Rapid and transient evolution of local adaptation to seasonal host fruits in an invasive pest fly.

Both local adaptation and adaptive phenotypic plasticity can influence the match between phenotypic traits and local environmental conditions. Theory predicts that environments stable for multiple generations promote local adaptation, whereas highly heterogeneous environments favor adaptive phenotypic plasticity. However, when environments have periods of stability mixed with heterogeneity, the relative importance of local adaptation and adaptive phenotypic plasticity is unclear. Here, we used Drosophila suzukii as a model system to evaluate the relative influence of genetic and plastic effects on the match of populations to environments with periods of stability from three to four generations. This invasive pest insect can develop within different fruits, and persists throughout the year in a given location on a succession of distinct host fruits, each one being available for only a few generations. Using reciprocal common environment experiments of natural D. suzukii populations collected from cherry, strawberry, and blackberry, we found that both oviposition preference and offspring performance were higher on medium made with the fruit from which the population originated than on media made with alternative fruits. This pattern, which remained after two generations in the laboratory, was analyzed using a statistical method we developed to quantify the contributions of local adaptation and adaptive plasticity in determining fitness. Altogether, we found that genetic effects (local adaptation) dominate over plastic effects (adaptive phenotypic plasticity). Our study demonstrates that spatially and temporally variable selection does not prevent the rapid evolution of local adaptation in natural populations. The speed and strength of adaptation may be facilitated by several mechanisms including a large effective population size and strong selective pressures imposed by host plants.

Surveys of Drosophila suzukii (Diptera: Drosophilidae) and Its Host Fruits and Associated Parasitoids in Northeastern China.

Spotted-wing drosophila, Drosophila suzukii (Matsumura), is a worldwide quarantine pest that is currently undergoing a rapid range expansion in the Americas, Europe, and parts of Africa. It feeds and breeds on soft-skinned fruits such as raspberries, blueberries, and cherries, and can cause significant economic losses to fruit production. This study investigated the occurrence of D. suzukii and its wild host fruits and parasitoids in Liaoning, Northeast China for the first time. Sentinel traps were used to monitor D. suzukii adults, and suspected fruits were collected weekly in four different locations (Wafangdian, Faku, Fengcheng, and Shenyang). The results showed that D. suzukii were distributed in the sweet soft-skinned fruit-production areas of Liaoning, and raspberry was the most infested fruit. During the field survey, four species of wild berries from non-crop habitats were found infested by D. suzukii, and two species of parasitoids (Leptopilina japonica and Asobara japonica) were collected. D. suzukii adult-population dynamics throughout the survey period (June to October) were similar in different survey locations; adult fly populations increased and peaked in August, and then declined until the fly was no longer detectable in October.

Use of Age-Stage, Two-Sex Life Table to Compare the Fitness of Bactrocera dorsalis (Diptera: Tephritidae) on Northern and Southern Host Fruits in China.

Bactrocera dorsalis (Hendel), as a quarantine pest in many countries and regions, has shown a trend of northward diffusion in the past century in China. In order to determine whether B. dorsalis will cause great harm to the dominant northern fruits, the age-stage two-sex life tables of peaches and apples were constructed, with oranges as the control. The results showed that the developmental rate, intrinsic rate of increase (r), and finite rate of increase (λ) on oranges and peaches were significantly greater than on apples. Additionally, the prediction of population growth 90 days after oviposition revealed that the whole population on oranges and peaches increased by 13,667.3 and 12,112.1 times, respectively, indicating that B. dorsalis is very likely to endanger peach orchards. The population increased on apples by 4311 times, though this is lower than that on oranges and peaches. Overall, peaches with high fitness similar to oranges are very suitable as a host for B. dorsalis and are likely to become a new favorable host, while apples may also become a potentially new host, though with lower fitness. Therefore, the most pressing solutions to take are population monitoring, comprehensive prevention, and control in the case of any potential large-scale outbreak of B. dorsalis in northern China.

Lonchaeidae (Diptera) species and their host plants in the Cerrado biome in the state of Piauí, Brazil / Espécies de Lonchaeidae (Diptera) e seus hospedeiros no bioma Cerrado no estado do Piauí, Brasil

Some species of Lonchaeidae (Diptera) are considered frugivorous and polyphagous pests, and are widely distributed in Neotropical regions. The relationship between a fly and its host plant is important for studies on behavior and distribution of frugivorous flies. The objective of this work was to identify the Lonchaeidae fly species and their host plants in the Cerrado biome, specifically in the state of Piauí, Brazil. Eighty-one adults (33 ♀ and 48 ♂) from the genus Neosilba McAlpine (Lonchaeidae), represented by the species Neosilba inesperata Strikis & Prado, Neosilba pendula Bezzi, and Neosilba zadolicha McAlpine, were collected from fruit samples. Oranges [Citrus sinensis (L.) Osbeck] and guava (Psidium guajava L.) had the highest frequencies of infestation. A Neosilba species was considered a primary invader in orange. These results are the first ones reported of Lonchaeidae species and their host plants in the state of Piauí.(AU)

Algumas espécies de Lonchaeidae (Diptera) são consideradas pragas frugívoras e polífagas, com ampla distribuição geográfica em regiões neotropicais. A relação mosca/planta hospedeira é de grande valor para estudos de comportamento e distribuição de moscas frugívoras. O objetivo deste trabalho foi identificar as espécies de Lonchaeidae e suas plantas hospedeiras no bioma Cerrado, especificamente no estado do Piauí, Brasil. Oitenta e um adultos (33 ♀ e 48 ♂) do gênero Neosilba McAlpine (Lonchaeidae), pertencentes às espécies Neosilba inesperata Strikis & Prado, Neosilba pendula Bezzi e Neosilba zadolicha McAlpine, foram coletados de amostras de frutas, sendo a laranja [Citrus sinensis (L.) Osbeck] e a goiaba (Psidium guajava L.) as de maiores frequências de infestação. Uma espécie de Neosilba foi considerada um invasor primário em laranjas. Esses resultados são os primeiros relatos de espécies de Lonchaeidae e suas plantas hospedeiras no estado do Piauí.(AU)

Invasion by Bactrocera dorsalis and niche partitioning among tephritid species in Comoros.

Ten economically important species belonging to the Tephritidae have been recorded in Union of the Comoros (an island nation off the coast of East Africa). Little is known about the distribution of these species and how they are affected by climatic factors in the Comoros archipelago. The main objectives of this study were to characterize: (i) the population dynamics of tephritid fruit flies in relation to season and host fruit availability and (ii) the geographic distribution of tephritids in relation to temperature and rainfall. The study was conducted during 2 years at 11 sites on three islands (Grande Comore, Anjouan, and Mohéli) in the archipelago. The site elevations ranged from 55 to 885 m a.s.l. At each site, flies were collected weekly in eight traps (four different lures, each replicated twice). Fruit phenology was also recorded weekly. The dominant tephritid species detected was the invasive Bactrocera dorsalis Hendel followed by Ceratitis capitata Wiedemann. Tephritid species were generally more abundant during the hot and rainy seasons than during the cold and dry seasons. Bactrocera dorsalis numbers were higher on Grande Comore than on the two other islands. On Anjouan and Mohéli, B. dorsalis numbers were very low in 2014 but sharply increased in 2015, suggesting a recent invasion of these islands. Abundances were significantly related to the fruiting of mango, strawberry guava, and guava for B. dorsalis and to the fruiting of mango, guava, and mandarin for C. capitata. Bactrocera dorsalis was more abundant in hot and humid low-altitude areas, while C. capitata was more abundant in dry medium-altitude areas, suggesting the occurrence of climatic niche partitioning between the two species.