C7p: Developing successful biological control programs in forest plantations

In view of future release for the control of the eucalypt pest Blastopsylla occidentalis, the parasitoid Psyllaephagus blastopsyllae was imported from South Africa into Brazil in 2015, where the specimens were kept in quarantine for preliminary bioecological studies. Within a few months, the specimens died and the establishment of a viable culture failed. While another introduction was planned, the parasitoid was found in eucalyptus plantations in Minas Gerais. This changed the focus of the project to monitor the population in the plantations in Minas Gerais and to search for the parasitoid in other areas in Brazil with eucalypt plantations. The monitoring of the parasitoid showed that the pest is associated with various eucalypt clones, especially those of Eucalyptus camaldulensis. The occurrence of the parasitoid was positively correlated (0.82) with the pest population but indifferent to the type of clone. The percentage of parasitism was higher between June and August, the dry season, coinciding with the population peak of the pest. Besides Minas Gerais, the parasitoid was also found in São Paulo and Mato Grosso do Sul. In a survey in SP in October 2018, the observed percentage of parasitism was around 9%. A similar survey in Três Lagoas, MS, in August, yielded a percentage of parasitization of about 11%. Our data represent a small sampling in terms of total eucalypt plantations in Brazil. For promoting biological control, we suggest to increase the number of areas to be surveyed for the occurrence of the parasitoid and to study its control potential.

Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae), is an exotic pest of great importance for Eucalyptus plantations. The use of the egg parasitoid Cleruchoides noackae (Hymenoptera: Mymaridae), is the most used control method. However, other techniques are studied, such as use of entomopathogenic fungi and chemical insecticides. The compatibility of chemical and biological control methods favors integrated pest management. The objective was to evaluate the action of mycoinsecticides and insecticides on the parasitoid C. noackae and its parasitism on T. peregrinus eggs. Two bioassays were performed: 1) cage surfaces (IOBC standard) were submitted to the application of Beauveria bassiana (Boveril) and Metarhizium anisopliae (Metarril), both with concentrations of 1 x 10⁸ conidia/g, Bifenthrin (Capture), with a concentration of 400 g/L, and control (water); after drying, 20 adults of the parasitoid were released per replicate (cage). 2) in this bioassay eggs of T. peregrinus were submitted to the same treatments; after drying 10 eggs of T. peregrinus treated by cage, and released a couple of C. noackae by replicate. Parasitism was allowed for 24 hours (T= 25±2º C; UR= 70±10% and photophase= 12h).  The statistical desing was completely randomized with four treatments and five replicates. Mortality, parasitism and viability were evaluated. B. bassiana was selective to parasitism and viability, and slightly harmful to adults of C. noackae; M. anisopliae was innocuous to adults and the viability of offspring, but it reduced parasitism; and bifenthrin was non-selective to C. noackae in all bioassays.

Tetrastichus howardi (Hymenoptera: Eulophidae) is a gregarious endoparasitoid and a facultative hyperparasitoid. This parasitoid has potential to use to control lepidopterous pests in Eucalyptus plantations in Brazil. The use of mycoinsecticides and insecticides in pest management may have deleterious effects on non-target organisms. The recommendation of selective insecticides has great appeal to the conservation of natural enemies and parasitoids. Therefore, the objective of the work was to evaluate the action of mycoinsecticides and insecticides used to Eucalyptus pests on the emergence of T. howardi. Pupae of Diatraea saccharalis were offered to T. howardi parasitoids, with parasitism allowed for 48 hours, after which they were individualized in glass tubes and maintained under controlled conditions (25±2º C; UR= 70±10% and 12h photophase). The statistical design was completely randomized with seven treatments and 10 replicates. When the pupae were close to emerging the treatments were prepared: Beauveria bassiana and Metarhizium anisopliae (both with concentrations of 1 x 10⁸ conidia/g), tiamethoxam, bifenthrin, imidacloprid and clorfenapyr (under higher recommended doses) and control (water). The pupae were immersed in the treatments for 10 seconds. After drying, they were transferred to polystyrene tubes until the parasitoids emerged. It was evaluated the number of parasitoids emerged and were retained in pupa. The insecticides were classified according to the International Organization for Biological Control (IOBC). None of the treated pupae affected the emergence of parasitoid adults, therefore, all products classified as innocuous. However, studies to verify the direct effect on the parasitoid still need to be done.

Eucalyptus red gum lerp psyllid, Glycaspis brimblecombei (Hemiptera: Aphalaridae) is one of the most important Eucalyptus exotic pests. Its first report in Brazil was in 2003, in the state of São Paulo, damaging Eucalyptus camaldulensis plantations. The parasitoid, Psyllaephagus bliteus (Hymenoptera: Encyrtidae), was reported together with the psyllid and a new introduction of parasitoids from Mexico was performed to improve the efficiency of biological control programs of this pest. Our objectives were to evaluate the genetic diversity of the psyllid and its parasitoid in Brazil using mitochondrial genes sequencing. Insects of both species were collected from different regions in Brazil. Thirty-four individuals of G. brimblecombei and twelve samples of Psyllaephagus spp were successful sequenced. A single COI gene haplotype was found in G. brimblecombei populations from Brazil and this is the same haplotype that occurs in Portugal samples, indicating one (or few) introduction events of G. brimblecombei in Brazil is originated from an invasive lineage distributed in other regions from the world. This fact suggests that the invasion routes of G. brimblecombei in the world are interconnected, which seems to be a standard for invasive Eucalyptus pests. Two distinct haplotypes, with a high genetic distance between them, were identified for the parasitoid. It confirms the presence of two parasitoid species in Brazil, one already identified, P. bliteus, and a second species of Psyllaephagus not morphologically identified. However, we can confirm that both parasitoid species collected in Brazil are exotic species originated from Australia.

The aim of this study was to evaluate the population dynamics of Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae), Glycaspis brimblecombei (Hemiptera: Aphalaridae) and its parasitoid Psyllaephagus bliteus (Hymenoptera: Encyrtidae) in three distinct regions of São Paulo State (Mogi Guaçu, São Simão, and Altinópolis) during 2014 to 2017. The pests and parasitoid monitoringwas correlated with meteorological data: maximum temperature (Tmax.), minimum temperature (Tmin.) and average (Tmed.); rainfall (P); daily solar radiation (R) and vapor pressure deficit (DPV). The insects monitoring was carried out with yellow stick traps (12.5 x 10 cm) monthly during for four years, totaling 275 sample sites. T. peregrinus population index declined over the years, differing from G. brimblecombei and P. bliteus, which ones increased. The correlation between T. peregrinus and meteorological data was positive with the considering Tmax., Tméd., R and DPV. Rainfall and Tmin. was negative for G. brimblecombei, but positively for Tmax., R and DPV. P. bliteus population had positive correlation for the population increasing and Tmax., R and DPV. These results were similar to field observations, demonstrating monitoring may be essential in decision making for pest control.

Key words: exotic pests, monitoring, Eucalyptus.

The bronze bug Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae), native of Australia, is one of the main Eucalyptus pest in Brazil. This pest can cause silvering, followed by bronzing and defoliation. The determination of predation rate of Atopozelus opsimus (Hemiptera: Reduviidae) on T. peregrinus is essential to improve biological control program of this pest. The objective was to evaluate the predation rate of T. peregrinus by A. opsimus, in different temperatures to promote the most efficient use of this predator. Ten adults of A. opsimus with different ages were individualized in Petri dishes containing cotton soaked in deionized distilled water. Ten adults and five T. peregrinus nymphs were offered for 24 hours, at 18, 24 and 30 ± 1°C (RH: 60 ± 10%; photophase: 12 h). The number of T. peregrinus preyed was recorded. The experiment had ten replications and data analyzed by ANOVA and compared by the Tukey test. The mean predation rate of adults and nymphs of T. peregrinus by A. opsimus at 18, 24 and 30ºC was 0.7, 2.5, 3.1 and 0.3, 0.7, 0.9, respectively. The number of insect (adults and nymphs) preyed at 24 e 30ºC did not differ significatively. The predator A. opsimus is a potential agent to control of T. peregrinus, with a tendency to increase predation as the temperature increases.

The blue gum chalcid wasp, Leptocybe invasa Fisher & La Salle, 2004 (Hymenoptera: Eulophidae) is a pest native from Australia that causes economical losses in Eucalyptus plantations. It was first detected in 2011 in Uruguay. Damage resulting from L. invasa galls can be particularly severe in Eucalyptus nurseries  and in young plantations. The use of biological control agents (BCA) and plant resistance have proven valuable tools in keeping L. invasa populations under control worldwide. To date, the bioecology and population dynamics of this pest in Uruguay is unknown. The objective of this work was to study the population fluctuation, distribution and management strategies for L. invasa in Uruguay. We conduct a survey among foresters. Four yellow sticky traps (YST) were distributed in an area of 0.5 ha of Eucalyptus spp. in Tacuarembó and replaced monthly from December 2015 to November 2018. Captures in YST were correlated with temperature and precipitation data. Some genotypes of Eucalyptus grandis, E. benthamii and E. grandis x E. camaldulensis hybrids recorded more damage by L. invasa. Currently, this species distributed mostly in the North and West parts of the country.  Captures in YST peaked on February, May and November and was negatively linked to accumulated precipitation. This study provides key data towards the implementation of biological control of L. invasa with Selitrichodes neseri (Hymenoptera: Eulophidae) which is currently ongoing in the country. 

The bronze bug is one of the main exotic pests occurs in Eucalyptus plantations in Brazil, affecting wood production. Monitoring is one of the most important motions for detection and also for pest control decision making in the field. This experiment had the objective of evaluating the effect of trap position on capture of adults and nymphs of Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae), . The study was carried out in October, 2018, in the municipality of Três Lagoas, MS, using yellow adhesive traps in three positions, 1) traps in the trunk, 2) traps between two trees in vertical position and 3) traps between two trees in  horizontal position. The traps were installed at 1.60 m, with the aid of strings, having a total of 30 replicates per treatment. After 30 days all traps were collected and sent to  laboratory  to proceed the insects counting. The average number of adult insects collected was 15 in the trunk, 36 in  horizontal and 6 in vertical, and for nymphs this number was seven in the trunk, 39 in horizontal and seven in vertical.  There was no significant difference among the traps positions (Scott-Knott test, p > 0.05%). More tests will be carried out in different regions of Brazil to confirm the best method of monitoring T. peregrinus.

Keywords: Bronze bug, Eucalypt, sampling

Ackowledgments: IPEF/PROTEF