Assessing fertility between haplotypes of the psyllid Bactericera cockerelli

Potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae) is economically detrimental to potato (Solanum tuberosum L.) and other crops in the Solanaceae. The psyllid causes direct feeding damage to hosts, but also vectors the recently discovered bacterium “Candidatus Liberibacter solanacearum”, the putative causal agent of zebra chip disease of potato. Potato psyllid is distributed in the United States, Mexico, Central America, and New Zealand. Four distinct genetic haplotypes of the potato psyllid, referred to as ‘Central’, ‘Western’, ‘Southwestern’, and ‘Northwestern’, have been described based upon variation in the mitochondrial CO1 gene. Little is known about the biological differences between these haplotypes, including differences in inter-haplotype breeding/fertility. The objective of this study was to determine whether the three most widespread haplotypes (Central, Western, and Northwestern) are interfertile. Our results indicated that all females from every cross contained spermatophores, indicating that females in all crosses had mated. However, eggs deposited by Northwestern females that had been mated by Central or Western males all failed to hatch.  Eggs deposited by the females from the remaining seven crosses, exhibited high rates of egg fertility (79-93% hatch).