A colony of the Pacific spider mite, Tetranychus pacificus McGregor, collected from California almond orchards during 1984 was found to be resistant (R) to propargite. This propargite-resistant colony was selected 25 times with propargite for 25 mo to ensure a homogeneous colony for mode of inheritance tests. Results of these tests were generally consistent with a model in which propargite resistance in this colony is primarily determined by a major semirecessive gene. Lines for the reciprocal F1, females (RS, SR) were not different, and dominance (D) was estimated to be -0.356 and -0.315, suggesting there were no maternal effects. Greenhouse populations held for 5 mo without selection with propargite retained their original resistance levels, as indicated by the percentage of survival of colonies initiated from RR (resistant), SR, and RS females and complete concentration-mortality lines conducted at the end of the experiment. Negative fitness did not appear to be associated with the resistance allele(s) under these conditions.
Document Type: Research Article
Publication date: February 1, 1989
More about this publication?
Entomological Society of America journals will no longer be available via ingentaconnect from February, 1, 2015. Please contact the publisher at firstname.lastname@example.org (USA) or email@example.com (UK and rest of world) for information on how to continue access to these titles.