Citrus greening or huanglongbing (HLB) is the main threat to the European citrus industry since one of its vectors, the African citrus psyllid, Trioza erytreae , has recently become established in mainland Europe. In this context, classical biological control programmes should be implemented to reduce the spread of the psyllid. The aims of this study were to: i) disentangle the parasitoid complex of T . erytreae combining morphological and molecular characterization; and ii) to study the biology of its main parasitoids in its area of origin in South Africa for their future importation into Europe. The main citrus producing areas of South Africa were surveyed during 2017. In contrast to previous studies, the parasitoid complex of T . erytreae included three species of primary parasitoids: Tamarixia dryi , Psyllaephagus pulvinatus and another parasitoid of the genus Tamarixia . Molecular analysis showed that it is a new species closely related to T . dryi . Tamarixia dryi was the most abundant parasitoid but its relative abundance varied among sampling sites. The sex ratio (males/females) of T . dryi and Tamarixia sp. decreased with T . erytreae size and became female biased when psyllid nymphs were larger than 0.6 and 1.2 mm 2 , respectively. These parasitoids were attacked by three species of hyperparasitoids, Aphidencyrtus cassatus , Marietta javensis and a species of the genus Aphanogmus . Aphidencyrtus cassatus , the most abundant hyperparasitoid, tended to emerge from large nymphs, and adult females lived as long as those of T . dryi . The implications of these results are discussed within the framework of the introduction of T . dryi into Europe.

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Martínez-Blay, V.; Pérez-Rodríguez, J.; Tena, A.; Soto Sánchez, AI. (2018). Density and phenology of the invasive mealybug Delottococcus aberiae on citrus: implications for integrated pest management. Journal of Pest Science. 91(2):625-637.Aknowledgements We would like to thank the owners of the orchards for allowing us to use their 19 plantations and P. Bru (IVIA) and J. Catalán (IVIA) for their help in sampling. This research was 20 supported by two predoctoral grants (FPU to V. Martínez-Blay and Val I+d to J. Pérez-Rodríguez from 21 the Spanish Ministry of Education, Culture and Sport and Generalitat Valenciana, respectively), the 22 European grants FP7-IAPP #324475 'Colbics' and FP7-IRSES #612566 'Biomodic', and a national 23 project provided by INIA (Project No. RTA2014-00067). The authors thank Debra Westall (UPV) for 24 revising the manuscript.25 26 27 2 Abstract 28 Delottococcus aberiae De Lotto (Hemiptera: Pseudococcidae) is a new invasive citrus pest in Spain. It 29 causes severe fruit distortions and, as a new invasive mealybug, there is a lack of information about its 30 biology. This research aims to examine the seasonal trend of D. aberiae in citrus, using several sampling 31 methods, as a first step to develop an integrated pest management program. Ten citrus orchards from 32 Eastern Spain were periodically sampled during three years using absolute (plant material) and relative 33 (corrugated cardboard band traps and sticky traps) sampling methods. The three sampling methods 34 showed that D. aberiae completes multiple generations per year, two of them being clearly defined and 35 resulting in high populations. D. aberiae peaked between May and June, damaging the developing fruit.36 Corrugated cardboard band traps were able to detect prepupa and pupa male instars and gravid females, 37 providing a quantitative measurement of D. aberiae density at its first population peak. The use of 38 corrugated cardboard band traps is recommended to monitor population levels and sticky traps to 39 determine male flight periods, representing simple sampling techniques to monitor D. aberiae. These 40 results will improve the sampling protocols and allow for the development of an integrated pest 41 management program.42 Keywords: corrugated and sticky traps, life cycle, sampling protocols, D. aberiae, citrus 43 44 45 Key message 46  Delottococcus aberiae is a new invasive citrus pest in Europe and its biology is unknown. 47  This work aims to study the density of developmental stages of D. aberiae throughout the year.48  Different sampling methods showed that D. aberiae completes several generations. Two of them 49 are clearly defined and result in high population levels. 50  These results are the first seasonal population trend of D. aberiae in citrus and may serve as a 51 basis for an integrated pest management program. 52 53 54 55 56 57 58 59 60 61 62 63 64

Delottococcus aberiae De Lotto (Hemiptera: Pseudococcidae) is the latest exotic mealybug species introduced in citrus in the Mediterranean basin. It causes severe distortion and size reduction on developing fruits. Due to its first interaction with citrus, D. aberiae economic thresholds are still unknown for this crop and the current Integrated Pest Management programs have been disrupted. The objectives of this study were to determine the aggregation patterns of D. aberiae in citrus, develop an efficient sampling plan to assess its population density, and calculate its Economic and Economic Environmental Injury Levels (EIL and EEIL, respectively). Twelve and 19 orchards were sampled in 2014 and 2015, respectively. At each orchard, population densities were monitored fortnightly in leaves, twigs, and fruit, and fruit damage was determined at harvest. Our results showed a clumped aggregation of D. aberiae in all organs with no significant differences between generations on fruit. Fruit damage at harvest was strongly correlated with fruit occupation in spring. Based on these results and using chlorpyrifos as the insecticide of reference, the EIL and EEIL were calculated as 7.1 and 12.1% of occupied fruit in spring, respectively. With all this, we recommend sampling 275 fruits using a binomial sampling method or alternatively, 140 fruits with an enumerative method bimonthly between petal fall and July.

Abstract. 1. Parasitoids are a valuable group for conservation biological control. In their role as regulators of aphid pests, it is critical that their lifecycle is synchronised with their hosts in both space and time. This is because a synchronised parasitoid community is more likely to strengthen the overall conservation biological control effect, thus damping aphid numbers and preventing potential outbreaks. One component of this host-parasitoid system was examined, that of migration, and the hypothesis that peak summer parasitoid and host migrations are synchronised in time was tested.2. Sitobion avenae Fabricius and six associated parasitoids were sampled from 1976 to 2013 using 12.2-m suction-traps from two sites in Southern England. The relationship between peak weekly S. avenae counts and their parasitoids was quantified.3. Simple regression models showed that the response of the peak parasitoids to the host was positive: generally, more parasitoids migrated with increasing numbers of aphids. Further, when averaged over time, the parasitoid migration peak date corresponded with the aphid migration peak. The co-occurrence of the peaks was between 51% and 64%. However, the summer peak in aphid migration is not steadily shifting forward with time unlike spring first flights of aphids. Cross-correlation analysis showed that there were no between-year lagged effects of aphids on parasitoids.4. These results demonstrate that the peak in migration phenology between host and parasitoid is broadly synchronised within a season. Because the threshold temperature for flight (> 12 ∘ C) was almost always exceeded in summer, the synchronising agent is likely to be crop senescence, not temperature. Studies are needed to assess the effects of climate change on the mismatch potential between parasitoids and their hosts.

Delottococcus aberiae (De Lotto) (Hemiptera: Pseudococcidae) is the most recent species of mealybug introduced to Spain that is affecting citrus. The feeding behavior of D. aberiae causes severe direct damage to citrus fruits, distorting their shape and/or causing reduction in size. There is no information available regarding its distribution within the citrus trees. The main objective of this study was to describe the seasonal distribution of D. aberiae within citrus trees and its migration patterns on the plants. Ten citrus orchards from eastern Spain were periodically sampled during 3 yr. In each orchard, the mealybug was sampled in different infested strata (canopy, trunk, and soil) and canopy structures (flower, fruit, leaf, and twig). Results showed that, within the sampled strata, D. aberiae was mostly in the canopy. Within the canopy, the feeding location of D. aberiae changed throughout the year. D. aberiae overwintered in the twigs and moved to the flowers and fruits in spring. Once there, its populations started to increase exponentially until August. From February to September, 5-30% of the mealybugs migrated to the trunk and soil. These results will facilitate an early detection of the pest in the areas where it is spreading and improve sampling protocols and pesticide applications.

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