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Cricket babies “warned” about spiders before birth

Feb. 22, 2010
Courtesy of University of Chicago Press Journals
and World Science staff

Just be­cause crick­et moms aban­don their eggs be­fore they hatch doesn’t mean they can’t pass wis­dom along to their ba­bies. A new study pub­lished in the re­search jour­nal Amer­i­can Nat­u­ral­ist sug­gests crick­ets can some­how “warn” their un­born off­spring about po­ten­tial pred­a­tor threats.

A new study pub­­lished in the re­search jour­­nal Amer­i­­can Nat­u­ral­ist sug­­gests crick­­ets can some­how “warn” their un­born of­f­spring about po­ten­­tial pred­a­­tor threats, sci­en­tists say. Above, the field crick­et Gryl­lus penn­syl­van­i­cus, the species used in the study. (Cour­te­sy of Co­dy Hough)
Jon­a­than Storm of the Uni­vers­ity of South Car­o­li­na Up­state and Ste­ven Li­ma of In­di­ana State Uni­vers­ity put preg­nant crick­ets in en­clo­sures with a wolf spi­der. The spi­ders’ fangs were cov­ered with wax so the spi­ders could stalk the crick­ets, but not kill them. 

Af­ter the crick­ets laid their eggs, the two re­search­ers com­pared the be­hav­ior of those off­spring to off­spring whose moth­ers had­n’t been ex­posed to spi­ders. The dif­fer­ences were dra­mat­ic, they said.

When placed in­to a ter­rar­i­um with a hun­gry wolf spi­der, crick­ets born of spi­der-ex­posed moth­ers were found to be more likely to seek shel­ter and stay there. They stayed hid­den 113 per­cent longer—and as a re­sult had high­er sur­viv­al rates—than off­spring from moth­ers not ex­posed to spi­ders, Storm and Li­ma said.

“Trans­fer of in­forma­t­ion from moth­er to off­spring about preda­t­ion risk, in the ab­sence of any pa­ren­tal care, may be more com­mon than one might think,” Storm said. 

It’s un­clear how the moth­ers in­flu­enced their pro­geny’s be­hav­ior, the sci­en­tists said. They spec­u­late that per­haps stress­ful events like pred­a­tor at­tacks trig­ger the re­lease of a hor­mone that af­fects the de­vel­op­ment of the em­bry­o.

“Fore­warned” crick­ets were al­so more likely to freeze when they en­coun­tered spi­der silk or fe­ces, ac­cord­ing to the re­search­ers, which could help them avoid de­tec­tion by a near­by spi­der. The two sci­en­tists al­so col­lect­ed preg­nant crick­ets from the wild—some from habi­tats where wolf spi­ders are com­mon, oth­ers from places where spi­ders are scarce. Ba­bies from moth­ers caught in spi­der-rich habi­tats tended to be more cau­tious around signs of spi­ders, much like the lab-reared crick­ets, the in­ves­ti­ga­tors said.

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Just because cricket moms abandon their eggs before they hatch might not mean they don’t pass wisdom along to their babies. A new study published in the research journal American Naturalist suggests crickets can somehow “warn” their unborn offspring about potential predator threats, scientists say. Jonathan Storm of the University of South Carolina Upstate and Steven Lima of Indiana State University put pregnant crickets in enclosures with a wolf spider. The spiders’ fangs were covered with wax so the spiders could stalk the crickets, but not kill them. After the crickets laid their eggs, the two researchers compared the behavior of those offspring to offspring whose mothers hadn’t been exposed to spiders. The differences were dramatic, they said. When placed into a terrarium with a hungry wolf spider, crickets born of spider-exposed mothers were found to be more likely to seek shelter and stay there. They stayed hidden 113 percent longer—and as a result had higher survival rates—than offspring from mothers not exposed to spiders, Storm and Lima said. “Transfer of information from mother to offspring about predation risk, in the absence of any parental care, may be more common than one might think,” Storm said. It’s unclear how the mothers influence their progeny’s behavior, the scientists said. They speculate that perhaps stressful events like predator attacks trigger the release of a hormone that affects the development of the embryo. “Forewarned” crickets were also more likely to freeze when they encountered spider silk or feces, according to the researchers, which could help them avoid detection by a nearby spider. The two scientists also collected pregnant crickets from the wild—some from habitats where wolf spiders are common, others from places where spiders are scarce. Babies from mothers caught in spider-rich habitats tended to be more cautious around spider cues, much like the lab-reared crickets, the investigators said.