Studies on the Biology ofHypogeococcus pungens(sensu stricto) (Hemiptera: Pseudococcidae) in Argentina to Aid the Identification of the Mealybug Pest of Cactaceae in Puerto Rico

Abstract

Hypogeococcus pungens Granara de Willink, sensu stricto, is a serious pest of cacti in Puerto Rico threating many Caribbean islands. A classical biological control program for H. pungens was initiated for Puerto Rico in 2010 with a survey for natural enemies of H. pungens in its native range of Argentina. Biological differences were observed between populations of H. pungens sampled on Amaranthaceae and Cactaceae. Molecular studies suggested that H. pungens populations from different host plant families are likely a complex of species. Our objective was to study the biology of H. pungens sensu stricto on specimens collected in the same locality and host plant as the holotype [Tucumán Province, Argentina; Alternanthera pungens Kunth (Amaranthaceae)]. We were interested in the reproductive biology of females, longevity and survival of adults, the effect of temperature on the development, and nymph performance (survival and development) on five Cactaceae species. We found that H. pungens s.s. showed marked biological differences from the populations collected on Cactaceae and exported to Australia for the biological control of the cactus Harrisia spp. The main differences were the presence of deuterotoky parthenogenesis and the fact that H. pungens did not attack Cactaceae in the laboratory. Our results provide biological evidence that H. pungens is a species complex. We propose that the population introduced to Australia is neither Hypogeococcus festerianus Lizer y Trelles nor H. pungens, but an undescribed species with three circuli, and that the Hypogeococcus pest of cacti in Puerto Rico is not H. pungens.

Untangling the Hypogeococcus pungens species complex (Hemiptera: Pseudococcidae) for Argentina, Australia, and Puerto Rico based on host plant associations and genetic evidence

“…pungens represented a unique species or a species complex, we used two types of species delimitation analyses: i) a multi-locus Bayesian approach [41] and ii) two single-locus approaches: Automatic Barcode Gap Discovery (ABGD) distance-based method [42] and multi-rate Poisson tree processes (mPTP) ML tree-based method [43]. In the multi-locus Bayesian analysis, we considered the well-supported clades identified in the phylogenetic analyses, combined with the results of experimental studies showing potential postzygotic reproductive barriers between mealybugs collected on Amaranthaceae and Cactaceae from Argentina, and the incapability of specimens collected on Cactaceae to develop and survive on Amaranthaceae and vice versa [26]. We employed the set of species trees estimated with BEAST v1.7.5 [44], including H .…”

“…The absence of viable offspring in the crosses was assumed as reproductive incompatibility between mealybugs from different hosts. Since females of the Amaranthaceae clade can reproduce by parthenogenesis [26], we used offspring sex ratio as an indicator of parthenogenetic reproduction. A Chi-square ( χ 2 ) test was used to determine if the sex ratio deviated from 1:1 in the offspring (similar number of males and females).…”

“…pungens sensu stricto ) and on Cactaceae, giving strong support to the idea that H . pungens is, in fact, a species complex [26]. Even though the progeny of gravid H .…”

“…Even though the progeny of gravid H . pungens collected on Amaranthaceae in nature was able to complete development on cactus hosts, it could not produce a viable second generation on Cactaceae [26]. Moreover, differences in fecundity, female body length, mode of reproduction, rate of development, and host range were also observed between H .…”

“…In this sense, it is worth noting that H . pungens sensu stricto can reproduce by both sexual reproduction and parthenogenesis by deuterotoky, whereas cactus breeding bugs only reproduce sexually [26].…”