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United States Department of Agriculture

Agricultural Research Service

Research Project: Latin American Biological Control of Weeds and Insects
2013 Annual Report

1a.Objectives (from AD-416):
The objective of this SCA is to discover, develop, evaluate, and ship biological control agents of invasive species. The invasive species of concern threaten agriculture and natural environments anywhere in the world, but the emphasis of the agreement will be on those invasive species that either originated in Latin America or that threaten Latin America. Discovery includes initial discovery of potential biological control agents (arthropods, nematodes, and microorganisms) and definition of their taxonomy sufficient for subsequent research, development, and regulation. Development includes refinement of methods for monitoring, rearing, and otherwise necessary methods for manipulation of the species. Evaluation of the biological control agent makes estimates of its efficacy against the target invasive species and determines specificity (i.e., avoids damage to non-target organisms). Basic information developed on systematics, behavior, bionomics, physiology, and other aspects of the biology of target and biological control organisms will be considered relevant to the overall effort.

1b.Approach (from AD-416):
Staff will travel to sites of native origin of invasive species, collect potential biological control agents, and perform other elements of the objectives either at their central facility or at collaborating institutions. Results of biological and other studies will be published in peer reviewed journals to the maximum extent possible. Project plans will be written and reviewed according to the procedures for an ARS laboratory. Reporting will include an annual report written in narrative style to complete requirements for the SCA. In addition, FUEDEI will provide the written materials for an ARS SF-421 annual report including SF-115s of publications and talks.

3.Progress Report:

(1) Biocontrol agents of Parkinsonia (Parkinsonia aculeata). Parkinsonia is used in Australia as ornamental and shade tree; it forms thorny, impenetrable thickets in drainage lines, depressions, and wetlands. Two insects from the Sonoran Desert were released since 1989 and one from Argentina in 1995. Additional agents are needed.

Collection of Eueupithecia species: One field trip was made along P. aculeata native range. Sixteen sites were surveyed and 741 Eueupithecia larvae were collected by beating foliage of P. aculeata. Collected material was held in plastic containers during the trip, provided with fresh leaves when necessary and transported to FuEDEI for subsequent emergence of adults.

Laboratory rearing: Rearing was carried out in controlled environment chambers (25±2°C: 60-80% RH; 16:8 L:D). Larvae were placed in 3-liter plastic containers with perforated lids and moist tissue paper and fed bouquets of freshly excised leaves with their petioles inserted in small recipients filled with water. Newly emerged adults (F1) from the same collection site were kept together to allow mating inside 3-litre plastic jars with moist tissue paper containing bouquets of excised fresh leaves of P. aculeata. After 2-3 days, females were separated in order to rear isofemale lines and breed pure colonies of Eueupithecia species. When dead, males and females were dissected to investigate genitalia morphology and confirm species identification.

Genitalia dissection and identification: The genitalia and abdomen were placed in a potassium hydroxide solution and kept at room temperature for 24 h. Following maceration, all genitalia preparations, abdomens and structural preparations were preserved temporarily in 96° ethanol, which allowed for their examination from various perspectives. The preparation of various structures was carried out using an Olympus SZ61 stereo microscope (maximum magnification: 45X). Dissections of the adults (98) emerged from the samples showed that specimens found corresponded to both Eueupithecia species.

Survey of plant use: One site in the province of Formosa with a population of P. aculeata and the co-occurring legumes Acacia aroma, Geoffroea decorticans and Prosopis ruscifolia was sampled for the presence of insects by beating foliage. Immature insects were held in plastic containers and provided fresh leaves until the emergence of adults. A total of 62 larvae of Eueupithecia sp. 2 were collected by beating on P. aculeata. No Eueupithecia sp. 2. larvae were collected on any of the other surveyed legume species.

(2) Biological control of the Harrisia cactus mealybug (Hypogeococcus pungens) in Puerto Rico. The mealybug is a severe pest of cacti. In its South American native land it also affects plants of other families. Current distribution in the Caribbean includes Florida, Puerto Rico and Barbados. Cacti are important members of the dry forests in Puerto Rico with native, endemic, and endangered species. It also presents negative impact to agriculture and will spread to offshore islands (Mona, Desecheo, Vieques and Culebra) which harbor wild populations of endangered cacti. At present, it has also been detected in California.

Taxonomic identification: So far, taxonomical identification indicates that the 3 haplotypes in Argentina would correspond to H. pungens, H. festerianus and Hypogeococcus sp. close to festerianus, and that the mealybug present in Puerto Rico might be a different species. At present, work is being done with two different protocols to make observations with scanning electron microscopy to clarify the position of these groups.

Biological identification: In Argentina 2 out of 3 clades present were abundant (Clade Amaranthaceae-Argentina, and Clade Cactaceae-Argentina). These populations were biologically characterized and compared. It was observed that members of clades Amaranthaceae-Argentina and Cactaceae-Argentina differed in their fecundity, reproductive period, time and rate of development, and type of reproduction; females of clade Amaranthaceae-Argentina showed facultative parthenogenetic reproduction, while females of clade Cactaceae-Argentina did not. Although these differences could have been the consequence of the host plant quality, it was observed that nymphs of any of the two clades did not develop in the host plant of the other clade.

Reproductive compatibility: To determine if reproductive compatibility occurs between the members of both clades, we conducted reciprocal crosses and their respective controls. Given that females of clade Amaranthaceae-Argentina showed parthenogenetic reproduction, we incorporated sperm presence in the spermathecae of females as a new response variable to confirm the copula. Preliminary cross-mating results confirmed that members of both clades do not hybridize.

Parasitoids of HCM: (a) Encyrtids. Preliminary identification of Gyranusoidea pseudococci, Anagyrus sp., and Apoanagyrus montivagus will be confirmed comparing the type materials at Museo de La Plata and Museo Rivadavia, Argentina; (b)Signiphorids. They were confirmed to be hyper parasitoids of the Encyrtids.

Last Modified: 4/19/2014
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