Entomological Society of Ontario 134:131­–134.

Brues CT (1923) A note on the genus Pelecinus. Psyche 35:205–209.

Johnson NF & Musetti L (1999) Revision of the Proctotrupoid genus Pelecinus Latreille (Hymenoptera: Pelecinidae). Journal of Natural History 33:1513–1543.

Johnson NF & Musetti L (1998) Geographic variation of sex ratio in Pelecinus polyturator (Drury) (Hymenoptera: Pelecinidae). Journal of Hymenoptera Research 7:48–56.

Johnson NF & Musetti L. The Pelecinus Project.

Male Parcoblatta lata from Raleigh, May 1974

Dictyoptera: Blattaria: Blattellidae: Parcoblatta lata (Brunner, 1865)

This week’s insect is a small (0.5-1.0 inches in length), common wood cockroach native to pine forests in the eastern U.S., Parcoblatta lata. There are only about 70 cockroach species that occur in the United States and Canada.

Cockroaches have evolved several methods for protecting their eggs (egg cases are called oothecae), including encased ovipary (ootheca),  externally retained ootheca, internally retained ootheca, and pseudoviviparity (where the ootheca is effectively lost). The more “popular” Madagascar hissing cockroach (Gromphadorhina portentosa) females carry the ootheca internally and release nymphs after the eggs hatch. The egg cases of Parcoblatta lata need the perfect balance of moisture and are most often deposited in damp, rotting logs.  This species has only one generation per year, with females producing an average of 41 eggs per oothecae, or about 517 offspring during their lifetime (Horn & Hanula 2002). Researchers have found as many as 20 oothecae in 1 meter of moist log – if all eggs survived to emergence, that would be about 820 Parcoblatta nymphs emerging in one log!

Commonly known as the broad wood cockroach, Parcoblatta lata is one of the most common wood roaches present in snags (standing dead trees) and logs in pine forests. They can easily be found scurrying about or hiding in the loose bark in rotten logs where there is better protection from predators, and are very commonly found at night in pine boles.

As is the case with all species within the cockroach genus Parcoblatta, females have reduced wings and are flightless, while males have long wings used for flight. The roaches overwinter as nymphs, and females normally live about 2 months longer than males.

Ensign wasps (Hymenoptera: Evaniidae) develop as solitary predators of cockroach eggs (the Deans lab studies systematics of Evaniidae).   This video, taken by Matt Bertone, is of Hyptia thoracica (Blanchard) ovipositing in Parcoblatta lata oothecae in Raleigh in July, 2010. MB collected a female H. thoracica from his house and exposed her to several oothecae of Parcoblatta lata under laboratory conditions. We are still waiting to see what, if anything, emerges from this (presumed) oviposition.

We have 65 specimens of P. lata in the NCSU Insect Collection -  half (32) are from Raleigh, while the remaining North Carolina specimens are from Madison, Harnett, Brunswick, Buncombe, Rowan, Davie, New Hanover, Yadkin, Guilford, Alamance, Forsyth and Currituck Counties. There are 3 specimens from Rutherford Co., T.N., Fallston, Maryland, and Mobile, Alabama.  The oldest specimen is from Raleigh in 1946! The counties in North Carolina where we have collecting records are in green on the map below.

Find out more:

Horn, S. and J.L. Hanula. 2002.  Life History and Habitat Associations of the Broad Wood Cockroach, Parcoblatta lata (Blattaria: Blattellidae) and Other Native Cockroaches in the Coastal Plain of South Carolina. Annals of the Entomological Society of America, Vol. 95, no, 6.

Blattodea Species File Online

GBIF record -  only 1 record

BugGuide (Parcoblatta)

I’m in the middle of paternity leave right now (hence the quiet blog), but I just had to emerge briefly to acknowledge that our recent grant has been highlighted as a top 100 stimulus project by Senators Coburn and McCain:

What is the best way to simultaneously preserve an insect collection, promote a haiku contest and produce bug baseball cards? Simple. A grant to the North Carolina State University Insect Museum. The museum boasts being an ‘internationally recognized resource for the study of insects and mites in North Carolina, the Southeastern United States, and, in several insect groups, the world.’ (p. 37) [emphasis mine]

Thanks guys! They really loved our outreach ideas and blog and even gave a shout-out to the haiku contest (which is neither funded nor promoted by the NSF grant, as I use funds from my own pocket for that)! Looks like our hard work—databasing, replacing cabinetry, drawers, and unit trays (all bought from American suppliers), and reaching out to educate North Carolinians (and others), hiring 5 people—is really paying off. It feels pretty good to get some attention from prominent, national figures.