Selectiveness of Cnaphalocrocis medinalis to Host Plants

A field experiment was conducted to study the selectiveness of Cnaphalocrocis medinalis Guenee （commonly known as the rice leaffolder or rice leafroller） towards five rice varieties （Yangfujing 8, Yangdao 6, Shanyou 136, Huaidao 9 and Nin.gjing 1） and three weed species （Echinochloa crusgalli, Leptochloa chinensis and Leersia hexandra）. The results showed that the rice varieties carried significantly higher numbers of C. medinalis moths and eggs than the weed species. Among the rice varieties, Yangfujing 8 was associated with a higher moth number. However, there was little difference in the number of C. medinalis eggs among the rice varieties. Additionally, a laboratory experiment was performed to investigate the olfactory response of female C. medinalis towards volatile compounds from different rice varieties, as well as its oviposition preference towards these rice varieties. The volatiles of Yangfujing 8, Yangdao 6 and Shanyou 136 attracted C. medinalis similarly to those of TN 1. In contrast, the volatiles of Huaidao 9 and Ningjing 1 clearly deterred C. medinalis. Nevertheless, C. medinalis did not exhibit clear oviposition preference towards any of the five tested rice varieties.

Host selection behavior and incidence of the bark beetle Scolytus kashmirensis (Coleoptera:Curculionidae:Scolytinae) attacking elm (Ulmus spp.) trees in Kashmir

The status of the incidence of the bark beetle Scolytus kashmirensis Schedl on elm （Ulmus spp.） trees was determined in four districts of the Kashmir Valley in 2009. The incidence of the borer was higher in the Anantnag （25.93%） and Shopian （22.35%） districts of the Kashmir Valley, followed by the Ganderbal （17.14%） and Baramulla （16.67%） districts. The overall infestation re- corded in these districts was 20.52%. The beetle under study chewed the scars on twigs of both the host and tentative non-host plants supplied to them in cages but bored and laid eggs in only one of them （the host plant）. Both species of elm, Ulmus wallichiana and U. villosa, were susceptible to borer attacks; however, U. villosa showed low susceptibility and high resistance compared to U. wallichiana. Older, taller elms were preferred for feeding by bark beetles and are therefore much more susceptible to its infestation compared to younger elms. This bark beetle species also preferred to oviposit in branches of the host plants with diameters of 9-12 mm.

Why cuckoos should parasitize parrotbills by laying eggs randomly rather than laying eggs matching the egg appearance of parrotbill hosts?

The coevolutionary interaction between cuckoos and their hosts has been studied for a long time, but to date some puzzles still remain unsolved. Whether cuckoos parasitize their hosts by laying eggs randomly or matching the egg morphs of their hosts is one of the mysteries of the cuckoo problem. Scientists tend to believe that cuckoos lay eggs matching the appearance of host eggs due to selection caused by the ability of the hosts to recognize their own eggs.In this paper, we first review previous empirical studies to test this mystery and found no studies have provided direct evidence of cuckoos choosing to parasitize host nests where egg color and pattern match. We then present examples of unmatched cuckoo eggs in host nests and key life history traits of cuckoos, e.g. secretive behavior and rapid egg-laying and link them to cuckoo egg laying behavior. Finally we develop a conceptual model to demonstrate the egg laying behaviour of cuckoos and propose an empirical test that can provide direct evidence of the egg-laying properties of female cuckoos. We speculate that the degree of egg matching between cuckoo eggs and those of the host as detected by humans is caused by the ability of the hosts to recognize their own eggs, rather than the selection of matching host eggs by cuckoos. The case of Common Cuckoos(Cuculus canorus) and their parrotbill hosts(Paradoxornis alphonsianus), where it has been shown that both have evolved polymorphic eggs(mainly blue and white), was used to develop a conceptual model to demonstrate why cuckoos should utilize parrotbill hosts by laying eggs randomly rather than laying eggs matching the appearance of host eggs.In conclusion, we found no evidence for the hypothesis that cuckoos lay eggs based on own egg color matching that of the parrotbill-cuckoo system. We argue theoretically that laying eggs matching those of the hosts in this system violates a key trait of the life history of cuckoos and therefore should be maladaptive.

Host Preference by Monochamus alternatus (Hope) during Maturation Feeding on Pine Species and Masson Pine Provenances

Host preferences pine of the sawyer beetle, Monochamus alternates (Hope), during maturation feeding on 8 conifer trees and 40 masson pine provenances, were investigated using 3 types of laboratory bioassay of consistent feeding preference, feeding area and visitation frequency. M. alternatus adults have the highest frequency of feeding and prefer to feed on the branches of P. massoniana and P. densiflora and had significant host selectivity on 8 conifer trees in the area of Nanjing. The adult feeding vi...

Selectivity mechanism of Anoplophora glabripennis on four different species of maples

Anoplophora glabripennis(Motsch.)is a wood-boring beetle that is native to China.For a long time,it caused great losses in the economy and ecology of northwest China.Attractants are often used to control insects.The volatiles emitted from the host plant play an important role for insects in finding their target.To explore the mechanism of selec-tivity to different host plants,the response of Anoplophora glabripennis to four different host plants was investigated,which included Acer negundo L.,Acer mono Maxim.,Acer truncatum Bunge.and Acer platanoides L.,and the com-pounds in the profiles of volatiles were identified from these species.The olfactory responses of Anoplophora glabripennis to the odors of different plants showed preference for certain host plants:Acer negundo,Acer mono and Acer truncatum.The attraction of Acer negundo and Acer mono was signifi-cantly different(p<0.05).The attraction of Acer negundo to the insects was stronger than to Acer mono.Acer platanoides neither attracted nor repelled the insects.Compounds in the profiles of volatiles from the above four species were identified and quantified by gas chromatography-mass spec-trometry(GC-MS)equipped with a CP-4020 termodesorp-tion and cold trap(TCT)device.The constituents of volatiles and the relative concentrations were different in the four host species.The amount of ketones,alcohols and aldehydes in the four plants showed the same order:Acer negundo<Acer mono<Acer truncatum<Acer platanoides,while that of alkanes and esters was quiet different:Acer negundo L.>Acer mono Maxim.>Acer truncatum Bunge.>Acer platanoides L..1-penten-3-ol,ocimene and trans-Germanylacetone were repellent to Anoplophora glabripennis.1-penten-3-ol and trans-gerranylacetone were identified in Acer platanoides,and Ocimene was the most attractive to Anoplophora glabripennis among these species.The extent of feeding damage caused by Anoplophora glabripennis differed among four species.The sequences was Acer negundo>Acer mono>Acer truncatum>Acer platanoides.The epidermal hairs of the four host plants revealed that the extent of damage was related to the physical characteristics of the host plants.

Molecular and functional characterization of three odorant-binding proteins from the wheat blossom midge,Sitodiplosis mosellana

Sitodiplosis mosellana,a periodic but devastating wheat pest,relies on wheat spike volatiles as a cue in sclecing hosts for oviposition.Insect odorant-binding proteins(OBPs)are thought to play essential roles in filtering,binding and transporting hydropho-bic odorant molecules to specific receptors.To date,the molecular mechanisms underlying S.mosellana olfaction are poorly understood.Here,three S.mosellana antenna-specific OBP genes,SmosOBPII,16 and 21,were cloned and bacterially expressed.Binding properties of the recombinant proteins to 28 volatiles emitted from wheat spikes were in-vestigated using fluorescence competitive binding assays.Sequence analysis suggested that these SmosOBPs belong to the Classic OBP subfamily.Ligand-binding analysis showed that all three SmosOBPs preferentially bound alcohol,ester and ketone com-pounds,and SmosOBP11 and 16 also selectively bound terpenoid compounds.In par-ticular,the three SmosOBPs had high binding affinities(Ki<20μmol/L)to 3-hexanol and cis-3-hexenylacetate that elicited strong electroantennogram(EAG)response fromfemale antennae.In addition,SmosOBP11 displayed significantly higher binding(Ki<8μmo/L)than SmosOBP16 and 21 to l-octen-3-ol,D-panthenol,a-pinene and heptyl acetate which elicited significant EAG response,suggesting that SmosOBP11 plays a ma-jor role in recognition and transportation of these volatiles.These findings have provided important insight into the molecular mechanism by which S.mosellana specifically rec-ognizes plant volatiles for host selection,and have facilitated identification of effective volatile attractants that are potentially useful for pest monitoring and trapping.