The Delphacidae are the most diverse and economically important family of planthoppers.  Fifty-five species are known pests on 25 crops (Wilson & O’Brien 1987) including 5 of the top 10 major world food commodities (Table 1).  Delphacids cause damage both through direct feeding damage and as vectors of plant viral diseases (e.g., Nault 1994, Kuniata et al. 1994, Narayana & Muniyappa 1996, Garat et al. 1999, Remes-Lenicov & Virla 1999a, b; Laguna et al. 2002, Brentassi & Maldonado 2002, Liu et al. 2002, Dhileepan & Croft 2003, Rubia-Sanchez et al. 2003, Dintinger et al. 2005, Costamagna et al. 2005, Yin et al. 2005, Wilson 2005, Grilli 2006, Grimshaw & Donaldson 2007).   About 30 species are known plant disease vectors (Table 2).  Most plant pathogens vectored by delphacids (Table 3) appear to be viruses (including the pathogen for the emerging Ramu stunt disease of sugarcane, Braithwaite et al. 2007), except the Saccharosydnini are reported to vector phytomlasmas. 

Of particular importance is the impact of planthoppers on rice production.  The Ricehoppers blog (http://ricehoppers.net/) reports especially regarding planthoppers in that context.  The International Rice Research Institute (IRRI) recently (23-25 June 2008) held a conference on planthopper problems and control in Asia (synopsis here). The press release for the conference, called planthoppers a “major threat to Asian rice production” and noted that:

“Problems caused by planthoppers, a major type of rice pest that can destroy one-fifth of a harvest, have intensified across Asia in recent years. Major outbreaks in Vietnam in 2007 contributed to recent dramatic rises in the cost of rice, which have threatened to push millions of people deeper into poverty. If not effectively controlled, these pests could hamper rice production and help keep prices high.”

 

Available online is:

Heong, K.L. and B. Hardy, (eds). 2009. Planthoppers: New Threats to the Sustainability of Intensive Rice Production Systems in Asia. International Rice Research Institute, Los Baños, Philippines.

Table 1. Top world agricultural crops with delphacid pest taxa (2004 FAO data)
Harvest ranking	Crop	Million metric tons 2004	Delphacid pest genus (e.g.)	Plant diseases vectored
1	Sugar Cane	1,324	Perkinsiella, etc.	Fiji disease, yellow leaf phytoplasma
2	Maize	721	Peregrinus, etc.	Maize stripe, mosaic, rough dwarf
3	Wheat	627	Javesella, etc.	Wheat striate mosaic, stripe virus
4	Rice	605	Nilaparvata, etc.	Grassy stunt, Hoya blanca, Rice stripe
9	Barley	154	Laodelphax, etc.	Yellow striate mosaic, yellow dwarf

A blog (“Ricehoppers”) on the “latest information and issues relevant to managing rice planthopper problems”. Of greatest significance is to rice is Nilaparvata lugens, about which Herdt (1987) reports estimated losses of $1.06 billion from rice crops in Southeast Asia each year and over $5 billion as the equity weighted value of output foregone due to N. lugens.  While I have not found more recent calculations of these figures, the significance of major rice pests is unlikely to be declining at a time when concerns over world rice shortages are a topic of popular news media.  If anything, it appears that concerns over rice planthoppers are increasing, with recent news items such as the “Sichuan Rice Disaster” in 2007 where migratory planthoppers caused the “…worst rice pest disaster in 16 years. Rice plant hoppers have already attacked 5.2 million mu (about 0.85 million acres) rice fields in 85 counties and county-level cities across the province.”  (Nilaparvata lugens is not native to Sichuan, but the species is well-known for its migratory behavior; e.g., Holt et al. 1989, Riley et al. 1991, 1994; Turner et al. 1999, Otuka et al. 2005a, b; Furuno et al. 2005). The New York Times (May 18, 2008), reported on the threat of planthoppers to world food supplies at a time when research money is being cut.  The main planthopper rice pests in Asia – Nilaparvata lugens and Sogatella furcifera – are not established in the New World.

Table 2. Delphacid Plant Disease Vectors (updated from Wilson 2005).
Delphacid species	Pathogen	Select Hosts	Region
Caenodelphax taepae	UHBV	Plantain signalgrass	NT
Chilodelphax albifascia (= Unkanodes (C.) albifascia)	NCMV, RSV, RBSDV	Rice	PA-E
Delphacodes catilina (as "Toya catilina")	MMV (as ACSV)	Wheat, Oats, Barley, Rye, Corn	IM
Delphacodes kuscheli	MRCV	Maize	PA-W
Dicranotropis hamata	MRDV, OSDV, PGSV	Grasses (Oats, etc.)	HO
Eumetopina flavipes	Ramu stunt (evidently a virus)	Sugarcane	AP
Javesella discolor	OSDV	Grasses (Oats, etc.)	HO
Javesella dubia	EWSMV, OSDV	Grasses (Wheat, etc.)	HO
Javesella obscurella	EWSMV, OSDV	Grasses (Wheat, etc.)	HO
Javesella pellucida	EWSMV, OSDV, MRDV (experimentally BYSMV)	Grasses (Wheat, etc.)	HO
Laodelphax striatellus	BYSMV, MIMV, MRDC, NCMV, RSV, RBSDV, WCSV, WRSV; Maize streak dwarf (?) nucleorhabdovirus	Grasses (Wheat, etc.)	IM, PA
Megadelphax sordidulus	PGSV	Grasses (Timothy, etc.)	PA-W
Metadelphax propinqua	CCSV, MRDV, BYSMV	Maize, Bermudagrass, &c.	All
Muellerianella fairmairei	NCMV	Grasses (Oats, etc.)	PA-W
Nilaparvata bakeri	RGSV, RRSV	Rice	IM
Nilaparvata lugens	RGSV, RRSV	Rice	AP, IM
Nilaparvata muiri	RGSV	Rice	IM
Peregrinus maidis	FMMV, IMMV (MIMV), MMV, MSSV, MSV, MSpV, Maize line virus	Maize, Sorghum	AF, AP, IM
Perkinsiella saccharicida	FDV	Sugarcane	AF, AP
Perkinsiella vastatrix	FDV	Sugarcane	AF, AP
Perkinsiella vitiensis	FDV	Sugarcane	AP
Saccharosydne saccharivora	SCYLP*	Sugarcane	NT
Sogatella furcifera	PSV, SRBSDV	Grasses, Rice	AP, IM
Sogatella kolophon	BWSpV, DiSV, MSSV	Maize, grasses	AF, AP, IM
Sogatella vibex	ERSV, FMMV, MRDV, MSSV	Maize, grasses	AP, IM, PA
Tagosodes cubanus	EHBV, RHBV	Maize, coconut	AF, NT
Tagosodes orizicolus	MRCV, RHBV	Rice, Echinochloa, grasses	NA, NT
Tarophagus prosperina	CBV	Taro	AP, IM
Terthron albovittatum	RSV, RBSDV	Rice, Echinochloa	IM, PA-E
Unkanodes sapporonus	NCMV, RSV, RBSDV	Rice	IM, PA-E
Unkanodes tanasijevici	IMMV (MIMV)	Maize, grasses	PA-W
Unkanodes tanasijevici (as Ribautodelphax notabilis)	IMMV (MIMV), MRDV, RBSDV	Maize, grasses	PA-W
Sources: Wilson (2005) et cite, plus Lockhart (1986), Kuniata et al (1994), Arocha et al. (2005), Costamagna et al (2005); Braithwaite et al. (2007); Mattio et al. (2008); Universal Virus Database, v. 4. http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/ For virus abbreviations see below.  Biogeographic Region Abbreviations: AF-Afrotropical, AP-Australo-Pacific, HO-Holarctic, IM-Indo-Malayan, NA-Nearctic. NT-Neotropical, PA-Palearctic, PA-E-Eastern Palearctic, PA-W-Western Palearctic. * A phytoplasma - all others are viruses.

Of the 30 delphacid species known to be crop disease vectors, only 8 are known from continental United States.  Of these, one (Perkinsiella saccharicida, a sugarcane specialist) is introduced from the Australo-Pacific region (Sosa 1983, 1985; Meagher et al. 1991, 1993; Emeljanov 1994), and a second (Metadelphax propinqua) may have been introduced near the end of the 19th century (Gonzon and Bartlett 2008).  Two other species are introduced: Harmalia anacharsis (found secondarily on rice) and Conomelus anceps (Holdom et al. 1989, Wooten et al 1993, Wheeler and Hoebeke, 2008).   The latter species, evidently introduced from Europe into Nova Scotia, illustrates that even species intuitively unlikely to become invasive may be introduced.  Conomelus is a rush (Juncus spp.) specialist, and ordinarily brachypterous and sedentary.     One species, Megamelus scutellaris, is likely to be introduced as a biological control agent of water hyacinth in Florida (USDA 2010).

Hawaii has had 10 immigrant delphacid species including 4 pest species (Peregrinus maidis (on corn), Perkinsiella saccharicida (on sugarcane), and two Tarophagus species (on taro); Asche 1997).   The introduction of Perkinsiella saccharicida was particularly significant since it resulted in a total annual output of sugar for the Hawaiian Islands to be reduced by 16% within 2 years of introduction (in 1900; Swezey 1936).

Table 3. Pathogens known to be vectored by delphacid planthoppers. Names are being updated to conform with ICTV, and links are given to VIDE or DPVweb (links to ICTV appear to go to the index).
Pathogen	Pathogen Name
ACSV	African Cereal Streak Virus (apparently = MSV = MMV)
BWSpV	Brazilian wheat spike disease (tentative Tenuivirus, =Wheat white spike disease) (see Caetano al 1970)
BYSMV	Barley yellow striate mosaic cytorhabdovirus (also here)
CBV	Colocasia bobone disease (?) rhabdovirus
CCSV	Cynodon chlorotic streak nucleorhabdovirus
DiSV	Digitaria striate (?) cytorhabdovirus
EHBV	Echinochloa hoja blanca virus (= rice hoja blanca tenuivirus)
ERSV	Echinochloa ragged stunt oryzavirus
EWSMV	European wheat striate mosaic virus (= wheat European striate mosaic (?) tenuivirus)
FDV	Sugarcane Fiji disease fijivirus
FMMV	Finger millet mosaic nucleorhabdovirus
IMMV	Iranian maize mosaic (?) nucleorhabdovirus (Maize Iranian mosaic virus (MIMV)
	Maize line virus
MIMV	Maize Iranian mosaic virus (see  IMMV above) (ICTV taxonomic proposal)
MMV	Maize mosaic nucleorhabdovirus (VIDE Rhabdoviridae) (see also here)
MRCV	Mal de Rio Cuarto fijivirus (also here [.doc])
MSV	Maize stripe virus (=MMV and ACSV above)
MSpV	Maize stripe tenuivirus (FL extension bulletin) (ICTV)
MRDV	Maize rough dwarf fijivirus
	Maize streak dwarf (?) nucleorhabdovirus
MSSV	Maize sterile stunt virus (= Barley yellow striate mosaic cytorhabdovirus (also here))
NCMV	Northern cereal mosaic virus
OSDV	Oat sterile dwarf fijivirus (and here)
PGSV	Phleum green stripe (?) tenuivirus
PSV	Pangola stunt fijivirus
RBSDV	Rice black-streaked dwarf fijivirus (and here)
RGSV	Rice grassy stunt tenuivirus
RHBV	Rice hoja blanca tenuivirus
RRSV	Rice ragged stunt oryzavirus
RSV	Rice stripe tenuivirus
(none)	Ramu stunt (appears to be a virus despite assertions to the contrary; see Braithwaite et al. 2007)
SCYLP	Sugarcane yellow leaf phytoplasma (see Arocha et al 2005)
SRBSDV	Southern Rice Black Streak Dwarf fijivirus (new!) (see Zhou et al. 2008)
UHBV	Urochloa hoja blanca tenuivirus (unassigned here)
WCSV	Wheat chlorotic streak virus (same as Northern Mosaic cereal virus)
ZRSV	Wheat rosette stunt virus (= Cereal northern mosaic cytorhabdovirus)

 

The following table summarizes the delphacid species intercepted at US ports from 1986 to 2008.

 

Table 4. Delphacid interceptions at US ports 1986-2008 (USDA-APHIS-PPQ; F. Kuehn, DE Dept Ag, pers. com.)
Identification	# intercept.
Asiraca clavicornis**	1
Calligypona sp.**	1
Delphacodes puella	1
Delphacodes sp.	18
Laodelphax striatellus**	1
Liburnia sp.*	1
Nilaparvata lugens **	9
Nilaparvata sp.	4
Peregrinus maidis	13
Perkinsiella saccharicida	1
Saccharosydne sp.	1
Sogata sp.*	1
Sogatella sp.	1
Stenocranus sp.	1
Tagosodes sp.	3
Tarophagus prosperina**	1
Family ID only	349
total	407
*Genera of dubious standing. ** Taxa not occurring in North America.

 

Since 2009, Stuart McKamey has graciously agreed to save delphacid specimens intercepted at ports and sent to the USNM Sytematics lab for identification. 

Recent interceptions (2007-2009) were reported as follows (McKamey Identifications)

Genus	Species	#
Delphacidae	spp.	51
Neosydne	spp nr leahi	1
Nilaparvata	spp. ? lugens	1
Peregrinus	maidis	3
Stenokelisia	angusta	4

Also 1 Dictyopharidae and 1 cicadellid nymph

Of the specimens listed above as recent interceptions - I have checked/reviewed the following:

Delphacidae

 Delphacinae: Tropidocephalini

 - Columbiana sp. (♂) - intercepted Miami Air CBP, FL from Columbia 5 Nov 2009 Antirrhinum sp (snapdragon)

 - Columbisoga sp. FL Miami Air CPB, ex Columbia, 17.vi.2011, on Ruscus sp. (Asparagaceae) (APMFL111686766010)

 - Columbisoga sp. FL Miami Air CPB, ex Columbia, 28.iv.2010, on Chrysanthemum sp., with cut flower (APMFL101181151024)

Delphacinae: Delphacini

 - Chionomus sp. (♀) - Intercepted Miami AFB, FL from Columbia, 5 Aug. 2009, on Grevillia sp. (Proteaceae)

 - Chionomus sp. (♀) - intercepted Miami Air CBP, FL from Peru, 15 May 2009 on Lactuca satvia (Lettuce) (2 specimens, other was Tagosodes).

 - Chionomus balboae (1♂) - FL Miami Air CPB, from Dominican Republic, 8.vii.2011, Capsicum sp. (Pepper), APMFL111896766003

 - Chionomus havanae - intercepted Otay Mesa CBP, CA from Mexico, 3 Nov. 2008 Carica papaya (on fruit) (papaya).

- Delphacini (♀), possibly Delphacodes lutulenta - intercepted San Luis CBP, AZ from Mexico 6 Jul 2009, on automobile.

- Delphacini (♀), possibly Delphacodes lutulenta - intercepted San Luis CBP, AZ from Mexico 6 May 2009, on Origanum majorana (Marjoram).

- Delphacini (♀), possibly Sogatella kolophon - intercepted Philadelphia CBP, PA from Costa Rica, 8 May 2009 on Ananas comosus (Bromeliaceae, Pineapple).

- Delphacini (♀), possibly Delphacodes nr campestris - intercepted  Otay Mesa CBP, CA from Mexico 1 Feb. 2009, on Mentha sp. (mint).

- Delphacini (♀), possibly Delphacodes latidens; intercepted AZ, Nogales CPB, from Mexico; on Zea mays (APTAZ101306168011)

- Delphacini (♀), intercepted San Francisco CBP, CA from Mexico 12 Jan 2010 on Ocimum basilcum (basil).

- Delphacini (♀), intercepted San Luis CBP, AZ, from Mexico, 27 Jul 2009 in travelers bag of hitch hiker.

- Delphacini (♀), intercepted Calexico CPB East, CA from Mexico 19 Nov 2008 on Petroselinum crispum (Parsley).

- Delphacini (♀), intercepted Calexico CPB East, CA from Mexico 22 Dec. 2008 on Coriandrum sativum (Coriander).

- Delphacini (♀), possibly Euides sp., intercepted FL, Miami Sea CBP, from Panama, 15.xi.2010 ex Ananas comosus (Pineapple), with fruit (APMFL103191485001)

- Delphacini (♀), poss. Metadelphax propinqua, intercepted Otay Mesa CBP, CA from Mexico 11.ii.2011 on Coriandrum sativum (Coriander) (APSCA110426661001).

- Delphacini (♀), poss. Metadelphax propinqua, intercepted AZ, San Luis CPB, AZ, from Mexico; 27.v.2010, on Thymus vulgarus (common thyme); APTAZ101472913012.

- Delphacini (♀), intercepted Miami Air CBP, FL from Guatemala, 22 Mar 2009, on Lactuca sp. (Lettuce)

- Delphacini (♀), poss. Metadelphax propinqua, intercepted Calexico CPB East, CA from Mexico 21 Feb 2009 on Anethum graveolens (Dill).

- Delphacini (♀), poss. Metadelphax propinqua, intercepted NY NY JFK CBP, from Ecuador, 20.iii.2011, on Ocimum basilicum (sweet basil) (APNNY11079474003)

- Delphacini (nymph), intercepted JFK CPB NY, from Columbia 20 Sept 2008, Origanum sp. (a mint)

- Delphacini (♀),  possibly Nothodelphax sp., intercepted Los Angeles CBP, CA from Columbia 08 Apr 2010 on Alstroemeria sp. (Peruvian Lily or Lily of the Incas, Alstroemeriaceae) (the genus can not be confirmed by a female; if it is Nothodelphax it did not originate form Columbia but probably is from the local fauna; the genus is very common in California).

- Delphacini (♀), possibly Sogatella furcifera (but the specimen appears too pale); intercepted Houston Sea CBP, TX from Viet Nam, 12 Nov 2010, with equipment (APHTX103192700001)

- Delphacini (♀), possibly Sogatella kolophon; Intercepted FL, Miami Air CPB, from Ecuador, 17.xi.2010; on Solidago sp. (goldenrod) (APMFL103215868013)

- Delphacini (♀), possibly Toya nigra, FL Miami Air CPB, ex Columbia, 16.ii.2011, ex Cut flowers, APMFL110471952007

- Delphacini (♀), possibly Toya sp. FL Miami Air CPB, ex Peru 13.v.2009, Origanum majorana (sweet marjoram) (APMF091333336036)

- Delphacodes nr campestris (♂) - intercepted Otay Mesa CBP, CA from Mexico, 3 Nov. 2008

- Delphacodes nr campestris (2 ♂) - intercepted Calexico, CA from Mexico 19 Dec 2008; 3 specimens: 2 on Coriandrum sativum (Coriander); 1 on Petroselinum crispum (Parsley).

- Delphacodes nr campestris (♂) - intercepted Calexico, CA from Mexico 9 Dec 2008; on Brassica oleracea var. acephala (kale or collard greens).

- Delphacodes nr campestris (♂) - intercepted San Luis CBP, AZ from Mexico 26 June 2008 on Citrullus lanatus (watermelon).

 - Delphacodes fulvidorsum (2♂, 1♀), intercepted Otay Mesa CBP, CA from Mexico, 5 Jan 2009, Brassica chinensis (bok choy).

 - Delphacodes prob. nigripennis (Crawford) (♂) - intercepted Otay Mesa CBP, CA from Mexico 25 Oct 2009 on Spinacia oleracea (spinach).

 - Delphacodes prob. nigripennis (Crawford) (♂) - intercepted Otay Mesa CBP, CA from Mexico 4 Dec 2008 on Ocimum basilcum (basil).

 - Delphacodes pacifica (♂) - intercepted Otay Mesa CBP, CA from Mexico, 5 Jan 2009, on Origanum sp.

 - Euides weedi (♂) - intercepted Port Manatee CBP, FL from Honduras 19 Feb 2010 on Cucumis melo (Melon).

 - Euides weedi (♂) - intercepted TX Dallas/Fort Worth CPB, ex from Netherlands, 12.v.2010; Hydrangea sp. on cut flower stem APHTX101326191004 (note: Euides weedi is a North American species)

- Laodelphax striatellus (1♀) - Intercepted TX, Houston Sea CBP, from Italy; 26.x.2010; with tiles (APHTX102992700007)).

- Megamelus sp. (2 males, poss. electrae; will check) - intercepted Miami Air CPB, FL from Haiti, 25 Jan 2008, 'at large'.

- Megamelus sp. (1♀) - intercepted Miami Air CBP, FL, from Columbia, 10.vii.2010, ex Dianthus sp., with cut flowers (APMFL101913353006)

- Metadelphax propinqua (♂) - intercepted Calexico, CA, from Mexico, 31 Oct 2008; on Brassica oleracea var. cephala.

- Metadelphax propinqua (♂) - intercepted Otay Mesa, CA, from Mexico, 2 Dec 2009; on Anethum graveolens (Dill)

- Metadelphax propinqua (2♂) - intercepted A, Calexico, CBP East, from Mexico, 16 April 2010; on Brassica chinensis (pak choi); APSCA101071551006 (specimens are washed-out pale, but clearly this species).

 

 - Nilaparvata lugens - intercepted Tampa CBP. FL from Viet Nam, 16 Feb 2010, with ceramic wares.

 - Nilaparvata lugens - intercepted CA, Los Angeles CBP; from Singapore, 30.v.2009; ex Dendrobium sp. (Orchid) APLCA091504874001.

- Nilaparvata probably lugens (1♀), GA Atlanta CPB, from South Korea, 25.11.2010, Nephelium lappaceum (rambutan); (APAGA103295500003)

 - Peregrinus maidis - intercepted San Francisco, CA, 2 Mar. 2007, from Mexico, on Anethum graveolens (Dill).

 - Peregrinus maidis - intercepted Nogales, AZ from Mexico, on corn (Zea mays); 6.v.2008 AND 7.v.2008 AND 29.vii.2009.

 - Peregrinus maidis - intercepted Los Angeles CBP, CA from Peru, 26 Apr 2010 on Lycopodium sp. (clubmoss).

 - Peregrinus maidis - intercepted Miami Air CBP, FL from Costa Rica, 16 Dec. 2009 on Agapanthus sp. ("Lily of the Nile", Agapanthaceae).

 - Peregrinus maidis - (1 male, 2 nymphs) intercepted Miami Air CBP, FL from Haiti 13.ix.2009 ex Zea mays (APMFL092596563001)

 - Peregrinus maidis - (1♀) CA, San Diego, CBP, from Ecuador, 20.vi.2011, ex Ananas comosus (Pineapple) (APSCA111716593003)

- Sardia rostrata - intercepted Honolulu predeparture PPQ, Hawaii 27 Jan 2009 on Ocimum sp. (a mint; [basal?) (this is the specimen identified as Neosydne above; this species is introduced to Hawaii)

 - Tagosodes sp. (♀) poss. approximatus (not cubanus or orizicolus)- intercepted Miami Air CBP, FL from Peru, 15 May 2009 on Lactuca satvia (Lettuce) (2 specimens, 2nd was Chionomus)

- Tagosodes orizicolus (♂) - intercepted Philadelphia CBP, PA from Costa Rica, 27 Apr 2010 Cucumis melo (with fruit) (Melon).

- Tagosodes orizicolus (♂) - intercepted Miami Air CBP, FL from Columbia, 30 Jan 2010 on Ocimum basilcum (basil).

- Tarophagus colocasiae (1♂, 1♀) intercepted JFK CPB, NY from Columbia on 21 Apr 2008, on Origanum sp. (a mint) (This is an odd interception - Tarophagus, the taro planthoppers, are Old World).

- Tarophagus colocasiae (2♂, 2♀, 3 nymphs) - Intercepted NV, Los Vegas CBP, from Philippines, 22.v.2009; on unknown plant; (APLNV091460593001; TSU 1003399)

 

- Toya nigra (♂), Intercepted San francisco CPB from Mexico 17 Nov 2008 on Origanum vulgarae (oregano).

 

Dictyopharidae

1 nymph (possibly Dictyophara europaea): - intercepted from JFK CPB, NY, from Netherlands, 2 Dec 2009 on Berzelia sp. (a shrub in the Bruniaceae).