Effects of Aspergillus niger contamination on biological fitness of Lygus hesperus (Heteroptera: miridae)

The effect of Aspergillus niger (USDA, ARS Robert T. Gast Rearing Laboratory, Mississippi State, MS isolate) contaminated artificial diet on Lygus hesperus Knight (Heteroptera: Miridae) is described. A standard number of A. niger spores was inoculated into an artificial diet used to rear L. hesperus, and the effect on biological fitness of the insect was measured. Biological fitness was defined as total number of surviving adults, mean biomass (dry weight) accumulated per cage over the total test period, egg production, time to adult emergence, and time to the beginning of egg laying. These measurements were all significantly different for insects reared on the inoculated diet from those reared on the control diet. The insects reared on the diet inoculated with A. niger showed a high mortality of nymphs, a decrease in mean biomass, delayed development time, and a decrease in egg production. This study demonstrates the devastating effect A. niger diet contamination can have on a laboratory colony of L. hesperus and emphasizes the need for constant vigilance and adherence to strict sanitation methods in an insect rearing facility.