Journal Articles

Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915

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    Stronger Antipredatory Vigilance of Prey to Olfactory Cues From Injured Vulnerable Conspecifics
    (British Ecological Society and John Wiley and Sons Ltd, 2025-10-06) Simkhada R; Kundun J; Sofkova-Bobcheva S; He XZ
    Predation risk is a key evolutionary force shaping prey behaviors and life-history strategies across taxa. Predators often target vulnerable life stages of prey, but how prey females adjust their reproductive strategies in response to cues from injured conspecifics of these stages remains unclear, particularly in haplodiploid species, where mothers can adjust offspring sex ratios in response to social environments. Using the predatory mite Phytoseiulus persimilis and its prey, the spider mite Tetranychus ludeni, we first investigated the stage-specific vulnerability by exposing T. ludeni eggs, deutonymphs, and female adults to P. persimilis for choice. We then tested whether ovipositing T. ludeni females adjusted reproductive performances and survival when exposed to potential predatory cues from those injured conspecifics. Results show that P. persimilis significantly preferred T. ludeni eggs for feeding, indicating their higher vulnerability to predators. T. ludeni females responded most strongly to potential predatory cues from injured eggs, reducing fecundity and producing smaller eggs, but without trading off their longevity. Additionally, when exposed to injured adult cues, T. ludeni females adjusted offspring sex ratios, producing more dispersing daughters by fertilizing more smaller eggs, an evolved strategy to escape from the risky environments. In contrast, egg hatching and immature survival were unaffected by conspecific cues. Our results demonstrate that T. ludeni females may discriminate among cues from injured conspecifics of different life stages, with the strongest vigilance elicited by cues from the most vulnerable stage (i.e., eggs). This study highlights the role of indirect, life stage-specific cues in shaping antipredator strategies and reveals that non-consumptive effects of predation risk could influence prey population dynamics in ways beyond direct predation. Our findings provide a mechanistic understanding of reproductive plasticity in haplodiploid systems, offering new insights into how prey balance current and future reproductive investments under predation pressure.
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    Development of Biphasic Culture System for an Entomopathogenic Fungus Beauveria bassiana PfBb Strain and Its Virulence on a Defoliating Moth Phauda flammans (Walker)
    (MDPI (Basel, Switzerland), 2025-03-05) Gao Y-P; Shi D-X; Li Y-H; He XZ; Wang X-Y; Lin K; Zheng X-L
    Beauveria bassiana PfBb is a new strain with high host specificity to the target pest Phauda flammans. We conducted a series of experiments to optimize the biphasic fermentation system of B. bassiana PfBb by screening the medium compositions and fermentation environmental conditions in both liquid and solid fermentations. In the liquid fermentation, glucose and yeast extract with a C:N ratio of 17:1 were the optimal carbon and nitrogen sources, respectively, for B. bassiana PfBb mycelium growth and blastospore production, and liquid fermentation with an inoculation concentration of 1 × 108/mL and an inoculum content of 50 mL conidial suspension, at 180 rpm/min rotation speed, pH 7 and 26 °C, favored mycelium growth. However, additional trace elements did not significantly improve liquid fermentation. In the solid fermentation, wheat bran and chaff at a ratio of 8:2 were identified as the best substrates that facilitated B. bassiana PfBb sporulation and conidial germination, and optimal substrates with 20% inoculum content, 50% water content, and 3-day fermentation in darkness had the highest conidia yield. The resulting conidia, stored at −20, 4, and 20 °C for one year, did not significantly change the water content, and with prolonged storage duration, conidial germination was significantly higher at −20 and 4 °C. Moreover, conidia stored at 4 °C for one year maintained its validity and virulence, which were toxic to all instar larvae of P. flammans. Our results provide essential support for the commercial production of B. bassiana PfBb-based biopesticides.
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    Reproductive plasticity in response to the changing cluster size during the breeding period: a case study in a spider mite
    (Springer Nature, 2023-10) Weerawansha N; Wang Q; He XZ
    Animals living in clusters should adjust their reproductive strategies to adapt to the social environment. Theories predict that the benefits of cluster living would outweigh the costs of competition. Yet, it is largely unknown how animals optimize their reproductive fitness in response to the changing social environment during their breeding period. We used Tetranychus ludeni Zacher, a haplodiploid spider mite, to investigate how the ovipositing females modified their life-history traits in response to the change of cluster size (i.e., aggregation and dispersal) with a consistent population density (1 ♀/cm2). We demonstrate that (1) after females were shifted from a large cluster (16 ♀♀) to small ones (1 ♀, 5 and 10 ♀♀), they laid fewer and larger eggs with a higher female-biased sex ratio; (2) after females were shifted from small clusters to a large one, they laid fewer and smaller eggs, also with a higher female-biased sex ratio, and (3) increasing egg size significantly increased offspring sex ratio (% daughters), but did not increase immature survival. The results suggest that (1) females fertilize more larger eggs laid in a small population but lower the fertilization threshold and fertilize smaller eggs in a larger population, and (2) the reproductive adjustments in terms of egg number and size may contribute more to minimize the mate competition among sons but not to increase the number of inhabitants in the next generation. The current study provides evidence that spider mites can manipulate their reproductive output and adjust offspring sex ratio in response to dynamic social environments.
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    Life history and behavior of Tamarixia triozae parasitizing the tomato-potato psyllid, Bactericera cockerelli
    (Elsevier B V) Chen C; He XZ; Zhou P; Wang Q
    Tamarixia triozae is an important primary parasitoid of the tomato-potato psyllid, Bactericera cockerelli, a serious cosmopolitan pest of solanaceous crops. However, without better information about its life history and behavior, it will be difficult to use this parasitoid in effective biological control programs. We carried out a series of experiments to characterize its parasitism, adult feeding, and oviposition behaviors and its sex allocation in response to different life stages of its host, and their fitness consequences. We show that T. triozae females fed on all host instars with a preference for mid-aged ones, and preferred to parasitize later instars, thus inflicting mortality on all instars simultaneously. Host feeding and parasitism peaked during the first week of female life and declined markedly after two weeks. Parasitoids allocated more fertilized eggs to older and larger nymphs, and super-parasitism declined with increasing host density. The oviposition rate of fertilized eggs peaked when females were four to five days old, with >90% of daughters produced during the first half of adult life. The body size and egg loads of progeny increased with increasing host instar at parasitism, demonstrating a positive relationship between the host size and offspring fitness.
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    Attraction of the Indian Meal Moth Plodia interpunctella (Lepidoptera: Pyralidae) to Commercially Available Vegetable Oils: Implications in Integrated Pest Management
    (2024-09-06) Liu J; Yu Z; He XZ; Zhou G; Guo M; Deng J
    The Indian meal moth, Plodia interpunctella, poses a significant threat to global agricultural products. Although pheromone-based technologies show promise for P. interpunctella management, limitations such as single-sex targeting necessitate exploring complementary strategies. Vegetable- based oils represent a potential alternative but their efficacy, sex-specificity, and interaction with sex pheromones remain unclear. To address these questions, we first examined the attraction of P. interpunctella female and male adults to 10 commercially available vegetable oils in semi-field conditions. Sesame, olive, and blended oils were the most attractive, capturing significantly more adults compared to other oils. We then evaluated the effectiveness of these three attractive oils and their combinations with P. interpunctella sex pheromones in a grain warehouse. Traps baited with these oils captured significantly more females and males compared to control traps without attractants; however, the addition of sex pheromones did not improve male capture and significantly reduced female capture, suggesting an inhibitory effect. Finally, we demonstrated that female mating status (mated vs. virgin) did not influence the attractiveness of traps baited with these effective oils. Our findings highlight the potential of standalone traps baited with blended, olive, or sesame oil as a practical, economic, and effective management strategy for P. interpunctella in storage facilities.
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    Diets for Tamarixia triozae adults before releasing in augmentative biological control
    (Springer Nature, Switzerland AG for International Organization for Biological Control, 2022-06) Chen C; He XZ; Zhou P; Wang Q; Riddick E
    The effectiveness of augmentative biological control using parasitoids often depends on their physiological state and the pest population density at the time of release. Tamarixia triozae (Burks) (Hymenoptera: Eulophidae) is a primary host-feeding parasitoid of a serious invasive pest Bactericera cockerelli (Šulc) (Hemiptera: Triozidae). Here we investigated the effects of adult diets (honey, water, yeast, and hosts) and timing of their provision on T. triozae fitness and oviposition patterns, providing knowledge for enhancement of its biological control potential. Adults fed with honey for four days with no access to hosts or with water or yeast for one day followed by host feeding for three days had similar longevity and lifetime pest killing ability. Adults fed with only water for one day before release had significantly greater intrinsic rate of increase, shorter doubling time, and higher daily fecundity peak. Adults fed with honey or yeast for one day followed by host feeding for three days significantly flattened their daily oviposition curves. These findings have several implications for augmentative biological control using T. triozae. First, honey diet may allow at least four days for successful shipment of host-deprived adults without compromising biological control effectiveness. Second, the release of host-deprived adults with one-day water feeding may achieve rapid pest suppression when the pest population density is high. Finally, releasing host-deprived adults with one-day honey or yeast feeding followed by three-day host feeding can increase their establishment success and reduce the risk of massive removal of hosts when the pest population density is low.
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    Tolerance of plantain (Plantago lanceolata) to translocated herbicides wiped on flower stems
    (2024-07-08) Shrivastav N; Harrington KC; Kemp PD; He XZ; Ghanizadeh H
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    Pupal cues increase sperm production but not testis size in an insect
    (MDPI AG (Basel, Switzerland), 2021-07-28) Liu J; He XZ; Zheng X-L; Zhang Y; Wang Q; Hoffmann KH
    Theoretic and empirical studies show that social surroundings experienced by male insects during their larval or adult stage can influence their testicular investment in diverse ways. Although insect pupae do not feed and crawl, they can communicate using sex-specific and/or non-sex specific cues. Yet, it is unknown, in any insect, whether and how male pupae can fine-tune their resource allocation to sperm production and testis size in response to socio-sexual environments. We investigated this question using a moth, Ephestia kuehniella, which produces fertile eupyrene sperm and unfertile apyrene sperm. We held male pupae individually or in groups with different sex ratios, and dissected adults upon eclosion, measured their testis size, and counted both types of sperm. We demonstrated that after exposure to conspecific pupal cues regardless of sex, male pupae increased production of eupyrenes and apyrenes at the same rate but kept testis size unchanged. We suggest that testis size is fixed after pupation because most morphological traits are formed during the larval stage, allowing little room for pupae to adjust testis size. Like adults, male pupae with fully grown testes have sufficient resources to produce more sperm of both types according to the perceived increase in sperm competition risk