Planococcus ficus (Hemiptera: Pseudococcidae) movement and demography: Methods for generating cohorts for laboratory studies

Authors: Sisterson, Mark; Uchima, Sean

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2023
Publication Date: 11/18/2023
Citation: Sisterson, M.S., Uchima, S.Y. 2023. Planococcus ficus (Hemiptera: Pseudococcidae) movement and demography: Methods for generating cohorts for laboratory studies. Journal of Economic Entomology. 117(1):118-126. https://doi.org/10.1093/jee/toad210.
DOI: https://doi.org/10.1093/jee/toad210

Interpretive Summary: The vine mealybug (Planococcus ficus) is a worldwide threat to grapevine production. In California, table grape growers are currently spending $500 an acre for vine mealybug management alone. There are no known measures that can eliminate vine mealybugs from vineyards. Development of novel control methods is hampered because conducting manipulative experiments with vine mealybug is difficult. To provide methods for conducting manipulative laboratory experiments, ARS scientists in Parlier, California developed protocols for producing cohorts of mealybugs of known age and size. Results will be used to support studies on vine mealybug genomics, identification of entomopathogens, and evaluation of susceptibility to insecticides.

Technical Abstract: The vine mealybug is a worldwide pest of grapevine. Mealybugs overwinter under bark and move into the grape canopy as the season progresses. Because crawlers are more active than later stages, mealybug movement behavior is likely to be stage specific. To quantify vine mealybug population phenology and movement behavior, a series of laboratory experiments were conducted. First, vine mealybug populations were monitored on grapevine seedlings to describe survival, change in size, timing of male pupation, and timing of oviposition over a 6-week period. Subsequently, cohorts of mealybugs were generated by infesting grapevines with crawlers and holding infested grapevines for a specified duration of 0 (crawlers), 1, 2, 3, or 4 weeks. Crawlers (0-week) were more likely to move upwards and towards a light source, than all other age cohorts tested. Further, mealybugs from 4-week-old cohorts were more likely to move downward than all other age cohorts tested. Results suggest that crawlers are more likely to move to the top of grapevines by moving upwards and orienting towards either the sun or the moon than all other age-cohorts tested, whereas older gravid females are more likely to move downward. Passive movement of mealybugs on farm machinery or animals requires surviving a host free period. To quantify risk of passive movement, establishment rates and effects of starvation on each age cohort were quantified. Larger and older mealybugs were more likely to establish on grapevines than smaller and younger mealybugs. Further, mealybug longevity in absence of food was greater for older cohorts compared to younger cohorts. Crawlers survived an average of 2 days without food, whereas females from 4-week-old cohorts survived for an average of 11 days without food. Further, 70% of starved females from 4-week-old cohorts deposited fertile eggs. In the absence of food, some mealybugs from cohorts aged 2-, 3-, and 4-weeks formed pupa with viable males emerging. Adult males from starved nymphs lived for an average of 3 days post-emergence. Results provide methods for producing cohorts of mealybugs of predictable size and stage and provide insight into mealybug population phenology and movement behavior.