Mealybug Explained

Mealybugs are insects in the family Pseudococcidae, unarmored scale insects found in moist, warm habitats. Of the more than 2000 described species, many are considered pests as they feed on plant juices of greenhouse plants, house plants and subtropical trees and also act as a vector for several plant diseases. Some ants live in symbiotic relationships with them, protecting them from predators and feeding off the honeydew which they excrete.

Description

Mealybugs are sexually dimorphic: females appear as nymphs, exhibiting reduced morphology, and lack wings, although unlike many female scale insects, they often retain legs and can move. Males are smaller, gnat-like and have wings. Since mealybugs (as well as all other Hemiptera) are hemimetabolous insects, they do not undergo complete metamorphosis in the true sense of the word. However, male mealybugs do exhibit a radical change during their life cycle, changing from wingless, ovoid nymphs to wasp-like flying adults.

Mealybug females feed on plant sap, normally in roots or other crevices, and in a few cases the bottoms of stored fruit. They attach themselves to the plant and secrete a powdery wax layer (hence the name "mealy" bug) used for protection while they suck the plant juices. In Asia, mango mealybug is considered a major menace for the mango crop. The males on the other hand are short-lived as they do not feed at all as adults and only live to fertilize the females. Male citrus mealy bugs fly to the females and resemble fluffy gnats.

Some species of mealybug lay their eggs in the same waxy layer used for protection in quantities of 50–100; other species are born directly from the female.

The most serious pests are mealybugs that feed on citrus; other species damage sugarcane, grapes, pineapple (Jahn et al. 2003), coffee trees, cassava, ferns, cacti, gardenias, papaya, mulberry, sunflower and orchids. Mealybugs only tend to be serious pests in the presence of ants because the ants protect them from predators and parasites.^[1] Mealybugs are also a vector of viruses in grapevines, spreading grapevine leafroll and grapevine red blotch viruses.^[2] Mealybugs also infest some species of carnivorous plant such as Sarracenia (pitcher plants); in such cases it is difficult to eradicate them without repeated applications of insecticide such as diazinon. Small infestations may not inflict significant damage. In larger amounts though, they can induce leaf drop. In recent years, some of the mealybug species have become invasive pests in localities posing a great problem to the new agro-ecosystems. In India, Withania somnifera plant have been reported as a new reservoir host for an invasive mealybug species Phenacoccus solenopsis.^[3]

Some mealybugs of the Hypogeococcus are used as biological pest controls of invasive cacti in South Africa, including Harrisia balansae, H. martinii, and Opuntia cespitosa.^[4]

Fossil specimens of genus Acropyga ants have been recovered from the Burdigalian stage Dominican amber deposits and several individuals are preserved carrying the extinct mealybug genus Electromyrmococcus.^[5] These fossils represent the oldest record of the symbiosis between mealybugs and Acropyga species ants.^[5]

Control methods

Insecticides such as pyrethroids (e.g. permethrin, bifenthrin, cyfluthrin) have been used for control,^[6] but this approach is often considered counter-productive due to mortality of mealybug natural enemies.

Some gardeners use species of predatory beetles (e.g. Cryptolaemus) and green lacewings (Chrysopidae) larvae to control mealybug infestations, as the larval lacewings are voracious predators of aphids and other small insects.^[7]

Metabolism

Mealybugs have a highly sophisticated metabolism that involves not one but two bacterial endosymbionts, one inside the other. The endosymbionts make essential amino acids that the mealybug is not able to acquire directly from its diet. Genetically, mealybugs rely on a "mosaic" of metabolic pathways in which proteins are transported across membranes between what were once independent organisms.^[8]

Use in the Textile Industry

In Oaxaca Mexico, where mealybugs are known as cochinilla algodonosa, the insects are intentionally cultivated and farmed. Dried mealybugs are traditionally ground into a red dust, which is used to dye fabrics.

Genera

The following are included in BioLib.cz:^[9]

1. Acaciacoccus
2. Acinicoccus
3. Acrochordonus
4. Adelosoma
5. Aemulantonina
6. Agastococcus
7. Albertinia (bug)
8. Allococcus
9. Allomyrmococcus
10. Allotrionymus
11. Amonostherium
12. Anaparaputo
13. Anisococcus
14. Annulococcus
15. Anthelococcus
16. Antonina
17. Antoninella
18. Antoninoides
19. Apodastococcus
20. Archeomyrmococcus
21. Artemicoccus
22. Asaphococcus
23. Asphodelococcus
24. Asteliacoccus
25. Atriplicicoccus
26. Atrococcus
27. Australicoccus
28. Australiputo
29. Balachowskya
30. Balanococcus
31. Benedictycoccina
32. Bessenayla
33. Birendracoccus
34. Bolbococcus
35. Boninococcus
36. Boreococcus
37. Borneococcus
38. Bouhelia
39. Brevennia
40. Brevicoccus
41. Calicoccus
42. Callitricoccus
43. Calyptococcus
44. Cannococcus
45. Casuarinaloma
46. Cataenococcus
47. Caulococcus
48. Chaetococcus
49. Chaetotrionymus
50. Chloeoon
51. Chlorizococcus ^[10]
52. Chlorococcus
53. Chryseococcus
54. Cintococcus
55. Circaputo
56. Clavicoccus
57. Coccidella
58. Coccidohystrix
59. Coccura
60. Coleococcus
61. Conicoccus
62. Conicosoma
63. Conulicoccus
64. Coorongia
65. Cormiococcus
66. Crenicoccus
67. Criniticoccus
68. Crisicoccus
69. Crocydococcus
70. Cryptoripersia
71. Cucullococcus
72. Cyperia
73. Cypericoccus
74. Cyphonococcus
75. Dawa (bug)
76. Delococcus
77. Delottococcus
78. Dicranococcus
79. Discococcus
80. Distichlicoccus
81. Diversicrus
82. Doryphorococcus
83. Drymococcus
84. Dysmicoccus
85. Eastia
86. Ehrhornia
87. Epicoccus
88. Eriocorys
89. Erioides
90. Erium
91. Eucalyptococcus
92. Eumirococcus
93. Eumyrmococcus
94. Eupeliococcus
95. Euripersia
96. Eurycoccus
97. Exallomochlus
98. Exilipedronia
99. Extanticoccus
100. Farinococcus
101. Ferrisia
102. Ferrisicoccus
103. Fijicoccus
104. Fonscolombia
105. Formicococcus
106. Gallulacoccus
107. Geococcus (bug)
108. Glycycnyza
109. Gouxia
110. Gomezmenoricoccus
111. Greenoripersia
112. Grewiacoccus
113. Grewiacococcus
114. Hadrococcus
115. Hambletonrhizoecus
116. Heliococcus
117. Hemisphaerococcus
118. Heterococcopsis
119. Heterococcus (bug)
120. Hippeococcus
121. Hopefoldia
122. Hordeolicoccus
123. Humoccoccus
124. Humococcus
125. Hypogeococcus
126. Iberococcus
127. Idiococcus
128. Inopicoccus
129. Ityococcus
130. Kaicoccus
131. Kenmorea
132. Kermicus
133. Kiritshenkella
134. Lachnodiella
135. Lachnodiopsis
136. Lacombia
137. Laingiococcus
138. Laminicoccus
139. Lanceacoccus
140. Lantanacoccus
141. Lenania
142. Leococcus
143. Leptococcus
144. Leptorhizoecus
145. Liucoccus
146. Lomatococcus
147. Londiania
148. Longicoccus
149. Maconellicoccus
150. Macrocepicoccus
151. Macrocerococcus
152. Maculicoccus
153. Madacanthococcus
154. Madagasia
155. Madangiacoccus
156. Madeurycoccus
157. Malaicoccus
158. Malekoccus
159. Mammicoccus
160. Marendellea
161. Mascarenococcus
162. Maskellococcus
163. Mediococcus
164. Melanococcus
165. Metadenopsis
166. Metadenopus
167. Miconicoccus
168. Mirococcopsis
169. Mirococcus
170. Miscanthicoccus
171. Misericoccus
172. Mollicoccus
173. Mombasinia
174. Moystonia
175. Mutabilicoccus
176. Naiacoccus
177. Nairobia
178. Natalensia
179. Neochavesia
180. Neoclavicoccus
181. Neorhizoecus
182. Neoripersia
183. Neosimmondsia
184. Neotrionymus
185. Nesococcus
186. Nesopedronia
187. Nesticoccus
188. Nipaecoccus
189. Octococcus
190. Odacoccus
191. Ohiacoccus
192. Oracella
193. Orstomicoccus
194. Oudablis
195. Oxyacanthus
196. Palaucoccus
197. Palmicultor
198. Paludicoccus
199. Pandanicola
200. Papuacoccus
201. Paracoccus
202. Paradiscococcus
203. Paradoxococcus
204. Paraferrisia
205. Paramococcus
206. Paramonostherium
207. Paramyrmococcus
208. Parapaludicoccus
209. Parapedronia
210. Paraputo
211. Pararhodania
212. Paratrionymus
213. Pedrococcus
214. Pedronia
215. Peliococcopsis
216. Peliococcus
217. Pellizzaricoccus
218. Penthococcus
219. Peridiococcus
220. Perystrix
221. Phenacoccopsis
222. Phenacoccus
223. Pilococcus
224. Planococcoides
225. Planococcus
226. Pleistocerarius
227. Plotococcus
228. Poecilococcus
229. Polystomophora
230. Porococcus
231. Promyrmococcus
232. Prorhizoecus
233. Prorsococcus
234. Pseudantonina
235. Pseudococcus
236. Pseudorhizoecus
237. Pseudorhodania
238. Pseudoripersia
239. Pseudotrionymus
240. Pygmaeococcus
241. Quadrigallicoccus
242. Radicoccus
243. Rastrococcus
244. Renicaula
245. Rhizoecus
246. Rhodania
247. Ripersia
248. Ritsemia
249. Saccharicoccus
250. Saliococcus
251. Sarococcus
252. Scaptococcus
253. Seabrina
254. Serrolecanium
255. Seyneria
256. Sinococcus
257. Spartinacoccus
258. Sphaerococcus
259. Spilococcus
260. Stachycoccus
261. Stemmatomerinx
262. Stipacoccus
263. Strandanna
264. Strombococcus
265. Synacanthococcus
266. Syrmococcus
267. Takahashicoccus
268. Tasmanicoccus
269. Thaimyrmococcus
270. Tomentocera
271. Trabutina
272. Trabutinella
273. Trechocorys
274. Tridiscus
275. Trimerococcus
276. Trionymus
277. Trochiscococcus
278. Tylococcus
279. Tympanococcus
280. Ventrispina
281. Villosicoccus
282. Volvicoccus
283. Vryburgia
284. Xenococcus
285. Yudnapinna

Extinct genera:

• †Electromyrmococcus
• †Phyllococcus (monotypic)

Note:

• the genus Puto is now placed in its own family
• Lachnodius is now placed in the Eriococcidae

Further reading

• Jahn, G. C. and J. W. Beardsley (1994). "Big-headed ants, Pheidole megacephala: Interference with the biological control of gray pineapple mealybugs". In D.F. Williams [ed.] Exotic Ants: Biology, Impact and Control of Introduced Species. Boulder, Col.: Westview Press, 199–205. .
• Jahn, G. C. and J. W. Beardsley (1998). "Presence/absence sampling of mealybugs, ants, and major predators in pineapple". J. Plant Protection in the Tropics 11(1):73–79.
• Jahn, Gary C., J. W. Beardsley, and H. González-Hernández (2003). "A review of the association of ants with mealybug wilt disease of pineapple". Proceedings of the Hawaiian Entomological Society. 36:9–28.

External links

• NCIPM (National Centre for Integrated Pest Management) – Cotton Mealybugs
• Mealy bugs Pseudococcus spp.—BBC gardening advice
• CISR – Vine Mealybug—Center for Invasive Species Research summary on Vine Mealybug
• On the University of Florida / Institute of Food and Agricultural Sciences Featured Creatures website:
  • Hypogeococcus pungens
  • Nipaecoccus nipae, coconut mealybug

Notes and References

1. 3503828. Fire Ants Protect Mealybugs against Their Natural Enemies by Utilizing the Leaf Shelters Constructed by the Leaf Roller Sylepta derogata. PLOS ONE. 7. 11. e49982. November 21, 2012. Noe, Ronald. US National Library of Medicine National Institutes of Health. 23185505. 10.1371/journal.pone.0049982. 2012PLoSO...749982Z. free.
2. Web site: Bettiga . Larry J . Assessing Grapevine Leafroll and Red Blotch Disease Impacts in Local Vineyards . ANR Blogs . Salinas Valley Agriculture . 23 December 2022 . en-us . 8 September 2015.
3. Sharma, A. . Pati, P. K. . First record of Ashwagandha as a new host to the invasive mealybug (Phenacoccus solenopsis Tinsley) in India . Entomological News . 2013 . 123 . 1 . 59–62 . 10.3157/021.123.0114 . 85645762 .
4. Web site: Cactus control in the Klein Karoo . . 2014-09-17 . 2021-04-19.
5. Johnson . M.S. . 2001 . Acropyga and Azteca Ants (Hymenoptera: Formicidae) with Scale Insects (Sternorrhyncha: Coccoidea): 20 Million Years of Intimate Symbiosis . American Museum Novitates . 3335 . 1–18 . 10.1206/0003-0082(2001)335<0001:AAAAHF>2.0.CO;2. 55067700 . etal.
6. 2003 . SP290-S-Mealybugs on Ornamentals . The University of Tennessee Agricultural Extension Service. SP290S-1.5M-5/03(Rev) E12-4615-00-030-03.
7. Web site: Cryptolaemus and lacewings for mealybug and scale control . Department of Primary Studies, NSW . New South Wales . 25 May 2021.
8. Callier . Viviane . Mitochondria and the origin of eukaryotes . Knowable Magazine . 8 June 2022 . 10.1146/knowable-060822-2 . free . 18 August 2022.
9. https://www.biolib.cz/en/taxon/id17160/ BioLib.cz: family: mealybugs - Pseudococcidae Heymons, 1915
10. https://www.gbif.org/species/2093521 GBIF