Oviposition-deterring pheromone deposited on blueberry fruit by the parasitic wasp, Diachasma alloeum

TY - JOUR

T1 - Oviposition-deterring pheromone deposited on blueberry fruit by the parasitic wasp, Diachasma alloeum

AU - Stelinski, L. L.

AU - Oakleaf, R.

AU - Rodriguez-Saona, C.

PY - 2007/4

Y1 - 2007/4

N2 - Insect parasitoids are known to deposit chemical signals on utilized hosts following oviposition. It is believed that these chemical signals alert future conspecifics of an exploited and thus sub-optimal host alleviating potential suffering among brood that would otherwise compete over a limited resource. Diachasma alloeum (Muesebeck) is a braconid wasp that specifically attacks two species of fruit-parasitic flies in the genus Rhagoletis. Female wasps lay a single egg into a second or third instar fly maggot developing in blueberry, hawthorn, or apple fruit. Following oviposition, female wasps press and drag their ovipositor across the fruit surface depositing a clear liquid; this has been termed 'excreting' behaviour. In this report, we describe excreting behaviour in a field population of D. alloeum attacking the blueberry maggot fly, Rhagoletis mendax Curran. Subsequently, we demonstrate in a series of laboratory assays that D. alloeum females deposit a substance on blueberry fruit directly following egg laying that deters subsequent naïve females from ovipositing into the marked fruit. Marking fruit with this putative oviposition-deterring pheromone without associated egg laying was sufficient to induce the deterring effect, while oviposition alone without subsequent marking had no effect. The oviposition-deterring effect was removed by rinsing fruit with a solution of 50% ethanol in water. Spraying unmarked fruit with an ethanol-water rinsate of previously-marked berries induced the oviposition-deterring effect. Significant deterrence of oviposition lasted up to 7 days after marking. To our knowledge, this is the first demonstration of a hymenopteran oviposition-deterring pheromone that is deposited externally on the surface of the fruit skin rather than on the surface of the parasitized larva. Female D. alloeum maximally parasitize second-instar R. mendax larvae during a short 4-5 d window. The length of activity of the oviposition-deterring pheromone described here should be sufficient to prevent multiple egg-laying into a host that cannot support more than one parasitoid larva, and thus reduce intraspecific competition.

AB - Insect parasitoids are known to deposit chemical signals on utilized hosts following oviposition. It is believed that these chemical signals alert future conspecifics of an exploited and thus sub-optimal host alleviating potential suffering among brood that would otherwise compete over a limited resource. Diachasma alloeum (Muesebeck) is a braconid wasp that specifically attacks two species of fruit-parasitic flies in the genus Rhagoletis. Female wasps lay a single egg into a second or third instar fly maggot developing in blueberry, hawthorn, or apple fruit. Following oviposition, female wasps press and drag their ovipositor across the fruit surface depositing a clear liquid; this has been termed 'excreting' behaviour. In this report, we describe excreting behaviour in a field population of D. alloeum attacking the blueberry maggot fly, Rhagoletis mendax Curran. Subsequently, we demonstrate in a series of laboratory assays that D. alloeum females deposit a substance on blueberry fruit directly following egg laying that deters subsequent naïve females from ovipositing into the marked fruit. Marking fruit with this putative oviposition-deterring pheromone without associated egg laying was sufficient to induce the deterring effect, while oviposition alone without subsequent marking had no effect. The oviposition-deterring effect was removed by rinsing fruit with a solution of 50% ethanol in water. Spraying unmarked fruit with an ethanol-water rinsate of previously-marked berries induced the oviposition-deterring effect. Significant deterrence of oviposition lasted up to 7 days after marking. To our knowledge, this is the first demonstration of a hymenopteran oviposition-deterring pheromone that is deposited externally on the surface of the fruit skin rather than on the surface of the parasitized larva. Female D. alloeum maximally parasitize second-instar R. mendax larvae during a short 4-5 d window. The length of activity of the oviposition-deterring pheromone described here should be sufficient to prevent multiple egg-laying into a host that cannot support more than one parasitoid larva, and thus reduce intraspecific competition.

KW - Blueberry maggot fly

KW - Competition

KW - Epideictic pheromone

KW - Marking pheromone

KW - Oviposition behaviour

KW - Parasitoids

UR - http://www.scopus.com/inward/record.url?scp=34249986048&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34249986048&partnerID=8YFLogxK

U2 - https://doi.org/10.1163/156853907780755996

DO - https://doi.org/10.1163/156853907780755996

M3 - Article

VL - 144

SP - 429

EP - 445

JO - BEHAVIOUR

JF - BEHAVIOUR

SN - 0005-7959

IS - 4

ER -