Nesting Biology, Sexual Dimorphism, and Populational Morphometric Variation in Podium denticulatum F. Smith, 1856 (Hymenoptera: Sphecidae)

Mariana Marchi Santoni,Luci Shibata,Vinicius De Oliveira Silva,Marco Antonio Del Lama

doi:10.13102/sociobiology.v67i4.5785

Abstract

Podium denticulatum occurs from Mexico to southern Brazil, including northeastern Argentina. Females use pre-existing cavities to build nests, consisting of cells separated by walls of mud and resin and massively provisioned with paralyzed cockroaches. Trap nests were disposed in three localities in the state of São Paulo, Brazil (Araras, São Carlos, Rifaina), resulting in the collection of 201 nests from December/2003 to June/2007. The founding nests were brought to the laboratory, opened and the pupae transferred to identified vials until the emergence of the adults, when they were then weighed, sexed and stored at -20ºC. The nesting activity was seasonal, with a higher number of nests in the warm and rainy season of the year. The number of constructed cells ranged from one to nine per nest. The emergence rate of adults in the 716 brood cells was 74%, with homogeneous distribution of mortality by egg, larva and pupa stages. This mortality was partly due to parasitism observed in 39% of nests, predominantly by Melittobia sp. and rarely by Diptera (Tachinidae). A 1:1 sex ratio was observed among the newly emerged adults of each locality analyzed. Strong sexual dimorphism was characterized by linear measurements of wings and body mass, with females and males showing a mass between 27-116 mg and 14-70 mg, respectively. The geometric morphometry confirmed this dimorphism and revealed significant variation of wing size and shape among individuals of the analyzed populations, a result that deserves subsequent studies to point out the factors that account for this differentiation.

Highlights

Studies on nesting biology in wasp and bee species using preexisting cavities have enhanced our understanding of behavior, life cycle, trophic niche and sex ratio issues, among others, contributing to the enlightenment of the life histories, ecology and evolution of these insects (Michener, 2007; Costa & Gonçalves, 2019)
The data obtained in this work generally confirm previous data on nesting biology in P. denticulatum
New information was obtained: i) nesting by females in longer trap-nests, which may have resulted in the larger number of cells per nest observed here; ii) longer periods of diapause; iii) the first description of nests founded by a P. denticulatum female that was used by a second species; iv) the possible occurrence of more than six generations per year

Summary

Introduction

Studies on nesting biology in wasp and bee species using preexisting cavities have enhanced our understanding of behavior, life cycle, trophic niche and sex ratio issues, among others, contributing to the enlightenment of the life histories, ecology and evolution of these insects (Michener, 2007; Costa & Gonçalves, 2019). (fumigatum group), occurs in a large area of the Neotropical region, from Mexico to southern Brazil and northeastern Argentina, whose females show the nesting behavior in preexisting cavities (Bohart & Menke, 1976; Krombein, 1958; Genaro, 1994; Morato & Campos, 2000; Morato, 2001; Gazola, 2003). Information on the nesting biology of P. denticulatum has already been reported (Camillo et al, 1996; Assis & Camillo, 1997; Camillo, 2001; Gazola, 2003), as well

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