Impact of citrus species on the biological characteristics and life table parameters of Eutetranychus orientalis (Klein) (Acari: Tetranychidae)

Biological characteristics and life table parameters of Eutetranychus orientalis (Klein) were revealed on four different citrus species: grapefruit (Citrus paradisi Macf. cv. Star Ruby), lemon (C. limon (L.) Burm. f. cv. Meyer), mandarin (C. reticulata Blanco cv. Okitsu) and orange (C. sinensis L. cv. Washington Navel) under laboratory conditions. Results show that oviposition period, fecundity, and life table parameters varied significantly depending on the host plant species. Furthermore, host plant species had little effect on immature development, except for the teleiochrysalis and total developmental period, which was significantly shorter on lemon (13.77 days for females, 12.67 days for males). Total mean numbers of eggs laid by E. orientalis was 15.92 on mandarin and 29.78 on lemon. In addition, intrinsic rate of increase (rm), net reproductive rate (R0), finite rate of increase (λ) and doubling time (DT) are 0.12 day–1, 10.41 ♀/♀, 1.13 day–1 and 5.59 days for lemon, 0.17 day–1, 22.36 ♀/♀, 1.19 day–1 and 4.04 days for grapefruit, respectively. However, shortest and longest mean generation times (To) were obtained at 18.26 days on orange and 19.37 days on grapefruit. Our results demonstrate that intergeneric differences of Citrus should be considered when determining E. orientalis population abundance and dynamics in field conditions.

Effect of host plant on the life history of the carnation tortrix moth Cacoecimorpha pronubana (Lepidoptera: Tortricidae)

The carnation tortrix moth, Cacoecimorpha pronubana (Hübner, [1799]) (Lepidoptera: Tortricidae), is one of the most economically important insect species affecting the horticultural industry in the UK. The larvae consume foliage, flowers or fruits, and/or rolls leaves together with silken threads, negatively affecting the growth and/or aesthetics of the crop. In order to understand the polyphagous behaviour of this species within an ornamental crop habitat, we hypothesized that different host plant species affect its life history traits differently. This study investigated the effects of the host plant species on larval and pupal durations and sizes, and fecundity (the number of eggs and the number and size of egg clutches). At 20°C, 60% RH and a 16L:8D photoperiod larvae developed 10, 14, 20 and 36 days faster when reared on Christmas berry, Photinia (Rosaceae), than on cherry laurel, Prunus laurocerasus (Rosaceae), New Zealand broadleaf, Griselinia littoralis (Griseliniaceae), Mexican orange, Choisya ternata (Rutaceae), and firethorn, Pyracantha angustifolia (Rosaceae), respectively. Female pupae were 23.8 mg heavier than male pupae, and pupal weight was significantly correlated with the duration of larval development. The lowest and the highest mean numbers of eggs were produced by females reared on Pyracantha (41) and Photinia (202), respectively. Clutch size differed significantly among moths reared on different host plants, although the total number of eggs did not differ. This study showed that different ornamental host plants affect the development of C. pronubana differently. Improved understanding of the influence of host plant on the moth's life history parameters measured here will help in determining the economic impact that this species may have within the ornamental plant production environment, and may be used in developing more accurate crop protection methodologies within integrated pest management of this insect.

What should a poor mother do? Influence of host plant quality on oviposition strategy and behavior in a polyphagous moth

To maximise fitness, individuals may apply different reproductive strategies. Such strategies could be phenotypically plastic and vary depending on the environment. For example, when resources are limited females often face a trade-off between investing in offspring quantity and quality, and how she balances this trade-off may depend on the environment. For phytophagous insects, and especially generalist insects, variation in host plant quality could have large effects on mating, reproduction and offspring performance. Here, we study if the polyphagous moth Spodoptera littoralis, which selects host plants through experience-based preference induction, also has a flexible allocation between egg weight and egg number as well as in temporal egg-laying behavior depending on larval host plant species. We found that S. littoralis has a canalized egg size and that an increased reproductive investment is made in egg quantity rather than egg quality. This increased investment depends on larval host plant species, probably reflecting parental condition. The constant egg weight may be due to physiological limitations or to limited possibilities to increase fitness through larger offspring size. We furthermore found that differences in onset of egg-laying is mainly due to differences in mating propensity between individuals raised on different host plant species. Thus, females do not seem to make a strategic reproductive investment in challenging environments. Instead, the low-quality host plant induces less and later reproduction, which could have consequences for population dynamics in the field.

First report of the leaf-mining genus Parornix Spuler from China, with descriptions of two new species (Lepidoptera, Gracillariidae, Parornichinae)

The subfamily Parornichinae and thus the genus Parornix Spuler, 1910 are reported for the first time in China. Two new species, P. sinensis Liu, sp. n. feeding on Amygdalus davidiana and P. yuliella Liu & Teng, sp. n. on Cerasus japonica, are described herein. Both host plant species belong to Rosaceae. Adult, genitalia of both sexes, and leaf mines are described and illustrated for both species. A Maximum Likelihood tree based on DNA barcodes available for Parornix is also provided for species separation. Reference barcodes for both new species are generated.

Diversity of insect galls from Mato Grosso State, Brazil: Cerrado

The Midwest region of Brazil possesses large areas dominated by the Cerrado that is poorly known concerning insect gall and their interactions. In this study, we inventory the gall morphology, host plants, and the gall makers from Parque Nacional da Chapada dos Guimarães, Mato Grosso State, in areas of natural vegetation from Cerrado, for the first time. Samplings occurred in two expeditions, July 2012 and January 2013. We characterized 295 morphotypes of insect galls in 140 host plant species, with 89 gall makers; the richest family in host plants was Fabaceae (16.7%), and the species was Protium heptaphyllum (Aubl.) Marchand (Burseraceae, 3.7%). Parque Nacional da Chapada dos Guimarães is the richest Brazilian cerrado area in gall morphotypes (295) and the second in average morphotypes/host plant species (2.1). Additionally, six genera and 38 species are new records as host plants; two of them, Bernardia similis Pax and K.Hoffm and Ormosia macrophylla Benth., are new occurrences for Mato Grosso State, and other two, Vochysia petraea Warm. and Talisia subalbens (Mart.) Radlk. are listed in the Red List of Threatened Species IUCN. This inventory data represents a testimony of insect-plant interactions in a Brazilian Cerrado area that was consumed by an unprecedented fire in the dry season of 2020.