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The leaf traits and microclimate in different positions of a host plant often influence the host choice and performance of herbivore insects. In the present study, the relation of leaf biochemical characters with the infestation of citrus leafminer (CLM), Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) on six citrus cultivars; Meyer Lime (lemon × mandarin hybrid), Kinnow, and Feutrell’s Early (Citrus mandarins), Fairchild (C. tangerines), Succari and Musambi (C. sinensis) was determined. It was also hypothesized that the CLM damage increases from lower to upper canopy of the plant. The highest level of infestation was observed on the upper canopy of citrus plants, followed by a middle and lower canopy in the case of all citrus cultivars. The CLM damage also varied between six citrus cultivars with the highest level of 24.24% for Meyer Lime and 21.42% for Kinnow cultivars and the least affected cultivar by CLM feeding was Musambi with 9.31% infestation. Among the leaf traits, nitrogen and moisture contents showed significant and positive relation with CLM infestation in all citrus cultivars. Total minerals in leaves didn’t show the significant (P > 0.05) relation with CLM damage in all citrus cultivars. Crude proteins showed significant relation with CLM only in the case of the Meyer Lime cultivar. Our findings suggest that the moisture level and nitrogen contents in the leaves are important factors for enhancing the activity of CLM and this interaction can impact the growth and productivity of citrus plants. [ABSTRACT FROM AUTHOR]

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Many studies have described post-parasitization physiological changes in insect hosts for koinobiont endoparasitoids. However, not much is known regarding idiobiont ectoparasitoids that how these parasitoids affect their target hosts' physiology. The present study aimed to determine the effect of parasitization by Bracon hebetor (Hymenoptera: Braconidae), an efficient idiobiont ectoparasitoid of many lepidopterous larvae, on the total haemocyte counts (THCs) of 5th instar larvae of Corcyra cephalonica and Ephestia kuehniella, two important stored product pyralid pests. Results showed that B. hebetor parasitization differentially affected THCs in parasitized E. kuehniella and C. cephalonica larvae. In E. kuehniella larvae, THCs steadily increased till 12th hour observation after a sharp decline in the very first hour of parasitization and then started decreasing from 24th hour post-parasitization. Highest THCs value (2800 ± 300 cells mL-1) was observed at 6th day of parasitization. While on the contrary, C. cephalonica THCs exhibited a boost in first 6 hours of post-parasitization with maximum THCs value (3413 ± 139 cells mL-1) at 6th hour, but then gradually decreased till the end of experiment on 9th day. Average THCs in fresh unparasitized larvae of E. kuehniella and C. cephalonica were 2078 ± 137 and 1474 ± 47 cells mL-1, respectively. These findings indicate that parasitization by idiobiont parasitoids may alter the haemocyte profiles of their hosts and these responses are species-specific. However, future studies on the interaction of post-parasitization changes in haemocyte profiles and immunity mechanisms of host larvae would help in better comprehension of the effects of ectoparasitoids parasitization on their host physiology. [ABSTRACT FROM AUTHOR]

Host plant nutritional quality can directly and indirectly affect the third trophic levels. The aphid-parasitoid relationship provides an ideal system to investigate tritrophic interactions (as the parasitoids are completely dependent for their development upon their hosts) and assess the bottom up forces operating at different concentrations of nitrogen applications. The effects of varying nitrogen fertilizer on the performance of Aphidius colemani (V.) reared on Sitobion avenae (F.) and Aphidius rhopalosiphi (D.) reared on Rhopalosiphum padi (L.) were measured. Parasitism and percent emergence of parasitoids were positively affected by nitrogen fertilizer treatments while developmental duration (egg, larval, and pupal stages) was not affected by increasing nitrogen inputs. In males and females of both parasitoid species, adult longevity increased with the increasing nitrogen fertilizer. Hind tibia length andmummyweight of both parasitoid species increased with nitrogen fertilizer concentrations, as a result of larger aphids. This study showed that nitrogen application to the soil can have important consequences for aboveground multitrophic interactions. [ABSTRACT FROM AUTHOR]

Plant quality can directly and indirectly affect the third trophic level. The predation by all the instars of green lacewing, Chrysoperla carnea ( S.) ( Neuroptera: Chrysopidae) on the cereal aphids, Rhopalosiphum padi ( L.), and Sitobion avenae ( F.) at varying nitrogen fertilizer levels was calculated under laboratory conditions. Wheat plants were grown on four nitrogen fertilizer levels and aphids were fed on these plants and subsequently offered as food to the C. carnea. Aphid densities of 10, 30, and 90 were offered to first, second, and third instar larvae of green lacewing. Increased nitrogen application improved nitrogen contents of the plants and also the body weight of cereal aphids feeding on them. Aphid consumption by green lacewings was reduced with the increase in nitrogen content in the host plants of aphids. Predation of both aphid species by first, second, and third instars larvae of C. carnea was highest on aphids reared on plants with the lowest rate of fertilization, suggesting a compensatory consumption to overcome reduced biomass (lower aphid size). Total biomass devoured by C. carnea on all nitrogen fertilizer treatments was not statistically different. Additionally, the heavier host prey influenced by the plant nutrition had an effect on the life history characteristics of green lacewings. The larval duration, pupal weight, pupal duration, fecundity, and male and female longevity were significantly affected by the level of nitrogen fertilization to the aphid's host plants, except for pupal duration when fed on S. avenae. This study showed that quantity of prey supplied to the larvae affects the prey consumption and thereafter the life history characteristics of green lacewings. [ABSTRACT FROM AUTHOR]