| The zoophytophagous predator Nesidiocoris tennis (Heteroptera:Miridae) is an important natural enemies of insect pests on crops. The present dissertation was designed to investigate developmental performances affected by supplementary foods and observe5th-instar nymph, male or female N. tenuis predation behaviors on Bemisia tabaci patch and the female N. lenuis predation behaviors on different density patches of P. litura neonate. Through the biology and behavior research of N. tenuis. Main results and conclusions obtained from the study are summarized as below.1. Effects of supplementary foods on N. tenuis developmentA factorial experiment on two food factors was conducted, including four plant foods (water, sucrose solution, tomato and tobacco leaf) and two animal food treatments (with or without neonate caterpillars of P. litura).The nymph development was individually observed until adults emerged. The result showed that N. tenuis was not able to complete its nymphal development by feeding on plant foods in the absence of the animal food. The nymph can develop to adults under four plant treatments combined with caterpillars. While the survival rate under the treatment of tomato leaf plus caterpillars was highest (88%) among all treatments, it was the lowest (40.7%) under water plus caterpillar treatment, and the survival was between above treatments under sucrose or tobacco plus caterpillars. Nymph development time was15.5±0.29(mean±SE) d、15.08±0.43d、14.05±0.24d、13.53±0.33d under treatments of sucrose, water, tomato leaf and tobacco leaf, respectively. There was a significant difference in nymphal development time of females between food treatments, but not of males. The hind tibia length of female adults was significantly longer under the treatment of sucrose solution plus caterpillars than the other treatments of plant foods. The experiment result suggests that animal prey is essential but plant foods can be important to nymphal development of N. tenuis. 2. Predation of B. tabaci by different stages of N. tenuis.To evaluate predation of the white fly B. tabaci, experiments were made to observe the predation by the5th-instar nymph, male or female N. tenuis in microcosms. The study found that the predation consisted of searching, probing, capturing, water-sucking, grooming and resting behaviors. Female, male adults and5th-instarnymph can prey on low-instar nymphs (1st-3th instar) and pseudopupae (4th instar) of the whitefly, but rarely consumed eggs. During the1h observation period, consumption of low-instar nymphs was13.2±2.29,3.0±0.89,2.8±0.97by female, male adult and5th nymph, respectively, accounting for63.81%,83.33%,85.01%of all prey consumed, respectively. The results suggested that N. tenuis mainly prey on low instar B. tabaci and females are mre voracious than males and5th instar nymphs.3. Foraging and predation behaviors of N. tenuis on prey patch of P. litura neonateTo provide data for evaluation of N. tenuis in the control of insect pests, a laboratory trial was conducted to examine the predation and concomitant behaviors of N. tenuis female adults that were each provided with first instar larvae of P. litura at the density of either5,10,20, or30larvae per leaf of tobacco, Nicotiana tabacum L. Predation behaviors were continuously observed and recorded. The study found that a N. tenuis adult consumed2.44±0.32,3.01±0.47,4.05±0.82, and5.34±0.54larvae on patches containing5,10,20, and30prey larvae, respectively, showing an increasing consumption with rising prey density. Cox proportion hazard model fiting results showed that the risk of being preyed decreased with increasing prey density, in which the instant probability of being preyed on patches of10-,20-, and30-larvae per leaf was69%,53%and53%that on the5-larvae per leaf patch. The predator spent more time on searching, capturing and plant-feeding, which altogether accounted for more than80%of the patch residence time, but less time on grooming and resting. Searching and plant-feeding time accounted for a larger proportion of total time on the low density patches, but prey-capturing time took a larger proportion of time on the high density prey patches. Patch residence time of N. tenuis was16.01,68.03,75.14,102.30,133.89minutes on0,5,10,20, or30larvae patches, respectively.The patch residence time was significantly longer on the30larvae patche than on the5larvae patch. The results suggested that N. tenuis can consume more neonate larvae of P. litura on higher density prey-patches by spending over-proportion time, leading to lower predation efficiency. |
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