Diuraphis noxia (Russian wheat aphid).

D. noxia has a great economic impact on cereal crops (Brooks et al., 1994). It is a phloem feeder like other aphids and the symptoms evident on plants are a result of this feeding mechanism. By feeding on the phloem, the aphid damages the plants through nutrient drainage (Dixon, 1985) which results in chlorosis, necrosis, wilting, stunting, and curling of the leaves, misshapen or nonappearance of new growth, and localised cell death at the site of aphid feeding. D. noxia further elicits an increase in essential amino acids in the phloem sap by triggering the breakdown of proteins in infested wheat leaves (Burd and Burton, 1992; du Toit, 1986; Ma et al., 1998; Miller et al., 2001). The damage to the foliar tissue is thought to play a role in the pest's ability to increase nutritional quality of the host plant (Botha et al., 2006).

Functional Analysis of Alkaline Phosphatase in Whitefly Bemisia tabaci (Middle East Asia Minor 1 and Mediterranean) on Different Host Plants

Alkaline phosphatases (ALPs: EC 3.1.3.1) are ubiquitous enzymes and play crucial roles in the fundamental phosphate uptake and secretory processes. Although insects are regarded as the most diverse group of organisms, the current understanding of ALP roles in insects is limited. As one type of destructive agricultural pest, whitefly Bemisia tabaci, a phloem feeder and invasive species, can cause extensive crop damage through feeding and transmitting plant diseases. In this study, we retrieved five ALP genes in MEAM1 whitefly, nine ALP genes in MED whitefly via comparative genomics approaches. Compared with nine other insects, whiteflies’ ALP gene family members did not undergo significant expansion during insect evolution, and whiteflies’ ALP genes were dispersed. Moreover, whiteflies’ ALP gene family was conserved among insects and emerged before speciation via phylogenetic analysis. Whiteflies’ ALP gene expression profiles presented that most ALP genes have different expression patterns after feeding on cotton or tobacco plants. Female/male MED whiteflies possessed higher ALP activities on both cotton and tobacco plants irrespective of sex, relative to MEAM1 whiteflies. Meanwhile, adult MED whiteflies possessed higher ALP activity in both whole insect and salivary samples, relative to MEAM1 whiteflies. We also found that both MED and MEAM1 whiteflies could upregulate ALP activities after feeding on cotton compared with feeding on tobacco plants. These findings demonstrated the functions of whiteflies ALPs and will assist the further study of the genomic evolution of insect ALPs.

Spotted Lanternfly (Hemiptera: Fulgoridae) Can Complete Development and Reproduce Without Access to the Preferred Host, Ailanthus altissima

Despite its broad host range, the spotted lanternfly Lycorma delicatula (White), is known to have a marked preference for Ailanthus altissima. However, whether this polyphagous phloem feeder can complete its life cycle in the absence of A. altissima is unknown. We examined the performance of L. delicatula with and without access to A. altissima by tracking development, survival, host tree species association, and oviposition in large enclosures planted with Salix babylonica and Acer saccharinum along with either A. altissima or Betula nigra. We monitored enclosures from late May 2019 through June 2020. Lycorma delicatula survival was slightly higher in enclosures with A. altissima and 50% of individuals in A. altissima enclosures reached the adult stage ~6.5 d earlier than in enclosures without A. altissima. In the presence of A. altissima, nymphs were most frequently observed on this host while adults were found at similar frequencies on A. altissima and A. saccharinum. In the absence of A. altissima, nymphs were most frequently associated with S. babylonica and A. saccharinum, while adults were most often found on A. saccharinum. Females laid a total of 46 and 6 egg masses in enclosures with and without A. altissima, respectively, before freezing temperatures killed the remaining adults. The proportion of eggs that hatched per egg mass did not differ between treatments. Although L. delicatula can complete development and reproduce on other host species without access to A. altissima, fitness was reduced. These findings have implications for management that relies exclusively on treatment of A. altissima.

Footprints and Ootheca of Lycorma delicatula Influence Host-Searching and -Acceptance of the Egg-Parasitoid Anastatus orientalis

The spotted lanternfly, Lycorma delicatula White (1845) (Hemiptera: Fulgoridae), is an invasive insect that was first reported in North America in Berks County, Pennsylvania, in 2014. It is a polyphagous phloem feeder that attacks over 70 plant species, threatening the agricultural, lumber, and ornamental industries of North America. Infestations of the pest have been reported in several U.S. counties, and a lack of endemic predators and parasitoids feeding on L. delicatula suggests a release from natural enemies in the invaded range. An egg-parasitoid Anastatus orientalis (Hymenoptera: Eupelmidae) was reported attacking L. delicatula at high rates in its native range and may play a key role in reducing its populations there. To better understand the foraging behavior of A. orientalis, a series of behavioral experiments were conducted to determine successful parasitism and behavioral responses to traces left by adult L. delicatula and to the oothecae which cover their eggs. Our results suggest that wasps detected chemical traces left by L. delicatula adults while walking on surfaces and exhibited a strong arrestment response. Moreover, wasps preferred to oviposit in egg masses with intact oothecae. The implications of these findings are herein discussed with regard to the exploitation of host kairomones by foraging wasps, as well as to its ability to overcome host structural defenses.

Real time EPG recordings of tomatopotato psyllid (Bactericera cockerelli) feeding on tomato

The stylet penetration behaviour of tomatopotato psyllid (TPP; Bactericera cockerelli Hemiptera Psyllidae) a phloem feeder was monitored using an electrical penetration graph (EPGDC system) technique Fifteen adult psyllids were randomly selected from a colony and monitored for 8 h on tomato plants under laboratory conditions EPG waveforms generated during stylet penetration into the plant tissues were categorised based on amplitude frequency voltage level and electrical origin The main waveforms representing salivary sheath secretion and other stylet pathway activities (C) first contact with phloem (D) salivation in phloem sieve tubes (E1) and phloem sap ingestion (E2) were similar to the Asian citrus psyllid Diaphorina citri and this was confirmed by histological studies Phloem ingestion was seen from 12 out of 15 psyllids tested The time to first contact of phloem from the beginning of recording was 1163 h and the total duration of phloem ingestion recorded was from 1 min to 52 h within the 8 h recording period The information gathered on the feeding behaviour of TPP from this study will be applicable for future studies to understand the transmission of Candidatus Liberibacter solanacearum by TPP as well as other Liberibacter and TPP management studies