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Hypogeococcus pungens, a mealybug native of southern South America, is devastating native cacti in Puerto Rico and threatening cactus diversity in the Caribbean, and potentially in Central and North America. The taxonomic status of H. pungens is controversial since it has been reported feeding not only on Cactaceae but also on other plant families throughout its distribution range. However, in Australia, where the species had been exported from Argentina to control weedy American cacti, it was never found on host plants other than Cactaceae. These conflicting pieces of evidence not only cast doubt on the species identity that invaded Puerto Rico, but also have a negative impact on the search for natural enemies to be used in biological control programs against this pest. Here we present reproductive incompatibility and phylogenetic evidences that give support to the hypothesis that H. pungens is a species complex in which divergence appears to be driven by the host plants. The nuclear EF1α and 18S and the mitochondrial COI genes were used as markers to evaluate the phylogenetic relationships among H. pungens populations collected in Argentina, Australia and Puerto Rico feeding on Cactaceae and/or Amaranthaceae. Additionally, we conducted reciprocal crosses between mealybugs from both hosts. Species delimitation analysis revealed two well-supported putative species within H. pungens, one including mealybugs feeding on Amaranthaceae (H. pungens sensu stricto), and a new undescribed species using Cactaceae as hosts. Additionally, we found asymmetric reproductive incompatibility between these putative species suggesting recent reproductive isolation. The Bayesian species delimitation also suggested that the Australian mealybug population may derive from another undescribed species. Overall, the patterns of genetic differentiation may be interpreted as the result of recent speciation events prompted by host plant shifts. Finally, the finding of a single haplotype in the Puerto Rico population suggests only one invasive event. We still need to identify the geographical origin of the pest in order to enable the use of biological control to reduce the threat to cacti diversity in the Caribbean.

Over the last decade, India has witnessed unintentional entry of five species of invasive species of mealybugs, perhaps due to globalization and global trade, leading to negative economic and ecological consequences. Through this paper, the first occurrence of the destructive mealybug Hypogeococcus pungens Granara de Willink is reported in India infesting two nursery plant species of Alternanthera and a wild Portulaca sp. As early detection, identification, and rapid reporting are essential for the successful management of destructive species, the field and diagnostic characters of slide mounted H. pungens were described in details with help of field and microphotographic images. The identity of the mealybug was also confirmed through molecular studies by sequencing mitochondrial cytochrome c oxidase I (COX I) and 28 S ribosomal gene regions. Information on host range, natural enemies, and distribution of the mealybug is provided. Management options in the event of an outbreak are discussed briefly. This new arrival warrants special attention in India as it is a potentially damaging plant pest in landscapes, and vertical gardening practiced in offices, commercial complexes, and luxury apartments.

The Harrisia cactus mealybug (HCM), Hypogeococcus sp. (Hemiptera: Pseudococcidae), is devastating native cacti in Puerto Rico and threatens cacti throughout the Caribbean, Mexico, Central and North America. In South America, its native area, various natural enemies keep HCM under control. Two South American parasitoids, Anagyrus cachamai Triapitsyn, Logarzo & Aguirre and A. lapachosus Triapitsyn, Aguirre & Logarzo (Hymenoptera: Encyrtidae), were selected as potential biological control agents. Rearing protocol to conduct mass production, specificity studies and several aspects of the biology of these species were studied under laboratory conditions in Argentina. Anagyrus cachamai and A. lapachosus successfully attacked early instars of Hypogeococcus sp., have a balanced sex ratio, exhibited a development time synchronized with that of the host, and presented differences in their reproductive biology and development time. All these characteristics make these parasitoids promising candidates for introduction as biological control agents against the HCM pest in Puerto Rico.

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. Hypogeococcus pungens is a species complex native to South America. Some of its members are cactophilic, and one of them has been reported as a pest threatening cactus diversity in the Caribbean and North America. Using a combination of genome‐wide SNPs and mtDNA, we found that the complex comprises at least five different species, each strongly associated with specific host plants. Our study also shows that the Puerto Rican cactus pest derives from southeastern Brazilian mealybugs. These results will help to design reliable strategies for biological control using natural enemies of the pest from its native range.

Tropical dry forests are threatened by invasive species. In Puerto Rican dry forests, two of these invasive species are the Harrisia cactus mealybug Hypogeococcus sp. (HCM), a member of the H. pungens-complex (Hemiptera: Pseudococcidae), and the liana Jasminum fluminense (Oleaceae). Here, we aim to determine the effects of HCM and J. fluminense on the flower and fruit production of Pilosocereus royenii and on the short-term mortality of the native columnar (P. royenii and Stenocereus fimbriatus), semi-epiphytic (Selenicereus trigonus and Leptocereus quadricostatus), and globular (Melocactus intortus) cacti of Puerto Rico. To assess HCM infestation, we created a numerical infestation index with six categories, ranging from uninfested and healthy, to heavily infested cacti (0–5) based on the number and size of tumors. Flower and fruit production of P. royenii was observed at three sites, while the survival of all cactus species was observed at twelve sites for 2 years. Mortality of all cacti species increased with severe HCM infestation. Mortality was highest in M. intortus, and lowest in St. fimbriatus and L. quadricostatus. Mortality of P. royenii was negatively correlated to precipitation, and positively to HCM and liana infestation. Individuals of P. royenii that were heavily infested with both HCM and lianas were more likely to die than healthy cacti only infested with lianas, while P. royenii flower and fruit production was negatively correlated only with HCM infestation. This suggests that J. fluminense becomes a better competitor during dry periods when P. royenii is infested with HCM. While other members of the H. pungens-complex are considered biocontrol agents in places where columnar cacti are not native, this study demonstrates that HCM species found in Puerto Rican dry forests could potentially decrease the biodiversity of these cacti in their native habitats.

Parasitoids, both primary and secondary (hyperparasitoids), of Hypogeococcus spp. mealybugs (Hemiptera: Pseudococcidae) are reviewed to report results of the surveys in the New World conducted during 2009 to 2017 for prospective natural enemies of the Harrisia cactus mealybug, Hypogeococcus sp., which is devastating native cacti in Puerto Rico and threatening cacti in the adjacent Caribbean islands. Five species of Encyrtidae (Hymenoptera: Chalcidoidea) are recorded as primary parasitoids of Hypogeococcus spp., including the newly described Leptomastidea hypogeococci Triapitsyn sp. n., which is the only species of the genus Leptomastidea García Mercet in the New World where the clava of the female antenna is contrastingly white. Genetic analysis of the individuals of L. hypogeococci from Argentina, Brazil, and Puerto Rico (USA) corroborates the morphological data that the same species occurs in South America, the Caribbean islands, and Florida (USA). A key to the New World species of Leptomastidea is given and taxonomic notes are provided on its other known species in the Neotropical region. Leptomastidea antillicola Dozier, syn. n. from Puerto Rico is synonymized under L. abnormis (Girault). Based on the presented molecular data, Anagyrus ciomperliki Triapitsyn syn. n. (Encyrtidae), originally described from Puerto Rico, is synonymized under A. quilmes Triapitsyn, Logarzo & Aguirre, where the known distributional range is expanded to also include Brazil. Anagyrus cachamai Triapitsyn, Logarzo & Aguirre, A. lapachosus Triapitsyn, Aguirre & Logarzo, and A. quilmes are newly recorded from Paraguay. The previously unknown male of Prochiloneurus argentinensis (De Santis) (Encyrtidae) is described from Misiones Province of Argentina, and that of P. narendrani Noyes & Triapitsyn is described from Mona Island, Puerto Rico. So far, Anagyrus cachamai and A. lapachosus are considered to be the primary target species for introduction from Argentina and Paraguay into Puerto Rico for the biological control of Harrisia cactus mealybug. The holotype of Anagyrus tanystis De Santis from Buenos Aires, Argentina, host associations are unknown, and is illustrated to facilitate its recognition from other congeneric species.

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.

Five mealybug (Hemiptera: Pseudococcidae) species were identified as new records for Spain: Phenacoccus madeirensis (Green), Phenacoccus solani Ferris , Dysmicoccus boninsis (Kuwana), Hypogeococcus pungens Granara de Willink and Ferrisia malvastra (McDaniel).