0000000000015875
AUTHOR
Pablo Mendiola
Dialipsis villahermosaeHumala & Selfa n. sp. (Hymenoptera: Ichneumonidae), the second European species of the genus, with biological notes and a key of Palaearctic species
Abstract The small genus Dialipsis Forster 1869 (Hymenoptera: Ichneumonidae) includes two known species, of which one is common in Central and Northern Europe. Here we describe the male and female of a new species, Dialipsis villahermosae Humala & Selfa, which was reared from mushrooms collected in Eastern Spain. The host fungus gnat, Mycetophila blanda Winnertz, is a new record for the whole genus, while the rate of parasitism seems very low. Based on environmental data of the collection localities and data available for other two species it is suggested that Dialipsis species occur preferably in cool temperatures habitats. A key of identification of the two known Palaearctic species is pr…
Female–female attraction influences nest establishment in the digger wasp Stizus continuus (Hymenoptera: Crabronidae)
Although digger wasps are good models for the study of nest site selection, the behaviour of females in relation to time of nest establishment has rarely been considered despite this being the key to discrimination between substrate availability-based and a female attraction-based selection. We carried out a study on nest establishment by the digger wasp Stizus continuus (Klug), giving to all nests dug by the wasps both spatial (nearest neighbour distance to nests, proximity of vegetation, soil hardness) and temporal (day of excavation) attributes. Stizus continuus females dug more nests under bush edges, where the soil was much softer. There was no tendency for females to maximize distance…
Emergence and dispersal relative to natal nest in the digger wasp Stizus continuus (Hymenoptera: Crabronidae).
The position of the emerging point has rarely been investigated as a factor possibly affecting the future nest settlement behaviour in Hymenoptera, in particular within nest aggregations. We studied the emergence and dispersion patterns of the digger wasp Stizus continuus. Individuals emerged daily in clumped patterns, possibly revealing a certain synchrony of emergence from the same nests, and protandry appeared both at seasonal and daily level. Differences between the number of females that nested relatively close or far from their emergence holes (EH) were either significant or not, depending on the year, and observed dispersal distances from the natal nests did not differ from those obt…
Predatory habits of the grasshopper-hunting waspStizus continuus(Hymenoptera: Crabronidae): diet preference, predator–prey size relationships and foraging capacity
In a coastal salt-marsh of Spain, the digger wasp Stizus continuus primarily hunted for grasshoppers of the genus Heteracris, revealing (at least in the period of the study and in this area) this wasp to be almost monophagous. In contrast, grasshoppers of the genus Acrotylus were ignored by the wasps in spite of their high abundance in the environment. We hypothesize that this bias occurred because Acrotylus is found more often on the soil and on grasses, while Heteracris is nearly only found on Sarcocornia bushes, which probably represent the habitat mostly exploited by the wasps for hunting. The greater variance in size of the prey collected by larger females produced weak wasp–prey size …
Host detection and rate of parasitism by Acroricnus seductor (Hymenoptera: Ichneumonidae), a natural enemy of mud-dauber wasps (Hymenoptera: Sphecidae)
Abstract The behavioural ecology of ichneumonid wasps that attack aculeate Hymenoptera is still largely unknown. Field observations and morphological analyses were devoted to investigate host detection and rate of parasitism by Acroricnus seductor (Scopoli), a natural enemy of the black and yellow mud dauber wasp Sceliphron caementarium (Drury). At the study site, about half of the host nests suffered parasitism by A. seductor. No significant difference was found between the rate of parasitism in sheltered (inside human building) and unsheltered (outside building) nests. Larger nests did not suffer a higher rate of parasitism, and larger brood cells were not more likely to be parasitized. …