Liang GuangWen

Foraging behavior and recruitment of red imported fire ant Solenopsis invicta Buren in typical habitats of South China

Abstract The foraging behavior consisted of three steps: searching, recruitment and transportation. Searching time was different for different foods; searching time for honey was longer than that for any other food tested. It was also affected by habitats with the searching time of fire ants in a litchi orchard being significantly longer than that for other habitats (p

Life-History Traits and Population Relative Fitness of Trichlorphon-Resistant and -Susceptible Bactrocera dorsalis (Diptera: Tephritidae)

Life tables were established for trichlorphon-resistant and susceptible Bactrocera dorsalis strains based on the laboratory observations. Trichlorphon-resistant B. dorsalis strain had longer pupal and preoviposition periods, and mean generation time compared to the trichlorphon susceptible strain. Lower fecundity, emergence rate, and probability of standard fecundity 𝑃𝐹, and shorter female and male longevity also were apparent in the trichlorphon resistant strain. Based on the life tables, the life population trend index (𝐼) of the resistant strain was 86.80, while that of the susceptible strain was 116.97. The net reproduction rate (𝑅0) and the intrinsic rate of increase (𝑟𝑚) of the resistant strain were 1565.33 and 0.0164, while those of susceptible strain were 2184.00 and 0.0173, respectively. The results from this research revealed that the resistant strain was at a reproductive and developmental disadvantage relative to the susceptible strain.

CHARACTERISTICS OF ARTHROPOD COMMUNITY AND THEIR DIVERSITY RESTORATION IN LEAFY VEGETABLE FIELDS

Abstract  The effect of chemical insecticides on the structure and diversity of arthropod communities in various vegetable fields and the restoration of their biodiversity after stopping application of chemical insecticides were studied. The results showed that the effect of chemical insecticides on the arthropods in vegetable fields could be characterized the species structure, the diversity index and the evenness of species distribution. Components of arthpod species depended closely on the species number of insect pests, predatory natural enemies and spiders. Investigations showed that the numbers of species in the vegetable fields managed with chemical insecticides were obviously reduced, and their diversity indices were lower comparing with that without chemical insecticides. When the applications of chemical insecticides were stopped in vegetable fields, the index of population trend (I) of dominant insect pests decreased greatly, the control effect of natural enemies on major insect pests increased, and the diversity index of arthropod increased at the same time. Thus, limiting the application of chemical insecticides, resuming the environment of vegetable fields destroyed by using chemical insecticides, escalating the control ability of natural enemies on main insect pests will play an important role in the ecological control of insect pests in vegetable fields.

Relationship of occurrence of Fruhstorferiola tonkinensis Will. and plant communities on riversides in northern Guangdong Province, China

Abstract Plant communities on riversides in northern Guangdong Province were investigated with all-survey method, where a kind of native grasshopper Fruhstorferiola tonkinensis Will. broke out severely. 108 plant species belonging to 43 families were identified, and some plant indexes in those plant communities including their name, average height, congregation index, total coverage rate, phenological phase and biod were noted. In addition, plant comparability, plant abundance, quantity character and attribute symbol of dominant species in plant communities on riversides were studied. The results showed that the arrangement and distribution of vegetations on riversides offered a favorable habitat for F. tonkinensis. Moreover, the density of first instar nymphs of F. tonkinensis in plant communities was calculated. The results of partial correlation analysis (PCA) about the relationship between plant communities and occurrence of F. tonkinensis showed that Pterocarya stenoptera C. DC. was the most palatable plant to F. tonkinensis, presenting a very significantly positive correlation between coverage rate of P. stenoptera and occurrence of F. tonkinensis. The partial correlation coefficient (PCC) was 0.856072 (F=32.92012, P=0.0001). Bambusa flexuosa was a non-preferable plant of F. tonkinensis, presenting a significantly negative correlation between them, and the partial correlation coefficient was −0.607920 (F=0.16173, P=0.0211). Those results would help us to propose some approaches for the ecology control of F. tonkinensis on riversides in northern Guangdong Province.

Electrophysiology and Behavioural Feedback of Diamondback moth, Plutella xylostella (L.) (Lep., Plutellidae) to Volatiles from a non-Host Plant, Lantana camara L. (Verbenaceae var. aculeate)

Abstract Electroantennograms (EAGs) were recorded from laboratory-reared male and female Plutella xylostella (Lepidoptera: Plutellidae) adults in response to the essential oil and its selected components belonging to oxy-and hydrocarbon monoterpenoids as well as a sesquiterpenoid from the non-host plant, Lantana camara L. (Verbenaceae var. aculeate). Measurable EAG responses were elicited to all compounds tested; and, mean, pooled EAGs to the sesquiterpene were larger in magnitude than those in response to oxy- and hydrocarbon monoterpenoids. Females were found to be more responsive than males. However, their responses to hydrocarbon monoterpenoids are smaller than those of male moths. Subsequent behavioural analyses in a four-armed olfactometer revealed R-(+)-limonene and (-) germacrene-D to be attractive to female moths. In laboratory cages, these two volatiles also stimulated oviposition and had little repulsive effect on third instar-larvae of the test insect.