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New species of spider wasp may use chemical signals from dead ants to protect nest

A new species of spider wasp, the ‘Bone-house Wasp,’ may use chemical cues from dead ants as a nest protection strategy, according to a recent study published July 2, 2014 in the open-access journal PLOS ONE by Michael Staab from University of Freiburg, Germany, and his colleagues from China and Germany.

Wasps use a wide variety of nest protection strategies, including digging holes or occupying pre-existing cavities such as in wood. Previous studies showed that the nests of cavity-nesting wasps contain several brood cells separated by thin walls of plant debris, resin, or soil. Once the females have finished constructing the nest, laying eggs, and providing food, they construct an outermost vestibular cell to close the nest. After construction, female wasps abandon the brood and do not care for their offspring anymore. Nest protection strategies play a central role in brood survival, and in this study, scientists interested in better understanding these strategies collected ~800 nests of cavity-nesting wasps with ~1900 brood cells belonging to 18 species in South-East China.

The scientists found a nesting behavior previously unknown in the entire animal kingdom: in over 70 nests they found an outer vestibular cell filled with dead ants. The species constructing these ant-filled vestibular cell was so far unknown to science and was described in the same study as the ‘Bone-house Wasp’ (Deuteragenia ossarium), after graveyard bone-houses or ossuaries. The scientists also found lower parasitism rates in “Bone-house” nests than in nests of similar cavity-nesting wasps. The authors suggest that D. ossarium nests are less vulnerable to natural enemies, potentially supporting the outer cell’s role in defense, which most likely involves chemical cues emanating from the dead ants used as nest-building material.

Dr. Staab added, “Our discovery demonstrates in an impressive way, what fascinating strategies of offspring-protection have evolved in the animal kingdom.”

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The above story is based on materials provided by PLOS. Note: Materials may be edited for content and length.

Agriculture and Food News — ScienceDaily

US (CA): Predator wasp used to fight disease threat

US (CA): Predator wasp used to fight disease threat

Pesticides haven’t worked. Quarantines have been useless. Now California citrus farmers have hired an assassin to knock off the intruder threatening their orchards. The killer-for-hire is Tamarixia radiata, a tiny parasitic wasp imported from Pakistan.

Its mission: Rub out the Asian citrus psyllid, which has helped spread a disease that turns citrus fruit lumpy and bitter before destroying the trees. The wasp, which flew coach in a carry-on bag from Pakistan’s Punjab region, is a parasite half the size of a chocolate sprinkle. But it kills psyllids like a horror movie monster, drinking their blood like a vampire. The female wasp can lay an egg in the psyllid’s belly. When it hatches, it devours its host.

The US Department of Agriculture has enacted quarantines in nine states, including Florida, Texas and California. The quarantines prohibit interstate movement of citrus trees and require labeling of citrus nursery stocks from areas where greening has been detected.

In California, the quarantine covers nine counties. The northern border of the quarantine region had stretched across Santa Barbara, Ventura, Los Angeles and San Bernardino counties, but on Wednesday, agriculture officials expanded it to 178 square miles in Tulare County where the psyllid was detected.

That recent discovery raises the fear that the pest is creeping into prime citrus growing areas. It could threaten California’s $ 2-billion industry, which accounts for about 80% of the US fresh market citrus production. Florida’s citrus is primarily processed for juice.

Source: latimes.com

Publication date: 8/6/2013


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