Diaspidid (Hemiptera: Coccoidea) size plasticity as an adaptive life history trait

Abstract

Abstract. The size and fecundity of Hemiberlesia lataniae (Signoret) (Hemiptera: Diaspididae) on partially resistant and susceptible kiwifruit (Actinidia spp.) varieties was measured. The size ratio of mature H. lataniae grown on a partially resistant genotype, compared with those on a susceptible genotype, was 0.67-0.51 for 2 nd instar exuviae area, 0.32 for adult body area and 0.18 for estimated body volume. The fertility ratio was 0.1, but the pre-oviposition period and the size of the crawlers were the same. Diaspidid scale insects' unusual ability to continue growing after the final moult appears to be a key feature allowing these insects to show extreme size plasticity while retaining the ability to reproduce even when very small. These observations challenge current theories of insect development that postulate the need to achieve a critical weight threshold before the final moult. We suggest that this strategy may have assisted the evolution of polyphagy within the Diaspididae.

The response of resistant kiwifruit (Actinidia chinensis) to armoured scale insect (Diaspididae) feeding

“…9). The insect was alive but only one-fifth of the size of a scale growing on a susceptible cane (Hill et al 2011). …”

Phylogeny and classification of armored scale insects (Hemiptera: Coccomorpha: Diaspididae)

“…Males have extremely unusual sperm, each cell having dozens of microtubules (Paoli et al 2015;Robison 1990;Ross & Normark 2015). Females continue to grow as adults, something insects are usually regarded as unable to do (Hill et al 2011). Armored scale insects include some of the most highly polyphagous species in the world, feeding on over 100 families of host plants (García Normark & Johnson 2011;Peterson et al 2015).…”

Susceptibility of kiwifruit shelter species to two armoured scale insects

“…Differences between the shelter species in the number of settled H. lataniae per cutting 1 week after being infested, and the numbers of live H. lataniae and those reaching full adult size (>1.2 mm 2 cap area (Hill et al 2011a)) per cutting at the end of the experiment were tested using one way ANOVA (Minitab 16), with log transformation where necessary. The standards were not included in the analysis, nor were shelter species that had zero settlement or survival.…”