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Buenos Aires, Argentina

Wheeler G.S.,U.S. Department of Agriculture | Silverson N.,225 College Avenue | Dyer K.,U.S. Department of Agriculture | Kay F.M.,Fuedei
Florida Entomologist

Brazilian peppertree, Schinus terebinthifolia Raddi (Sapindales: Anacardiaceae), is one of the most invasive weeds in Florida and Hawaii. In the invaded range, this fast-growing weed from South America poses a threat to agriculture and cattle production and decreases the biodiveristy of natural areas. The thrips Pseudophilothrips ichini (Hood) (Thysanoptera: Phlaeothripidae) is being studied as a potential agent for the biological control of this weed. The laboratory life history and native range of P. ichini in Brazil were examined over 10 yr. The thrips life history includes 2 feeding larval stages that occur on the plant and 3 non-feeding pupal stages that occur in the soil. Development time, body length, and distinct features of each life stage are described. The larva-to-adult development required 20 d, and adults lived for an average of 50 d. Pseudophilothrips ichini had a wide latitudinal range in Brazil along the eastern coast from Bahia (11.4°S) south to Santa Catarina State (27.1°S). It was collected from sea level to 1,329 m elevation. Observations in Brazil indicated that this thrips occurs year round and may occasionally reach high densities (>20 thrips/leaf). Despite searches in its native range of related plants, the thrips was found only on Brazilian peppertree. Considering the short generation time, broad environmental tolerance, host specificity, and damage caused to the host if this thrips is released for biological control, it will contribute significantly to the management of Brazilian peppertree. Source

Varone L.,Fuedei | Logarzo G.A.,Fuedei | Briano J.A.,Fuedei | Hight S.D.,U.S. Department of Agriculture | Carpenter J.E.,U.S. Department of Agriculture
Biological Invasions

A central aspect in biology and ecology is to determine the combination of factors that influence the distribution of species. In the case of herbivorous insects, the distribution of herbivorous species is necessarily associated with their host plants, a pattern often referred to as “host use”. Novel interactions that arise during a biological invasion can have important effects on the dynamics of that invasion, especially if it is driven by only a subset of the genetic diversity of the invading species. This is the case of the wellknown South American cactus moth, Cactoblastis cactorum, a successfully used biological control agent of non-native Opuntia cacti in Australia and South Africa, but now threatening unique cactus diversity and agriculture in North America. We studied the patterns of host plant usage by and host plant availability for C. cactorum under field conditions in Argentina, covering the geographical range of the four C. cactorum phylogroups and the recently documented southern distribution. We also assessed female preference and larval performance under laboratory conditions. Cactoblastis cactorum showed a geographical pattern of host use in its native range that was related to host availability. Laboratory assays of female preference showed some degree of preference to oviposit on O. ficus-indica, O. leucotricha and O. quimilo, but it was not positively correlated with the performance of larvae. These findings contribute to the further comprehension of the host use dynamics of C. cactorum in the insects’ native range, and could provide useful information for assessing the risk and future spread of this insect in North America. © 2014, Springer International Publishing Switzerland. Source

Gonalons C.M.,Grupo de Estudio de Insectos Sociales | Varone L.,Fuedei | Logarzo G.,Fuedei | Guala M.,Fuedei | And 3 more authors.
Florida Entomologist

The cactus moth, Cactoblastis cactorum (Berg) (Lepidoptera: Pyralidae), is a pest that threatens native Opuntia spp. in North America. Control tactics developed and implemented against this invasive pest successfully eradicated the moth in Mexico and on barrier islands in the United States. However, with the cancellation of the regional management program in the United States, no control tactics are being implemented to mitigate the expansion of the moth's geographical range. Hence, an integrated approach including biological control is proposed to regulate the population of C. cactorum in North America. Field surveys of the recently described parasitoid, Apanteles opuntiarum Martínez & Berta, were carried out within the C. cactorum native range in Argentina, and laboratory studies were conducted to develop a parasitoid rearing protocol. Apanteles opuntiarum was the most common parasitoid of C. cactorum and their field distributions were similar. In the laboratory, the parasitoid's reproductive success was maximized when one or two female wasps were exposed to 30 host larvae within a 500 ml container. Laboratory reared females were less successful at parasitizing hosts than field collected females. In spite of the success achieved with laboratory rearing, male bias was observed throughout the experiments. Because this bias might be related to the presence of the reproductive parasite Wolbachia, both laboratory colony and field collected individuals were screened and Wolbachia was detected. This study provides useful field and laboratory information on (1) laboratory rearing techniques for A. opuntiarum; (2) developing host specificity test protocols for studies under quarantine conditions; and (3) selecting parasitoid populations that best match the climatic conditions present in the C. cactorum invaded areas of North America. © Florida Entomologist 2014. Source

Varone L.,Fuedei | Acosta M.M.,Instituto Nacional Of Medicina Tropical | Logarzo G.A.,Fuedei | Briano J.A.,Fuedei | And 2 more authors.
Florida Entomologist

The cactus moth, Cactoblastis cactorum (Berg), is native to South America. Since its unintentional arrival to the United States in 1989 and to Mexican islands in 2006, it has become a serious threat to the diversity of both wild and cultivated species of Opuntia Mill, in North America. The native ecological host range of C. cactorum has not been directly ascertained and host acceptance is unclear. Taxonomic nomenclature of Opuntia spp. has been confusing, contradictory, and rapidly changing, leading to inaccurate conclusions about host plant use by C. cactorum in its native South American range. This study was conducted to better understand the biology and ecology of C. cactorum in Argentina by evaluating, under laboratory conditions, the insects' performance (survivorship, development time, potential fecundity) on 8 Opuntia spp. occurring in Argentina. Feeding trials were conducted on 5 Opuntia spp. native to Argentina and 3 Opuntia spp. native to Mexico. Cactoblastis cactorum larvae failed to feed on 2 native Opuntia spp., and had their greatest performance on the North American O. ficus-indica (L). Mill, and O. robusta H. L. Wendl. ex Pfeiff., and the South American O. arechavaletae Speg. Because the insects for the experiments were originally collected on O. ficus-indica, a reciprocal cross feeding experiment with insects collected on O. megapotamica Arechav. was also conducted to test for a potential host plant-mediated local adaptation effect. Some evidence for host plant adaptation was detected in populations collected on the South American host, O. megapotamica. Local adaptation, as documented here, could have consequences for the invasion process of C. cactorum in North America. Source

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