First record, new cultivated host and host plant preference of the invasive oak lace bug (Corythucha arcuata Say, 1832) (Heteroptera: Tingidae) in Transcarpathia (West Ukraine)

Oak lace bug (Corythucha arcuata) has continuously spread through Europe since its appearance in 2000, and it has become a dangerous pest of Quercus species in most countries. Despite of its high abundance in the surrounding countries it was found in West Ukraine only in 2020. During our investigation carried out in 2020 OLB was detected in all studied large forest patches of the Ukrainian part of the Carpathian Lowland. These were one of the newest distribution data from Ukraine after its appearance in the far coast of Black See near Yalta (South Ukraine). OLB most live on Q. robur and Q. petraea but in an orchard located near an infested forest patch we found infested sweet cherry (P. avium) trees, which is a new, formerly not mentioned cultivated host of the pest.

Predation risk differentially affects aphid morphotypes: impacts on prey behavior, fecundity and transgenerational dispersal morphology

To avoid predation, prey initiate anti-predator defenses such as altered behavior, physiology and/or morphology. Prey trait changes in response to perceived predation risk can influence several aspects of prey biology that collectively contribute to individual success and thus population growth. However, studies often focus on single trait changes in a discrete life stage or morphotype. We assessed how predation risk by Harmonia axyridis affects several important traits in the aphid, Myzus persicae: host plant preference, fecundity and investment in dispersal. Importantly, we examined whether these traits changed in a similar way between winged (alate) and wingless (apterous) adult aphid morphotypes, which differ in morphology, but also in life-history characteristics important for reproduction and dispersal. Host plant preference was influenced by the presence of H.axyridis odors in choice tests; wingless aphids were deterred by the odor of plants with H.axyridis whereas winged aphids preferred plants with H.axyridis present. Wingless aphids reared in the presence of ladybeetle cues produced fewer offspring in the short-term, but significantly more when reared with exposure to predator cues for multiple generations. However, winged aphid fecundity was unaffected by H.axyridis cues. Lastly, transgenerational plasticity was demonstrated in response to predation risk via increased formation of winged aphid morphotypes in the offspring of predator cue-exposed wingless mothers. Importantly, we found that responses to risk differ across aphid polyphenism and that plasticity in aphid morphology occurs in response to predation risk. Together our results highlight the importance of considering how predation risk affects multiple life stages and morphotypes.

Infection of susceptible/tolerant barley genotypes with Barley yellow dwarf virus alters the host plant preference of Rhopalosiphum padi clones depending upon their ability to transmit BYDV

Discovering mechanisms of plant–virus–vector interactions is fundamental to understand their ecology and evolution and to apply this knowledge in plant protection. To study the influence of varying Barley yellow dwarf virus (BYDV) transmission efficiencies on host plant preference of Rhopalosiphum padi (L.) clones, we performed host choice experiments with two barley cultivars (BYDV susceptible cv. ‘Rubina’ and BYDV tolerant cv. ‘Vixen’) including healthy and virus-infected plants. For the susceptible barley cultivar ‘Rubina’, aphid clone R07 (high transmission efficiency) preferred BYDV-infected over healthy host plants after 24 h, while clones D10 (medium transmission efficiency) and R09 (low transmission efficiency) preferred neither host. In contrast, BYDV infection of ‘Vixen’ did not affect the plant’s appeal for aphid clone R07. Host plant access, indicated by ingestion and observed by electrical penetration graph technique for a period of 2 h, was facilitated on BYDV-infected cv. ‘Rubina’ for the clones R07 and D10, whereas an opposite effect was observed for the clone R09. For R07 and R09, the difference was not visible after a period of 5 h. As observed earlier for BYDV-infected wheat, enhanced emission of volatile organic compounds associated with virus-induced attraction was detected for BYDV-infected cv. ‘Rubina.’ It is concluded that host plant preference is possibly linked with a high BYDV transmission efficiency as observed for the clone R07, leading to a fitness advantage of this clone as indicated by early increased ingestion. This advantage is not present on BYDV-tolerant genotypes most likely due to the absence of infection symptoms.

Aleyrodes lonicerae Walker (Hemiptera: Aleyrodidae)’nın Viola tricolor L. Üzerinde Biyolojik Özellikleri ve Ölümü Esas Alan Yaşam Çizelgesi

Biology of the lonicera whitefly, Aleyrodes lonicerae Walker (Aleyrodidae: Hemiptera) were studied on violet, Viola tricolor L. (Violaceae) plants. Whitefly adults were collected from Mercurialis annua L. (Euphorbiaceae) plants in Adana. The development duration of egg, first, second, third, fourth larval (pupa) stages of A. lonicerae on V. tricolor were 9.17, 6.33, 5.83, 4.00, 5.17 and 30.50 days for the females and 10.27, 5.91, 5.55, 4.82, 4.55 and 31.10 days for the males, respectively. The total development duration from egg to adult of female and males of A. lonicerae were 30.50 and 31.10 days. The mortality rate (%) of egg, 1., 2., 3. and 4. larva (pupae) stages on violet leaves were 22.45, 18.37, 12.25, 4.08 and 8.16, respectively. According to life table depending on pre-adult stages on violet plants, the biggest k value determined was for the first larvae stage (k=0.1174). At the same time, the k-values determined indicated the stage with the highest mortality rates. In the studies conducted for host plant preference, the average numbers of eggs deposited by the females of A. lonicerae were significantly different between rose (2.67/two leaves) and violet (15.83/two leaves) in the same experimental area. The study was conducted in a climate-controlled room in at 20±2°C, 40%±5 relative humidity.