Lethal and Sub-Lethal Effects of Insecticides on the Pink Hibiscus Mealybug, Maconellicoccus hirsutus (Hemiptera: Pseudococcidae)

Abstract

The pink hibiscus mealybug, Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae) is a pest of many plants, and a new problem on dates in California. The effects of seven insecticides and water on different life stages of this mealybug were studied to identify the best material for control. Water did not have any significant effect on mealybugs, but the insecticide treatments significantly affected all life stages tested. The egg hatch rate ranged from 28.5% to 17.2% for spirotetramat, bifenthrin, flupyradifurone, fenpropathrin, and buprofezin treatments, and was lower for sulfoxaflor (2.8%) and acetamiprid (0.1%). Despite high survival of neonate crawlers in the non-treated control and water treatments, 53.1% and 34.6% survived in the spirotetramat and buprofezin treatments, respectively; survival was zero in the other treatments. Spirotetramat and buprofezin caused very low mortality of nymphs in the first day post-treatment, but mortality significantly increased over time and reached 42.8% and 50.6% by day 6, respectively. The other treatments were highly toxic to the nymphs (79.4–99.4% on day 6). Insecticides also had a significant effect on the feeding ability of nymphs. By day 6 after treatment, 73.9% to 100% of nymphs treated with different insecticides stopped feeding although they were still alive. Insecticides showed no effect on the mortality of adult females, but the percentages of ovipositing females were significantly reduced (51.1% to 10.6%) in all insecticide treatments, except buprofezin, which was not statistically different from water and the non-treated control. In the process of our studies, we identified abnormalities in the appearance of eggs from females treated with various insecticides, and these aberrant eggs are described.

Spatial Roguing Reduces the Incidence of Leafroll Disease and Curtails Its Spread in a Finger Lakes Cabernet franc Vineyard

“…However, since the virus titer was not determined in the infected vines used as donor plants in this study, it is challenging to reasonably speculate on a root cause of the differential transmission rates with regards to specific viruses. Another more plausible explanation for the rate of virus spread observed in the 'Cabernet franc' study site despite low-density grape mealybugs could be the timing of spirotetramat applications that may have provided incomplete or delayed mortality, as described for the pink hibiscus mealybug (Ganjisaffar et al 2019), thus enabling some viruliferous crawlers to transmit viruses before the advent of full insecticide toxicity. Alternatively, our insect vector survey method may have underestimated mealybug abundance.…”

Integrated control of the mealybug Phenacoccus solenopsis (Hemiptera: Pseudococcidae) in Australian cotton with insecticides and naturally occurring beneficial arthropods

“…Buprofezin, a chitin biosynthesis inhibitor, has little or no effect on many beneficial arthropod species (Cloyd & Dickinson 2006) and adult mealybugs (Ganjisaffar et al . 2019), and controls population growth by adversely affecting egg hatch and preventing moulting in the juvenile stages (De Cock & Degheele 1998).…”

Laboratory evaluation of the life history of hibiscus mealybug,Nipaecocus viridis(Hemiptera: Pseudococcidae), on selected citrus and potential non-citrus hosts in Florida

“…The viability of the transferred mealybugs was confirmed after 1 h to ensure that none were killed during transfer by gently probing crawlers with a fine-tip camel-hair brush and observing for leg movement under a Leica MZ6 stereomicroscope. Mealybugs were considered dead if they failed to move their legs after probing (Ganjisaffar et al 2019) and were subsequently replaced before the start of the bioassay. Petri dish arenas were sealed with Parafilm and completely randomized within a Percival growth chamber (Model 136 LL, Percival-Scientific Inc.) maintained at 25 ± 5 °C, 70 ± 10% RH, and 16:8 h (L:D).…”

“…Adult longevity was recorded as the duration between adult eclosion and death (Pacheco da Si lva et al 2017). Mealybug viability was determined as described previously (Ganjisaffar et al 2019).…”