Identifying factors determining the altitudinal distribution of the invasive pest leafminersLiriomyza huidobrensisandLiriomyza sativae

Abstract

Abiotic and biotic factors that change with altitude can influence the distribution of herbivorous insects. We examined factors influencing the distribution of the generalist leafminers Liriomyza sativae Blanchard and Liriomyza huidobrensis Blanchard (Diptera: Agromyzidae), two pests of agricultural crops, in the tropical Dieng mountainous area of Central Java, Indonesia. Liriomyza huidobrensis predominated at altitudes above 700 m a.s.l. and was the only species collected above 1 400 m a.s.l. In contrast, L. sativae predominated below 600 m a.s.l. and was not found above 1 200 m where the average temperature was 20.7°C. Parasitoid diversity decreased with altitude, but parasitism did not change. The distribution of neither species was affected by parasitoids; L. huidobrensis predominant at high altitudes was preferred by Opius parasitoids common at these altitudes. Intra-and interspecific competition was detected in laboratory experiments where larval density was high, but led to coexistence rather than species displacement. No competition was detected in a field experiment when larval density was low. However, L. sativae failed to reproduce at the highest altitude, whereas L. huidobrensis established at all altitudes. Host composition varied with altitude and one host (faba beans) preferred by L. huidobrensis was common at high altitudes. By relating published data on the performance of the leafminer species to altitudinal temperature changes, we were partly successful in predicting the altitude at which the dominant species switched. Temperature plays an overriding influence on the altitudinal distribution of leafminers.

Elevational gradients in plant defences and insect herbivory: recent advances in the field and prospects for future research

“…1A). However, several other studies assessing changes in both enemy abundance and pressure have found no elevational patterns (McMillin andWagner 1998, Roininen et al 2006), and other authors that have reported expected decreases in parasitoid diversity or predator abundance with elevation have not found concomitant elevational gradients in parasitism or predation (Straw et al 2009, Tantowijoyo and Hoffmann 2010, Zehnder et al 2010. In these latter studies, elevational gradients in insect herbivore abundance and plant damage were presumably influenced by abiotic factors that directly (or indirectly via effects on host plants) influence herbivores rather than via indirect defence.…”

Changes in host–parasitoid food web structure with elevation

“…), a decreased window of parasitoid activity at higher elevations may limit the number of host species that each species of parasitoid can attack (Hance et al . ). The weighted mean number of parasitoid species attacking each leaf miner species (vulnerability) will decrease with increasing elevation: Given that parasitoids of leaf miners are often generalists (Askew & Shaw ; Hawkins & Bradford ), and leaf miners generally support relatively large assemblages of parasitoids per host species (Hawkins, Askew & Shaw ; Hochberg & Hawkins ), we predict that the number of parasitoid species attacking each host is likely to decrease with elevation, coinciding with a decrease in overall parasitoid species richness (Tantowijoyo & Hoffmann ; Péré, Jactel & Kenis ). The overall complexity (quantitative weighted connectance) of food webs will change with elevation : If the number of interactions per species decreases with elevation (see Hypotheses 1 and 2), but the number of species comprising webs remains constant, connectance will decrease with elevation. Conversely, if there is an overall decrease in species richness with elevation, as has been shown for several (Longino & Colwell ; Hoiss et al .…”

Potential for biological control of the vegetable leafminer, Liriomyza sativae (Diptera: Agromyzidae), in Australia with parasitoid wasps

“…). The most abundant parasitoid attacking L. huidobrensis in the highlands (Tantowijoyo & Hoffmann ), O. chromatomyiae is now moving to lowland areas and is parasitising L. sativae in the Lesser Sunda Islands of Indonesia (Wahyuni et al . ).…”

“…, ), while L. huidobrensis is the dominant agromyzid pest of vegetables at higher elevations (>1000 m asl) in tropical Asia (Rauf et al . ; Tantowijoyo & Hoffmann ; Weintraub et al . ).…”