Morphological features of the larvae of spider crab <Emphasis Type="Italic">Pugettia quadridens</Emphasis> (Decapoda: Majidae) from the Northwestern Sea of Japan

The entire cycle of larval development of the spider crab Pugettia quadridens (de Haan, 1850) (Decapoda: Majidae), widespread in Peter the Great Bay (Sea of Japan) is studied under the laboratory conditions. The development cycle of this species comprises prezoea, zoea I, zoea II, and megalopa. At a temperature of 18–20° C larval development took from 11 to 15 days. Zoea II is described in detail for the first time. Many morphological characters are found distinguishing zoea and megalopa of P. Quadridens in Russian waters from the larvae of this species in Japanese and Korean waters. Some characters of larvae are similar in P. Quadridens and the related species of the genus Pugettia. The larvae of P. Quadridens occur in the plankton of Vostok Bay from late June to late October with a density up to 5 ind/m³ at a surface water temperature of 13–21°C. They are easily distinguished from the other brachyuran larvae of this region by the absence of lateral spines on the carapace.Original Russian Text Copyright © 2004 by Biologiya Morya, Kornienko, Korn.     

Eighteen trinucleotide microsatellite loci for the solitary vespid wasp Monobia quadridens

We identified 18 polymorphic, trinucleotide microsatellite loci for the solitary vespid wasp Monobia quadridens. These markers are to be used for parentage assessment and for studying population structure and inbreeding. Forty-eight diploid females from Southwest Michigan, USA were screened for allelic variation at each locus. Observed heterozygosities ranged from 0.50 to 0.88. The primers were also tested on two other solitary vespid wasps Ancistrocerus adiabatus and Ancistrocerus antilope.     

Why do larvae of Utetheisa ornatrix penetrate and feed in pods of Crotalaria species? Larval performance vs. chemical and physical constraints

Larvae of Utetheisa ornatrix (L.)(Lepidoptera: Arctiidae) are found mainly inside unripe pods of several alkaloid‐bearing Crotalaria (Fabaceae) species. Although eggs are laid on the leaves, the larvae are usually found feeding on unripe seeds in the pods. In this work, we investigated the selective pressures that could explain why U. ornatrix larvae feed primarily on unripe pods with seeds and not on leaves. Our results showed that larval survivorship in the laboratory was unaffected by feeding on leaves or unripe seeds, and that larval development up to the pupal stage was better in larvae that fed on unripe seeds, although perforating unripe pods to reach seeds was costly in terms of survivorship. Females were also heavier when fed on unripe seeds, but there was no significant difference in the fecundity of females fed either of the two diets. Feeding on unripe seeds in pods had other benefits for U. ornatrix, including a lower predation rate for larvae that fed inside compared to larvae that fed outside the pods. Similarly, adults derived from larvae that fed on unripe seeds were preyed upon less frequently by the orb‐weaving spider Nephila clavipes than were adults that fed on leaves. The latter benefit may be closely related to the high concentration of pyrrolizidine alkaloids in unripe seeds, which is about five times more than in leaves. These alkaloids are sequestered by the larvae and transferred to adults, which then become chemically protected. However, this chemical defence does not protect the larvae against ants such as Ectatomma quadridens and Camponotus crassus. Pods with unripe seeds that confer physical protection to larvae and pyrrolizidine alkaloids that confer chemical protection to adults limit the use of leaves by U. ornatrix larvae.