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Food Limitation of Reproduction and Survival For Populations of Brachinus (Coleoptera: Carabidae)
Author(s) -
Juliano Steven A.
Publication year - 1986
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1939826
Subject(s) - reproduction , biology , facultative , ecology , competition (biology) , food supply , zoology , larva , food intake , agricultural science , endocrinology
In order to determine whether natural levels of food for adult bombardier beetles (Brachinus) were low enough to lead to reduced reproduction and survival, laboratory and field experiments were conducted in southeastern Arizona, USA. In the laboratory, feeding affected reproduction over a period of months, but had no detectable effect on short—term egg production. Females did not reproduce until the 2nd yr of adulthood, and increased feeding did not lead to facultative early reproduction. Survival was reduced by moderately low food (tenerals) or very low food (nontenerals). A condition factor (CF) based on the relationship of body mass to elytron length provided a measure of feeding rate that responded to changes in food availability in as little as 16 d. CF differed among field sites, with a permanent pond yielding the best fed Brachinus and semipermanent and temporary ponds yielding the most severely underfed individuals. Experimental supplementation of food in the field significantly raised the CF of teneral and nonteneral B. lateralis relative to controls. Trends for nonteneral B. mexicanus were consistent with increased feeding rate, but were not significant. Food for adults appears to be important for reproduction, and is in short supply at many sites. Competition for food is possible, and may help explain spatial differences in assemblage composition.