Species complex diversification by host plant use in an herbivorous
insect: The source of Puerto Rican cactus mealybug pest and implications
for biological control
Abstract
Cryptic taxa have often been observed in the form of host‐associated
species that diverged as the result of adaptation to alternate host
plants. Untangling cryptic diversity in species complexes that encompass
invasive species is a mandatory task for pest management. Moreover,
investigating the evolutionary history of a species complex may help to
understand the drivers of their diversification. The mealybug
Hypogeococcus pungens was believed to be a polyphagous species from
South America and has been reported as a pest devastating native cacti
in Puerto Rico, also threatening cactus diversity in the Caribbean and
North America. There is neither certainty about the identity of the
pest, nor the source population from South America. Recent studies
pointed to substantial genetic differentiation among local populations,
suggesting that H. pungens is a species complex. In this study, we used
a combination of genome-wide SNPs and mtDNA variation to investigate
species diversity within H. pungens sensu lato to establish host plant
ranges of each one of the putative members of the complex, to evaluate
whether the pattern of host plant association drove diversification in
the species complex, and to determine the source population of the
Puerto Rican cactus pest. Our results suggested that H. pungens
comprises at least five different species, each one strongly associated
with specific host plants. We also established that the Puerto Rican
cactus pest derives from southeastern Brazilian mealybugs. This is an
important achievement because it will help to design reliable strategies
for biological control using natural enemies of the pest from its native
range.