Pollen analysis of Agathirsia wasps

Abstract

Parasitic wasps are one of the most abundant natural enemies of insect pests and the most ecologically understudied. Agathirsia is a genus of solitary, parasitic wasps, restricted to arid regions of the south-western United States of America and Mexico. They often parasitise the larvae of lepidopteran (butterflies and moths) crop pests. Pollen analyses were conducted on 127 specimens of 19 Agathirsia species to determine possible food sources and plant taxa important to these beneficial insects. Pollen was examined with both light microscopy (LM) and scanning electron microscopy (SEM). Pollen was removed from the head more than any other insect part (96% of the time). In the LM analyses, nearly 1700 pollen grains were recorded and assigned to 117 pollen types, 49% of which were Asteraceae. For the SEM analyses, pollen was identified but not counted. Eighty-eight pollen types were identified, of which 48% were Asteraceae. Pollen from 36 families, 65 genera and nine species were identified. Asteraceae pollen was classified into more genera than any other plant family. Common taxa included Ambrosia, Artemisia and Baccharis. The large diversity and high number of Asteraceae indicates that these plants can help sustain Agathirsia populations near crop fields, and ultimately reduce the amount of applied pesticides and save farmers time and money.